PAT Roberts

Roundup: Types of optical filters

At Envin Scientific we supply two main types of optical filters, which can cater for a wide range of different characteristics and properties.

The two types of optical filters we supply are:

Within both of these categories, there is a huge variation of different shapes, sizes, substrates and filtering techniques to choose from – let’s take a look in a little more detail below.

Optical thin film filters and coated filters

Thin film and coated filters can work by absorption or reflection, controlling the range of frequencies and wavelengths passed on from the incident light.

As a result, they can eliminate unwanted or harmful wavelengths such as infrared and ultraviolet, limit the colour of the light output, or reduce reflection and glare.

The choice of substrate and the shape of the filter is important too. They can function as flat reflective mirrors or windows, or they can be manufactured as prisms, lenses or aspheric surfaces that offer a much smaller focal spot size.

Absorption and spectral filters

Spectral and absorption filters use glass, optical resin and dichroic materials to eliminate specific wavelengths from the incident light.

Again this can be used to pass or prevent IR and UV wavelengths, as well as parts of the visible light spectrum, or filters can have neutral density – effectively reducing the intensity but not the spectral shape of the incident light.

Filters can act on narrow and broad ranges of light frequencies, reduce all frequencies by the same amount, or they can be highly selective to eliminate or pass only a specific wavelength.

Combined and laminated filters

Optical filters can combine multiple properties by laminating materials with different characteristics on to the surface of the same substrate or lens.

At Envin Scientific we do this to the highest standards, with detailed testing of each laminated lens, filter or mirror we manufacture, so you know its precise characteristics.

We welcome enquiries for custom combined filters and can advise on a suitable combination of substrate and coatings to achieve the output you need.

To find out more, contact us today. All enquiries are welcome and we relish a challenge if you need something extremely specific.