| 摘要 |
For the purpose of distance measurement, use is made of an optical correlator which has at least one imaging system (11, 15), at least one optically active grid structure (10) and a photoelectric receiver system (20-27) assigned to said structure. A principal maximum in the output signal of the photoelectric receiver system characterises the geometrical image position. For the purpose of uniquely determining this maximum as against other possible maxima, different beam paths are produced in the image space and/or Fourier space, and photoelectric receiver systems are assigned to them. In the case of an axial relative movement of an object image with respect to the grid structure, there is produced at each of these photoelectric receiver systems an output signal which always differs from that obtained from another beam path in terms of its frequency and differs in its phase angle in the ratio of the two signal frequencies, both signals having the same phase angles for the principal maximum. The geometrical image position of the principal maximum with respect to the geometric image positions of other possible maxima is determined by comparing these phase angles. <IMAGE> |
