Optics: measuring and testing – Lamp beam direction or pattern – With lamp focusing
Patent
1975-04-07
1976-08-31
McGraw, Vincent P.
Optics: measuring and testing
Lamp beam direction or pattern
With lamp focusing
356124, 356167, 356212, 356237, 356239, G01B 1130, G01N 2148
Patent
active
039777898
ABSTRACT:
An apparatus is disclosed which automatically measures the geometrical deviations of a reflecting surface from a reference surface, and which also can be used to automatically measure the deviations of some light beam deviating property of a transparent article from a reference in a non-contacting manner over a plurality of lines on the article being measured. A narrow beam of laser light is scanned simultaneously in a raster pattern over the test article and a reference surface. A uniformly rotating multi-faceted reflector device which has suitably chosen pyramidal angles and which is placed near the focal point of a collimating lens produces the scaning, collimated laser beam. A transparent optical element containing a partially reflective, partially transmissive reference surface is placed in the scanning laser beam between the collimating lens and the test article to produce two beams, namely, a reference beam which is reflected from the reference surface and a measurement beam which is transmitted by the reference surface. The reference beam is collected by the collimating lens and is focused onto a first two-axis photoelectric position sensor. The measurement beam is either reflected by the surface of a reflective test article or for a transparent test object autoreflected by a master reflector surface for double-pass transmission through the transparent test article. After probing the test article, the measurement beam passes back through the optical element containing the reference surface and is focused onto a second two-axis photoelectric position sensor by the collimating lens. The reference beam and the measurement beam, after it has probed the test article, are each tilted slightly with respect to the optical axis of the collimating lens to separate the two light spots formed by focusing these beams. The information obtained from the two photodetectors can be processed electronically or by computers to obtain desired information about the differences between the reference surface and the test object. Preferably, electronic circuitry processes the signals generated by the two photoelectric position sensors to provide outputs indicative of the geometrical deviations of the test article surface or the deviations of some light beam deviating property of the test article. A signal indicating whether the test article is within or outside a predetermined tolerance range is also available.
REFERENCES:
patent: 3761179 (1973-09-01), Plummer et al.
patent: 3885875 (1975-05-01), Rosenfeld et al.
Hunter George C.
Zanoni Carl A.
McGraw Vincent P.
Zucker Milton
Zygo Corporation
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