PASSIVE-OPTOELECTRONIC RANGEFINDING

摘要

A rangefinder has a linear array of pairs of photo-sensitive devices (40) mounted as two rows of photo-sensitive devices, viewing the same scene. Each photo-sensitive device is responsive to the intensity of illumination of a small patch of the scene. The outputs from the photo-sensitive devices of the first row are weighted by a first angular sensitivity function g( alpha ). The outputs from the photo-sensitive devices of the second row are weighted by a second angular sensitivity function g'( alpha ) which is the angular spatial derivative of the function g( alpha ). A spatial function h'(T), which is a translation function, is applied to the weighted outputs of the photo-sensitive devices of the first row and a second spatial function h(T), which is the integral of the function h'(T) is applied to the weighted outputs of the photo-sensitive devices of the second row. The doubly weighted outputs of the photo-sensitive devices of each row are summed and the ratio of the signals indicating the two summed, doubly weighted, output signals is obtained using a comparator (56). This ratio signal is indicative of the range or proximity of an object in the scene. In a rangefinder for blind persons, each photo-sensitive device (40) is a four-quadrant photodiode, the weighting functions are applied using banks of resistors (52) and the output signal from the comparator is converted into a frequency signal which drives an audio signal generator (58).