Neutral
density (ND) filter
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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: D
Transmittance: T
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| Absorption
glass ND 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 : ¡À5%
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| Metallic
Coated Neutral Density Filter |
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Metallic
coated ND filters are glass or quartz substrates with
a precision metallic coating (Inconel) that provides uniform
attenuation across a wide spectral range.
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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%
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