Optical Thin Film Filters- Applications
Optical thin film filters have a variety of applications in selectively passing a specific wavelength or range of frequencies of visible light.
These range from the very simple – for example, colouring a visible light to a particular hue for aesthetic effect – to the more complicated, such as filtering luminescence for use in biological imaging detectors. We can custom make glass filters to a very thin natural density for any bespoke project.
However mundane or exotic the application may be, a good quality optical thin film filter is key to the highest quality of output, whether that means a very accurate bandpass range, strong signal to noise ratio, or long-term environmental stability.
Envin Scientific designs and manufactures a wide range of optical thin film filters for any application, including custom designed products where required, all tested and qualified using industry standard spectrophotometers that operate in the range from 175 nm to 30 microns.
Bandpass filters are high performance optical filters for chemical analysis isolate a narrow absorption or emission range from the full spectrum of wavelengths.
They may include soft coatings and more durable hard coatings for rugged applications, and often involve several filters mounted into a mechanism like a filter wheel.
Finished filters produced by Envin Scientific typically range from 1 mm square to a diameter of more than 100 mm with a thickness of as little as 0.2 mm.
Contrast Enhancement and Imaging
Contrast enhancement can allow discrimination between good and bad finished products and the identification of manufacturing flaws.
Filters for this can be shortpass or longpass, but are often single or multiple bandpass to focus on a specific wavelength or wavelengths.
Contrast enhancement filters have applications in common systems like bar code scanning, automated number plate recognition, near-IR imaging and security marker verification.
Dichroic Colour Filters
Dichroic colour filters pass only a selected range of the visible light spectrum and can be used to narrow the spectrum of the incident beam or adjust a light source’s colour temperature.
They have applications in biotech, medical and signal lighting, and for light sources both broadband (e.g. xenon, halogen) and narrowband (e.g. LEDs).
Due to their industrial applications, many dichroic filters must be durable even under harsh environmental conditions, with good environmental stability and minimal to zero shift.
Envin Scientific specialise in fluorescence filters for many different fluorophores and for both excitation and emission frequencies.
We can manufacture fluorescence filters with high blocking levels and steep transition edges, ideal for applications where excitation and emission bands are closely adjacent to one another.
Fluorescence filters are made more durable through the use of substrates which are themselves low auto-fluorescent, ensuring a high quality output.
Infrared filters from Envin Scientific fall into the 2 micron to 8 micron spectrum and contain relatively thick layer structures each tens of microns thick.
These filters are designed for environmental stability, excellent adhesion, non-radioactive coatings and optional anti-reflective coatings.
A wide choice of substrates includes silicon, zinc sulphide, germanium zinc selenide, calcium fluoride, chalcogenide glass and sapphire.
Laser Optical Filters
Laser optical filters work on the narrow wavelength bands of laser light sources and can manipulate the beam in a number of different ways.
These can include, for example, anti-reflective coatings, beam splitters, single wavelength blocking filters, bandpass filters, partial reflectors and multi-wavelength high optical density blocking filters.
Laser filters offer shift-free long life, temperature stability and suitability for short pulse and high power applications.
LED filters can be used to fine tune LED light sources, for example to stabilise the emitted wavelengths to overcome limitations in manufacturing tolerances and performance over time.
They generally fall into shortpass, longpass and bandpass categories, with wavelengths in the full range of visible light, near-infrared and ultraviolet.
Applications include signal lighting, biotech and automated number plate recognition among many, many others.
Near Infrared Optical Filters
Near infrared optical filters have an increasing range of applications in systems like automated number plate recognition, telecommunications, imaging and lasers.
They fall into the wavelength band from 700 nm to 2,000 nm but are increasingly coupled with parts of the visible light spectrum.
Envin Scientific have considerable experience at choosing the specific materials needed to produce near-IR optical filters with the precise spectral performance required.
Telecoms and Fibre Optics
Telecoms optical filters typically work in the wavelength regions 830, 1,310 and 1,550 nm and with fibre optics to divide and modify the transmitted signal.
Attenuation must be minimised as much as possible, with low-loss coatings and ball lenses that couple fibres together efficiently.
Custom applications can extend these principles to other frequencies, and in some cases filters are applied directly as coatings on the fibres.
Find out more
For more information about any of the above including Notch filters and longpass filters, or to speak to Envin Scientific about a custom application for thin film optical filters, please get in touch immediately.
We work with clients to create custom optical thin film filters that are perfectly suited to your application, and welcome enquiries via any of the contact details on this site.