Abstract: A method and apparatus for inspecting a three dimensional structure, such as an electronic component, using collimated light for accurately measuring the three-dimensional structure of members protruding above the surface of the component. Collimated light illuminates the surface, and spherical or other three-dimensional structure on the surface is analyzed, using stereoscopic, holographic, Moire, or conoscopic analysis of light reflected or scattered by the structure, using an array of optical detectors in a detector plane.

Abstract: A linear conoscope producing a conoscopic interferogram of an object wherein the phase shift giving rise to the interferogram is substantially linearly dependent on displacement of an object from a geometrical axis. Two anisotropic optical elements are provided and oriented with respect to one another in such a manner as to cancel the predominant term in which the phase shift depends quadratically on displacement from the geometrical axis.

Abstract: An optical device for generating a signal based on a distance of an object from the optical device. The optical device includes a first polarizer, a birefringent crystal positioned optically downstream from the first polarizer, and a second polarizer arranged optically downstream from the birefringent crystal. The second polarizer creates a pair of interferograms by adjusting a phase of the light. Two outputs are generated by separately integrating an amount of light of at least a part of each of the pair of interferograms. Finally, the two outputs are combined such that the signal, depending only on the distance between the object and the optical system, is obtained.

Abstract: The present invention concerns a holographic process including a stage consisting in producing the hologram of a point P thank to an optical device including a crystal (131) and two polarizers (132,135) placed respectively before and after the crystal (131), characterized by the fact that it includes in addition the stages consisting in: 1) separating the answers of the optical system corresponding to two different polarizations and 2) combining both these answers in order to obtain a signal which depends only on the distance between the point P ant the optical device. The invention concerns also a device which allows the implementation or this process.