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

• N-BK7 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	50.0mm x 50.0mm
  Thickness	2.0mm
  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. To get a quote on a custom filter please use our online quote tool.