| 摘要 |
Optical method and means for high-speed characterization of the distance between a substantially transparent plane-parallel disk (20) in rotation about an axis (21) perpendicular to its largest surface, and a substantially flat object (30) that is nearly in contact with the disk surface (25). A collimated light beam (2) is first divided into two parallel, spatially separated and orthogonally polarized beams (5,7) which are incident upon the disk surface (25) at Brewster's angle. One beam (5) passes through the disk unreflected and impinges upon the surface of object (30) and reflects back from object (30). The other beam (7) is partially reflected from the bottom surface of the disk (25) and is subsequently recombined with beam (5) and caused to interfere. Optical means (90,91,100,110,150) together with electronic detection and analysis means (130,131; 120,121; 99) determine the phase of the interference. At the same time, a second pair of beams (6,8) is created by division of the collimated source light (2) into two parallel, spatially separated beams having a polarization chosen so that they both reflect from the disk surface (25) and a spatial position such that neither beam (6,8) is effected by the presence of the object (30). These beams (6,8) are recombined and caused to interfere. The phase difference is recorded electronically (130,132; 120,122; 99) and is used to remove from the first measurement the unwanted details concerning the variations in volume and surface profile of the disk (20) as it rotates. Specialized detector arrays (121,122;131,132) having independently-accessed detector elements, provided information about the orientation (pitch and roll) of the object at high speed for efficiently phase sampling along the surface of object (30).
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