PHASE DIFFERENCE DETECTOR

摘要: PURPOSE:To obtain extremely stable beat frequency by interposing an acousto- optical modulation element to one of two paths and forming difference between the laser beams paths. CONSTITUTION:The linear polarized beam single from a source is split into S-wave P-wave, both which have planes polarization crossing each other at right angle, splitter 12. For example, plane rotated 45 deg. with respect incident surface The P-wave transmitted through 12 condensed object 16 be measured first lens 14 brought parallel second 18 reflected mirror 24 reach 28 acousto-optical 26. This 26 equipped light pervious substrate 30 ultrasonic oscillator 32 provided end part thereof deflected diffraction action according cyclical refractive index change corresponding elastic wave generated shift frequency.