NonPolarizing Cube Beamsplitters (700  1100 nm)
 Beamsplitter Coating for 700  1100 nm
 10:90, 30:70, 50:50, 70:30, or 90:10 (R:T) Split Ratio
 AR Coating on Both Input and Output Faces
BS008
5 mm
BS005
1/2"
BS020
1"
Engravings Mark the Directions
of Light Propagation
BS032
2"
1" Beamsplitter Cube Shown in CCM14ER Prism Cage Cube
Please Wait
General Specifications  

Wavelength Range  700  1100 nm  
AR Coating (All Four Surfaces, Click for Plot) 
R_{avg} < 0.5% at 0° AOI from 700  1100 nm 

Substrate Material  NBK7^{a}  
Dimensional Tolerance  +0.0 / 0.2 mm  
Reflected Beam Deviation  90° ± 5 arcmin  
Surface Quality  4020 ScratchDig 
Click to Enlarge
5 mm Beamsplitter Cube Mounted in the FBTB Compact Kinematic Mount on a Ø1" Post with a Post Spacer
(Refer to the BS Cube Mounting Tab for Other Options)
Cube Beamsplitter Diagram (Coating and Cement Layer Not to Scale)
Features
 Broadband ARCoated Faces for 700  1100 nm
 Broadband Beamsplitter Coating on Internal Diagonal Surface
 10:90, 30:70, 50:50, 70:30, or 90:10 (R:T) Split Ratio
 Sizes from 5 mm to 2" (See Below for Details)
 NBK7 Substrate
Thorlabs' nonpolarizing beamsplitter cubes are offered here with broadband AR and beamsplitter coatings designed for 700  1100 nm. These cubes provide a 10:90, 30:70, 50:50, 70:30, or 90:10 beamsplitting ratio with a minimal dependence on the polarization of the incident light (see the tables below for the polarization split ratio tolerances).
Each cube is fabricated from NBK7 and designed for minimal beam offset. A single reflecting surface also avoids ghost images. The dielectric beamsplitter coating is applied to the hypotenuse of one of the two prisms that make up the cube. Then, cement is used to bind the two prism halves together. These cubes are engraved with arrows that indicate the direction in which the beam is incident on the beamsplitter coating layer, as shown in the diagram to the right. Although light can enter through any of the other ARcoated surfaces, specifications are guaranteed when light is first incident on the side of the beamsplitter coating; see the diagram to the right.
Please refer to the BS Cube Mounting tab above for information on mounting options and compatibility. Alternatively, we offer mounted 1" nonpolarizing beamsplitter cubes and 20 mm nonpolarizing beamsplitter cubes. The 1" cubes are mounted inside 30 mm cage compatible cubes, each of which features four SM1threaded (1.035"40) access ports, while the 20 mm cubes are mounted within 16 mm cage compatible cubes, each of which features four SM05threaded (0.535"40) access ports. Additionally, Thorlabs offers pellicle beamsplitters (cube mounted and ring mounted) and plate beamsplitters. For a direct comparison of the performance of our nonpolarizing beamsplitter cube, plate, and pellicle at 633 nm, see the Lab Facts tab.
NonPolarizing Cube Beamsplitters 

Visible (400  700 nm) Beamsplitters 
NIR (700  1100 nm) Beamsplitters 
IR (1100  1600 nm) Beamsplitters 
Mounted Cube Beamsplitters 
General Specifications  

Wavelength Range  700  1100 nm  
AR Coating (All Four Surfaces, Click for Plot)  R_{avg} < 0.5% at 0° AOI from 700  1100 nm  
Substrate Material  NBK7^{a}  
Dimensional Tolerance  +0.0/0.2 mm  
Reflected Beam Deviation  90° ± 5 arcmin  
Surface Quality  4020 ScratchDig 
Item #  Size  Surface Flatness (@ 633 nm) 
Transmitted Wavefront Error (@ 633 nm) 
Transmitted Beam Deviation 
Overall Performance^{b} 

10:90 (R:T) Split Ratio  
BS035^{a}  5 mm Cube    <λ/4  0° ± 5 arcmin  T_{abs} = 87 ± 10%, R_{abs} = 7 +10/7%, and T_{abs} + R_{abs} > 85% T_{s}  T_{p} < 10% and R_{s}  R_{p} < 10% 
BS038  10 mm Cube  
BS041  1/2" (12.7 mm) Cube  T_{abs} = 87 ± 10%, R_{abs} = 7 +10/5%, and T_{abs} + R_{abs} > 85% T_{s}  T_{p} < 10% and R_{s}  R_{p} < 10% 

BS044  20 mm Cube  T_{abs} = 87 ± 10%, R_{abs} = 7 +10/7%, and T_{abs} + R_{abs} > 85% T_{s}  T_{p} < 10% and R_{s}  R_{p} < 10% 

BS026  1" (25.4 mm) Cube  T_{abs} = 87 ± 10%, R_{abs} = 7 +10/5%, and T_{abs} + R_{abs} > 85% T_{s}  T_{p} < 10% and R_{s}  R_{p} < 10% 

30:70 (R:T) Split Ratio  
BS047^{a}  5 mm Cube    <λ/4  0° ± 5 arcmin  T_{abs} = 62 ± 10%, R_{abs} = 27 ± 10%, and T_{abs} + R_{abs} > 80% T_{s}  T_{p} < 10% and R_{s}  R_{p} < 10% 
BS050  10 mm Cube  
BS053  1/2" (12.7 mm) Cube  
BS080  20 mm Cube  
BS020  1" (25.4 mm) Cube  
50:50 (R:T) Split Ratio  
BS008^{a}  5 mm Cube    <λ/4  0° ± 5 arcmin  T_{abs} = 47 ± 10%, R_{abs} = 47 ± 10%, and T_{abs} + R_{abs} > 90% T_{s}  T_{p} < 10% and R_{s}  R_{p} < 10% 
BS011  10 mm Cube  
BS005  1/2" (12.7 mm) Cube  
BS017  20 mm Cube  
BS014  1" (25.4 mm) Cube  
BS032  2" (50.8 mm) Cube  <λ  T_{abs}= 47 ± 10%, R_{abs}= 47 ± 10% T_{abs} + R_{abs} > 85% T_{avg} + R_{avg }> 90% T_{s}  T_{p} < 10% and R_{s}  R_{p} < 10% 

70:30 (R:T) Split Ratio  
BS056  5 mm Cube    <λ/4  0° ± 5 arcmin  T_{abs} = 27 ± 10%, R_{abs} = 67 +5/15%, and T_{abs} + R_{abs} > 85% T_{s}  T_{p} < 10% and R_{s}  R_{p} < 10% 
BS059  10 mm Cube  
BS062  1/2" (12.7 mm) Cube  
BS065  20 mm Cube  
BS023  1" (25.4 mm) Cube  <λ/10  <5 arcmin  
90:10 (R:T) Split Ratio  
BS068  5 mm Cube    <λ/4  0° ± 5 arcmin  T_{abs} = 7 +10/5%, R_{abs} = 87 ± 10%, and T_{abs} + R_{abs} > 85% T_{s}  T_{p} < 10% and R_{s}  R_{p} < 10% 
BS071  10 mm Cube  
BS074  1/2" (12.7 mm) Cube  
BS077  20 mm Cube  
BS029  1" (25.4 mm) Cube 
Thorlabs Lab Fact: Beamsplitter Package Matters
We present laboratory measurements of the polarization angle, split ratio, and total throughput power of a beam transmitted through Thorlabs plate, cube, and pellicle beamsplitters. While all nonpolarizing beamsplitters function similarly, the exact performance is different for different types of beamsplitter. Each type of beamsplitter contains its own advantages and disadvantages compared to other types of beamsplitters. Appropriate choice of beamsplitter is essential to sensitive experimental systems. We present a complete analysis and comparison of optical parameters for three common types of nonpolarizing beamsplitters.
For our experiment we used the former generation HRS015 stabilized HeNe laser (replaced by the HRS015B) as the light source for our investigation. A linear polarizer is used to set the laser beam's polarization axis to 45° in order to provide equal S and Ppolarized light incident on the beamsplitter. The beamsplitter under investigation was then placed in the beampath, and its split beams directed to appropriate detectors. The total power though the optic, polarization states, split ratios, and angle of incidence effects were investigated under this configuration.
The plots below summarize the measured results for all three types of beamsplitters. From these graphs the performance of each optic can be easily compared to one another. The bottom left plot summarizes the results for the total power throughput for each optic. The total power throughput is measured as the fraction of input power. While the plate and pellicle beamsplitters perform rather similarly, the cube shows signs of absorption inside the optic. Additionally, this plot shows the relative insensitivity of throughput power to angle of incidence. The bottom middle graph summarizes the results for the output polarization angle for each optic. The cube shows the most similar polarization angles between the reflected and transmitted beams, with the plate producing the largest difference in polarization between beams. The bottom right plot summarizes the results for the split ratio, as a fraction of input power, for the beamsplitters. Here it can be shown that the plate beamsplitter demonstrates the most ideal for 50/50 power splitting. For details on the experimental setup employed and the results summarized here, please click here.
Damage Threshold Specifications^{a}  

Split Ratio  Laser Type  Damage Threshold 
50:50  Pulse  0.25 J/cm^{2} (810 nm, 10 ns, 10 Hz, Ø0.166 mm) 
CW^{b}  10 W/cm (1070 nm, Ø1.012 mm) 
Damage Threshold Data for Thorlabs' 50:50 (R:T) NonPolarizing Cube Beamsplitters
The specifications to the right are measured data for Thorlabs' nonpolarizing cube beamsplitters with wavelength range from 700 to 1100 nm. Damage threshold specifications are constant for all coatings, regardless of the size of the beamsplitter.
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 scratchdig 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/DIS 11254 and ISO 21254 specifications.
First, a lowpower/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 BB1E02 mirror.
The photograph above is a protected aluminumcoated mirror after LIDT testing. In this particular test, it handled 0.43 J/cm^{2} (1064 nm, 10 ns pulse, 10 Hz, Ø1.000 mm) before damage.
Example Test Data  

Fluence  # of Tested Locations  Locations with Damage  Locations Without Damage 
1.50 J/cm^{2}  10  0  10 
1.75 J/cm^{2}  10  0  10 
2.00 J/cm^{2}  10  0  10 
2.25 J/cm^{2}  10  1  9 
3.00 J/cm^{2}  10  1  9 
5.00 J/cm^{2}  10  9  1 
According to the test, the damage threshold of the mirror was 2.00 J/cm^{2} (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 LongPulse 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, laserinduced 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.
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:
 Wavelength of your laser
 Beam diameter of your beam (1/e^{2})
 Approximate intensity profile of your beam (e.g., Gaussian)
 Linear power density of your beam (total power divided by 1/e^{2} 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 nonuniform 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):
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 ultrashortpulse regime various mechanics, such as multiphotonavalanche 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:
 Wavelength of your laser
 Energy density of your beam (total energy divided by 1/e^{2} area)
 Pulse length of your laser
 Pulse repetition frequency (prf) of your laser
 Beam diameter of your laser (1/e^{2} )
 Approximate intensity profile of your beam (e.g., Gaussian)
The energy density of your beam should be calculated in terms of J/cm^{2}. 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/e^{2} 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/cm^{2} at 1064 nm scales to 0.7 J/cm^{2} at 532 nm):
You now have a wavelengthadjusted 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:
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, LaserInduced 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.
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/e^{2} 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:
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 AC127030C 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:
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/e^{2}). The average energy density of each pulse is found by dividing the pulse energy by the beam area:
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/cm^{2}.
The energy density of the beam can be compared to the LIDT values of 1 J/cm^{2} and 3.5 J/cm^{2} for a BB1E01 broadband dielectric mirror and an NB1K08 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:
This adjustment factor results in LIDT values of 0.45 J/cm^{2} for the BB1E01 broadband mirror and 1.6 J/cm^{2} for the Nd:YAG laser line mirror, which are to be compared with the 0.7 J/cm^{2} 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/e^{2}) 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/cm^{2}. The damage threshold of an NDUV10A Ø25 mm, OD 1.0, reflective neutral density filter is 0.05 J/cm^{2} for 10 ns pulses at 355 nm, while the damage threshold of the similar NE10A absorptive filter is 10 J/cm^{2} 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:
This scaling gives adjusted LIDT values of 0.08 J/cm^{2} for the reflective filter and 14 J/cm^{2} 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 longpulse laser emits a Gaussian 12.7 mm diameter beam (1/e^{2}) 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/cm^{2} per pulse. This can be compared to the LIDT values for a WPQ10E980 polymer zeroorder quarterwave plate, which are 5 W/cm for CW radiation at 810 nm and 5 J/cm^{2} 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/cm^{2} 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 highpower CW beam.
Thorlabs offers a variety of mounting solutions for our beamsplitter cubes. The mounts below allow our cubes to be postmounted or integrated into our 16 mm or 30 mm cage systems. Postmountable solutions are compatible with our Ø1/2" Posts as well as Ø1" Posts with 832 (M4) taps.
PostMountable Mounts for Beamsplitter Cubes  

Click Photo to Enlarge (Cubes Not Included) 

Item #  PCM(/M)  BSH10(/M) BSH05(/M) BSH20(/M) BSH1(/M) BSH2(/M) 
FBTB(/M)  KM100PM(/M)  KM200PM(/M)  KM100B(/M)  KM200B(/M)  K6XS 
Required Accessories  Base: PCMP(/M)      Clamp: PM3(/M) or PM4(/M) 
Clamp: PM3(/M) or PM4(/M) 
Clamp: PM3(/M) or PM4(/M) 
Clamp: PM3(/M) or PM4(/M) 
Adapter: K6A1(/M) 
Mounting Options  Ø1/2" Posts  Ø1/2" Posts^{a,b}  Ø1/2" Posts  Ø1/2" Posts  Ø1/2" Posts  Ø1/2" Posts  Ø1/2" Posts  Ø1/2" Posts 
Features  Compact  Compact  GlueIn Mount with Precision Tip, Tilt, and Rotation  Tip and Rotation  Tip and Rotation  Kinematic Mount  Kinematic Mount  6Axis Mount 
Compatible Beamsplitter Cube Size(s) 
Up to 20 mm  10 mm, 1/2", 20 mm, 1", 2" 
5 mm  Up to 20 mm^{c} Up to 1" ^{d} 
Up to 20 mm^{c} Up to 1" ^{d} Up to 2" ^{e} 
Up to 20 mm^{c} Up to 1" ^{d} 
Up to 20 mm^{c} Up to 1" ^{d} Up to 2" ^{e} 
5 mm 10 mm 1/2" 
Cage System Mounts for Beamsplitter Cubes  

Click Photo to Enlarge (Cubes Not Included) 

Item #  Cage Cube: SC6W 
ARV1  CRM1(/M) or CRM1P(/M)  Cage Cube: C4W or C6W^{ a}  CCM14ER(/M)  CCM1A4ER(/M)  CCM1B4ER(/M)  CCM1C4ER(/M)  
Required Accessories  Clamp: SB6C, Platform: SPM2 
  Adapter: K6A1(/M) 
Clamp: B6C, Platform: B3C(/M) or B4C(/M) 
Clamp: B6C, Platform: B3CR(/M) or B4CRP(/M) 
       
Mounting Options 
16 mm Cage Systems  30 mm Cage Systems  30 mm Cage Systems or Ø1/2" Posts  30 mm Cage Systems  30 mm Cage Systems or Ø1/2" Posts  
Features  Compact  Compact  Rotation Mount  Fixed or Kinematic Platforms  Rotation Platforms    One Rotation Mount  Two Rotation Mounts @ 180°  Two Rotation Mounts @ 90° 
Compatible Beamsplitter Cube Size(s) 
10 mm  5 mm 10 mm 
5 mm 10 mm 1/2" 
1/2" 20 mm 1" 
5 mm (with BS5CAM Adapter) 10 mm (with BS10CAM Adapter) 1/2" (with BS127CAM Adapter) 20 mm (with BS20CAM Adapter) 1" (Directly Compatible) 
Posted Comments:  
Alex Karn
(posted 20240115 08:30:43.21) Does Beam Deviation (for transmitted and reflected beam) depends on wavelength? It looks than our BS014 whith 6501100 coating significantly deviate our 650nm beam from 1550nm beam (about 1 arcminute). jdelia
(posted 20240125 12:53:49.0) Thank you for contacting Thorlabs. Beam deviation is related to the change in refractive index of beams of different wavelengths passing through the optic. BS014 is designed for 7001100nm; the max deviation of transmitted beam and reflected beam will be 0° ± 5 arcmin and 90° ± 5 arcmin respectively. We recommend you use BS014 under the design wavelength range. The 650nm/1550nm is out of coating range and its performance will differ from lot to lot, so the phenomenon you observed is normal. Kevin Castrillón
(posted 20230518 12:41:14.963) I am using a beam splitter BS017. When the laser is directed along the marked input arrow, there are beams along all other three directions. Is this behavior normal? Is there any way to prevent the light to come out from the wrong output? jdelia
(posted 20230519 04:43:29.0) Thank you for contacting Thorlabs! Yes, this behavior is normal, the other direction light is caused by surface reflection, you can add a beam block or trap product to absorb this light, or install this BS017 to cage cube (for example, BS20CAM+CCM14ER), then add a cap (SM1CP1) to block light. user
(posted 20220426 17:01:38.293) Do you have data concerning the phase change in transmission for the nonpolarizing 50:50 7001100 nm beamsplitter? I would be interested in how well the initial polarization state of the light is preserved after passing through the cube? Thanks. cdolbashian
(posted 20220502 01:33:05.0) Thank you for contacting Thorlabs. We currently do not have data on the performance of these nonpolarizing cube beamsplitters in terms of phase change. Stepan V
(posted 20200827 06:52:25.593) Is the wavefront error specification valid for the reflected beam as well? llamb
(posted 20200902 11:29:29.0) Thank you for contacting Thorlabs and for your suggestion about the specs of reflected wavefront error. Currently the wavefront error spec is only valid for the transmitted beam, but we will consider adding a reflected wavefront error spec. Our Tech Support team will reach to you about looking into this spec further. user
(posted 20200206 08:43:16.587) Do you have a 1 inch size of 10:90 (R:T) NonPolarizing Beamsplitter Cube, 700  1100 nm? Thanks. llamb
(posted 20200213 08:49:56.0) Thank you for your feedback. Unfortunately we do not have a 1" version of this particular cube beamsplitter at this time, but I have added your suggestion to our internal product forum for further discussion. Vladimir Makarov
(posted 20190411 22:07:10.89) I am using BS044 beamsplitter. Can you provide estimate of the magnitude of reflections from the internal surfaces of the beamsplitter? For example, how much light will be reflected at ~650750nm wavelength when incident on internaltoexternal surface of the beam splitter?
Is the AR coating effective in this direction as well, or does it only guarantee low reflection (due to AR coating) when light is travelling from air into the glass? YLohia
(posted 20190429 11:07:07.0) Hello, thank you for contacting Thorlabs. The AR coating is effective in this direction of travel as well. The reflectivity on the exit surface of the beamsplitter cube will be ~0.25% due to the AR coating. martin.gersing
(posted 20181107 12:43:11.177) In the Damage ThresholdsTab for the NonPolarizing Beam Splitter Cubes (7001100nm) the maximum cwPower Density is given with 10W/cm. However for the same Beam Splitter Cubes with other ARCoatings (400700nm and 11001600nm) this Damage Threshold is significantly higher with 150W/cm.
Is this difference only due to the ARCoating, or is this maybe just a typo?
Best regards and thanks in advance. YLohia
(posted 20190131 09:23:42.0) Hello, thank you for your feedback. Both of these damage thresholds are correct. There are a couple of reasons for the discrepancy : more absorption in these regions or due to heat dissipation issues (because of differentlysized samples). h.wu
(posted 20170607 10:19:22.77) Is it possible to help us permanently mount BS029 to the 1" beamsplitter cube (like CCM1BS014/M)? Please include engravings mark (the directions of light propagation) on the outside surface of the cube. Thanks nbayconich
(posted 20170614 10:26:03.0) Thank you for contacting Thorlabs. I will reach out to you directly about offering the BS029 mounted in a cage cube as a special item. m.c.ashby
(posted 20151110 00:31:03.903) Can these splitter cubes be used in reverse to combine two beams (ie one beam incident on the cement side of the beamsplitting interface)? If so, would you still expect a 50:50 attenuation of the power (from a the 50:50 cube)? Thanks smcelwee
(posted 20151116 11:45:36.0) Response from Sean M at Thorlabs: Thank you for your inquiry. These 50:50 beam splitters can also be used in reverse to combine two beams. The coating will be a 50:50 split going in both directions, so you would expect 50% power loss from each of the incident beams.
The most feasible way to combine two beams and keep their power is using a polarizing beam splitter in reverse. However, this requires each input beam to already be linearly polarized. art471
(posted 20140611 19:05:36.06) In the case of Michelson Interferometer using BS029,I'm wondering final intensity ratio of two arms at detector. A beam transmitting at the BS029 will be reflected back by a mirror in the interferometer. Then the beam reflected by the mirror will be reflected by the BS029 to head to detector. In this case, what about the remained intensity of the beam arrived at the detector? Thanks. besembeson
(posted 20140730 06:37:42.0) Response from Bweh at Thorlabs: The intensity ratio will be ~1 assuming the reflectivity of both mirrors is the same. This is because when these combine, it will be 10% of 90% and 90% of 10% of original intensity. adrien.nicolas
(posted 20130301 12:20:41.18) Having tested three 50:50 BS (ref BS005 and BS014) in my lab with 852 nm light, I found them to exhibit the following features: 55% transmission and 36% reflection (9% losses). I tested all four input faces, with any input polarization angle (the transmission and reflection ratios are indeed very well polarization independant) at different angles of incidence and found always the same ratios (up to <2% variations). This seems to be quite far from the specified 50:50 splitting ratio (anyway it is not suitable for interferometric applications where the outputs need carefull balancing). Is this compatible with the guaranteed tolerance on R and T coefficients ? Can you provide NPBS cubes designed to have well balanced outputs at a specified wavelength ?
Thanks in advance tcohen
(posted 20130307 15:27:00.0) Response from Tim at Thorlabs: The specifications for these beamsplitters are Tabs=50+/15%, Rabs=50+/15%, Tabs+Rabs>90%, TsTp<15% and RsRp<15%, 7001100nm, 0deg AOI as indicated on the drawings. We will update the website to remove any ambiguity in the wording there may currently be. The split ratio will vary with wavelength and I will contact you to discuss solutions for your wavelength directly. tcohen
(posted 20130102 09:39:00.0) Response from Tim at Thorlabs: Although no timeline for this release exists as of yet, we do have this product in development. The complexity of this design is slightly higher than the rest of the products on this page. While an ideal design is being developed we are able to offer the 90:10 (R:T) Cube Beamsplitter (BS029) as a possible alternative. We will increase the priority of this product as a result of your request and inform you upon its release. gediminas.juska
(posted 20121217 16:32:50.987) Are you planning to produce 10:90 (R:T) nonpolarizing beamsplitter? What would be the aproximate price of such a custom made element? jlow
(posted 20120830 08:18:00.0) Response from Jeremy at Thorlabs: At larger AOIs, one would typically see a slightly larger polarization dependence and slightly lower polarization dependence at lower AOIs. With that in mind, if you have unpolarized light, then the transmission will be slightly higher at lower (and vice versa). franxm
(posted 20120824 14:00:28.0) How is the transmission affected by incident angle (e.g., 45+15 to 4515 deg)?
Thanks,
Fran dgardner
(posted 20120703 12:19:00.0) A response from Dave at Thorlabs to cc375: Thank you for pointing out this error. The specs tab now correctly lists the R:T ratio of each cube, which is consistent with the rest of this page. cc375
(posted 20120703 08:36:15.0) You've listed the T/R ratios wrong. On the 'Specs' tab you've shown the BS020 as 30% transmission whereas the 'BS Selection Guide' shows 70% transmission for this cube. 
Beamsplitter Selection Guide
Thorlabs' portfolio contains many different kinds of beamsplitters, which can split beams by intensity or by polarization. We offer plate and cube beamsplitters, though other form factors exist, including pellicle and birefringent crystal. For an overview of the different types and a comparison of their features and applications, please see our overview. Many of our beamsplitters come in premounted or unmounted variants. Below is a complete listing of our beamsplitter offerings. To explore the available types, wavelength ranges, splitting/extinction ratios, transmission, and available sizes for each beamsplitter category, click More [+] in the appropriate row below.Plate Beamsplitters
NonPolarizing Plate Beamsplitters 

Polarizing Plate Beamsplitters 

Cube Beamsplitters
NonPolarizing Cube Beamsplitters 

Polarizing Cube Beamsplitters 

Pellicle Beamsplitters
NonPolarizing Pellicle Beamsplitters 

Crystal Beamsplitters
Polarizing Crystal Beamsplitters 

Other
Other Beamsplitters 

The data above is relative to the power of the incident beam. Note that some light will be absorbed by the beamsplitter coating. The blue shaded regions denote the transmission and reflection bands for which the performance is guaranteed to meet the stated specifications. The data shown here is typical and runtorun variations will occur within the given specifications. Performance outside the shaded regions is not guaranteed.
Item #  BS035  BS038  BS041  BS044  BS026 

Cube Side Length  5 mm  10 mm  1/2" (12.7 mm)  20 mm  1" (25.4 mm) 
Clear Aperture  >3.5 x 3.5 mm  >8.0 x 8.0 mm  >10.2 x 10.2 mm  >16.0 x 16.0 mm  >20.3 x 20.3 mm 
Transmitted Wavefront Error^{a} 
<λ/4  
Transmitted Beam Deviation 
0° ± 5 arcmin  
Overall Performance^{b} 
T_{abs} = 87 ± 10%, R_{abs} = 7 +10/7%, T_{abs} + R_{abs} > 85%, T_{s}  T_{p} < 10%, and R_{s}  R_{p} < 10% 
T_{abs} = 87 ± 10%, R_{abs} = 7 +10/5%, T_{abs} + R_{abs} > 85%, T_{s}  T_{p} < 10%, and R_{s}  R_{p} < 10% 
T_{abs} = 87 ± 10%, R_{abs} = 7 +10/7%, T_{abs} + R_{abs} > 85%, T_{s}  T_{p} < 10%, and R_{s}  R_{p} < 10% 
T_{abs} = 87 ± 10%, R_{abs} = 7 +10/5%, T_{abs} + R_{abs} > 85%, T_{s}  T_{p} < 10%, and R_{s}  R_{p} < 10% 
The data above is relative to the power of the incident beam. Note that some light will be absorbed by the beamsplitter coating. The blue shaded regions denote the transmission and reflection bands for which the performance is guaranteed to meet the stated specifications. The data shown here is typical and runtorun variations will occur within the given specifications. Performance outside the shaded regions is not guaranteed.
Item #  BS047  BS050  BS053  BS080  BS020 

Cube Side Length  5 mm  10 mm  1/2" (12.7 mm)  20 mm  1" (25.4 mm) 
Clear Aperture  >3.5 x 3.5 mm  >8.0 x 8.0 mm  >10.2 x 10.2 mm  >16.0 x 16.0 mm  >20.3 x 20.3 mm 
Transmitted Wavefront Error^{a} 
<λ/4  
Transmitted Beam Deviation  0° ± 5 arcmin  
Overall Performance^{b}  T_{abs} = 62 ± 10%, R_{abs} = 27 ± 10%, and T_{abs} + R_{abs} > 80%, T_{s}  T_{p} < 10% and R_{s}  R_{p} < 10% 
The data above is relative to the power of the incident beam. Note that some light will be absorbed by the beamsplitter coating. The blue shaded regions denote the transmission and reflection bands for which the performance is guaranteed to meet the stated specifications. The data shown here is typical and runtorun variations will occur within the given specifications. Performance outside the shaded regions is not guaranteed.
Item #  BS008  BS011  BS005  BS017  BS014  BS032 

Cube Side Length  5 mm  10 mm  1/2" (12.7 mm)  20 mm  1" (25.4 mm)  2" (50.8 mm) 
Clear Aperture  >3.5 x 3.5 mm  >8.0 x 8.0 mm  >10.2 x 10.2 mm  >16.0 x 16.0 mm  >20.3 x 20.3 mm  >40.6 x 40.6 mm 
Transmitted Wavefront Error^{a} 
<λ/4  <λ  
Transmitted Beam Deviation  0° ± 5 arcmin  
Overall Performance^{b}  T_{abs} = 47 ± 10%, R_{abs} = 47 ± 10%, and T_{abs} + R_{abs} > 90%, T_{s}  T_{p} < 10% and R_{s}  R_{p} < 10% 
T_{abs}= 47 ± 10%, R_{abs}= 47 ± 10%, T_{abs} + R_{abs} > 85% T_{avg} + R_{avg }> 90% T_{s}  T_{p} < 10% and R_{s}  R_{p} < 10% 

Damage Threshold 
Pulsed: 0.25 J/cm^{2} (810 nm, 10 ns, 10 Hz, Ø0.166 mm) CW^{c}: 10 W/cm (1070 nm, Ø1.012 mm) 
The data above is relative to the power of the incident beam. Note that some light will be absorbed by the beamsplitter coating. The blue shaded regions denote the transmission and reflection bands for which the performance is guaranteed to meet the stated specifications. The data shown here is typical and runtorun variations will occur within the given specifications. Performance outside the shaded regions is not guaranteed.
Item #  BS056  BS059  BS062  BS065  BS023 

Cube Side Length  5 mm  10 mm  1/2" (12.7 mm)  20 mm  1" (25.4 mm) 
Clear Aperture  >3.5 x 3.5 mm  >8.0 x 8.0 mm  >10.2 x 10.2 mm  >16.0 x 16.0 mm  >20.3 x 20.3 mm 
Surface Flatness^{a}    λ/10  
Transmitted Wavefront Error^{a} 
<λ/4  
Transmitted Beam Deviation  0° ± 5 arcmin  <5 arcmin  
Overall Performance^{b}  T_{abs} = 27 ± 10%, R_{abs} = 67 +5/15%, and T_{abs} + R_{abs} > 85%, T_{s}  T_{p} < 10% and R_{s}  R_{p} < 10% 
The data above is relative to the power of the incident beam. Note that some light will be absorbed by the beamsplitter coating. The blue shaded regions denote the transmission and reflection bands for which the performance is guaranteed to meet the stated specifications. The data shown here is typical and runtorun variations will occur within the given specifications. Performance outside the shaded regions is not guaranteed.
Item #  BS068  BS071  BS074  BS077  BS029 

Cube Side Length  5 mm  10 mm  1/2" (12.7 mm)  20 mm  1" (25.4 mm) 
Clear Aperture  >3.5 x 3.5 mm  >8.0 x 8.0 mm  >10.2 x 10.2 mm  >16.0 x 16.0 mm  >20.3 x 20.3 mm 
Transmitted Wavefront Error^{a} 
<λ/4  
Transmitted Beam Deviation  0° ± 5 arcmin  
Overall Performance^{b}  T_{abs} = 7 +10/5%, R_{abs} = 87 ± 10%, and T_{abs} + R_{abs} > 85%, T_{s}  T_{p} < 10% and R_{s}  R_{p} < 10% 