Create an Account  |   Log In

View All »Matching Part Numbers


Your Shopping Cart is Empty
         

Air-Spaced Doublet Collimators - FC/PC, FC/APC, & SMA


  • Multi-Element Lens Design for Diffraction-Limited Performance
  • Options for FC/PC, FC/APC, or SMA Connectors
  • Collimated Beam Diameters Range from 6.4 - 8.0 mm
  • Simplifies Fiber-Coupled Detection Systems

F810FC-780

F810SMA-2000

Application Idea

F810FC-780 in
AD15F Adapter

Related Items


Please Wait

SMA Air-Spaced Doublet Collimators

Features

  • Fiber Collimation
  • Popular SMA Connectors
  • Each Collimation Package is Factory Aligned
  • Multi-Element Lens Design for Diffraction-Limited Performance
  • Simplifies Free-Space Laser to Fiber Coupling
  • Lens Material: N-SF6 or Equivalent
  • Non-Magnetic Stainless Steel Housing

The F810SMA Series of fiber collimation packages is pre-aligned to collimate a laser beam propagating from the tip of an SMA-connectorized fiber with diffraction-limited performance at the design wavelength. Since the F810 Series fiber collimators do not have any movable parts, they are compact and not susceptible to misalignment. Due to chromatic aberration, the effective focal length (EFL) of the doublet lens is wavelength dependent. As a result, these collimators will only perform optimally at the design wavelength. The doublet lens is factory aligned so that it is one focal length away from the fiber tip when inserted into the collimator. This distance is equal to the focal length of the aspheric lens at the design wavelength. In addition, the doublet lens has an AR coating that minimizes surface reflections.

We can align collimation packages at custom wavelengths if a standard version is not suitable for your application. We also offer a line of adjustable collimation packages called FiberPorts that are well suited for a wide range of wavelengths and are ideal solutions for adjustable, compact fiber couplers. For other collimation and coupling options, please contact our Technical Support group.

While these F810SMA fiber collimation packages will work with multimode fibers, they are optimized for single mode fibers, and are compatible with our SMA-connectorized hybrid single mode fiber optic patch cables.

Item # Alignmenta
Wavelength
AR Coatingb Dc
(mm)
θd
(deg)
Divergence
Plot
NALens f
(mm)
Damage Threshold Suggested
Adapters
F810SMA-543 543 nm 350-700 nm 6.4 0.006° 0.26 34.74 7.5 J/cm2
(532 nm, 10 ns, 10 Hz, Ø0.362 mm)
AD15FAD15NT
F810SMA-635 635 nm 350-700 nm 6.7 0.007° 0.25 35.41 - AD15FAD15NT
F810SMA-780 780 nm 650-1050 nm 7.5 0.008° 0.25 36.01 - AD15FAD15NT
F810SMA-1064 1064 nm 1054-1074 nm 8.0 0.010° 0.25 36.60 7.5 J/cm2
(1064 nm, 10 ns, 10 Hz, Ø0.442 mm)
AD15FAD15NT
F810SMA-1310 1310 nm 1050-1620 nm 6.7 0.014° 0.24 36.90 - AD15FAD15NT
F810SMA-1550 1550 nm 1050-1620 nm 7.0 0.016° 0.24 37.13 - AD15FAD15NT
F810SMA-2000 2 µm 1.8 - 2.4 µm 7.3 0.02° 0.24 37.52 - AD15FAD15NT
  • For optimal collimation these packages should be used at the alignment wavelength. For some applications they may also be used within the AR coating range. Please contact Tech Support for custom alignment packages.
  • For data on Thorlabs' standard AR coatings, refer to the AR Coatings tab above.
  • Collimated Beam Diameter: Theoretical 1/e2 diameter @ 1 focal length from lens; fibers: 460HP (543 nm), SM600 (635 nm), 780HP (780 nm), SM980-5.8-125 (1064 nm), SMF-28 (1310 & 1550 nm), SM2000 (2000 nm)
  • Theoretical full-angle beam divergence; fibers: 460HP (543 nm), SM600 (635 nm), 780HP (780 nm), SM980-5.8-125 (1064 nm), SMF-28 (1310 & 1550 nm), SM2000 (2000 nm)


Click to Enlarge

Theoretical Approximation of the Divergence Angle

The divergence angle is easy to approximate theoretically using the formula shown below as long as the light emerging from the fiber has a Gaussian intensity profile. This works well for single mode fibers, but will underestimate the divergence angle for multimode fibers where the light emerging from the fiber has a non-Gaussian intensity profile.

θ Divergence Angle
D Mode-Field Diameter (MFD)
f Focal Length of Collimator

The divergence angle (in degrees) where D and f must be in the same units.
divergence formula

Example Calculation
For F810FC-543 package collimating 515 nm light from 460HP fiber:

  • D = 3.5 µm
  • f ≈ 34.7 mm (approximate, since design wavelength is 543 nm)

Using the equation given above, we can calculate the approximate divergence angle:

θ ≈ (0.0035 mm/34.7 mm)*(180/3.1416) ≈ 0.006°

Coating Information
Coating Designation A B 1064 C D
Coating Range 350 - 700 nm 650 - 1050 nm 1050 - 1075 nm 1050 - 1700 nm 1.65 - 3.0 µm
Damage Threshold Specifications
Item # Damage Threshold
F810SMA-543 7.5 J/cm2 (532 nm, 10 ns, 10 Hz, Ø0.362 mm)
F810SMA-1064 7.5 J/cm2 (1064 nm, 10 ns, 10 Hz, Ø0.442 mm)

Damage Threshold Data for Thorlabs' Air-Spaced Doublet Collimators

The specifications to the right are measured data for a selection of Thorlabs' air-spaced doublet collimators. Damage threshold specifications are constant for these collimators, regardless of the connector type.

 

Laser Induced Damage Threshold Tutorial

The following is a general overview of how laser induced damage thresholds are measured and how the values may be utilized in determining the appropriateness of an optic for a given application. When choosing optics, it is important to understand the Laser Induced Damage Threshold (LIDT) of the optics being used. The LIDT for an optic greatly depends on the type of laser you are using. Continuous wave (CW) lasers typically cause damage from thermal effects (absorption either in the coating or in the substrate). Pulsed lasers, on the other hand, often strip electrons from the lattice structure of an optic before causing thermal damage. Note that the guideline presented here assumes room temperature operation and optics in new condition (i.e., within scratch-dig spec, surface free of contamination, etc.). Because dust or other particles on the surface of an optic can cause damage at lower thresholds, we recommend keeping surfaces clean and free of debris. For more information on cleaning optics, please see our Optics Cleaning tutorial.

Testing Method

Thorlabs' LIDT testing is done in compliance with ISO/DIS11254 and ISO 21254 specifications.

First, a low-power/energy beam is directed to the optic under test. The optic is exposed in 10 locations to this laser beam for 30 seconds (CW) or for a number of pulses (pulse repetition frequency specified). After exposure, the optic is examined by a microscope (~100X magnification) for any visible damage. The number of locations that are damaged at a particular power/energy level is recorded. Next, the power/energy is either increased or decreased and the optic is exposed at 10 new locations. This process is repeated until damage is observed. The damage threshold is then assigned to be the highest power/energy that the optic can withstand without causing damage. A histogram such as that below represents the testing of one BB1-E02 mirror.

LIDT metallic mirror
The photograph above is a protected aluminum-coated mirror after LIDT testing. In this particular test, it handled 0.43 J/cm2 (1064 nm, 10 ns pulse, 10 Hz, Ø1.000 mm) before damage.
LIDT BB1-E02
Example Test Data
Fluence # of Tested Locations Locations with Damage Locations Without Damage
1.50 J/cm2 10 0 10
1.75 J/cm2 10 0 10
2.00 J/cm2 10 0 10
2.25 J/cm2 10 1 9
3.00 J/cm2 10 1 9
5.00 J/cm2 10 9 1

According to the test, the damage threshold of the mirror was 2.00 J/cm2 (532 nm, 10 ns pulse, 10 Hz, Ø0.803 mm). Please keep in mind that these tests are performed on clean optics, as dirt and contamination can significantly lower the damage threshold of a component. While the test results are only representative of one coating run, Thorlabs specifies damage threshold values that account for coating variances.

Continuous Wave and Long-Pulse Lasers

When an optic is damaged by a continuous wave (CW) laser, it is usually due to the melting of the surface as a result of absorbing the laser's energy or damage to the optical coating (antireflection) [1]. Pulsed lasers with pulse lengths longer than 1 µs can be treated as CW lasers for LIDT discussions.

When pulse lengths are between 1 ns and 1 µs, laser-induced damage can occur either because of absorption or a dielectric breakdown (therefore, a user must check both CW and pulsed LIDT). Absorption is either due to an intrinsic property of the optic or due to surface irregularities; thus LIDT values are only valid for optics meeting or exceeding the surface quality specifications given by a manufacturer. While many optics can handle high power CW lasers, cemented (e.g., achromatic doublets) or highly absorptive (e.g., ND filters) optics tend to have lower CW damage thresholds. These lower thresholds are due to absorption or scattering in the cement or metal coating.

Linear Power Density Scaling

LIDT in linear power density vs. pulse length and spot size. For long pulses to CW, linear power density becomes a constant with spot size. This graph was obtained from [1].

Intensity Distribution

Pulsed lasers with high pulse repetition frequencies (PRF) may behave similarly to CW beams. Unfortunately, this is highly dependent on factors such as absorption and thermal diffusivity, so there is no reliable method for determining when a high PRF laser will damage an optic due to thermal effects. For beams with a high PRF both the average and peak powers must be compared to the equivalent CW power. Additionally, for highly transparent materials, there is little to no drop in the LIDT with increasing PRF.

In order to use the specified CW damage threshold of an optic, it is necessary to know the following:

  1. Wavelength of your laser
  2. Beam diameter of your beam (1/e2)
  3. Approximate intensity profile of your beam (e.g., Gaussian)
  4. Linear power density of your beam (total power divided by 1/e2 beam diameter)

Thorlabs expresses LIDT for CW lasers as a linear power density measured in W/cm. In this regime, the LIDT given as a linear power density can be applied to any beam diameter; one does not need to compute an adjusted LIDT to adjust for changes in spot size, as demonstrated by the graph to the right. Average linear power density can be calculated using the equation below. 

The calculation above assumes a uniform beam intensity profile. You must now consider hotspots in the beam or other non-uniform intensity profiles and roughly calculate a maximum power density. For reference, a Gaussian beam typically has a maximum power density that is twice that of the uniform beam (see lower right).

Now compare the maximum power density to that which is specified as the LIDT for the optic. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately. A good rule of thumb is that the damage threshold has a linear relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 10 W/cm at 1310 nm scales to 5 W/cm at 655 nm):

CW Wavelength Scaling

While this rule of thumb provides a general trend, it is not a quantitative analysis of LIDT vs wavelength. In CW applications, for instance, damage scales more strongly with absorption in the coating and substrate, which does not necessarily scale well with wavelength. While the above procedure provides a good rule of thumb for LIDT values, please contact Tech Support if your wavelength is different from the specified LIDT wavelength. If your power density is less than the adjusted LIDT of the optic, then the optic should work for your application. 

Please note that we have a buffer built in between the specified damage thresholds online and the tests which we have done, which accommodates variation between batches. Upon request, we can provide individual test information and a testing certificate. The damage analysis will be carried out on a similar optic (customer's optic will not be damaged). Testing may result in additional costs or lead times. Contact Tech Support for more information.

Pulsed Lasers

As previously stated, pulsed lasers typically induce a different type of damage to the optic than CW lasers. Pulsed lasers often do not heat the optic enough to damage it; instead, pulsed lasers produce strong electric fields capable of inducing dielectric breakdown in the material. Unfortunately, it can be very difficult to compare the LIDT specification of an optic to your laser. There are multiple regimes in which a pulsed laser can damage an optic and this is based on the laser's pulse length. The highlighted columns in the table below outline the relevant pulse lengths for our specified LIDT values.

Pulses shorter than 10-9 s cannot be compared to our specified LIDT values with much reliability. In this ultra-short-pulse regime various mechanics, such as multiphoton-avalanche ionization, take over as the predominate damage mechanism [2]. In contrast, pulses between 10-7 s and 10-4 s may cause damage to an optic either because of dielectric breakdown or thermal effects. This means that both CW and pulsed damage thresholds must be compared to the laser beam to determine whether the optic is suitable for your application.

Pulse Duration t < 10-9 s 10-9 < t < 10-7 s 10-7 < t < 10-4 s t > 10-4 s
Damage Mechanism Avalanche Ionization Dielectric Breakdown Dielectric Breakdown or Thermal Thermal
Relevant Damage Specification No Comparison (See Above) Pulsed Pulsed and CW CW

When comparing an LIDT specified for a pulsed laser to your laser, it is essential to know the following:

Energy Density Scaling

LIDT in energy density vs. pulse length and spot size. For short pulses, energy density becomes a constant with spot size. This graph was obtained from [1].

  1. Wavelength of your laser
  2. Energy density of your beam (total energy divided by 1/e2 area)
  3. Pulse length of your laser
  4. Pulse repetition frequency (prf) of your laser
  5. Beam diameter of your laser (1/e2 )
  6. Approximate intensity profile of your beam (e.g., Gaussian)

The energy density of your beam should be calculated in terms of J/cm2. The graph to the right shows why expressing the LIDT as an energy density provides the best metric for short pulse sources. In this regime, the LIDT given as an energy density can be applied to any beam diameter; one does not need to compute an adjusted LIDT to adjust for changes in spot size. This calculation assumes a uniform beam intensity profile. You must now adjust this energy density to account for hotspots or other nonuniform intensity profiles and roughly calculate a maximum energy density. For reference a Gaussian beam typically has a maximum energy density that is twice that of the 1/e2 beam.

Now compare the maximum energy density to that which is specified as the LIDT for the optic. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately [3]. A good rule of thumb is that the damage threshold has an inverse square root relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 1 J/cm2 at 1064 nm scales to 0.7 J/cm2 at 532 nm):

Pulse Wavelength Scaling

You now have a wavelength-adjusted energy density, which you will use in the following step.

Beam diameter is also important to know when comparing damage thresholds. While the LIDT, when expressed in units of J/cm², scales independently of spot size; large beam sizes are more likely to illuminate a larger number of defects which can lead to greater variances in the LIDT [4]. For data presented here, a <1 mm beam size was used to measure the LIDT. For beams sizes greater than 5 mm, the LIDT (J/cm2) will not scale independently of beam diameter due to the larger size beam exposing more defects.

The pulse length must now be compensated for. The longer the pulse duration, the more energy the optic can handle. For pulse widths between 1 - 100 ns, an approximation is as follows:

Pulse Length Scaling

Use this formula to calculate the Adjusted LIDT for an optic based on your pulse length. If your maximum energy density is less than this adjusted LIDT maximum energy density, then the optic should be suitable for your application. Keep in mind that this calculation is only used for pulses between 10-9 s and 10-7 s. For pulses between 10-7 s and 10-4 s, the CW LIDT must also be checked before deeming the optic appropriate for your application.

Please note that we have a buffer built in between the specified damage thresholds online and the tests which we have done, which accommodates variation between batches. Upon request, we can provide individual test information and a testing certificate. Contact Tech Support for more information.


[1] R. M. Wood, Optics and Laser Tech. 29, 517 (1998).
[2] Roger M. Wood, Laser-Induced Damage of Optical Materials (Institute of Physics Publishing, Philadelphia, PA, 2003).
[3] C. W. Carr et al., Phys. Rev. Lett. 91, 127402 (2003).
[4] N. Bloembergen, Appl. Opt. 12, 661 (1973).

In order to illustrate the process of determining whether a given laser system will damage an optic, a number of example calculations of laser induced damage threshold are given below. For assistance with performing similar calculations, we provide a spreadsheet calculator that can be downloaded by clicking the button to the right. To use the calculator, enter the specified LIDT value of the optic under consideration and the relevant parameters of your laser system in the green boxes. The spreadsheet will then calculate a linear power density for CW and pulsed systems, as well as an energy density value for pulsed systems. These values are used to calculate adjusted, scaled LIDT values for the optics based on accepted scaling laws. This calculator assumes a Gaussian beam profile, so a correction factor must be introduced for other beam shapes (uniform, etc.). The LIDT scaling laws are determined from empirical relationships; their accuracy is not guaranteed. Remember that absorption by optics or coatings can significantly reduce LIDT in some spectral regions. These LIDT values are not valid for ultrashort pulses less than one nanosecond in duration.

Intensity Distribution
A Gaussian beam profile has about twice the maximum intensity of a uniform beam profile.

CW Laser Example
Suppose that a CW laser system at 1319 nm produces a 0.5 W Gaussian beam that has a 1/e2 diameter of 10 mm. A naive calculation of the average linear power density of this beam would yield a value of 0.5 W/cm, given by the total power divided by the beam diameter:

CW Wavelength Scaling

However, the maximum power density of a Gaussian beam is about twice the maximum power density of a uniform beam, as shown in the graph to the right. Therefore, a more accurate determination of the maximum linear power density of the system is 1 W/cm.

An AC127-030-C achromatic doublet lens has a specified CW LIDT of 350 W/cm, as tested at 1550 nm. CW damage threshold values typically scale directly with the wavelength of the laser source, so this yields an adjusted LIDT value:

CW Wavelength Scaling

The adjusted LIDT value of 350 W/cm x (1319 nm / 1550 nm) = 298 W/cm is significantly higher than the calculated maximum linear power density of the laser system, so it would be safe to use this doublet lens for this application.

Pulsed Nanosecond Laser Example: Scaling for Different Pulse Durations
Suppose that a pulsed Nd:YAG laser system is frequency tripled to produce a 10 Hz output, consisting of 2 ns output pulses at 355 nm, each with 1 J of energy, in a Gaussian beam with a 1.9 cm beam diameter (1/e2). The average energy density of each pulse is found by dividing the pulse energy by the beam area:

Pulse Energy Density

As described above, the maximum energy density of a Gaussian beam is about twice the average energy density. So, the maximum energy density of this beam is ~0.7 J/cm2.

The energy density of the beam can be compared to the LIDT values of 1 J/cm2 and 3.5 J/cm2 for a BB1-E01 broadband dielectric mirror and an NB1-K08 Nd:YAG laser line mirror, respectively. Both of these LIDT values, while measured at 355 nm, were determined with a 10 ns pulsed laser at 10 Hz. Therefore, an adjustment must be applied for the shorter pulse duration of the system under consideration. As described on the previous tab, LIDT values in the nanosecond pulse regime scale with the square root of the laser pulse duration:

Pulse Length Scaling

This adjustment factor results in LIDT values of 0.45 J/cm2 for the BB1-E01 broadband mirror and 1.6 J/cm2 for the Nd:YAG laser line mirror, which are to be compared with the 0.7 J/cm2 maximum energy density of the beam. While the broadband mirror would likely be damaged by the laser, the more specialized laser line mirror is appropriate for use with this system.

Pulsed Nanosecond Laser Example: Scaling for Different Wavelengths
Suppose that a pulsed laser system emits 10 ns pulses at 2.5 Hz, each with 100 mJ of energy at 1064 nm in a 16 mm diameter beam (1/e2) that must be attenuated with a neutral density filter. For a Gaussian output, these specifications result in a maximum energy density of 0.1 J/cm2. The damage threshold of an NDUV10A Ø25 mm, OD 1.0, reflective neutral density filter is 0.05 J/cm2 for 10 ns pulses at 355 nm, while the damage threshold of the similar NE10A absorptive filter is 10 J/cm2 for 10 ns pulses at 532 nm. As described on the previous tab, the LIDT value of an optic scales with the square root of the wavelength in the nanosecond pulse regime:

Pulse Wavelength Scaling

This scaling gives adjusted LIDT values of 0.08 J/cm2 for the reflective filter and 14 J/cm2 for the absorptive filter. In this case, the absorptive filter is the best choice in order to avoid optical damage.

Pulsed Microsecond Laser Example
Consider a laser system that produces 1 µs pulses, each containing 150 µJ of energy at a repetition rate of 50 kHz, resulting in a relatively high duty cycle of 5%. This system falls somewhere between the regimes of CW and pulsed laser induced damage, and could potentially damage an optic by mechanisms associated with either regime. As a result, both CW and pulsed LIDT values must be compared to the properties of the laser system to ensure safe operation.

If this relatively long-pulse laser emits a Gaussian 12.7 mm diameter beam (1/e2) at 980 nm, then the resulting output has a linear power density of 5.9 W/cm and an energy density of 1.2 x 10-4 J/cm2 per pulse. This can be compared to the LIDT values for a WPQ10E-980 polymer zero-order quarter-wave plate, which are 5 W/cm for CW radiation at 810 nm and 5 J/cm2 for a 10 ns pulse at 810 nm. As before, the CW LIDT of the optic scales linearly with the laser wavelength, resulting in an adjusted CW value of 6 W/cm at 980 nm. On the other hand, the pulsed LIDT scales with the square root of the laser wavelength and the square root of the pulse duration, resulting in an adjusted value of 55 J/cm2 for a 1 µs pulse at 980 nm. The pulsed LIDT of the optic is significantly greater than the energy density of the laser pulse, so individual pulses will not damage the wave plate. However, the large average linear power density of the laser system may cause thermal damage to the optic, much like a high-power CW beam.

Fiber Collimator Selection Guide

Click on the collimator type or photo to view more information about each type of collimator.

Type   Description
Fixed FC, APC, or SMA Fiber Collimators Fixed SMA Fiber Collimator These fiber collimation packages are pre-aligned to collimate light from an FC/PC-, FC/APC-, or SMA-terminated fiber. Each collimation package is factory aligned to provide diffraction-limited performance for wavelengths ranging from 405 nm to 4.55 µm. Although it is possible to use the collimator at detuned wavelengths, they will only perform optimally at the design wavelength due to chromatic aberration, which causes the effective focal length of the aspheric lens to have a wavelength dependence.
Air-Spaced Doublet, Large Beam Collimators Air-Spaced Doublet Fiber Collimator For large beam diameters (Ø6.6 - Ø8.5 mm), Thorlabs offers FC/PC, SMA, and FC/APC air-spaced doublet collimators. These collimation packages are pre-aligned at the factory to collimate a laser beam propagating from the tip of an FC or SMA-terminated fiber and provide diffraction-limited performance at the design wavelength.
Adjustable Fiber Collimators Adjustable Fiber Collimator These collimators are designed to connect onto the end of an FC/PC or FC/APC connector and contain an AR-coated aspheric lens. The distance between the aspheric lens and the tip of the FC-terminated fiber can be adjusted to compensate for focal length changes or to recollimate the beam at the wavelength and distance of interest.
Zoom Fiber Collimators Zoom Fiber Collimator These collimators provide a variable focal length between 6 and 18 mm, while maintaining the collimation of the beam. As a result, the size of the beam can be changed without altering the collimation. This universal device saves time previously spent searching for the best suited fixed fiber collimator and has a very broad range of applications. They are offered with FC/PC, FC/APC, or SMA905 connectors with three different antireflection wavelength ranges to choose from.
Large Beam Fiber Collimators large beam collimators Thorlabs' Large-Beam Fiber Collimators are designed with an effective focal length (EFL) of 40 mm or 80 mm over three different wavelength ranges and are available with FC/PC or FC/APC connectors. A four-element, air-spaced lens design produces a superior beam quality (M2 close to 1) and less wavefront error when compared to aspheric lens collimators. As a result, these collimators are very flexible; they can be used as free-space collimator or coupler. They may also be used over a long distance in pairs, which allows the free-space beam to be manipulated prior to entering the second collimator and may be useful in long-distance communications applications.
FiberPorts Fiberport Fiber Collimator These compact, ultra-stable FiberPort micropositioners provide an easy-to-use, stable platform for coupling light into and out of FC/PC, FC/APC, or SMA terminated optical fibers. It can be used with single mode, multimode, or PM fibers and can be mounted onto a post, stage, platform, or laser. The built-in aspheric or achromatic lens is available with three different AR coatings and has five degrees of alignment adjustment (3 translational and 2 pitch). The compact size and long-term alignment stability make the FiberPort an ideal solution for fiber coupling, collimation, or incorporation into OEM systems.
Triplet Collimators Triplet Fiber Collimator Thorlabs' High Quality Triplet Fiber Collimation packages use air-spaced triplet lenses that offer superior beam quality performance when compared to aspheric lens collimators. The benefits of the low-aberration triplet design include an M2 term closer to 1 (Gaussian), less divergence, and less wavefront error.
Reflective Collimators Reflective Fiber Collimator Thorlabs' metallic-coated Reflective Collimators are based on a 90° off-axis parabolic mirror. Mirrors, unlike lenses, have a focal length that remains constant over a broad wavelength range. Due to this intrinsic property, a parabolic mirror collimator does not need to be adjusted to accommodate various wavelengths of light, making them ideal for use with polychromatic light. Our reflective collimators are ideal for single-mode fiber.
Pigtailed Collimators Pigtailed Fiber Collimator Our pigtailed collimators come with one meter of either single mode or multimode fiber, have the fiber and AR-coated aspheric lens rigidly potted inside the stainless steel housing, and are collimated at one of six wavelengths: 532, 830, 1030, 1064, 1310, or 1550 nm. Although it is possible to use the collimator at any wavelength within the coating range, the coupling loss will increase as the wavelength is detuned from the design wavelength.
GRIN Fiber Collimators GRIN Fiber Collimator Thorlabs offers gradient index (GRIN) fiber collimators that are aligned at a variety of wavelengths from 630 to 1550 nm and have either FC terminated, APC terminated, or unterminated fibers. Our GRIN collimators feature a Ø1.8 mm clear aperture, are AR-coated to ensure low back reflection into the fiber, and are coupled to standard single mode or graded-index multimode fibers.
GRIN Lenses GRIN Lens These graded-index (GRIN) lenses are AR coated for applications at 630, 830, 1060, 1300, or 1560 nm that require light to propagate through one fiber, then through a free-space optical system, and finally back into another fiber. They are also useful for coupling light from laser diodes into fibers, coupling the output of a fiber into a detector, or collimating laser light. Our GRIN lenses are designed to be used with our Pigtailed Glass Ferrules and GRIN/Ferrule sleeves.

Please Give Us Your Feedback
 
Email Feedback On
(Optional)
Contact Me:
Your email address will NOT be displayed.
 
 
Please type the following key into the field to submit this form:
Click Here if you can not read the security code.
This code is to prevent automated spamming of our site
Thank you for your understanding.
  
 
Would this product be useful to you?   Little Use  1234Very Useful

Enter Comments Below:
 
Characters remaining  8000   
Posted Comments:
Poster:jqmai
Posted Date:2017-08-25 14:46:03.5
Hello, I'd like to collimate mercury lamp white light which comes out from a fiber. And I wish the beam size can be larger than 5mm. Which collimator do you recommend? Thanks.
Poster:tcampbell
Posted Date:2017-08-30 12:38:01.0
Hello, thank you for contacting Thorlabs. You may be interested in our reflective collimators, which have a constant focal length over a broad wavelength range. You can view our selection here: https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=4093
Poster:info
Posted Date:2017-01-09 16:55:40.72
Hello, I'd like to collimate a 150W laser diode @980nm from a 0.22NA / 105µm fiber. I'd also like to collimate a 60W laser diode @915nm from 0.22NA / 105µm fiber. Which collimator shall I use ? Best Regards.
Poster:tfrisch
Posted Date:2017-01-11 01:58:58.0
Hello, thank you for contacting Thorlabs. I will reach out to you directly about your high power application.
Poster:rune0823
Posted Date:2016-09-21 15:06:17.477
Hello, Could we use F810SMA-1064 for collimating a high-power 980nm pump diode at a power level of 200 Watts? Or what is the maximum optical power rating of such a collimator? Thanks!
Poster:jlow
Posted Date:2016-09-26 01:54:43.0
Response from Jeremy at Thorlabs: Unfortunately we do have test data on the damage threshold for these collimators. We will post the damage threshold data once they are available.
Poster:ssharpe
Posted Date:2015-02-27 12:03:24.24
We are interested in using the F810SMA to collimate white light coming out of our multimode 0.22NA fiber from Avantes (FC4-UV400-2). After the light passes through our test subject we would like to then re-collimate into another F810SMA that connects to a thorlabs fiber Thorlabs M40LO2 to an ocean optics spectrometer. We are interested in a spot size as large as possible. We are interested in the wavelength region from 400-900nm. We have lots of signal so the chromatic aberration is not an issue. Do the collimators come with a broadband AR coating or narrowband around the wavelength listed. I assume we should choose a focal length for 500-600 nm as well. Would the F810SMA-543 be the appropriate collimator for both, or should we get a custom?
Poster:jlow
Posted Date:2015-03-24 11:24:25.0
Response from Jeremy at Thorlabs: These have broadband AR coatings with the exception of the -1064 version. You can see the wavelength range and reflectivity graph in the "AR Coatings" tab. The wavelength range you have is quite broad so these will probably not work well. I will contact you directly to discuss more about this.
Poster:tomas.sikorsky
Posted Date:2014-07-17 13:28:49.657
Good afternoon. We would be interested in buying F810APC-780 large beam collimator, but we need it for 461nm light and FC/APC connector is also important. So we need something like F810APC-543 or F810APC-461. We need 6 pieces. Would it be possible to assemble this item for us? What will be the price? Thank you Regards Tomas Sikorsky
Poster:jlow
Posted Date:2014-08-01 11:52:22.0
Response from Jeremy at Thorlabs: We can align the collimator to a user-defined wavelength as a custom. We will contact you for a quote. You can also request a quote by sending an e-mail to techsupport@thorlabs.com.
Poster:bernd.steffen
Posted Date:2014-03-12 12:41:25.623
Hello, can you please give me a quote on a F810APC-custom with C coating focust for 1050nm. Berst regards, Bernd Steffen
Poster:jlow
Posted Date:2014-03-12 08:22:12.0
Response from Jeremy at Thorlabs: We will contact you to provide a quote.
Poster:tibor.giesen
Posted Date:2014-02-11 09:54:32.817
Hello, is it possible to get yozr collimators without any coating os i can use the collimator from 300 - 1800nm?
Poster:jlow
Posted Date:2014-02-11 04:15:10.0
Response from Jeremy at Thorlabs: We can make the collimator using uncoated optics. However, the lens material used in the collimator transmit poorly below around 400nm (transmission around 48%, 10mm sample @ 380nm, uncoated). For such a broad wavelength range, we have the reflective collimator that you can use instead. You can find this at http://www.thorlabs.com/navigation.cfm?guide_id=2328. The UV-enhanced version have decent reflectivity down to around 250nm. You can see the typical reflectivity curve below. I will contact you directly to discuss about your application and what we can offer.
Poster:ira02
Posted Date:2013-03-14 12:03:24.3
Hello, Would it be possible to have a ZEMAX file for the F810SMA-543 collimator please? Best Regards, Ian Ashton
Poster:tcohen
Posted Date:2013-03-14 13:23:00.0
Response from Tim at Thorlabs: Thank you for contacting us Ian. I will send you the Zemax file for your review.
Poster:jlow
Posted Date:2012-10-26 15:11:00.0
Response from Jeremy at Thorlabs: I will get in touch with you directly regarding the Zemax files for these and your applications.
Poster:fapoliveira
Posted Date:2012-10-26 07:29:48.53
Dear Sirs, I would like to have the zemax file for the F810FC-1310 and F810FC-1550 collimators. Thank you
Poster:tcohen
Posted Date:2012-05-01 13:39:00.0
Response from Tim at Thorlabs: Thank you for your feedback! We do offer our Air-Spaced Doublet Collimators in a 2um APC compatible version: the F810APC-2000. We are also looking to expand our optics and our Fixed Fiber Optic Collimation Packages to include a 2um APC version in the near future.
Poster:kkmion
Posted Date:2012-05-01 04:12:49.0
Do you supply the 2µm FC/APC Collimation Package?
Poster:tcohen
Posted Date:2012-02-29 09:33:00.0
Response from Tim at Thorlabs: Thank you for your feedback. I have contacted you directly with the F810SMA-543 Zemax file.
Poster:paul.lauria
Posted Date:2012-02-28 21:10:12.0
Hi, I too would like a zemax file, but for the F810SMA-543. Thank you.
Poster:Thorlabs
Posted Date:2011-01-31 16:42:53.0
Response from Javier at Thorlabs to Brice: we have sent you the ZEMAX files for the F810SMA-780 large diameter collimator. We are also working on compiling all the files and will publish them on the web in the future.
Poster:brice
Posted Date:2011-01-24 19:29:26.0
I was wondering if it would be possible to get the optalix or zemax files for this component? Many Thanks
Poster:Thorlabs
Posted Date:2010-08-19 11:59:25.0
Response from Javier at Thorlabs to jiajingyuwhu: Thank you for your feedback. For your application, the largest beam diameter that can be used at the input is actually limited by the clear aperture of the large lens used on the F810 collimator, which is 18 mm. So, assuming that you have an input beam diameter of 17 mm (8.5 mm radius), a wavelength of 405 nm, and a focal length of 32.52 nm (this is the EFL of the collimator at 405nm), you can calculate the diffraction limited spot at the 99% contour using the following formula: D = (f x lambda)/radius The resulting spot size is ~ 1.55 um, which is much smaller that the diameter of your fiber, so the collimator should be able to effectively focus the collimated beam.
Poster:jiajingyuwhu
Posted Date:2010-08-18 21:16:50.0
Ive bougth your product FC810SMA-custom(designed at 405nm) I want to use it to focused a collimated light beam into a fiber (NA=0.48 0.6mm diameter fiber) I want to ask what is the largest diameter of the collimated light beam? I measured the collimated lens diameter is about 17mm, if it means that the largest permited diameter is 17mm? wish your reply~~~
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
F810SMA-543 Support Documentation
F810SMA-543543 nm SMA Collimation Package, NA = 0.26, f = 34.74 mm
$220.00
Today
F810SMA-635 Support Documentation
F810SMA-635635 nm SMA Collimation Package, NA = 0.25, f = 35.41 mm
$220.00
Today
F810SMA-780 Support Documentation
F810SMA-780780 nm SMA Collimation Package, NA = 0.25, f = 36.01 mm
$220.00
Today
F810SMA-1064 Support Documentation
F810SMA-10641064 nm SMA Collimation Package, NA = 0.25, f = 36.60 mm
$220.00
Today
F810SMA-1310 Support Documentation
F810SMA-13101310 nm SMA Collimation Package, NA = 0.24, f = 36.90 mm
$220.00
Today
F810SMA-1550 Support Documentation
F810SMA-15501550 nm SMA Collimation Package, NA = 0.24, f = 37.13 mm
$220.00
3-5 Days
F810SMA-2000 Support Documentation
F810SMA-20002 µm SMA Collimation Package, NA = 0.24, f = 37.52 mm
$220.00
Today

FC/PC Air-Spaced Doublet Collimators

Features

  • Fiber Collimation
  • Popular FC/PC Connectors
  • Each Collimation Package is Factory Aligned
  • Multi-Element Lens Design for Diffraction-Limited Performance
  • Simplifies Free-Space Laser to Fiber Coupling
  • Lens Material: N-SF6 or Equivalent
  • Non-Magnetic Stainless Steel Housing
  • Accepts Connectors with up to 2.1 mm Wide Keys

The F810FC Series of fiber collimation packages is pre-aligned to collimate a laser beam propagating from the tip of an FC/PC-connectorized fiber with diffraction limited performance at the design wavelength. Since the F810 Series fiber collimators do not have any movable parts, they are compact and not susceptible to misalignment. Due to chromatic aberration, the effective focal length (EFL) of the doublet lens is wavelength dependent. As a result, these collimators will only perform optimally at the design wavelength. The doublet lens is factory aligned so that it is one focal length away from the fiber tip when inserted into the collimator. This distance is equal to the focal length of the aspheric lens at the design wavelength. In addition, the doublet lens has an AR coating that minimizes surface reflections.

We can align collimation packages at custom wavelengths if a standard version is not suitable for your application. We also offer a line of adjustable collimation packages called FiberPorts that are well suited for a wide range of wavelengths and are ideal solutions for adjustable, compact fiber couplers. For other collimation and coupling options, please contact our Technical Support group.

We recommend using these collimators with our AR-coated single mode fiber optic patch cables. These cables feature an antireflective coating on one fiber end for increased transmission and improved return loss at the fiber to free space interface.

Item # Alignmenta
Wavelength
AR Coatingb Dc
(mm)
θd
(deg)
Divergence
Plot
NALens f
(mm)
Damage Threshold Suggested
Adapters
F810FC-543 543 nm 350-700 nm 6.4 0.006° 0.26 34.74 7.5 J/cm2
(532 nm, 10 ns, 10 Hz, Ø0.362 mm)
AD15FAD15NT
F810FC-635 635 nm 350-700 nm 6.7 0.007° 0.25 35.41 - AD15FAD15NT
F810FC-780 780 nm 650-1050 nm 7.5 0.008° 0.25 36.01 - AD15FAD15NT
F810FC-1064 1064 nm 1054-1074 nm 8.0 0.010° 0.25 36.60 7.5 J/cm2
(1064 nm, 10 ns, 10 Hz, Ø0.442 mm)
AD15FAD15NT
F810FC-1310 1310 nm 1050-1620 nm 6.7 0.014° 0.24 36.90 - AD15FAD15NT
F810FC-1550 1550 nm 1050-1620 nm 7.0 0.016° 0.24 37.13 - AD15FAD15NT
F810FC-2000 2 µm 1.8 - 2.4 µm 7.3 0.02° 0.24 37.52 - AD15FAD15NT
  • For optimal collimation these packages should be used at the alignment wavelength. For some applications they may also be used within the AR coating range. Please contact Tech Support for custom alignment packages.
  • For data on Thorlabs' standard AR coatings, refer to the AR Coatings tab above.
  • Collimated Beam Diameter: Theoretical 1/e2 diameter @ 1 focal length from lens; fibers: 460HP (543 nm), SM600 (635 nm), 780HP (780 nm), SM980-5.8-125 (1064 nm), SMF-28 (1310 & 1550 nm), SM2000 (2000 nm)
  • Theoretical full-angle beam divergence; fibers: 460HP (543 nm), SM600 (635 nm), 780HP (780 nm), SM980-5.8-125 (1064 nm), SMF-28 (1310 & 1550 nm), SM2000 (2000 nm)


Click to Enlarge

Theoretical Approximation of the Divergence Angle

The divergence angle is easy to approximate theoretically using the formula shown below as long as the light emerging from the fiber has a Gaussian intensity profile. This works well for single mode fibers, but will underestimate the divergence angle for multimode fibers where the light emerging from the fiber has a non-Gaussian intensity profile.

θ Divergence Angle
D Mode-Field Diameter (MFD)
f Focal Length of Collimator

The divergence angle (in degrees) where D and f must be in the same units.
divergence formula

Example Calculation
For F810FC-543 package collimating 515 nm light from 460HP fiber:

  • D = 3.5 µm
  • f ≈ 34.7 mm (approximate, since design wavelength is 543 nm)

Using the equation given above, we can calculate the approximate divergence angle:

θ ≈ (0.0035 mm/34.7 mm)*(180/3.1416) ≈ 0.006°

Coating Information
Coating Designation A B 1064 C D
Coating Range 350 - 700 nm 650 - 1050 nm 1050 - 1075 nm 1050 - 1700 nm 1.65 - 3.04 µm
Damage Threshold Specifications
Item # Damage Threshold
F810FC-543 7.5 J/cm2 (532 nm, 10 ns, 10 Hz, Ø0.362 mm)
F810FC-1064 7.5 J/cm2 (1064 nm, 10 ns, 10 Hz, Ø0.442 mm)

Damage Threshold Data for Thorlabs' Air-Spaced Doublet Collimators

The specifications to the right are measured data for a selection of Thorlabs' air-spaced doublet collimators. Damage threshold specifications are constant for these collimators, regardless of the connector type.

 

Laser Induced Damage Threshold Tutorial

The following is a general overview of how laser induced damage thresholds are measured and how the values may be utilized in determining the appropriateness of an optic for a given application. When choosing optics, it is important to understand the Laser Induced Damage Threshold (LIDT) of the optics being used. The LIDT for an optic greatly depends on the type of laser you are using. Continuous wave (CW) lasers typically cause damage from thermal effects (absorption either in the coating or in the substrate). Pulsed lasers, on the other hand, often strip electrons from the lattice structure of an optic before causing thermal damage. Note that the guideline presented here assumes room temperature operation and optics in new condition (i.e., within scratch-dig spec, surface free of contamination, etc.). Because dust or other particles on the surface of an optic can cause damage at lower thresholds, we recommend keeping surfaces clean and free of debris. For more information on cleaning optics, please see our Optics Cleaning tutorial.

Testing Method

Thorlabs' LIDT testing is done in compliance with ISO/DIS11254 and ISO 21254 specifications.

First, a low-power/energy beam is directed to the optic under test. The optic is exposed in 10 locations to this laser beam for 30 seconds (CW) or for a number of pulses (pulse repetition frequency specified). After exposure, the optic is examined by a microscope (~100X magnification) for any visible damage. The number of locations that are damaged at a particular power/energy level is recorded. Next, the power/energy is either increased or decreased and the optic is exposed at 10 new locations. This process is repeated until damage is observed. The damage threshold is then assigned to be the highest power/energy that the optic can withstand without causing damage. A histogram such as that below represents the testing of one BB1-E02 mirror.

LIDT metallic mirror
The photograph above is a protected aluminum-coated mirror after LIDT testing. In this particular test, it handled 0.43 J/cm2 (1064 nm, 10 ns pulse, 10 Hz, Ø1.000 mm) before damage.
LIDT BB1-E02
Example Test Data
Fluence # of Tested Locations Locations with Damage Locations Without Damage
1.50 J/cm2 10 0 10
1.75 J/cm2 10 0 10
2.00 J/cm2 10 0 10
2.25 J/cm2 10 1 9
3.00 J/cm2 10 1 9
5.00 J/cm2 10 9 1

According to the test, the damage threshold of the mirror was 2.00 J/cm2 (532 nm, 10 ns pulse, 10 Hz, Ø0.803 mm). Please keep in mind that these tests are performed on clean optics, as dirt and contamination can significantly lower the damage threshold of a component. While the test results are only representative of one coating run, Thorlabs specifies damage threshold values that account for coating variances.

Continuous Wave and Long-Pulse Lasers

When an optic is damaged by a continuous wave (CW) laser, it is usually due to the melting of the surface as a result of absorbing the laser's energy or damage to the optical coating (antireflection) [1]. Pulsed lasers with pulse lengths longer than 1 µs can be treated as CW lasers for LIDT discussions.

When pulse lengths are between 1 ns and 1 µs, laser-induced damage can occur either because of absorption or a dielectric breakdown (therefore, a user must check both CW and pulsed LIDT). Absorption is either due to an intrinsic property of the optic or due to surface irregularities; thus LIDT values are only valid for optics meeting or exceeding the surface quality specifications given by a manufacturer. While many optics can handle high power CW lasers, cemented (e.g., achromatic doublets) or highly absorptive (e.g., ND filters) optics tend to have lower CW damage thresholds. These lower thresholds are due to absorption or scattering in the cement or metal coating.

Linear Power Density Scaling

LIDT in linear power density vs. pulse length and spot size. For long pulses to CW, linear power density becomes a constant with spot size. This graph was obtained from [1].

Intensity Distribution

Pulsed lasers with high pulse repetition frequencies (PRF) may behave similarly to CW beams. Unfortunately, this is highly dependent on factors such as absorption and thermal diffusivity, so there is no reliable method for determining when a high PRF laser will damage an optic due to thermal effects. For beams with a high PRF both the average and peak powers must be compared to the equivalent CW power. Additionally, for highly transparent materials, there is little to no drop in the LIDT with increasing PRF.

In order to use the specified CW damage threshold of an optic, it is necessary to know the following:

  1. Wavelength of your laser
  2. Beam diameter of your beam (1/e2)
  3. Approximate intensity profile of your beam (e.g., Gaussian)
  4. Linear power density of your beam (total power divided by 1/e2 beam diameter)

Thorlabs expresses LIDT for CW lasers as a linear power density measured in W/cm. In this regime, the LIDT given as a linear power density can be applied to any beam diameter; one does not need to compute an adjusted LIDT to adjust for changes in spot size, as demonstrated by the graph to the right. Average linear power density can be calculated using the equation below. 

The calculation above assumes a uniform beam intensity profile. You must now consider hotspots in the beam or other non-uniform intensity profiles and roughly calculate a maximum power density. For reference, a Gaussian beam typically has a maximum power density that is twice that of the uniform beam (see lower right).

Now compare the maximum power density to that which is specified as the LIDT for the optic. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately. A good rule of thumb is that the damage threshold has a linear relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 10 W/cm at 1310 nm scales to 5 W/cm at 655 nm):

CW Wavelength Scaling

While this rule of thumb provides a general trend, it is not a quantitative analysis of LIDT vs wavelength. In CW applications, for instance, damage scales more strongly with absorption in the coating and substrate, which does not necessarily scale well with wavelength. While the above procedure provides a good rule of thumb for LIDT values, please contact Tech Support if your wavelength is different from the specified LIDT wavelength. If your power density is less than the adjusted LIDT of the optic, then the optic should work for your application. 

Please note that we have a buffer built in between the specified damage thresholds online and the tests which we have done, which accommodates variation between batches. Upon request, we can provide individual test information and a testing certificate. The damage analysis will be carried out on a similar optic (customer's optic will not be damaged). Testing may result in additional costs or lead times. Contact Tech Support for more information.

Pulsed Lasers

As previously stated, pulsed lasers typically induce a different type of damage to the optic than CW lasers. Pulsed lasers often do not heat the optic enough to damage it; instead, pulsed lasers produce strong electric fields capable of inducing dielectric breakdown in the material. Unfortunately, it can be very difficult to compare the LIDT specification of an optic to your laser. There are multiple regimes in which a pulsed laser can damage an optic and this is based on the laser's pulse length. The highlighted columns in the table below outline the relevant pulse lengths for our specified LIDT values.

Pulses shorter than 10-9 s cannot be compared to our specified LIDT values with much reliability. In this ultra-short-pulse regime various mechanics, such as multiphoton-avalanche ionization, take over as the predominate damage mechanism [2]. In contrast, pulses between 10-7 s and 10-4 s may cause damage to an optic either because of dielectric breakdown or thermal effects. This means that both CW and pulsed damage thresholds must be compared to the laser beam to determine whether the optic is suitable for your application.

Pulse Duration t < 10-9 s 10-9 < t < 10-7 s 10-7 < t < 10-4 s t > 10-4 s
Damage Mechanism Avalanche Ionization Dielectric Breakdown Dielectric Breakdown or Thermal Thermal
Relevant Damage Specification No Comparison (See Above) Pulsed Pulsed and CW CW

When comparing an LIDT specified for a pulsed laser to your laser, it is essential to know the following:

Energy Density Scaling

LIDT in energy density vs. pulse length and spot size. For short pulses, energy density becomes a constant with spot size. This graph was obtained from [1].

  1. Wavelength of your laser
  2. Energy density of your beam (total energy divided by 1/e2 area)
  3. Pulse length of your laser
  4. Pulse repetition frequency (prf) of your laser
  5. Beam diameter of your laser (1/e2 )
  6. Approximate intensity profile of your beam (e.g., Gaussian)

The energy density of your beam should be calculated in terms of J/cm2. The graph to the right shows why expressing the LIDT as an energy density provides the best metric for short pulse sources. In this regime, the LIDT given as an energy density can be applied to any beam diameter; one does not need to compute an adjusted LIDT to adjust for changes in spot size. This calculation assumes a uniform beam intensity profile. You must now adjust this energy density to account for hotspots or other nonuniform intensity profiles and roughly calculate a maximum energy density. For reference a Gaussian beam typically has a maximum energy density that is twice that of the 1/e2 beam.

Now compare the maximum energy density to that which is specified as the LIDT for the optic. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately [3]. A good rule of thumb is that the damage threshold has an inverse square root relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 1 J/cm2 at 1064 nm scales to 0.7 J/cm2 at 532 nm):

Pulse Wavelength Scaling

You now have a wavelength-adjusted energy density, which you will use in the following step.

Beam diameter is also important to know when comparing damage thresholds. While the LIDT, when expressed in units of J/cm², scales independently of spot size; large beam sizes are more likely to illuminate a larger number of defects which can lead to greater variances in the LIDT [4]. For data presented here, a <1 mm beam size was used to measure the LIDT. For beams sizes greater than 5 mm, the LIDT (J/cm2) will not scale independently of beam diameter due to the larger size beam exposing more defects.

The pulse length must now be compensated for. The longer the pulse duration, the more energy the optic can handle. For pulse widths between 1 - 100 ns, an approximation is as follows:

Pulse Length Scaling

Use this formula to calculate the Adjusted LIDT for an optic based on your pulse length. If your maximum energy density is less than this adjusted LIDT maximum energy density, then the optic should be suitable for your application. Keep in mind that this calculation is only used for pulses between 10-9 s and 10-7 s. For pulses between 10-7 s and 10-4 s, the CW LIDT must also be checked before deeming the optic appropriate for your application.

Please note that we have a buffer built in between the specified damage thresholds online and the tests which we have done, which accommodates variation between batches. Upon request, we can provide individual test information and a testing certificate. Contact Tech Support for more information.


[1] R. M. Wood, Optics and Laser Tech. 29, 517 (1998).
[2] Roger M. Wood, Laser-Induced Damage of Optical Materials (Institute of Physics Publishing, Philadelphia, PA, 2003).
[3] C. W. Carr et al., Phys. Rev. Lett. 91, 127402 (2003).
[4] N. Bloembergen, Appl. Opt. 12, 661 (1973).

In order to illustrate the process of determining whether a given laser system will damage an optic, a number of example calculations of laser induced damage threshold are given below. For assistance with performing similar calculations, we provide a spreadsheet calculator that can be downloaded by clicking the button to the right. To use the calculator, enter the specified LIDT value of the optic under consideration and the relevant parameters of your laser system in the green boxes. The spreadsheet will then calculate a linear power density for CW and pulsed systems, as well as an energy density value for pulsed systems. These values are used to calculate adjusted, scaled LIDT values for the optics based on accepted scaling laws. This calculator assumes a Gaussian beam profile, so a correction factor must be introduced for other beam shapes (uniform, etc.). The LIDT scaling laws are determined from empirical relationships; their accuracy is not guaranteed. Remember that absorption by optics or coatings can significantly reduce LIDT in some spectral regions. These LIDT values are not valid for ultrashort pulses less than one nanosecond in duration.

Intensity Distribution
A Gaussian beam profile has about twice the maximum intensity of a uniform beam profile.

CW Laser Example
Suppose that a CW laser system at 1319 nm produces a 0.5 W Gaussian beam that has a 1/e2 diameter of 10 mm. A naive calculation of the average linear power density of this beam would yield a value of 0.5 W/cm, given by the total power divided by the beam diameter:

CW Wavelength Scaling

However, the maximum power density of a Gaussian beam is about twice the maximum power density of a uniform beam, as shown in the graph to the right. Therefore, a more accurate determination of the maximum linear power density of the system is 1 W/cm.

An AC127-030-C achromatic doublet lens has a specified CW LIDT of 350 W/cm, as tested at 1550 nm. CW damage threshold values typically scale directly with the wavelength of the laser source, so this yields an adjusted LIDT value:

CW Wavelength Scaling

The adjusted LIDT value of 350 W/cm x (1319 nm / 1550 nm) = 298 W/cm is significantly higher than the calculated maximum linear power density of the laser system, so it would be safe to use this doublet lens for this application.

Pulsed Nanosecond Laser Example: Scaling for Different Pulse Durations
Suppose that a pulsed Nd:YAG laser system is frequency tripled to produce a 10 Hz output, consisting of 2 ns output pulses at 355 nm, each with 1 J of energy, in a Gaussian beam with a 1.9 cm beam diameter (1/e2). The average energy density of each pulse is found by dividing the pulse energy by the beam area:

Pulse Energy Density

As described above, the maximum energy density of a Gaussian beam is about twice the average energy density. So, the maximum energy density of this beam is ~0.7 J/cm2.

The energy density of the beam can be compared to the LIDT values of 1 J/cm2 and 3.5 J/cm2 for a BB1-E01 broadband dielectric mirror and an NB1-K08 Nd:YAG laser line mirror, respectively. Both of these LIDT values, while measured at 355 nm, were determined with a 10 ns pulsed laser at 10 Hz. Therefore, an adjustment must be applied for the shorter pulse duration of the system under consideration. As described on the previous tab, LIDT values in the nanosecond pulse regime scale with the square root of the laser pulse duration:

Pulse Length Scaling

This adjustment factor results in LIDT values of 0.45 J/cm2 for the BB1-E01 broadband mirror and 1.6 J/cm2 for the Nd:YAG laser line mirror, which are to be compared with the 0.7 J/cm2 maximum energy density of the beam. While the broadband mirror would likely be damaged by the laser, the more specialized laser line mirror is appropriate for use with this system.

Pulsed Nanosecond Laser Example: Scaling for Different Wavelengths
Suppose that a pulsed laser system emits 10 ns pulses at 2.5 Hz, each with 100 mJ of energy at 1064 nm in a 16 mm diameter beam (1/e2) that must be attenuated with a neutral density filter. For a Gaussian output, these specifications result in a maximum energy density of 0.1 J/cm2. The damage threshold of an NDUV10A Ø25 mm, OD 1.0, reflective neutral density filter is 0.05 J/cm2 for 10 ns pulses at 355 nm, while the damage threshold of the similar NE10A absorptive filter is 10 J/cm2 for 10 ns pulses at 532 nm. As described on the previous tab, the LIDT value of an optic scales with the square root of the wavelength in the nanosecond pulse regime:

Pulse Wavelength Scaling

This scaling gives adjusted LIDT values of 0.08 J/cm2 for the reflective filter and 14 J/cm2 for the absorptive filter. In this case, the absorptive filter is the best choice in order to avoid optical damage.

Pulsed Microsecond Laser Example
Consider a laser system that produces 1 µs pulses, each containing 150 µJ of energy at a repetition rate of 50 kHz, resulting in a relatively high duty cycle of 5%. This system falls somewhere between the regimes of CW and pulsed laser induced damage, and could potentially damage an optic by mechanisms associated with either regime. As a result, both CW and pulsed LIDT values must be compared to the properties of the laser system to ensure safe operation.

If this relatively long-pulse laser emits a Gaussian 12.7 mm diameter beam (1/e2) at 980 nm, then the resulting output has a linear power density of 5.9 W/cm and an energy density of 1.2 x 10-4 J/cm2 per pulse. This can be compared to the LIDT values for a WPQ10E-980 polymer zero-order quarter-wave plate, which are 5 W/cm for CW radiation at 810 nm and 5 J/cm2 for a 10 ns pulse at 810 nm. As before, the CW LIDT of the optic scales linearly with the laser wavelength, resulting in an adjusted CW value of 6 W/cm at 980 nm. On the other hand, the pulsed LIDT scales with the square root of the laser wavelength and the square root of the pulse duration, resulting in an adjusted value of 55 J/cm2 for a 1 µs pulse at 980 nm. The pulsed LIDT of the optic is significantly greater than the energy density of the laser pulse, so individual pulses will not damage the wave plate. However, the large average linear power density of the laser system may cause thermal damage to the optic, much like a high-power CW beam.

Fiber Collimator Selection Guide

Click on the collimator type or photo to view more information about each type of collimator.

Type   Description
Fixed FC, APC, or SMA Fiber Collimators Fixed SMA Fiber Collimator These fiber collimation packages are pre-aligned to collimate light from an FC/PC-, FC/APC-, or SMA-terminated fiber. Each collimation package is factory aligned to provide diffraction-limited performance for wavelengths ranging from 405 nm to 4.55 µm. Although it is possible to use the collimator at detuned wavelengths, they will only perform optimally at the design wavelength due to chromatic aberration, which causes the effective focal length of the aspheric lens to have a wavelength dependence.
Air-Spaced Doublet, Large Beam Collimators Air-Spaced Doublet Fiber Collimator For large beam diameters (Ø6.6 - Ø8.5 mm), Thorlabs offers FC/PC, SMA, and FC/APC air-spaced doublet collimators. These collimation packages are pre-aligned at the factory to collimate a laser beam propagating from the tip of an FC or SMA-terminated fiber and provide diffraction-limited performance at the design wavelength.
Adjustable Fiber Collimators Adjustable Fiber Collimator These collimators are designed to connect onto the end of an FC/PC or FC/APC connector and contain an AR-coated aspheric lens. The distance between the aspheric lens and the tip of the FC-terminated fiber can be adjusted to compensate for focal length changes or to recollimate the beam at the wavelength and distance of interest.
Zoom Fiber Collimators Zoom Fiber Collimator These collimators provide a variable focal length between 6 and 18 mm, while maintaining the collimation of the beam. As a result, the size of the beam can be changed without altering the collimation. This universal device saves time previously spent searching for the best suited fixed fiber collimator and has a very broad range of applications. They are offered with FC/PC, FC/APC, or SMA905 connectors with three different antireflection wavelength ranges to choose from.
Large Beam Fiber Collimators large beam collimators Thorlabs' Large-Beam Fiber Collimators are designed with an effective focal length (EFL) of 40 mm or 80 mm over three different wavelength ranges and are available with FC/PC or FC/APC connectors. A four-element, air-spaced lens design produces a superior beam quality (M2 close to 1) and less wavefront error when compared to aspheric lens collimators. As a result, these collimators are very flexible; they can be used as free-space collimator or coupler. They may also be used over a long distance in pairs, which allows the free-space beam to be manipulated prior to entering the second collimator and may be useful in long-distance communications applications.
FiberPorts Fiberport Fiber Collimator These compact, ultra-stable FiberPort micropositioners provide an easy-to-use, stable platform for coupling light into and out of FC/PC, FC/APC, or SMA terminated optical fibers. It can be used with single mode, multimode, or PM fibers and can be mounted onto a post, stage, platform, or laser. The built-in aspheric or achromatic lens is available with three different AR coatings and has five degrees of alignment adjustment (3 translational and 2 pitch). The compact size and long-term alignment stability make the FiberPort an ideal solution for fiber coupling, collimation, or incorporation into OEM systems.
Triplet Collimators Triplet Fiber Collimator Thorlabs' High Quality Triplet Fiber Collimation packages use air-spaced triplet lenses that offer superior beam quality performance when compared to aspheric lens collimators. The benefits of the low-aberration triplet design include an M2 term closer to 1 (Gaussian), less divergence, and less wavefront error.
Reflective Collimators Reflective Fiber Collimator Thorlabs' metallic-coated Reflective Collimators are based on a 90° off-axis parabolic mirror. Mirrors, unlike lenses, have a focal length that remains constant over a broad wavelength range. Due to this intrinsic property, a parabolic mirror collimator does not need to be adjusted to accommodate various wavelengths of light, making them ideal for use with polychromatic light. Our reflective collimators are ideal for single-mode fiber.
Pigtailed Collimators Pigtailed Fiber Collimator Our pigtailed collimators come with one meter of either single mode or multimode fiber, have the fiber and AR-coated aspheric lens rigidly potted inside the stainless steel housing, and are collimated at one of six wavelengths: 532, 830, 1030, 1064, 1310, or 1550 nm. Although it is possible to use the collimator at any wavelength within the coating range, the coupling loss will increase as the wavelength is detuned from the design wavelength.
GRIN Fiber Collimators GRIN Fiber Collimator Thorlabs offers gradient index (GRIN) fiber collimators that are aligned at a variety of wavelengths from 630 to 1550 nm and have either FC terminated, APC terminated, or unterminated fibers. Our GRIN collimators feature a Ø1.8 mm clear aperture, are AR-coated to ensure low back reflection into the fiber, and are coupled to standard single mode or graded-index multimode fibers.
GRIN Lenses GRIN Lens These graded-index (GRIN) lenses are AR coated for applications at 630, 830, 1060, 1300, or 1560 nm that require light to propagate through one fiber, then through a free-space optical system, and finally back into another fiber. They are also useful for coupling light from laser diodes into fibers, coupling the output of a fiber into a detector, or collimating laser light. Our GRIN lenses are designed to be used with our Pigtailed Glass Ferrules and GRIN/Ferrule sleeves.

Please Give Us Your Feedback
 
Email Feedback On
(Optional)
Contact Me:
Your email address will NOT be displayed.
 
 
Please type the following key into the field to submit this form:
Click Here if you can not read the security code.
This code is to prevent automated spamming of our site
Thank you for your understanding.
  
 
Would this product be useful to you?   Little Use  1234Very Useful

Enter Comments Below:
 
Characters remaining  8000   
Posted Comments:
Poster:jjurado
Posted Date:2011-03-14 16:13:00.0
Response from Javier at Thorlabs to marc.adams: I will send you this file shortly. Regards.
Poster:marc.adams
Posted Date:2011-03-14 11:46:54.0
Could I also get the Zemax file for the F810FC-1064?
Poster:jjurado
Posted Date:2011-02-15 09:50:00.0
Response from Javie at Thorlabs to jaraalmonte: I will send you this file shortly.
Poster:jaraalmonte
Posted Date:2011-02-14 17:03:21.0
Hi, do you have a zemax file for the F810FC-635 collimator?
Poster:Adam
Posted Date:2010-04-16 13:11:13.0
A response from Adam at Thorlabs to carlsonrt: It depends on the beam diameter of your light and the type of fiber you are using. We do not recommend using the coated lenses with powers higher than 100W/cm^2. In regards to the fiber, I am assuming it is single mode fiber. If that is the case and the core size is approximately 10um, then the maximum power the silica fiber can handle is 1MW/cm^2 or ~700mW. I would like to email you directly about this to see exactly how you are using this collimator. If you are coupling light into a fiber, we may suggest something that has more adjustments like a fiber port, PAF-X-5-C.
Poster:carlsonrt
Posted Date:2010-04-16 11:13:19.0
Regarding the F810-1550-FC collimator: I need to use this collimator up to a maximum power of 1watt, with 1550PMF/FC input. My input source has an optical isolator such that reflected power in the fiber is not a problem. Is there any reason the fiber and collimator could not be used at a 1W power level ?
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
F810FC-543 Support Documentation
F810FC-543543 nm FC/PC Collimation Package, NA = 0.26, f = 34.74 mm
$220.00
Today
F810FC-635 Support Documentation
F810FC-635635 nm FC/PC Collimation Package, NA = 0.25, f = 35.41 mm
$220.00
Today
F810FC-780 Support Documentation
F810FC-780780 nm FC/PC Collimation Package, NA =0.25, f = 36.01 mm
$220.00
Today
F810FC-1064 Support Documentation
F810FC-10641064 nm FC/PC Collimation Package, NA = 0.25, f = 36.60 mm
$220.00
Today
F810FC-1310 Support Documentation
F810FC-13101310 nm FC/PC Collimation Package, NA = 0.24, f = 36.90 mm
$220.00
Today
F810FC-1550 Support Documentation
F810FC-15501550 nm FC/PC Collimation Package, NA = 0.24, f = 37.13 mm
$220.00
3-5 Days
F810FC-2000 Support Documentation
F810FC-20002µm FC/PC Collimation Package, NA = 0.24, f = 37.52 mm
$220.00
Today

FC/APC Air-Spaced Doublet Collimators

Features

  • Fiber Collimation
  • Popular FC/APC Connectors
  • Each Collimation Package is Factory Aligned
  • Multi-Element Lens Design for Diffraction-Limited Performance
  • Simplifies Free-Space Laser to Fiber Coupling
  • Lens Material: N-SF6 or Equivalent
  • Non-Magnetic Stainless Steel Housing
  • Accepts Connectors with up to 2.2 mm Wide Keys

The F810APC Series of fiber collimation packages is pre-aligned to collimate a laser beam propagating from the tip of an FC/APC-connectorized fiber with diffraction limited performance at the design wavelength. Since the F810 Series fiber collimators do not have any movable parts, they are compact and not susceptible to misalignment. Due to chromatic aberration, the effective focal length (EFL) of the doublet lens is wavelength dependent. As a result, these collimators will only perform optimally at the design wavelength. The doublet lens is factory aligned so that it is one focal length away from the fiber tip when inserted into the collimator. This distance is equal to the focal length of the aspheric lens at the design wavelength. In addition, the doublet lens has an AR coating that minimizes surface reflections.

We can align collimation packages at custom wavelengths if a standard version is not suitable for your application. We also offer a line of adjustable collimation packages called FiberPorts that are well suited for a wide range of wavelengths and are ideal solutions for adjustable, compact fiber couplers. For other collimation and coupling options, please contact our Technical Support group.

We recommend using these collimators with our AR-coated single mode fiber optic patch cables. These cables feature an antireflective coating on one fiber end for increased transmission and improved return loss at the fiber to free space interface. Alternatively, our large selection of standard fiber patch cables can also be used.

Item # Alignmenta
Wavelength
AR Coatingb Dc
(mm)
θd
(deg)
Divergence
Plot
NALens f
(mm)
Damage Threshold Suggested
Adapters
F810APC-780 780 nm 650-1050 nm 7.5 0.008° 0.25 36.01 - AD15FAD15NT
F810APC-842 842 nm 650-1050 nm 7.8 0.008° 0.25 36.18 - AD15FAD15NT
F810APC-1064 1064 nm 1054-1074 nm 8.0 0.010° 0.25 36.60 7.5 J/cm2
(1064 nm, 10 ns, 10 Hz, Ø0.442 mm)
AD15FAD15NT
F810APC-1310 1310 nm 1050-1620 nm 6.7 0.014° 0.24 36.90 - AD15FAD15NT
F810APC-1550 1550 nm 1050-1620 nm 7.0 0.016° 0.24 37.13 - AD15FAD15NT
F810APC-2000 2 µm 1.8 - 2.4 µm 7.3 0.02° 0.24 37.52 - AD15FAD15NT
  • For optimal collimation these packages should be used at the alignment wavelength. For some applications they may also be used within the AR coating range. Please contact Tech Support for custom alignment packages.
  • For data on Thorlabs' standard AR coatings, refer to the AR Coatings tab above.
  • Collimated Beam Diameter: Theoretical 1/e2 diameter @ 1 focal length from lens; fibers: 460HP (543 nm), SM600 (635 nm), 780HP (780 nm), SM980-5.8-125 (1064 nm), SMF-28e (1310 & 1550 nm), SM2000 (2000 nm)
  • Theoretical full-angle beam divergence; fibers: 460HP (543 nm), SM600 (635 nm), 780HP (780 nm), SM980-5.8-125 (1064 nm), SMF-28 (1310 & 1550 nm), SM2000 (2000 nm)


Click to Enlarge

Theoretical Approximation of the Divergence Angle

The divergence angle is easy to approximate theoretically using the formula shown below as long as the light emerging from the fiber has a Gaussian intensity profile. This works well for single mode fibers, but will underestimate the divergence angle for multimode fibers where the light emerging from the fiber has a non-Gaussian intensity profile.

θ Divergence Angle
D Mode-Field Diameter (MFD)
f Focal Length of Collimator

The divergence angle (in degrees) where D and f must be in the same units.
divergence formula

Example Calculation
For F810FC-543 package collimating 515 nm light from 460HP fiber:

  • D = 3.5 µm
  • f ≈ 34.7 mm (approximate, since design wavelength is 543 nm)

Using the equation given above, we can calculate the approximate divergence angle:

θ ≈ (0.0035 mm/34.7 mm)*(180/3.1416) ≈ 0.006°

Coating Information
Coating Designation A B 1064 C D
Coating Range 350 - 700 nm 650 - 1050 nm 1050 - 1075 nm 1050 - 1700 nm 1.65 - 3.0 µm
Damage Threshold Specifications
Item # Damage Threshold
F810APC-1064 7.5 J/cm2 (1064 nm, 10 ns, 10 Hz, Ø0.442 mm)

Damage Threshold Data for Thorlabs' Air-Spaced Doublet Collimators

The specifications to the right are measured data for a selection of Thorlabs' air-spaced doublet collimators. Damage threshold specifications are constant for these collimators, regardless of the connector type.

 

Laser Induced Damage Threshold Tutorial

The following is a general overview of how laser induced damage thresholds are measured and how the values may be utilized in determining the appropriateness of an optic for a given application. When choosing optics, it is important to understand the Laser Induced Damage Threshold (LIDT) of the optics being used. The LIDT for an optic greatly depends on the type of laser you are using. Continuous wave (CW) lasers typically cause damage from thermal effects (absorption either in the coating or in the substrate). Pulsed lasers, on the other hand, often strip electrons from the lattice structure of an optic before causing thermal damage. Note that the guideline presented here assumes room temperature operation and optics in new condition (i.e., within scratch-dig spec, surface free of contamination, etc.). Because dust or other particles on the surface of an optic can cause damage at lower thresholds, we recommend keeping surfaces clean and free of debris. For more information on cleaning optics, please see our Optics Cleaning tutorial.

Testing Method

Thorlabs' LIDT testing is done in compliance with ISO/DIS11254 and ISO 21254 specifications.

First, a low-power/energy beam is directed to the optic under test. The optic is exposed in 10 locations to this laser beam for 30 seconds (CW) or for a number of pulses (pulse repetition frequency specified). After exposure, the optic is examined by a microscope (~100X magnification) for any visible damage. The number of locations that are damaged at a particular power/energy level is recorded. Next, the power/energy is either increased or decreased and the optic is exposed at 10 new locations. This process is repeated until damage is observed. The damage threshold is then assigned to be the highest power/energy that the optic can withstand without causing damage. A histogram such as that below represents the testing of one BB1-E02 mirror.

LIDT metallic mirror
The photograph above is a protected aluminum-coated mirror after LIDT testing. In this particular test, it handled 0.43 J/cm2 (1064 nm, 10 ns pulse, 10 Hz, Ø1.000 mm) before damage.
LIDT BB1-E02
Example Test Data
Fluence # of Tested Locations Locations with Damage Locations Without Damage
1.50 J/cm2 10 0 10
1.75 J/cm2 10 0 10
2.00 J/cm2 10 0 10
2.25 J/cm2 10 1 9
3.00 J/cm2 10 1 9
5.00 J/cm2 10 9 1

According to the test, the damage threshold of the mirror was 2.00 J/cm2 (532 nm, 10 ns pulse, 10 Hz, Ø0.803 mm). Please keep in mind that these tests are performed on clean optics, as dirt and contamination can significantly lower the damage threshold of a component. While the test results are only representative of one coating run, Thorlabs specifies damage threshold values that account for coating variances.

Continuous Wave and Long-Pulse Lasers

When an optic is damaged by a continuous wave (CW) laser, it is usually due to the melting of the surface as a result of absorbing the laser's energy or damage to the optical coating (antireflection) [1]. Pulsed lasers with pulse lengths longer than 1 µs can be treated as CW lasers for LIDT discussions.

When pulse lengths are between 1 ns and 1 µs, laser-induced damage can occur either because of absorption or a dielectric breakdown (therefore, a user must check both CW and pulsed LIDT). Absorption is either due to an intrinsic property of the optic or due to surface irregularities; thus LIDT values are only valid for optics meeting or exceeding the surface quality specifications given by a manufacturer. While many optics can handle high power CW lasers, cemented (e.g., achromatic doublets) or highly absorptive (e.g., ND filters) optics tend to have lower CW damage thresholds. These lower thresholds are due to absorption or scattering in the cement or metal coating.

Linear Power Density Scaling

LIDT in linear power density vs. pulse length and spot size. For long pulses to CW, linear power density becomes a constant with spot size. This graph was obtained from [1].

Intensity Distribution

Pulsed lasers with high pulse repetition frequencies (PRF) may behave similarly to CW beams. Unfortunately, this is highly dependent on factors such as absorption and thermal diffusivity, so there is no reliable method for determining when a high PRF laser will damage an optic due to thermal effects. For beams with a high PRF both the average and peak powers must be compared to the equivalent CW power. Additionally, for highly transparent materials, there is little to no drop in the LIDT with increasing PRF.

In order to use the specified CW damage threshold of an optic, it is necessary to know the following:

  1. Wavelength of your laser
  2. Beam diameter of your beam (1/e2)
  3. Approximate intensity profile of your beam (e.g., Gaussian)
  4. Linear power density of your beam (total power divided by 1/e2 beam diameter)

Thorlabs expresses LIDT for CW lasers as a linear power density measured in W/cm. In this regime, the LIDT given as a linear power density can be applied to any beam diameter; one does not need to compute an adjusted LIDT to adjust for changes in spot size, as demonstrated by the graph to the right. Average linear power density can be calculated using the equation below. 

The calculation above assumes a uniform beam intensity profile. You must now consider hotspots in the beam or other non-uniform intensity profiles and roughly calculate a maximum power density. For reference, a Gaussian beam typically has a maximum power density that is twice that of the uniform beam (see lower right).

Now compare the maximum power density to that which is specified as the LIDT for the optic. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately. A good rule of thumb is that the damage threshold has a linear relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 10 W/cm at 1310 nm scales to 5 W/cm at 655 nm):

CW Wavelength Scaling

While this rule of thumb provides a general trend, it is not a quantitative analysis of LIDT vs wavelength. In CW applications, for instance, damage scales more strongly with absorption in the coating and substrate, which does not necessarily scale well with wavelength. While the above procedure provides a good rule of thumb for LIDT values, please contact Tech Support if your wavelength is different from the specified LIDT wavelength. If your power density is less than the adjusted LIDT of the optic, then the optic should work for your application. 

Please note that we have a buffer built in between the specified damage thresholds online and the tests which we have done, which accommodates variation between batches. Upon request, we can provide individual test information and a testing certificate. The damage analysis will be carried out on a similar optic (customer's optic will not be damaged). Testing may result in additional costs or lead times. Contact Tech Support for more information.

Pulsed Lasers

As previously stated, pulsed lasers typically induce a different type of damage to the optic than CW lasers. Pulsed lasers often do not heat the optic enough to damage it; instead, pulsed lasers produce strong electric fields capable of inducing dielectric breakdown in the material. Unfortunately, it can be very difficult to compare the LIDT specification of an optic to your laser. There are multiple regimes in which a pulsed laser can damage an optic and this is based on the laser's pulse length. The highlighted columns in the table below outline the relevant pulse lengths for our specified LIDT values.

Pulses shorter than 10-9 s cannot be compared to our specified LIDT values with much reliability. In this ultra-short-pulse regime various mechanics, such as multiphoton-avalanche ionization, take over as the predominate damage mechanism [2]. In contrast, pulses between 10-7 s and 10-4 s may cause damage to an optic either because of dielectric breakdown or thermal effects. This means that both CW and pulsed damage thresholds must be compared to the laser beam to determine whether the optic is suitable for your application.

Pulse Duration t < 10-9 s 10-9 < t < 10-7 s 10-7 < t < 10-4 s t > 10-4 s
Damage Mechanism Avalanche Ionization Dielectric Breakdown Dielectric Breakdown or Thermal Thermal
Relevant Damage Specification No Comparison (See Above) Pulsed Pulsed and CW CW

When comparing an LIDT specified for a pulsed laser to your laser, it is essential to know the following:

Energy Density Scaling

LIDT in energy density vs. pulse length and spot size. For short pulses, energy density becomes a constant with spot size. This graph was obtained from [1].

  1. Wavelength of your laser
  2. Energy density of your beam (total energy divided by 1/e2 area)
  3. Pulse length of your laser
  4. Pulse repetition frequency (prf) of your laser
  5. Beam diameter of your laser (1/e2 )
  6. Approximate intensity profile of your beam (e.g., Gaussian)

The energy density of your beam should be calculated in terms of J/cm2. The graph to the right shows why expressing the LIDT as an energy density provides the best metric for short pulse sources. In this regime, the LIDT given as an energy density can be applied to any beam diameter; one does not need to compute an adjusted LIDT to adjust for changes in spot size. This calculation assumes a uniform beam intensity profile. You must now adjust this energy density to account for hotspots or other nonuniform intensity profiles and roughly calculate a maximum energy density. For reference a Gaussian beam typically has a maximum energy density that is twice that of the 1/e2 beam.

Now compare the maximum energy density to that which is specified as the LIDT for the optic. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately [3]. A good rule of thumb is that the damage threshold has an inverse square root relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 1 J/cm2 at 1064 nm scales to 0.7 J/cm2 at 532 nm):

Pulse Wavelength Scaling

You now have a wavelength-adjusted energy density, which you will use in the following step.

Beam diameter is also important to know when comparing damage thresholds. While the LIDT, when expressed in units of J/cm², scales independently of spot size; large beam sizes are more likely to illuminate a larger number of defects which can lead to greater variances in the LIDT [4]. For data presented here, a <1 mm beam size was used to measure the LIDT. For beams sizes greater than 5 mm, the LIDT (J/cm2) will not scale independently of beam diameter due to the larger size beam exposing more defects.

The pulse length must now be compensated for. The longer the pulse duration, the more energy the optic can handle. For pulse widths between 1 - 100 ns, an approximation is as follows:

Pulse Length Scaling

Use this formula to calculate the Adjusted LIDT for an optic based on your pulse length. If your maximum energy density is less than this adjusted LIDT maximum energy density, then the optic should be suitable for your application. Keep in mind that this calculation is only used for pulses between 10-9 s and 10-7 s. For pulses between 10-7 s and 10-4 s, the CW LIDT must also be checked before deeming the optic appropriate for your application.

Please note that we have a buffer built in between the specified damage thresholds online and the tests which we have done, which accommodates variation between batches. Upon request, we can provide individual test information and a testing certificate. Contact Tech Support for more information.


[1] R. M. Wood, Optics and Laser Tech. 29, 517 (1998).
[2] Roger M. Wood, Laser-Induced Damage of Optical Materials (Institute of Physics Publishing, Philadelphia, PA, 2003).
[3] C. W. Carr et al., Phys. Rev. Lett. 91, 127402 (2003).
[4] N. Bloembergen, Appl. Opt. 12, 661 (1973).

In order to illustrate the process of determining whether a given laser system will damage an optic, a number of example calculations of laser induced damage threshold are given below. For assistance with performing similar calculations, we provide a spreadsheet calculator that can be downloaded by clicking the button to the right. To use the calculator, enter the specified LIDT value of the optic under consideration and the relevant parameters of your laser system in the green boxes. The spreadsheet will then calculate a linear power density for CW and pulsed systems, as well as an energy density value for pulsed systems. These values are used to calculate adjusted, scaled LIDT values for the optics based on accepted scaling laws. This calculator assumes a Gaussian beam profile, so a correction factor must be introduced for other beam shapes (uniform, etc.). The LIDT scaling laws are determined from empirical relationships; their accuracy is not guaranteed. Remember that absorption by optics or coatings can significantly reduce LIDT in some spectral regions. These LIDT values are not valid for ultrashort pulses less than one nanosecond in duration.

Intensity Distribution
A Gaussian beam profile has about twice the maximum intensity of a uniform beam profile.

CW Laser Example
Suppose that a CW laser system at 1319 nm produces a 0.5 W Gaussian beam that has a 1/e2 diameter of 10 mm. A naive calculation of the average linear power density of this beam would yield a value of 0.5 W/cm, given by the total power divided by the beam diameter:

CW Wavelength Scaling

However, the maximum power density of a Gaussian beam is about twice the maximum power density of a uniform beam, as shown in the graph to the right. Therefore, a more accurate determination of the maximum linear power density of the system is 1 W/cm.

An AC127-030-C achromatic doublet lens has a specified CW LIDT of 350 W/cm, as tested at 1550 nm. CW damage threshold values typically scale directly with the wavelength of the laser source, so this yields an adjusted LIDT value:

CW Wavelength Scaling

The adjusted LIDT value of 350 W/cm x (1319 nm / 1550 nm) = 298 W/cm is significantly higher than the calculated maximum linear power density of the laser system, so it would be safe to use this doublet lens for this application.

Pulsed Nanosecond Laser Example: Scaling for Different Pulse Durations
Suppose that a pulsed Nd:YAG laser system is frequency tripled to produce a 10 Hz output, consisting of 2 ns output pulses at 355 nm, each with 1 J of energy, in a Gaussian beam with a 1.9 cm beam diameter (1/e2). The average energy density of each pulse is found by dividing the pulse energy by the beam area:

Pulse Energy Density

As described above, the maximum energy density of a Gaussian beam is about twice the average energy density. So, the maximum energy density of this beam is ~0.7 J/cm2.

The energy density of the beam can be compared to the LIDT values of 1 J/cm2 and 3.5 J/cm2 for a BB1-E01 broadband dielectric mirror and an NB1-K08 Nd:YAG laser line mirror, respectively. Both of these LIDT values, while measured at 355 nm, were determined with a 10 ns pulsed laser at 10 Hz. Therefore, an adjustment must be applied for the shorter pulse duration of the system under consideration. As described on the previous tab, LIDT values in the nanosecond pulse regime scale with the square root of the laser pulse duration:

Pulse Length Scaling

This adjustment factor results in LIDT values of 0.45 J/cm2 for the BB1-E01 broadband mirror and 1.6 J/cm2 for the Nd:YAG laser line mirror, which are to be compared with the 0.7 J/cm2 maximum energy density of the beam. While the broadband mirror would likely be damaged by the laser, the more specialized laser line mirror is appropriate for use with this system.

Pulsed Nanosecond Laser Example: Scaling for Different Wavelengths
Suppose that a pulsed laser system emits 10 ns pulses at 2.5 Hz, each with 100 mJ of energy at 1064 nm in a 16 mm diameter beam (1/e2) that must be attenuated with a neutral density filter. For a Gaussian output, these specifications result in a maximum energy density of 0.1 J/cm2. The damage threshold of an NDUV10A Ø25 mm, OD 1.0, reflective neutral density filter is 0.05 J/cm2 for 10 ns pulses at 355 nm, while the damage threshold of the similar NE10A absorptive filter is 10 J/cm2 for 10 ns pulses at 532 nm. As described on the previous tab, the LIDT value of an optic scales with the square root of the wavelength in the nanosecond pulse regime:

Pulse Wavelength Scaling

This scaling gives adjusted LIDT values of 0.08 J/cm2 for the reflective filter and 14 J/cm2 for the absorptive filter. In this case, the absorptive filter is the best choice in order to avoid optical damage.

Pulsed Microsecond Laser Example
Consider a laser system that produces 1 µs pulses, each containing 150 µJ of energy at a repetition rate of 50 kHz, resulting in a relatively high duty cycle of 5%. This system falls somewhere between the regimes of CW and pulsed laser induced damage, and could potentially damage an optic by mechanisms associated with either regime. As a result, both CW and pulsed LIDT values must be compared to the properties of the laser system to ensure safe operation.

If this relatively long-pulse laser emits a Gaussian 12.7 mm diameter beam (1/e2) at 980 nm, then the resulting output has a linear power density of 5.9 W/cm and an energy density of 1.2 x 10-4 J/cm2 per pulse. This can be compared to the LIDT values for a WPQ10E-980 polymer zero-order quarter-wave plate, which are 5 W/cm for CW radiation at 810 nm and 5 J/cm2 for a 10 ns pulse at 810 nm. As before, the CW LIDT of the optic scales linearly with the laser wavelength, resulting in an adjusted CW value of 6 W/cm at 980 nm. On the other hand, the pulsed LIDT scales with the square root of the laser wavelength and the square root of the pulse duration, resulting in an adjusted value of 55 J/cm2 for a 1 µs pulse at 980 nm. The pulsed LIDT of the optic is significantly greater than the energy density of the laser pulse, so individual pulses will not damage the wave plate. However, the large average linear power density of the laser system may cause thermal damage to the optic, much like a high-power CW beam.

Fiber Collimator Selection Guide

Click on the collimator type or photo to view more information about each type of collimator.

Type   Description
Fixed FC, APC, or SMA Fiber Collimators Fixed SMA Fiber Collimator These fiber collimation packages are pre-aligned to collimate light from an FC/PC-, FC/APC-, or SMA-terminated fiber. Each collimation package is factory aligned to provide diffraction-limited performance for wavelengths ranging from 405 nm to 4.55 µm. Although it is possible to use the collimator at detuned wavelengths, they will only perform optimally at the design wavelength due to chromatic aberration, which causes the effective focal length of the aspheric lens to have a wavelength dependence.
Air-Spaced Doublet, Large Beam Collimators Air-Spaced Doublet Fiber Collimator For large beam diameters (Ø6.6 - Ø8.5 mm), Thorlabs offers FC/PC, SMA, and FC/APC air-spaced doublet collimators. These collimation packages are pre-aligned at the factory to collimate a laser beam propagating from the tip of an FC or SMA-terminated fiber and provide diffraction-limited performance at the design wavelength.
Adjustable Fiber Collimators Adjustable Fiber Collimator These collimators are designed to connect onto the end of an FC/PC or FC/APC connector and contain an AR-coated aspheric lens. The distance between the aspheric lens and the tip of the FC-terminated fiber can be adjusted to compensate for focal length changes or to recollimate the beam at the wavelength and distance of interest.
Zoom Fiber Collimators Zoom Fiber Collimator These collimators provide a variable focal length between 6 and 18 mm, while maintaining the collimation of the beam. As a result, the size of the beam can be changed without altering the collimation. This universal device saves time previously spent searching for the best suited fixed fiber collimator and has a very broad range of applications. They are offered with FC/PC, FC/APC, or SMA905 connectors with three different antireflection wavelength ranges to choose from.
Large Beam Fiber Collimators large beam collimators Thorlabs' Large-Beam Fiber Collimators are designed with an effective focal length (EFL) of 40 mm or 80 mm over three different wavelength ranges and are available with FC/PC or FC/APC connectors. A four-element, air-spaced lens design produces a superior beam quality (M2 close to 1) and less wavefront error when compared to aspheric lens collimators. As a result, these collimators are very flexible; they can be used as free-space collimator or coupler. They may also be used over a long distance in pairs, which allows the free-space beam to be manipulated prior to entering the second collimator and may be useful in long-distance communications applications.
FiberPorts Fiberport Fiber Collimator These compact, ultra-stable FiberPort micropositioners provide an easy-to-use, stable platform for coupling light into and out of FC/PC, FC/APC, or SMA terminated optical fibers. It can be used with single mode, multimode, or PM fibers and can be mounted onto a post, stage, platform, or laser. The built-in aspheric or achromatic lens is available with three different AR coatings and has five degrees of alignment adjustment (3 translational and 2 pitch). The compact size and long-term alignment stability make the FiberPort an ideal solution for fiber coupling, collimation, or incorporation into OEM systems.
Triplet Collimators Triplet Fiber Collimator Thorlabs' High Quality Triplet Fiber Collimation packages use air-spaced triplet lenses that offer superior beam quality performance when compared to aspheric lens collimators. The benefits of the low-aberration triplet design include an M2 term closer to 1 (Gaussian), less divergence, and less wavefront error.
Reflective Collimators Reflective Fiber Collimator Thorlabs' metallic-coated Reflective Collimators are based on a 90° off-axis parabolic mirror. Mirrors, unlike lenses, have a focal length that remains constant over a broad wavelength range. Due to this intrinsic property, a parabolic mirror collimator does not need to be adjusted to accommodate various wavelengths of light, making them ideal for use with polychromatic light. Our reflective collimators are ideal for single-mode fiber.
Pigtailed Collimators Pigtailed Fiber Collimator Our pigtailed collimators come with one meter of either single mode or multimode fiber, have the fiber and AR-coated aspheric lens rigidly potted inside the stainless steel housing, and are collimated at one of six wavelengths: 532, 830, 1030, 1064, 1310, or 1550 nm. Although it is possible to use the collimator at any wavelength within the coating range, the coupling loss will increase as the wavelength is detuned from the design wavelength.
GRIN Fiber Collimators GRIN Fiber Collimator Thorlabs offers gradient index (GRIN) fiber collimators that are aligned at a variety of wavelengths from 630 to 1550 nm and have either FC terminated, APC terminated, or unterminated fibers. Our GRIN collimators feature a Ø1.8 mm clear aperture, are AR-coated to ensure low back reflection into the fiber, and are coupled to standard single mode or graded-index multimode fibers.
GRIN Lenses GRIN Lens These graded-index (GRIN) lenses are AR coated for applications at 630, 830, 1060, 1300, or 1560 nm that require light to propagate through one fiber, then through a free-space optical system, and finally back into another fiber. They are also useful for coupling light from laser diodes into fibers, coupling the output of a fiber into a detector, or collimating laser light. Our GRIN lenses are designed to be used with our Pigtailed Glass Ferrules and GRIN/Ferrule sleeves.

Please Give Us Your Feedback
 
Email Feedback On
(Optional)
Contact Me:
Your email address will NOT be displayed.
 
 
Please type the following key into the field to submit this form:
Click Here if you can not read the security code.
This code is to prevent automated spamming of our site
Thank you for your understanding.
  
 
Would this product be useful to you?   Little Use  1234Very Useful

Enter Comments Below:
 
Characters remaining  8000   
Posted Comments:
Poster:kenlee
Posted Date:2009-12-10 17:59:31.0
A response from Ken at Thorlabs to richard.fox: Thank you for your valuable suggestion. The F810APC-635 is now in our plan but it may take a few weeks before it is released. In the mean time, we can do this as a special. Please send your complete contact information to techsupport@thorlabs.com so that we can prepare a quotation for you.
Poster:richard.fox
Posted Date:2009-12-10 11:14:46.0
If you will be introducing a F810APC-635 anytime soon please let me know. The F810FC-635 doesnt work so well with APC fibers. Thank you
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
F810APC-780 Support Documentation
F810APC-780780 nm FC/APC Collimation Package, NA = 0.25, f = 36.01 mm
$250.00
Today
F810APC-842 Support Documentation
F810APC-842842 nm FC/APC Collimation Package, NA = 0.25, f = 36.18 mm
$250.00
Today
F810APC-1064 Support Documentation
F810APC-1064Customer Inspired!1064 nm FC/APC Collimation Package, NA = 0.25, f = 36.60 mm
$250.00
Today
F810APC-1310 Support Documentation
F810APC-13101310 nm FC/APC Collimation Package, NA = 0.24, f = 36.90 mm
$250.00
Today
F810APC-1550 Support Documentation
F810APC-15501550 nm FC/APC Collimation Package, NA = 0.24, f = 37.13 mm
$250.00
Today
F810APC-2000 Support Documentation
F810APC-20002µm FC/APC Collimation Package, NA = 0.24, f = 37.52 mm
$250.00
Today
Log In  |   My Account  |   Contact Us  |   Careers  |   Privacy Policy  |   Home  |   FAQ  |   Site Index
Regional Websites: West Coast US | Europe | Asia | China | Japan
Copyright 1999-2017 Thorlabs, Inc.
Sales: 1-973-300-3000
Technical Support: 1-973-300-3000


High Quality Thorlabs Logo 1000px:Save this Image