3 Frequency Heterodyne Laser Interferometer and Method of Length Measurement Using the Same

摘要

The present invention relates to a heterodyne laser interferometer having three frequencies and a method of measuring a physical quantity such as a length using the same.;The three-frequency heterodyne laser interferometer according to the present invention comprises a three-frequency laser oscillation means (1), a light beam splitter The polarizing beam splitter 3, the first and second corner cube prisms 4 and 5, the first and second polarizing plates 6 and 7, the first and second photodetectors 8 and 9, First and second amplifiers 10 and 11, first and second band-pass filters 12 and 13, a two-channel counter, and a length display.;According to the present invention, the second beat frequency is generated by the three-frequency oscillation laser and the second beat frequency is Doppler-shifted while the second corner cube prism 5 is moved. By the difference between the count value and the count value of the reference light flux There is an innovative effect that a length measurement in which the resolution is doubled can be performed by a method of calculating the moving distance of the second corner cube prism.