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
  
  

  Size	50.8mm x 50.8mm
  Thickness	1.0mm
  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
  Parallelism	<10'
  Edges	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.