For general broadband use, a protected aluminum coating offers the best option. A SiO coating is used to protect the delicate aluminum coating, making it suitable for laboratory and industrial use. This coating gives a reflectivity that most closely matches the reflection of a bare aluminum coating: Ravg>87% @400-1200nm.
Material: BK7 grade A optical glass
Dimension Tolerance: +/-0.2mm
Clear Aperture: >85% of diameter
Parallelism: < 1 arc minutes
Surface Quality: 60-40 S/D
Flatness: λ/4@632.8nm
Coating: R> 90% on S1
Bevel: 0.25mmx45deg