Optoelectronic sensing apparatus

Abstract

First and second optical systems each comprise identical converging lenses which focus light images of an object onto identical photosensor arrays, the lenses being parallel. First and second mirrors reflect the light images from the respective lenses onto the respective arrays. The first mirror is fixed whereas the second mirror is rotatable. Where the second mirror is rotated to a position where the light images on the arrays are identical, the distance to the object is a function of the position of the second mirror which is predetermined by triangulation. As the second mirror is rotated through a predetermined range the arrays are strobed a predetermined number of times to produce analog signals having magnitudes corresponding to incident light. The respective analog signals are subtracted and the resulting difference signals compared with a previously minimum value. Each time the arrays are strobed a counter is incremented. However, when a difference signal has a value lower than the minimum value (a previous difference signal), it becomes the new minimum value and the counter is reset. The count in the counter after the arrays are strobed the predetermined number of times corresponds to the position of the second mirror when the minimum value was sensed and thereby the distance to the object. A servo system may be provided to position a camera lens in accordance with the count in the counter and thereby automatically focus a camera.