Method of measuring the distance of a target and apparatus for its performance

摘要

The distance of a target object is determined from the time of travel of a measuring light pulse which is emitted by a transmitter toward the target object, reflected thereby and received by a receiver. In timed relation with the instant of generation of the measuring light pulse, a start signal for beginning a measuring signal transit time measurement is generated, and, on receipt of the reflected measuring light pulse, a stop signal is generated for terminating this time measurement. A completely independent reference light pulse is generated and forwarded along a reference light path establishing a predetermined time of travel from the transmitter to the receiver, and the respective reference signal transit time is measured which contains the same undesirable additional time spans contained in the measured transit time of the measuring signal. The reference signal transit time measurement value is subtracted from the measuring signal transit time value to eliminate the additional time spans and to obtain a high precision measurement value difference to which the predetermined time of travel of the reference light pulse is added to obtain the genuine time of travel of the measuring light pulse.