Optical workpiece surface imaging device - has ultrasonic wave transmitted into test piece and has measuring arm and reference arm giving time delay

摘要

The optical workpiece-face imaging device has an optical imaging system (3) which generates a first intermediate image (5a, 5b) of the workpiece surface (5) over half the lengths of the beam paths between two passages through a beam splitter (6) and consequently on the end mirrors (7, 8). The optical path length difference between the measuring and reference arms is d(1-1/n) and the delay time is defined by the expression d(n-1/n)/Co, where d is the thickness of the workpiece, n is the refractive index of the light beam in the interferometer and Co is the velocity of light.