Combination of grating lenses for color splitting and imaging.

A pair of planar reflection gratings is proposed and discussed for use in a color-splitting and imaging system, such as a projection-type color-scanner head. Red, green, and blue light reflected from a color subject are split by a color-splitting grating lens and imaged by an image-correction grating, consisting of three segments, onto three line sensors arranged in parallel. The phase-shift function of the image-correction grating was optimized for each color by numerical iteration with the ray-tracing method to suppress aberrations resulting from the wide view angle and the three different wavelengths. Gratings were designed and fabricated, and aberration suppression was experimentally confirmed.