30 Mar 2021 ND（Neutral Density） filters include absorptive and reflective filters，which are used in attenuating lasers and other optical signals. Absorptive filters minimize back reflections, which can be reduced further by adding an antireflection coating to the filter. Reflective filters are available with either a BK7 or UV Fused Silica substrate.
Specifications:
Materials: Colored Gray Glass
Diameter Tolerance: +/-0.20mm
Thickness: 0.5-3.0 mm
Parallelism<3 arc minute
Surface Quality: 60-40/80/50
Surface Figure: 2λ per 25mm
Clear Aperture> 85%
Optical Density Tolerance: +/-5%
Coating: Specified by customers | 
