NonPolarizing Cube Beamsplitters (1100  1600 nm)
 Beamsplitter Coating for 1100  1600 nm
 10:90, 30:70, 50:50, 70:30, or 90:10 (R:T) Split Ratio
 AR Coating on Both Input and Output Faces
BS009
5 mm
BS006
1/2"
Engravings Mark the Direction
of Light Propagation
BS024
1"
BS033
2"
1" Beamsplitter Cube Mounted Directly to Breadboard Using BSH1 Prism Mount
Please Wait
General Specifications  

Wavelength Range  1100  1600 nm  
AR Coating (All Four Surfaces, Click for Plot) 
R_{avg} < 0.5% at 0° AOI from 1100  1600 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
1" Beamsplitter Cube Shown in C6WR Cage Cube with B4CRP Rotation Platform and B6C Clamp
(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 1100  1600 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 1100  1600 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  1100  1600 nm  
AR Coating (All Four Surfaces, Click for Plot)  R_{avg} < 0.5% at 0° AOI from 1100  1600 nm  
Substrate Material  NBK7^{a}  
Dimensional Tolerance  +0.0/0.2 mm  
Reflected Beam Deviation  90° ± 5 arcmin  
Surface Quality  4020 ScratchDig 
Item #  Size  Transmitted Wavefront Error (@ 633 nm) 
Transmitted Beam Deviation 
Overall Performance^{b} 

10:90 (R:T) Split Ratio  
BS036^{a}  5 mm Cube  <λ/4  0° ± 5 arcmin  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% 
BS039  10 mm Cube  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% 

BS042  1/2" (12.7 mm Cube)  
BS045  20 mm Cube  
BS027  1" (25.4 mm) Cube  
30:70 (R:T) Split Ratio  
BS048^{a}  5 mm Cube  <λ/4  <5 arcmin  T_{abs} = 62 ± 10%, R_{abs} = 27 ± 10%, T_{abs} + R_{abs} > 80%, T_{s}  T_{p} < 10%, and R_{s}  R_{p} < 10% 
BS051  10 mm Cube  
BS054  1/2" (12.7 mm Cube)  
BS081  20 mm Cube  
BS021  1" (25.4 mm) Cube  0° ± 5 arcmin  
50:50 (R:T) Split Ratio  
BS009^{a}  5 mm Cube  <λ/4  0° ± 5 arcmin  T_{abs} = 47 ± 10%, R_{abs} = 47 ± 10%, T_{abs} + R_{abs} > 83%, T_{avg} + R_{avg} > 88%, T_{s}  T_{p} < 10%, and R_{s}  R_{p} < 10% 
BS012  10 mm Cube  
BS006  1/2" (12.7 mm) Cube  
BS018  20 mm Cube  
BS015  1" (25.4 mm) Cube  
BS033  2" (50.8 mm) Cube  <λ  T_{abs}= 47 ± 10% and R_{abs}= 47 ± 10% (1100  1390 nm and 1430  1600 nm) T_{abs} = 45 ± 10% and R_{abs} = 45 ± 10% (1390  1430 nm) T_{abs} + R_{abs} > 75%, T_{avg} + R_{avg} > 85%, T_{s}  T_{p} < 10%, and R_{s}  R_{p} < 10% 

70:30 (R:T) Split Ratio  
BS057^{a}  5 mm Cube  <λ/4  <5 arcmin  T_{abs} = 27 ± 10%, R_{abs} = 67 +5/15%, T_{abs} + R_{abs} > 85%, T_{s}  T_{p} < 10%, and R_{s}  R_{p} < 10% 
BS060  10 mm Cube  
BS063  1/2" (12.7 mm Cube)  
BS066  20 mm Cube  
BS024  1" (25.4 mm) Cube  
90:10 (R:T) Split Ratio  
BS069^{a}  5 mm Cube  <λ/4  0° ± 5 arcmin  T_{abs} = 7 +10/5%, R_{abs} = 87 ± 10%, T_{abs} + R_{abs} > 85%, T_{s}  T_{p} < 10%, and R_{s}  R_{p} < 10% 
BS072  10 mm Cube  
BS075  1/2" (12.7 mm Cube)  
BS078  20 mm Cube  
BS030  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  Pulsed  0.25 J/cm^{2} (1542 nm, 10 ns, 10 Hz, Ø0.282 mm) 
C^{}W^{b}  50 W/cm (1542 nm, Ø1.030 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 1100 to 1600 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:  
Kimhan Tan
(posted 20230810 13:30:33.893) Hi Thorlab team, I am using nonpolarized BS018 to split Red light (633nm) and IR (1310nm). As per checked in the BS018 raw data. The transmitivity T and reflectivity R for Ppolarization and Spolarization are as follow,
Source P(T) P(R) S(T) S(R)
Red (633nm) 33.7% 21.4% 19.2% 36.5%
IR (1310nm) 47.1% 46.7% 50.8% 42.7%
In my optical system, transmition and reflection are taking place, therefore my Red light and IR light will only remain about 7.0  7.2% and 21.7  22.0%, respectively, at the detector.
My question is, is there any beamsplitter replacement that can achieve nearly 50% transmission and 50% reflection (split ratio of 50:50) on Red light (633nm) and IR (1310nm)?
Thanks. cdolbashian
(posted 20230816 11:51:02.0) Thank you for reaching out to us with this inquiry. In this case, I think the best choice for this broad wavelength range would be a polkadot beamsplitter, as none of our dielectriccoated beamsplitters can produce a 50:50 split for these wavelengths simultaneously. Andreas Baum
(posted 20220125 03:14:47.01) Good morning,
is there a way to integrate a BS033 2" beamsplitter cube into a 60mm cage system so that it is aligned with the cage system?
Best regards
Andreas Baum jdelia
(posted 20220131 02:10:55.0) Thank you for contacting Thorlabs. Depending on how you are willing to mount your 2" beamsplitter cube, we may have some solutions for you. I have contacted you directly to discuss your application further. Héctor Álvarez
(posted 20220119 02:06:41.703) Good morning,
I am using a BS042 10:90 (R:T) to split a linearly polarized laser at 1396 nm. In principle, this nonpolarizing cubes have a minimal polarization depende but this is not what I observe in reflexion. The R port changes the output power drastically when the linear polarization is changed with a halfwave plate before the cube. Additionally, in the best case scenario, for this R port I get around 2 % of the incident power (never the 10%). Is this behaviour correct? Any piece of advice? Could you please provide me with an explanation?
Thanks in advance,
Héctor YLohia
(posted 20220120 03:03:16.0) Thank you for contacting Thorlabs. As stated in the spec sheet, the overall performance over the 11001600 nm coating range (0° AOI) is : T_abs = 87 ± 10%, R_abs = 7 +10/7%, and (T_abs + R_abs) > 85%, Ts  Tp < 10% and Rs  Rp < 10%", where R_abs= 7 +10/7%. The behavior you observed is normal for the BS042. The typical reflectance data for the 10:90 BS cubes can be found here:
https://www.thorlabs.com/images/TabImages/NPBS_IR_1090_Reflectance_G2780.gif. The reflectance data for ~1396 nm is indeed low. user
(posted 20191128 13:54:11.517) I would like to know what is the biggest ratio you can achieve in a beamsplitter. Can you achieve 991 or lower? nbayconich
(posted 20191211 02:39:43.0) Thank you for contacting Thorlabs, after evaluation a split ratio greater than 99:1 is beyond our current design capabilities. We apologies that we could not provide this at the moment, and we thank you for your feedback.
For your current application, will stacking two BS with a 90:10 ratio be a possible solution for you?
For example, use two CCM1BS015 and one CM1CC together. The other possible option is to use beam samplers such as BSF10C, which will provide approximately 1% reflection with a 45° angle of incidence and a PPolarized light field. jeremy.hulin2
(posted 20181017 13:06:41.647) Dear Thorlabs, I want to use the beam splitter BS030 with a 5W CW laser with a diameter of 3mm. Will it handle the beam ? Thanks YLohia
(posted 20181025 09:43:35.0) Hello, the beamsplitter coating on this can typically only withstand powers in the few mW region. Thus, we don't recommend this beamsplitter for your application. y.s.yong
(posted 20171204 17:52:55.677) Hi, could you please provide the typical reflection (%) curves for the beam splitters within 9002100 nm wavelength range (particularly BS030)? Thank you. nbayconich
(posted 20171208 04:32:31.0) Thank you for contacting Thorlabs. I will reach out to you directly with reflection curves for the BS030 beamsplitter. ekocabas
(posted 20160710 07:18:14.24) Do you have specs/graphs for the change in output polarization angle for the reflected and transmitted beams as a function of wavelength in the range 11001600 nm for the BS015 beam splitter cube? tcohen
(posted 20120906 10:39:00.0) Response from Tim at Thorlabs: We are able to manufacturer smaller sizes and I have contacted you to discuss your requirements. As for damage thresholds, typically lower wavelengths will reduce the damage threshold of an optic and a longer pulse length with increase it. Our “Damage Threshold” tutorial linked to this page explains more on relating our values for use with different parameters. That being said your energy density is lower than where we would expect to see damage. As always, make sure that the optic is kept clean and the surface quality is maintained to have the best performance. paul.taylor
(posted 20120831 08:13:51.0) I am considering buying a BS015 cube. I am working with a 1mJ pulse in a 0.45 cm (1e^2) radius beam of 1064 nm light in a Gaussian profile with a 100 ns pulse duration. Given that the fluence is only 1.6mJ/cm^2  do you think it would be OK from a damage threshold standpoint  given that we are a long way from the specified parameters? jikim
(posted 20120830 17:58:40.0) Could you manufacture a small size of the "BS024" and the "BS030", e.g. 5 mm or 10 mm? 
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 and Polyhedron 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 #  BS036  BS039  BS042  BS045  BS027 

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% 
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 #  BS048  BS051  BS054  BS081  BS021 

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  <5 arcmin  0° ± 5 arcmin  
Overall Performance^{b}  T_{abs} = 62 ± 10%, R_{abs} = 27 ± 10%, 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 #  BS009  BS012  BS006  BS018  BS015  BS033 

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  >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%, T_{abs} + R_{abs} > 83%, T_{avg} + R_{avg} > 88%, T_{s}  T_{p} < 10%, and R_{s}  R_{p} < 10% 
T_{abs}= 47 ± 10% and R_{abs}= 47 ± 10% (1100  1390 nm and 1430  1600 nm) T_{abs} = 45 ± 10% and R_{abs} = 45 ± 10% (1390  1430 nm) T_{abs} + R_{abs} > 75%, T_{avg} + R_{avg }> 85%, T_{s}  T_{p} < 10%, and R_{s}  R_{p} < 10% 

Damage Threshold 
Pulsed: 0.25 J/cm^{2} (1542 nm, 10 ns, 10 Hz, Ø0.282 mm) CW^{c}: 50 W/cm (1542 nm, Ø1.030 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 #  BS057  BS060  BS063  BS066  BS024 

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  <5 arcmin  
Overall Performance^{b}  T_{abs} = 27 ± 10%, R_{abs} = 67 +5/15%, 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 #  BS069  BS072  BS075  BS078  BS030 

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%, T_{abs} + R_{abs} > 85%, T_{s}  T_{p} < 10%, and R_{s}  R_{p} < 10% 