摘要:
The device serves the change of the length of the running path of an electromagnetic wave, and specifically of a light beam between the emitter and receiver. It comprises two oppositely lying reflection means between which the beam is reflected, as well as a means for changing the distance of these reflection means. The reflection means are arranged at an angle &bgr; to one another which lies between 0° and 45° so that the incident beam is thrown to and fro several times between the reflection means, until it is finally congruently thrown back.