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.
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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.
UV Fused Silica Transmission, Index of Refraction, and Brewster's 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.
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.
Click to Enlarge This graph shows the calculated index of refraction of UV fused silica as a function of wavelength.
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:
Please note that that the wavelength needs to be in microns when using the formula above. Brewster's angle is given by
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.
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 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
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
Please note that that the wavelength needs to be in microns when using the formula above.
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, clickMore [+] in the appropriate row below.
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 #
Compatible Brewster Window
Brewster Window Item #
Ø1/2" Smooth Bore
Ø1" Smooth Bore
The mounting surface is the surface for attaching a Brewster window mount to a kinematic mount or other optomechanical device.