Spectral matching imager using correlation image sensor and variable-wavelength illumination

This paper proposes a spectrally selective imaging system called 'spectral matching imager,' which consists of the variable wavelength monochrome light source and the correlation image sensor. The variable wavelength monochrome light source illuminates the scene while sweeping its wavelength with time to expand the spectral reflectance/transmittance function of objects along the time axis. At each pixel, the correlation image sensor produces the correlation in the time domain between the expanded spectral function and a reference spectral function. Consequently, pixels that establish a good spectral match have large values in the output image. The spectral matching imager satisfies (1) high spectral resolution, (2) efficient data compression, and (3) tunability to arbitrary optical filter characteristics. Experimental results demonstrate successful detection of objects having detailed narrowband structures, such as glass pieces doped with rare-earth elements.