ELECTRONIC SIMULATION OF VARIABLE INCLINATION REFERENCE BEAM FOR ACOUSTICAL HOLOGRAPHY

摘要

A method and apparatus for electronically simulating a plane wave reference beam of variable inclination for use in an acoustical holography system. The invention is based on the principle that the phase of a plane wave changes linearly over the plane of detection. In systems where the detection is obtained by scanning the aperture in the plane of detection, as in certain acoustical holography setups, the required reference beam simulating a plane wave can be generated by an electronic signal having a frequency slightly different from the one used to irradiate the object. The apparatus can be adjusted to obtain a simulated reference beam of any desired angle of incidence up to 90 DEG .