Micro Accuracy Penta Prism Stable 90 Degree Beam Deflection
Penta Prisms are precision optical prisms designed to deflect light by exactly 90° without inverting or reversing the image. Unlike mirrors, their unique five-sided geometry eliminates alignment sensitivity, ensuring stable performance in demanding optical systems.
Feature:
- Fixed 90° beam deflection independent of prism alignment
- Image remains erect and unreversed for accurate optical guidance
- Superior surface flatness and sub-micron polishing reduce distortion and loss
- High transmission with AR coatings or custom coatings across UV, Visible, and NIR ranges
- Custom sizes and geometries available for integration into compact or high-precision systems
Application: Surveying instruments, rangefinders, laser alignment, imaging systems, and photonic devices requiring stable 90° beam deflection and high optical accuracy.
Share to:
Precise90° Beam Deflection
The penta prism is designed to deflect an incoming light beam by a fixed 90°, regardless of the incident angle or prism orientation. This feature ensures a stable and predictable beam path, making it ideal for laser alignment, metrology, and precision positioning systems.
Maintains Image Orientation
Unlike right-angle prisms that invert the image, the penta prism preserves the original up-down and left-right orientation of the beam. This non-inverting property is critical in applications such as projectors, periscopes, and optical instruments where accurate image direction is required.

Versatile Material Options
Penta prisms are available in various optical materials to suit different spectral ranges.
- K9 optical glass for visible wavelengths with high transmission and cost-effectiveness;
- Fused silica for UV to NIR applications with excellent thermal and spectral stability;
- Germanium or silicon for infrared systems (up to 16 µm), ensuring low absorption and high transmittance.
High Precision and Coating Compatibility
Precision pentaprism offers angle tolerances as tight as ±5 arcseconds and surface roughness below 1 nm RMS for demanding optical systems. Reflective surfaces can be coated with aluminum, silver, or dielectric HR films to enhance reflectivity and laser damage resistance in applications where total internal reflection (TIR) is not achievable.
Environmental and Mechanical Stability
For harsh environments, materials like fused silica, with low thermal expansion (α ≈ 0.5 × 10⁻⁶/°C), help maintain angular precision under temperature fluctuations. Sapphire or glass-ceramic substrates enhance mechanical durability under vibration, and MgF₂ anti-corrosion coatings are available for humidity protection.
| Parameter | High-Standard Requirement |
|---|---|
| Material | H-K9L / BK7 Grade A Optical Glass |
| Dimension Tolerance | ±0.2mm |
| 90° Comprehensive Angle / Deviation Tolerance | <30 arc seconds |
| Surface Figure / Flatness | λ/4 @ 632.8nm or @ 633nm |
| Surface Quality | 40-20 (scratch/dig) |
| Coating | Protected Aluminum Coating + Single-layer MgF₂ Anti-Reflective Coating |
| Clear Aperture | >90% |
| Bevel | Protective |













