Patent ID: 7358516
Filing Date: 2008-04-15
Classification: G01B,G01S

Abstract:
1. A system for determining a position of two objects relative to each other, the system comprising: a source of coherent radiation; a light guiding arrangement for providing a measuring branch for a measuring beam having an optical path length dependent on the position of said two objects relative to each other; a radiation intensity sensor for measuring an intensity of an interfering superposition of radiation comprising at least radiation after passing through said measuring branch, and a computer configured to determine the position of said two objects relative to each other based on a measuring signal from the radiation intensity sensor; said measuring branch comprising: at least one emitter fixedly mountable on a first object of the two objects for emitting radiation supplied to said measuring branch into a space between said two objects; at least three retroreflectors mountable on a second object of said two objects at fixed distances relative to each other; and at least one receiver mountable at said first object for receiving radiation reflected back from said retroreflectors and for supplying the received radiation to the radiation intensity sensor, wherein said emitter is configured to emit the radiation as a divergent beam having an apex angle such that the beam impinges simultaneously on at least three of the at least three retroreflectors.