Sapphire (Al2O3)
Sapphire (Al2O3) optical material for high-temperature windows and durable UV-to-MWIR optics, with ordinary and extraordinary refractive-index references from the local RII database.
Key Properties
Primary engineering references for material screening, packaging review, and RFQ preparation.
About Sapphire (Al2O3)
Overview
Sapphire (Al2O3) is a practical material for protective windows, high-temperature viewing ports, and durable UV-to-MWIR optical components where hardness, chemical resistance, and mechanical survivability matter more than very low refractive index or LWIR transmission. In engineering review, Sapphire should be treated as an anisotropic single-crystal material rather than a generic isotropic window substrate.
Key Material Reference
| Parameter | Reference |
|---|---|
| Practical Transmission Guidance | 0.2-5.0 µm |
| Local RII Dataset Range | 0.20-5.0 µm |
| Reference Dataset | Malitson formula 1, 293 K, ordinary and extraordinary rays |
| Optical Character | Single-crystal anisotropic material |
| Refractive Index | no=1.7704 / ne=1.7623 at 0.55 µm |
Selected Refractive Index Reference
The values below are engineering references from the local RII dataset at 293 K. Final optical design should still confirm crystal orientation, optic axis, polarization sensitivity, thickness, and coating target.
| Wavelength (µm) | Ordinary no | Extraordinary ne |
|---|---|---|
| 0.250 | 1.8452 | 1.8355 |
| 0.300 | 1.8144 | 1.8053 |
| 0.550 | 1.7704 | 1.7623 |
| 1.000 | 1.7557 | 1.7478 |
| 3.000 | 1.7122 | 1.7047 |
| 5.000 | 1.6240 | 1.6184 |
Typical Applications
- High-temperature sight windows and protective windows
- Industrial pyrometry and process monitoring optics
- Durable UV, visible, and SWIR windows
- Harsh-environment sensor apertures and inspection ports
Engineering Notes
Sapphire is usually reviewed when the part must survive abrasion, pressure, aggressive cleaning, or elevated process temperature. It is not a normal long-wave infrared transmission material, so engineers should confirm the real operating band before assigning Sapphire to a thermal imaging or LWIR sensor path. If polarization, double refraction, or crystal-axis effects matter, the ray direction should be specified in the drawing or RFQ. For application context, compare the materials index, review MgF2 and CaF2, and check the related industrial pyrometry case.
Procurement Checklist
- State the exact wavelength band because Sapphire is useful in UV to MWIR review but not a default LWIR material.
- Specify whether the part is a protective window, pressure window, viewport, or polished substrate blank.
- Include diameter, thickness, clear aperture, quantity, and any coating target in the RFQ.
- Call out pressure load, operating temperature, cleaning method, and whether crystal orientation matters to the application.
Request Engineering Review
Send wavelength band, dimensions, quantity, coating target, and environment notes through the contact page for a practical Sapphire window or substrate review.