Optical detector for system movement - using total internal reflection in glass block and partially reflecting mirrors to produce phase shift in coherent light beam

摘要

The optical measuring device is build as a compact unit inside the system (1) whose velocity component it is required to measure. A coherent beam of light (4) e.g. laser beam, is emitted by a light source (2) and is aimed at an optically transparent glass block (6) having highly reflective mirror surfaces (7,7') so that after being reflected backwards and forwards N times, it leaves the block (6) at some point of low reflection as a light beam (4') again. After leaving the block (6), it is superimposed on part of the original light beam (5) which is stopped out of the coherent light source (3) by means of partly translucent mirrors (8,8') placed in front of the transparent glass block (6). An optical intensity detector (10) e.g. photodiode or photomultiplier is placed in the region of interference (9) so that if the system (1) is set in motion in the direction of the light source (2), a wave length change takes place, due to the Doppler effect. The phase difference in the interference region (9) is regi tered by the detector (10) and is proportional to the velocity component U of the system.