Application of Optical Triangulation Profilometry and Optical Phase Ranging Profilometry to the Figure Evaluation of Solar Mirrors

摘要

The techniques of optical triangulation profilometry (OTP) and optical phase ranging profilometry (OPRP) are proposed for evaluation of the figure of solar mirrors. The theoretical basis for each method is discussed and the results of initial feasibility experiments are reported. In OTP and OPRP the de-specularized mirror surface is probed with one or more visible laser beams. In OTP, two beams are required for the triangulation of coordinates on the mirror surface. In OPRP the second laser beam is retained within the instrument to form the reference leg of a long wavelength interferometer. Both methods are particularly adaptable to computer control for fast, automated analysis of mirror surfaces. In addition the proposed devices are compact and sturdy enough for easy implementation in field evaluation programs. The experimental resolution capability of the unoptimized OTP system is greater than or equal to 0.1 inch (2.54 mm). With further improvement of the beam projection and coincidence assessment systems, the design resolution goal of greater than or equal to 0.1 mm appears achievable. The results of the preliminary resolution capability experiments on the OPRP system are inconclusive. This is thought to be a result of poor performance of components comprising the modulation and detection subsystems. A full assessment of OPRP capability will require a further investigation effort. (ERA citation 06:007503)