Patent ID: 6297884
Filing Date: 2001-10-02
Classification: G01B

Abstract:
An interferometric instrument for scanning a surface of a test object, comprising:a radiation generating unit for emitting briefly coherent radiation having a plurality of spectral components;an arrangement for periodically changing a light path of a received beam component, the arrangement including at least two acousto-optical deflectors and a stationary reflecting element that receives the received beam component directly from the at least two acousto-optical deflectors;a beam splitter device for producing a first beam component and a second beam component in response to the briefly coherent radiation, the first beam component being aimed at the surface of the test object, and the second beam component being aimed at the reflecting element;an interference element for causing the first beam component reflected from the surface of the test object and the second beam component reflected from the reflecting element to interfere with one another in order to produce an interfered radiation;a photodetector arrangement including a plurality of photodetectors, each one of the plurality of photodetectors producing a corresponding one of a plurality of electrical signals in response to the interfered radiation;an analysis unit having at least one input for receiving the plurality of electrical signals;a frequency shift arrangement for producing a frequency shift between the first beam component and the second beam component and being provided in an optical path of at least one of the first beam component and the second beam component; anda beam splitting arrangement for splitting the interfered radiation into the plurality of spectral components and for supplying each one of the plurality of spectral components to a corresponding one of the plurality of photodetectors, wherein the beam splitting arrangement is positioned in an optical path of the interfered radiation upstream from the photodetector arrangement.