Interferometric measurement of positions, position changes, and physical quantities derived therefrom

A vibrometer for interferometrically measuring a position of a part, a position change of the part and a physical quantity of the part, the physical quantity being derived from the position and the position change, the part being tested using a heterodyne interferometry procedure, the vibrometer comprising:

• an optical bypass;
• laser diodes;
• a common control circuit;
• a downstream evaluation circuit;
• a measuring receiver including a photoelectric transducer;
• and
• an arrangement, using a time-variable pulsating injection current, modulating a laser to change a frequency of a radiation which is emitted by the part for generating a heterodyne frequency, the arrangement routing a first portion of the emitted radiation via the optical bypass to the part, the arrangement routing a second portion of the emitted radiation without the optical bypass to the part, the arrangement routing the second portion from the part to the measuring receiver,
• wherein a shape of a signal of the injection current has a rising edge, the edge being steeper as compared to a pulse length and a subsequent plateau of the signal,
• wherein the photoelectric transducer converts the signal, the arrangement evaluating the converted signal only after a predetermined time period following an occurrence of the edge of the injection current during the subsequent plateau of the signal,
• wherein a plurality of signals are correlated in a time multiplex mode to form a plurality of measurement channels, heterodyne signals of the measurement channels being generated in non-overlapping time windows,
• wherein the arrangement generates laser control signals for the measurement channels and delivers the laser control signals using the common control circuit, the laser diodes being assigned to each of the measurement channels, the photoelectric transducer which corresponds to the measurement channels being provided,
• wherein the signals are tapped off from the photoelectric transducer in accordance with the time multiplex mode, the signals being separately evaluated for each of the measurement channels in the downstream evaluation circuit.