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Brewster Windows


  • Uncoated UV Fused Silica Brewster Windows
  • Parallelism: ≤5 arcsec
  • Zero Reflection Loss for P-Polarized Light

BW0801

BW1602

BW0601

BW2502

Related Items


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UVFS Brewster Angle
Click to Enlarge

This graph shows the calculated reflectance of uncoated UV fused silica for polarized light at various angles of incidence. The reflectance for P-polarized light goes to zero at Brewster's angle.
Optic Cleaning Tutorial
Zemax Files
Click on the red Document icon next to the item numbers below to access the Zemax file download. Our entire Zemax Catalog is also available.

Features

  • Ideal for Laser Cavities
  • UV Fused Silica Substrate
  • Available Minor Diameters: 6 mm, 8 mm, 13 mm, 16 mm, 20 mm, and 25 mm
  • P-Polarized Light is Transmitted without Reflection Losses
  • Brewster Window Mounts Available

Brewster Windows are uncoated substrates that can be used in series as polarizers, or to clean up a partially polarized beam. When positioned at Brewster's Angle, the p-polarized component of the light enters and exits the window without reflection losses, while the s-polarized component is partially reflected. The graph to the right shows reflectance for both s- and p-polarization through UV fused silica at 633 nm. The 20-10 scratch-dig surface quality and λ/10 transmitted wavefront error of our Brewster windows make them an ideal choice for laser cavities.

These Brewster windows are manufactured from UV fused silica, which exhibits virtually no laser-induced fluorescence (as measured at 193 nm), making it an ideal choice for applications from the UV to the near IR; please see the Graphs tab for a transmission plot of UV fused silica. Since the index of refraction of UV fused silica varies with wavelength, Brewster's angle is wavelength dependent; the Graphs tab also contains details on this dependence.

We offer mounting options for 8 mm, 13 mm, 16 mm, 20 mm, and 25 mm minor diameter Brewster windows. These mounts are engineered with a 55° 32’ mounting angle (Brewster’s Angle at 633 nm) with an exit port for the reflected s-polarized light so that the mount may be used in either direction.

In addition to Brewster windows, Thorlabs also offers High Precision Windows, Narrowband Laser Windows, and a complete line of polarization optics.

UV Fused Silica Transmission, Index of Refraction, and Brewster's Angle

UVFS Brewster Angle
Click to Enlarge

This graph shows the calculated reflectance of uncoated UV fused silica for polarized light as a function of angle of incidence. The reflectance for P-polarized light goes to zero at Brewster's angle.
UVFS Transmission
Click to Enlarge

This graph shows the transmission of a 1 mm thick UV fused silica sample, including surface reflections, with the incident light normal to the surface.
UVFS Index of Refraction
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This graph shows the calculated index of refraction of UV fused silica as a function of wavelength.
Brewster Angle for Air to UVFS
Click to Enlarge

This graph shows the calculated value of Brewster's angle as a function of wavelength when light is passing from air to UV fused silica.

The index of refraction for UV fused silica is wavelength dependent, as shown in the graph above, and expressed by the following formula:

Index of Refraction for Fused Silica wavelength dependency.

Please note that that the wavelength needs to be in microns when using the formula above. Brewster's angle is given by

Brewster's Angle Equation.

Here, θB is Brewster's angle, ni is the index of refraction of the incident medium (1.0003 for air), and nt is the index of refraction of the transmitting medium (1.45701 for fused silica at 633 nm). Hence, Brewster's angle also displays a wavelength dependence, as shown in the plot above.

Polarization through a Brewster Window
The image above shows the reflection of s-polarized light and transmission of p-polarized light through a Brewster window. Some s-polarized light will be transmitted through the window.

Brewster Windows

Brewster windows are typically used as polarizers within laser cavities. When positioned at Brewster's angle (55° 32' at 633 nm), the p-polarized portion of the light will pass through the window with no losses, while a fraction of the s-polarized portion will be reflected off the Brewster window. When used in a laser cavity, the Brewster window essentially acts as a polarizer.

Brewster's angle is given by

Brewster's Angle Equation

θB is Brewster's angle.
ni is the index of refraction of the incident medium, which is 1.0003 for air.
nt is the index of refraction of the transmitting medium, which is 1.45701 for fused silica at 633 nm

It should be noted that the index of refraction is wavelength dependent. For fused silica, the index of refraction can be expressed as

Index of Refraction for Fused Silica wavelength dependency.

Please note that that the wavelength needs to be in microns when using the formula above.


Posted Comments:
Ramon.alvarez  (posted 2018-05-14 20:58:04.127)
What is the roughness of you elliptical Brewster windows?
YLohia  (posted 2018-05-15 10:10:42.0)
Hello, thank you for contacting Thorlabs. While we do not have an official specification for the surface roughness for these units, it is typically on the order of < 5 Å.
dt_m0hammed_temimi  (posted 2016-08-21 11:19:12.747)
please I need a brewster window with amount using with intracavity Nd:YAG laser
jlipa  (posted 2013-10-25 14:36:32.427)
I need some Brewster windows like BW1602, but made from IR grade fused silica. Can you supply them?
tcohen  (posted 2013-10-29 13:11:00.0)
Response from Tim at Thorlabs: Yes, we can quote this. We will contact you to discuss your requirements.
jack  (posted 2009-05-26 15:21:13.0)
Response from Jack at Techsupport: If you look at the surface at 0 deg. then youll see a circular surface, at any other angle the surface will appear to be elliptical. The models are fine but the front view in drawing needs to be corrected. Optic department has been informed.
csandberg  (posted 2009-05-26 05:24:03.0)
The solid model for these brewster windows seem to be wrong. The flat surfaces of the window should be elliptical when viewed perpendicular, and circular when viewed from the brewster angle. PS. Also see Lars Sandtroms comment on BW0601 earlier. It goes for all windows in this section.
lsandstrom  (posted 2009-05-26 02:34:45.0)
BW0601 seems to be associated with the wrong SolidWorks model. The front surface of the model is circular in the Solid model while elliptical on the real device.
Laurie  (posted 2009-05-01 13:36:20.0)
Response from Laurie at Thorlabs to egualda: Thank you for your interest in our Brewster Windows. At this time, we do not carry a standard mount for these optics. However, I have emailed a member of our mechanics unit to see if he has any ideas that we can share with you or any previous prototypes that may work.
egualda  (posted 2009-04-30 11:16:20.0)
Do you have any spetial holder for the following item: BW0801 Brewster Window, 8mm diameter 1 mm thickness?

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. 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.

Non-Polarizing Beamsplitters

Plate Beamsplitters
Cube Beamsplitters
Pellicle Beamsplitters
  • 45° AOI Unless Otherwise Noted

Polarizing Beamsplitters

Plate Beamsplitters
Cube Beamsplitters
Birefringent Crystal Beamsplitters
  • Mounted in a protective box, unthreaded ring, or cylinder.
  • Available unmounted or mounted in a protective box or unthreaded cylinder.

Other Beamsplitters

Other Beamsplitters

UV Fused Silica Brewster Windows, Uncoated

Item # BW0601 BW0801 BW0802 BW1302 BW1602 BW2002 BW2502
Minor Diameter  6.0 mm 8.0 mm 8.0 mm 13.0 mm 16.0 mm 20.0 mm 25.0 mm
Minor Diameter Tolerance +0.00 / -0.10 mm
Thickness 1.0 mm 2.0 mm
Thickness Tolerance ±0.1 mm ±0.2 mm ±0.1 mm
Brewster Angle 55° 32' @ 633 nm
Clear Aperture >90% of Minor Axis
Parallelism ≤5 arcsec
Transmitted Wavefront Errora <λ/10
Surface Quality 20-10 Scratch-Dig
Wavelength Range 185 nm - 2.1 μm (Uncoated)
Substrate UV Fused Silicab
Transmission Data
  • Measured at 633 nm
  • Click Link for Detailed Specifications on the Substrate
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
BW0601 Support Documentation
BW0601UVFS Brewster Window, 6.0 mm Minor Diameter, 1.0 mm Thick
$65.14
Today
BW0801 Support Documentation
BW0801UVFS Brewster Window, 8.0 mm Minor Diameter, 1.0 mm Thick
$82.21
Today
BW0802 Support Documentation
BW0802UVFS Brewster Window, 8.0 mm Minor Diameter, 2.0 mm Thick
$100.60
Today
BW1302 Support Documentation
BW1302UVFS Brewster Window, 13.0 mm Minor Diameter, 2.0 mm Thick
$107.16
Today
BW1602 Support Documentation
BW1602UVFS Brewster Window, 16.0 mm Minor Diameter, 2.0 mm Thick
$113.46
Today
BW2002 Support Documentation
BW2002Customer Inspired! UVFS Brewster Window, 20.0 mm Minor Diameter, 2.0 mm Thick
$123.97
Today
BW2502 Support Documentation
BW2502Customer Inspired! UVFS Brewster Window, 25.0 mm Minor Diameter, 2.0 mm Thick
$135.53
Today

Brewster Window Mounts

BW25M with SM1P1 Adapter mounted in a KS1RS
Click to Enlarge
View Imperial Product List
Item #QtyDescription
BW25021UVFS Brewster Window, 25.0 mm Minor Diameter, 2.0 mm Thick
BW25M1Brewster Window Mount, 25 mm Minor Axis Length, 2 mm Thick Optic
KS1RS1Kinematic Rotation Mount for Ø1" Optics
TR41Ø1/2" Optical Post, SS, 8-32 Setscrew, 1/4"-20 Tap, L = 4"
View Metric Product List
Item #QtyDescription
BW25021UVFS Brewster Window, 25.0 mm Minor Diameter, 2.0 mm Thick
BW25M1Brewster Window Mount, 25 mm Minor Axis Length, 2 mm Thick Optic
KS1RS1Kinematic Rotation Mount for Ø1" Optics
TR100/M1Ø12.7 mm Optical Post, SS, M4 Setscrew, M6 Tap, L = 100 mm
BW2502 Brewster Window in BW25M Mount with a KS1RS Kinematic Rotation Mount

These Brewster Window Optic Mounts are designed with steel flexure retention plates for holding the optics in place. The mounts feature a separate mounting surface for compatibility with Ø1/2" or Ø1" smooth bore mounts or internally SM1-threaded components. The exit port for the reflected s-polarized light allows the mount to be used in either direction. For more information, please see our full presentation here

Brewster Window Mount Item # Mounting Surfacea Compatible Brewster Window
Minor Diameter Thickness Brewster Window Item #
BW08M1 Ø1/2" Smooth Bore 8 mm 1 mm BW0801
BW08M2 8 mm 2 mm BW0802
BW13M Ø1" Smooth Bore 13 mm 2 mm BW1302
BW16M 16 mm 2 mm BW1602
BW20M 20 mm 2 mm BW2002
BW25M External SM1 25 mm 2 mm BW2502
  • The mounting surface is the surface for attaching a Brewster window mount to a kinematic mount or other optomechanical device.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
BW08M1 Support Documentation
BW08M1Brewster Window Mount, 8 mm Minor Axis Length, 1 mm Thick Optic
$72.10
Today
BW08M2 Support Documentation
BW08M2Brewster Window Mount, 8 mm Minor Axis Length, 2 mm Thick Optic
$72.10
Today
BW13M Support Documentation
BW13MBrewster Window Mount, 13 mm Minor Axis Length, 2 mm Thick Optic
$72.20
Today
BW16M Support Documentation
BW16MBrewster Window Mount, 16 mm Minor Axis Length, 2 mm Thick Optic
$77.25
Today
BW20M Support Documentation
BW20MBrewster Window Mount, 20 mm Minor Axis Length, 2 mm Thick Optic
$77.25
Today
BW25M Support Documentation
BW25MBrewster Window Mount, 25 mm Minor Axis Length, 2 mm Thick Optic
$87.55
Today
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