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Knight Optical(UK) Ltd - - +44 (0)1622 859444

Neutral density filter sets

What are you looking for in Stock?

Neutral Density filters attenuate light by a constant amount that is, independent of the wavelength. Neutral Density Filters are designed to equally reduce the transmission over a specified spectrum, either by absorption or reflection. Knight Optical stock several ranges for your specific application which are all available as sets. Buying neutral density filter sets is more cost effective than purchasing as individual filters and are supplied in a high quality wooden box; useful for laboratory and custom design applications and for ease of use and safe keeping.

The individual filters in these sets can be found on our neutral density filter product pages if you still require single wavelengths. For ease please use the “see also” tab below.

Gelatin neutral density filter sets: Gelatin ND filters are the cheapest but tend to have more fluctuation with wavelength and a narrower wavelength range than glass ND filters and metallic types. Gelatine neutral density filters work by absorption so care must be taken to avoid overheating which can lead to damage to the filter.  Gelatine ND filters can also be cut easily to bespoke custom sizes in your own laboratory which can be extremely useful.

Absorption neutral density filter sets: Glass neutral density filters are the most common ND filter and attenuate light by absorption just like the gelatine type. Glass ND filters are more robust and tend to have more uniform absorption characteristics.  As glass ND filters attenuate by absorption, care must be taken to avoid overheating.  Attenuation is achieved by polishing standard schott or equivalent NG glasses to a given thickness.

Metallic neutral density filter sets:  Metallic neutral density filters comprise a thin metallic layer on a borosilicate or equivalent or UV grade fused silica polished windows. Metallic ND filters attenuate the light by reflection and thus avoid the possible heating issues with glass and gelatine neutral density filter types. However care must be taken to ensure the reflected light does not cause problems. Our stock range of visible/NIR range of metallic neutral density filters are coated on low-expansion borosilicate glass substrates and cover the range from 350-2500nm. Our UV range of metallic neutral density filters are coated on UV grade fused silica and therefore cover the useful UV region down to 170nm. All metallic ND filters are supplied with a copy of the spectral transmittance scan taken on a filter at the time of the production coating. We stock uncoated borosilicate and UV fused silica substrates so custom metallic filters can be supplied to your specific request, please enquire.

Knight Optical supply high quality neutral density filters from stock or made to your exact specifications.  Every component is individually tested on our Agilent Cary 5000 spectrometers fitted with a UMA device for testing transmission and reflection at any given angle. Our Agilent 660 FTIR spectrometer is used for coatings between 3.5µm and 45µm.  All parts are tested by our highly skilled technicians in our state of art metrology lab to ensure all components meet our high quality standards. We can provide transmission and reflection curves at given wavelengths from 175nm up to 3200nm in TXT or CSV format, or other formatted options.

Gelatine type:        Gelatine neutral density filters
Absorption type:  Absorptive glass neutral density filters
Metallic type:        Metallic neutral density filters

  • Mounting of 25mm diameter and 50x50mm squares.
  • Antireflective coatings can be applied to one or both faces for improved transmission.
  • Filters can be custom made to larger sizes for larger camera filter mounts.
  • Empty camera filter mounts available to fit your custom filter in.
  • Other camera filter mounts available that we can custom manufacture filters to fit:
  • Other unmounted 25dia filters listed though the website are available pre-mounted on request.
  • Available as single filters (metallic neutral density filters)
  • Supplied in a wooden storage box for research and laboratory use.
  • Cutting down or edged to special shapes and sizes at short notice.
  • Available in sets, supplied in a wooden storage box for research and laboratory use.
  • Custom OD values to your specific requirement.
  • Available in sets, supplied in a wooden storage box for research and laboratory use.

Stock Optics

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Part No. DescriptionIncludesSize
FNG9100 Set of 13x12.5mmdia Absorption ND filters with box0.1 to 4.0 OD12.5mmdia £122.85
FNG9200 Set of 13x25mmdia Absorption ND filters with box0.1 to 4.0 OD25mmdia £197.00
FNG9500 Set of 12x50x50mm Absorption ND filters with box0.1 to 3.0 OD50x50mm £400.00
FNM0100 Set of 13x25mmdia Vis/NIR metallic ND filters with box0.03 to 3.0 OD25mmdia £198.72
FNM0200 Set of 13x50x50mm Vis/NIR metallic ND filters with box0.03 to 3.0 OD50x50mm £304.07
FNP0100 Set of 13 50x50mm Gelatin ND filters with box0.1 to 4.0 OD50x50mm £275.95
FNU0100 Set of 13x25mmdia UV metallic ND filters with box0.03 to 3.0 OD25mmdia £418.14
FNU0200 Set of 13x50x50mm UV metallic ND filters with box0.03 to 3.0 OD50x50mm £616.50

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Our Multi-Lingual Sales Team are here to help with your requirments:

UK +44 (0)1622 859444
UK +44 (0)1622 850614
UK +44 (0)1622 851078
+1 401 583 7846

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