For imaging applications, where the radiometers are fitted with an optical device or an optical train, systems can suffer from irradiance that varies with field angle, whether they are refractive, reflective, or both (catadioptric)
To calibrate the spectroradiometer, the spectral radiance of the integrating sphere is imaged onto the spectroradiometer's entrance slit. With the known spectral radiance of the uniform source the spectrometer can be calibrated for spectral radiance responsivity for the UV-VIS-NIR spectral region. Linearity and dynamic range can be characterized as well.
The sphere's exit port should be large enough to fill the instrument's field of view and is equipped with one or more lamps positioned outside this field of view. The region of the sphere wall viewed by the instrument is illuminated by multiple diffuse reflections so that a uniform field of radiance is presented to the instrument.
The luminance of the sphere system may be used to calibrate a luminance monitor as well.
Labsphere's line of Uniform Source Systems solve common problems in the calibration of both imaging and non-imaging radiometers. The integrating sphere approach eliminates sensitivity to alignment and polarization, which can affect other systems. Uniform Source Systems are readily adaptable to provide variable levels of spectral radiance, radiance, irradiance luminance, or illuminance, at constant CCT or variable spectrums.
For more information about spectroradiometer calibration or uniform source applications, check out the Labsphere Knowledge Base or the guides below.
