Neutral density (ND) filters are used to attenuate incident radiation without altering its spectral distribution. The neutral density value of an ND filter is related to the transmittance by: D=Log(1/T) Optical Density: OD Transmittance: T
Absorption glass Neutrol Density Filter
Specifications: Material: Optical Neutral Density Glass Flatness: 2l per 25 mm Surface Quality: 80/50 Parallelism: 3' Dimension: circle (dia.25.4mm typical) or square Dimension Tolerance: +/-0.2mm Optical Density Tolerance : ±5%
Metallic Coated Neutral Density Filter
Metallic coated ND filters are glass or quartz substrates with a precision metallic coating (Inconel) that provides uniform attenuation across a wide spectral range.
Specifications: Material: BK7 glass and Fused Silica Flatness: 2l per 25 mm Surface Quality: 80/50 Parallelism: 3' Dimension Tolerance: +/-0.2mm Coating: Vacuum-deposited metallic alloy Optical density Tolerance: +/-5%