Optical sensor array in an artificial compound eye

Abstract

Optical systems of compound eyes are of great interest in the study of micro-optics. We propose an artificial visual sensor in a model of the apposition eye of an insect. As a key component unit of the visual sensor, a sensor array consisting of 16 x 16 individual optical sensors each with a small view field is fabricated and examined. To achieve both the practical assembly and the compact size of the sensor array, a photodiode array, a glass substrate with a pinhole array, and a group of rod-type gradient-index microlenses are stacked. The optical thickness of the sensor array is 2.9 mm. Because of the low intensity of light received by the photodiode the photocurrent is amplified 10⁷ times in current-to-voltage conversion efficiency. The fabricated sensor array produces a mosaic image with 16 x 16 pixels and eight shades of gray scale. By arranging several of these sensor arrays along a circumference, a wide-field-angle visual sensor similar to a compound eye could be realized.