Filters, Metallic Coated, Neutral Density, BK-7

Esco PN:

Metallic Coated Filters provide uniform attenuation across a wide spectral range with a precision metallic coating (Inconel). The film is comprised of a very hard alloy material, resistant to aging under normal enviromental conditions. Esco offers two types of Metallic Coated Filters:

  • BK-7 Optical Glass, which is utilized in the visible spectrum (400-700nm) 
  • Fused Silica, where UV substrates allow for an even attenuation from (200-700nm)

Advantages of Metallic Coated Neutral Density Filters include:

  • Coating on fused silica allows controlled attenuation in the UV
  • Coating provides attenuation with greater linearity over a wide spectral range.
  • Coating can handle higher intensity light sources because part of the beam is reflected, rather than absorbed

    Metallic Coated Filters, Fused Silica


    50.8mm x 50.8mm



    Density tolerance

    +/- 10% of density for values <0.5 and +/- 5% for values >0.5

    Dimensional tolerance

    +/-0.25mm square

    Surface Accuracy

    <5λ per inch 

    Surface Quality

    60-40, scratch-dig




    Fine ground and beveled

Esco Optics also manufactures Custom Neutral Density Filters, for orders outside our standard lines of ND filters. Please contact Esco directly for information on our custom optics and applications.


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