OPTICAL MEASURING PROCESS AND PRECISION MEASURING MACHINE FOR DETERMINING THE DEVIATIONS FROM IDEAL SHAPE OF TECHNICALLY POLISHED SURFACES

摘要

In a known measuring process, the possibility for the generation of two measuring beams, by means of two measuring systems operating the same measurement strategy is given. The reflection angle of the measuring beams deflected onto a blank are detected as inclination deviations of the surface and analysed by difference. Systematic measuring deviations are conventionally reduced however mainly by the use of a single measuring strategy or system with a moving measuring beam. According to the invention, the measurement accuracy can be improved up to the sub-nanometre range by combining two different measuring strategies in the measuring process, carried out by differing measuring systems (13, 14), which can be an autocollimator (AKF) and a long-trace profilometer (LTP), the measuring beams of which can be directed at the blank (10) using different types of deflecting units (15). Measured results with an accuracy of up to 0.01 angle seconds, hence sub-nanometre range, for example, +/- 0,2 nm, can be achieved by means of suitable correlation of the measured values obtained from the differing scanning methods for offsetting the systematic measuring deviations of both measuring systems (13, 14). Precisely produced surfaces of almost any dimensions, for example, nanometre optical components can thus be highly precisely inspected.