The core principle of a metallic mirror harnesses the strong reflection of light waves by the free electrons in the metal material. Different metals dictate the mirror's spectral performance and application suitability. Aluminum coating is the most versatile but is prone to surface oxidation. Silver coating excels in the near-infrared region, yet it suffers from poor durability. Gold coating offers extremely high reflectance in the infrared spectrum but absorbs most visible and UV light intensely.
Wide spectral bandwidth.
Insensitive to polarization.
Modest laser-induced damage threshold (compared to dielectric mirrors).
Economical manufacturing cost.
| Material | H-K9L or Fused Silica |
| Surface Flatness | λ/4 @ 633 nm |
| Parallelism | < 3 arcsec |
| Diameter Tolerance | +0.0,-0.1mm |
| Thickness Tolerance | ± 0.2 mm |
| Reflective Coating | Aluminum, silver, gold |
| Surface Quality | 40-20 60-40 |
| Back Surface | Fine Ground |
