The use of optical interferometry for measurement of ultrasonic surface waves has been limited heretofore by the necessity of maintaining the surface under test within a fraction of a wavelength of light of some fixed position. A new technique, using two coherent light beams focused on the specimen surface, avoids this limitation. This technique is useful for directly recording standing‐wave ratio, attenuation, transmission, harmonic content, and other characteristics of surface waves at frequencies ranging from audio to beyond 200 MHz. In addition to excellent sensitivity, the method allows absolute calibration of the acoustic wave amplitude.