Heterodyne interferometer, has arms and optical modulator, where amplitude of input radiation to interferometer is modulated with frequency, before partitioning of arms, and that frequency is different from frequency change of radiation

摘要

The interferometer (1) has two arms (21,22) and an optical modulator (24) for modulating the frequency of the radiation guided over the arms. A control unit adjusts the frequency change and a detector unit evaluates the interfering output radiation. The amplitude of input radiation (11) to the interferometer is modulated with a frequency, before the partitioning of the arms. The frequency is different from the frequency change of the radiation in the modulator.