Abstract:
In an apparatus for measuring the relative distance and optionally the relative velocity of an object with respect to a reference system, the improvement comprising, using two optical correlator systems with differing distances from the object, forming an auxiliary signal by mixing the electric output signals of the correlator systems, wherein the auxiliary signal has the difference frequency of these output signals; and then counting the number of signal cycles of one of the correlator output signals obtained during the duration of a cycle of the auxiliary signal and indicating the number of signal cycles as a value proportional to the distance.
Abstract:
IN A DIGITALLY INDICATING DOUBLE-BEAM PHOTOMETER HAVING AT LEAST ONE PHOTOELECTRIC RECEIVER TWO SAW TOOTH GENERATORS ARE EMPLOYED. EACH SAW TOOTH GENERATOR IS RESPONSIVE TO ONE BEAM AND IS CONTROLLED BY ELECTRICAL SIGNALS CORRESPONDING TO THE LIGHT INTENSITY OF THE BEAM TO WHICH IT IS ATTACHED. THE RATIO OF THE ELECTRICAL VALUES DETERMINING THE RISE TIME OF THE SAW TOOTH GENERATORS IS 1:N, WHEREIN N REPRESENTS THE LIGHT INTENSITY OF THE COMPARISON BEAM AS MEASURED IN DIGITAL UNITS. THE OUTPUT SIGNAL OF THE SAW TOOTH GENERATOR TO THE COMPARISON BEAM CONTROLS A RELAY AFTER HAVING BEEN SUITABLY AMPLIFIED, THE OUTPUT SIGNAL OF THE SAW TOOTH GENERATOR RESPONSIVE TO THE MEASURING BEAM OPERATES A COUNTER MECHANISM. A FIRST EMBODIMENT IS DISCLOSED IN WHICH TWO PHOTOELECTRIC RECEIVERS ARE EMPLOYED, ONE IN THE PATH OF EACH BEAM. EACH ONE OF THE RECEIVERS IS CONNECTED TO ONE OF THE SAW TOOTH GENERATORS. A FURTHER EMBODIMENT IS DISCLOSED IN WHICH ONLY ONE PHOTOELECTRIC RECEIVER IS EMPLOYED WITH THE TWO BEAMS BEING ALTERNATELY SWITCHABLE ONTO THE ONLY RECEIVER. A DOUBLE THROW SWITCH IS CONNECTED TO THE RECEIVER AND IS ADAPTED TO CONNECT THE RECEIVER TO EITHER OF THE SAW TOOTH GENERATORS ALTERNATELY AND SYNCHRONOUSLY WITH THE SWITCHING OF THE BEAMS.