| 摘要 |
PURPOSE:To reduce the size of a reference light generation optical system by adopting an acoustooptical modulation element, in an optical waveguide recording medium reproducing device provided with a heterodyne detection optical system. CONSTITUTION:An ultrasonic wave generation element 101 is an electrostriction element or a piezoelectric element provided with an opening 101a through which a laser beam entering via a beam splitter is made incident, an acoustooptical medium block is the crystal of quarts, TeO2, etc., and the ultrasonic generation element 101 is formed on the incident end face with the electrostriction element composed of barium titanate or the piezoelectric element composed of crystal, etc. By applying intermittent high frequency electricity to the element 101, grid stripes whose refractive index changes according to the wavelength of the ultrasonic wave are generated within the block 100. The laser beam going through the block 100 is given phase delay and frequency displacement due to the Doppler effect of the ultrasonic wave, a part of it is reflected to return, and the reflection light is used as the reference light. |
