In contrast to Thin Film Optical Filters, Absorption Filters modify the light passing through them by Absorbing selective wavelength regions. This can be used to great advantage in systems where reflected light is problematic. The types of filter include Longpass, Shortpass, Bandpass & Neutral Density. The characteristics can be very useful but they are limited to specific criteria and are strongly dependant on thickness.
Absorption filters are available as Glass, Optical Resin or Dichroic Absorption Filter (in this case the thickness constraint is removed). Filters can be combined to provide a resultant performance within a single structure by Cementing, Laminating or direct Thin Film Coating. Using these methods the potential solutions to Electro-optical challenges are considerable.
Within our custom built modern facility we, at Envin Scientific Ltd, design and manufacture High Precision Optical Filters and Optical Thin Film Coatings for Ultraviolet, Visible and Infrared Applications. Our standard wavelength range is 175nm to 8 microns.
Filters are produced using a range of materials at sizes up to 350 x 250mm (larger for Resin Filters) and with thicknesses from 0.1mm to 10’s of mm. Final sizing can be from 1mm to >100mm in circular, rectangular or other shapes. These filters can be supplied as unmounted or within assemblies such as single filter holders, multiple filter wheels or matrix arrays.
Cemented, Laminated structures can be produced and Thin Film Coatings can be added. Glass Filters can also be supplied in Toughened form.
The range of Absorption based Optical Filter products available from Envin Scientific is comprehensive. The sections below provide more detail of examples of products which have already been designed and manufactured. They are categorised under headings which describe the main material or construction type.
The examples shown are by no means comprehensive as space and confidentiality prevent us from illustrating everything. Whatever your requirement it is very likely that we have already designed and manufactured something very similar.
Custom Optical Filters are a speciality of Envin Scientific. This can range from a small modification to a standard specification or change in physical dimension to a completely novel design deposited onto a ground & polished custom substrate and mounted in a custom designed assembly.
Absorption Filters in 50 x 50mm format are offered in 1, 2 & 3mm thickness as standard. In addition different sizes and shapes which are smaller than this (down to 1.4mm square) can be produced on a rapid prototype basis.
Further performance enhancement can be produced by Thin Film coating these parts. This is also offered as a rapid prototype service.
Dichroic Absorption Filters offer even greater possibilities for performance modification and thickness reduction.
All of our Optical Filters & Thin Film coatings are performance qualified using Top of the range Industry standard Spectrophotometers:-
We have two instruments to secure continuity of supply should a fault develop.
Despite its age this grating instrument still provides superior measurements.
All measurements are filed electronically and can be traced back to machine runs and process Logs.
