The optical quantity measured by a spectroradiometer system is determined by the input optic employed, as described in the table below. An approriate calibration source is required in each case.

Bentham manufactures spectroradiometers covering the spectral range 150nm to 30µm. All photometric, colorimetric, UV radiometric etc. quantities are most accurately determined by performing spectroradiometric measurements and using software to integrate/weight values as defined by CIE etc. However, Bentham also supplies a range of filter based radiometers/photometers with close match spectral responses for simple integral type measurements.

Typically a light source and UMS (universal measurement station) is added to spectroradiometer type systems in order to perform spectrophotometric measurements such as transmission and reflectance.

Typical Input Optic Measurement Quantity Unit Photometric Parameter Photometric Unit
Diffuser Spectral irradiance mW/(m2.nm) Illuminance lux
Telescope Spectral radiance mW/(sr.m2.nm) Luminance cd/m2
Baffled Tube Spectral radiant intensity mW/(sr.nm) Luminous intensity cd
Integrating Sphere Spectral total radiant flux mW/nm Total luminous flux lumens