OPTICAL INTERFEROMETER FOR DETECTION ULTRASONIC OSCILLATION

摘要

PROBLEM TO BE SOLVED: To provide an optical interferometer for detecting ultrasonic oscillation of an object to be measured using light. SOLUTION: The optical interferometer comprises a double-convex lens 3 inserted between a pair of translucent concave mirror 5 disposed oppositely. A light reflected directly on a semi-transparent concave mirror 5 is cased to interfere, in reverse phase, with an output light from the optical interferometer to produce an interfering light having an intensity closed to 0. Fluctuation in the optical frequency due to ultrasonic oscillation is detected by measuring phase difference between the intensity signal of the interfering light and an external reference signal.