Orthogonal-scanning microscope objective for vertical-scanning and phase- shifting interferometry

摘要

A broad-bandwidth interferometric device is adapted for longitudinal insertion into a cylinder cavity to produce irradiance signals at multiple vertical-scanning positions as a function of optical path differences between a reference mirror incorporated in the probe and the cylinder-wall surface. The light-source beam is passed through an objective lens placed longitudinally in the cylinder and then divided by a beam splitter disposed in fixed relation to the cylinder wall to produce a test beam directed radially to the wall and a reference beam directed axially to a reference mirror disposed in fixed relation to the lens. During scanning, the objective lens and reference mirror are translated together, while the beam splitter remains stationary with respect to the cylinder wall, thereby varying the position of the focal point of the test beam and providing the vertical-scanning effect required to produce interference fringes and a corresponding map of the tested cylinder surface. In order to reduce the length of the instrument, the reference beam may be folded to the side by a reflective surface and the reference mirror may be positioned perpendicularly to the main axis of the instrument. In that case, the lens, fold mirror and reference mirror are all translated together, while the beam splitter remains stationary and fixed with the test surface.