Spectral Response

The spectral response (R(λ)) of a waveband results from the spectral characteristics of the photodetector, filters, fore-optics, and the geometry of the detector.  The spectral response of 7 channels of a SeaWiFS radiometer are shown in the plot above, contrasted to a high-resolution solar spectrum.

R(λ) as a function of wavelength λ, is modeled as the spectral product of the response of the piece-parts, such as the detector, R_det(λ), with the spectral transmission of all filter components, T_filt(λ) and the diffuser (for irradiance), T_diff(λ).

C_r is a constant that accounts for geometric uncertainty in the optical arrangement.

Spectral response is often measured using a spectrally variable lamp source, such as combination lamp-monochromator, but different lasers are also commonly used for many applications.