Vignetted-aperture correction for spectral cameras with integrated thin-film Fabry-P\'erot filters

Abstract

Spectral cameras with integrated thin-film Fabry-P\'erot filters have become increasingly important in many applications. These applications often require the detection of spectral features at specific wavelengths or to quantify small variations in the spectrum. This can be challenging since thin-film filters are sensitive to the angle of incidence of the light. In prior work we modeled and corrected for the distribution of incident angles for an ideal finite aperture. Many real lenses however experience vignetting. Therefore in this article we generalize our model to the more common case of a vignetted aperture, which changes the distribution of incident angles. We propose a practical method to estimate the model parameters and correct undesired shifts in measured spectra. This is experimentally validated for a lens mounted on a visible to near-infrared spectral camera.