Optical Test and Calibration Ltd


Photometric Calibration Services

OTC has been offering photometric calibration services since 1995. Today, we can offer UKAS calibration as standard on luxmeters & luminance meters and fully traceable calibration on many other photometric instruments.

Photometric instruments are designed to give a quantitative answer to the general question ‘How bright is that?’, sometimes with the additional question of ‘What colour is it?’. Whether measuring the amount of light falling on a surface (illuminance) or the amount of light emitted or reflected by a surface (luminance), the meters are filtered to mimic the response of the human eye (photopic response).

Photometric Calibration

Most photometric calibrations are against Illuminant A (2856K) but we can also offer standard traceable calibration against a wide variety of other light sources (including your own specific sources).

Typical instruments covered include:

  • Lux/Illuminance meters
  • Luminance meters
  • Colour / Chromaticity meters
  • Display colour analysers
  • Light sources

Radiometric Calibration Services

OTC also has a long history of offering radiometric calibration services. Radiometric meters do not conform to the response of the human eye but measure absolute power.

Some units, such as UVA irradiance meters (365nm) and bilirubin/biliblanket phototherapy meters (450 - 460nm) are filtered to respond to a specific section of the electromagnetic spectrum. Others are ‘broad-band’ sensors, responding to a wide range of wavelengths. These either require knowledge of the wavelength of the source and the spectral response of the meter to enable accurate measurements (laser power meter) or are calibrated against a specific broadband source (solar irradiance meters).

We can offer UKAS calibration as standard on many UVA irradiance meters (at 365nm) and traceable calibration on other meters at wavelengths between 250nm and 1700nm. Solar irradiance meters and pyranometers are calibrated against our class A solar simulator. Spectral transmission and reflectance measurements are also available. For details of our calibration capabilities for fibre-optic devices such as OTDRs and stabilised light sources please see our Optical section.

Typical instruments covered include:

  • UV radiometers
  • Phototherapy meters
  • Solar power meters
  • Pyranometers
  • Thermopiles
  • Laser Power Meters
  • Light sources
  • Optical Filters (spectral transmission)
  • Reflectance targets (spectral reflectance)

The above lists are not exclusive! We also calibrate a wide variety of specialist equipment.