JPS643603A - Condenser color filter - Google Patents

Abstract

PURPOSE:To enable to integrate a condenser color filter in a small size by arranging a diffraction grating for color separation, a different pitch diffraction grating for condensing light, namely, a linear Fresnel lens to intersect almost orthogonally each other. CONSTITUTION:One of the grating patterns of crossed diffraction grating 1 constituted of a transparent body is a different pitch diffraction grating formed in the x direction of the crossed diffraction grating with a same recurrent period as the pitch of a photodetector in the x direction of a photodetector array 2, namely, a linear Fresnel lens. Accordingly, the light transmitted through a picture image 4 for condensing and separating color is separated into picture elements by many linear Fresnel lenses in the crossed diffraction grating, so the light from each picture element is condensed and subjected simultaneously to color separation, focusing each color component of the light to each focus at the opposite side of the crossed diffraction grating 1. By this constitution, a small sized condenser color filter having both condensing function and color separating function is obtd. because a condenser filter to be used for a color image sensor can be constituted on a transparent substrate.