PURPOSE: To simplify the circuit configuration and to reduce the size of the instrument itself by feeding the photodetection signal of a photodetecting means back to a light projecting means positively through an oscillation means.
CONSTITUTION: In prevent distance measuring instrument, a feedback (closed) loop is formed of a projection-side LD1, an object body, a photodetection-side PD2, an amplifier AP1, integration circuits 11 and 12 which are stacked double, and a projection-side LD1. Further, an oscillation circuit including an optical system is formed of the feedback loop and information regarding the distance lto be measured to the object body can be obtained in terms of the oscillation frequency of the oscillation circuit. Namely, the distance measuring instrument can holds the projection modulation intensity (feedback amplitude) of the projection side invariably constant regardless of the distance l to be measured to the object body.
YOSHIDA TOMIYOSHI
INOUE YUICHI
TAKIMASA HIROAKI
