这种测量技术提供了超声波自由接触干涉测量法,能够测量振动的位移、运动工件的表面变形,例如快速运动的工件,在轧制或退火中的热钢等。激光束由分光镜分成两束光:一束光投射到工件的被测点,称之为测量光束;另外一束光投射到工件上的被参考点处,称之为参考光束,且参考点接近于测量点。来自测量点和参考点的反射光束再经分光镜会合后射入检测器(见图)。这种光检测器可以是光电倍增管、光电二极管,也可以是雪崩光电二极管或光电半导体 This measurement technique provides ultrasonic free-contact interferometry to measure vibrational displacements, surface deformation of moving parts such as fast-moving parts, hot steel during rolling or annealing, and the like. The laser beam is split into two beams by a beam splitter: a beam of light is projected onto a measured point of the workpiece, which is called a measuring beam; another beam is projected onto a workpiece by a reference point, which is called a reference beam, and a reference point Close to the measuring point. The reflected beam from the measuring point and the reference point is incident on the detector through the beamsplitter (see figure). Such photodetectors may be photomultipliers, photodiodes, or avalanche photodiodes or optoelectronic semiconductors