Glass Neutral density filters These Glass Neutral Density Filters are an inexpensive form of absorption density filter. They are made using the Schott range of NG glass types.  Neutral density filters attenuate light by absorption whilst achieving minimum reflection. The density of neutrality of the filters is achieved through selection of the filter type and calculation of the thickness. The optical density is reasonably consistent in the visible (400-600nm) but may be higher or lower in the NIR depending on glass type.
Knight Optical > Filters > Glass neutral density filters 12.5 diameter (mm) This is the section containing 12.5 diameter (mm). 25 diameter (mm) This is the section containing 25 diameter (mm). 50 x 50 (mm) This is the section containing 50 x 50 (mm). Sets at a special price This is the section containing Sets at a special price. Only UK and EU customers are charged VAT at 17.5%, customers outside the EU and EU customers based outside the UK who have a valid EU VAT number will not be charged VAT Knight Optical > Filters > Glass neutral density filters
Specification   Material: Schott Colour Glass Optical Density : ± 12.5% (@546nm) Diameter: +0.0 / -0.2 mm Length / width: ± 0.2 mm Thickness: ± 0.1 mm Surface quality: <60-40 Flatness: <2.5λ over 90% test area Parallelism: <3 arcmin
Specific requirements We can manufacture Schott Colour-glass filters to any size at short notice, so if your requirements are not listed please contact us by telephone / fax or email: stockrequirement@knightoptical.co.uk Options available   · AR Coating   · Cutting down or edged to special shapes and sizes   · Mounting (circles) Technical Data Sheets Set of transmittance curves are available for each filter on request, please specify type. See also Metallic neutral density filters Gelatin neutral density filters See also FNG0400 12.5mm dia set (13 filters) FNG0200 125mm dia set (13 filters) FNG0300 50 x 50mm set (12 filters) For storage boxes (see accessories)