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Optical measurement

Transmittance

UKAS accredited measurements

Measurement and calibration of transmittance in the ultraviolet, visible and near-infrared (UV-vis-NIR) range

Regular transmittance

We provide UKAS accredited regular transmittance measurements from 200 nm to 2500 nm up to an optical density of 5.0 (however measurements up to 3000 nm are possible) at either selected wavelengths or by using a scanning technique at regular intervals.  Wavelength intervals are typically 5 nm and can be as low as 0.05 nm. Small wavelength interval scans are most useful when measuring wavelength standards that have narrow absorption bands. The spectral bandwidth used for wavelengths up to 800 nm is chosen by the customer and can be up to 5.0 nm. Above 800 nm, the bandwidth usually varies with wavelength up to a maximum of 20.0 nm. Typical measurement uncertainty for a 90% transmitting filter in the visible part of the spectrum is ± 0.2 %. Uncertainties for other transmittance values or wavelengths depend on the filter characteristics.

Calibration of optical filter glass

We have the capability to calibrate optical filter glass of many descriptions including metal on silica, neutral density glass, coloured glass, stray light filters and others on request. We can also make measurements on, and calibrate, cuvette type filters used for spectrophotometer calibrations, as well as in the validation and verification processes typical of these systems. Non-UKAS accredited measurements will be considered on a case-by-case basis, please contact us with your measurement requirements and specifications

Solar, colorimetric and other integrated values

Solar integrated values of transmittance can be calculated using Parry Moon air mass 0, 1 and 2, or Makarova air mass 0 solar data, or any other tabulated solar spectral distribution. We can also provide luminous transmittance and colorimetric values for filters used with CIE Standard Illuminants or other defined source spectral power distributions.

Wavelength and bandwidth filters

For narrow bandpass filters, we can provide calibrations of the wavelength of the transmittance / absorption peak, as well as other data such as the half height bandwidth, centre wavelength and wavelength of centre of gravity of peak.

We can conduct measurements and calibrations on wavelength standards such as Holmium glass filters, Didymium glass filters and McCrone glass filters.

Don’t see what you are looking for? Our diverse skill set enables us to provide bespoke solutions. Please contact us to discuss your requirements.

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Work with us

Our research and measurement solutions support innovation and product development. We work with companies to deliver business advantage and commercial success.
Contact our Customer Services team on +44 20 8943 7070