DOUBLE HETERODYNE INTERFERENCE APPARATUS USING ORTHOGONAL THREE-MODE LASER

摘要

PROBLEM TO BE SOLVED: To enhance the resolution composing and using a wavelength half the wavelength of a laser, by using as a light source a laser using a frequency drawing effect and having three spectral lines, and causing each spectral light of those to interfere and so on. ;SOLUTION: A double heterodyne interference apparatus is provided with a three-mode frequency-stabilized laser 1 which uses a frequency drawing effect. A three-mode light composed of spectrals L0, L1, L2 emitted from the laser 1 is split into the sets of L0 and L1, and L2 by a polarizing beam splitter 2, and they are caused to join by the beam splitter 2, after they are reflected by the reflecting mirrors 3, 4 of a reference optical path and a target circuit respectively. After the electric fields of the lights caused to join are lapped over by a polarizer 6 of a specified bearing, it is changed into a photoelectric current by a photodetector 7. This photoelectric current is composed of difference components of each frequency νL, νO, νH and a DC component. By squaring this current signal using a mixer 9, and performing processing with a filter 10, a wave number twice as large as that of the laser beam of a light source is obtained.;COPYRIGHT: (C)2000,JPO