The Brewster window is usually used to polarize the laser cavity. When placed at the Brewster angle, the P polarization component of the beam will be completely transmitted, and the S polarization component will be partially reflected, thereby increasing the loss of the S component in the cavity.
| Material | BK7 or UV fused silica |
| Diameter Tolerance | +0/-0.15mm |
| Thickness Tolerance | ±0.25mm |
| Clear Aperture | ＞Central 85% of diameter |
| Parallelism | ＜5″ |
| Surface Quality | 20/10 |
| Transmitted Wavefront | λ/10 @632.8nm |
| Brewster Angle (θ) | 56.6° @588nm（BK7）
56.1° @308nm（UVFS） |
| Chamfers | ＜0.35mm face width ×45° |