OPTICAL PROJECTOR
 Inventor: Emmet M. Fulkerson, Cincinnati, Ohio
 Assignee: General Electric Company, Cincinnati, Ohio
 Appl. No.: 466,741
 Filed: Feb. 15,1983
 Int. Q." G01B 11/14
 U.S. a 356/372; 356/375
 Field of Search 356/1, 373, 375, 376
 References Cited
U.S. PATENT DOCUMENTS
3,667,846 6/1972 Nater et al 356/120
4,074,104 2/1978 Fulkerson 219/121 LM
4,204,772 5/1980 Balasubramanian 356/1
4,326,804 4/1982 Mossey 356/375
FOREIGN PATENT DOCUMENTS
94871 1/1970 France .
0038159 3/1979 Japan 356/1
56-89005 7/1981 Japan .
IBM Technical Disclosure Bulletin, vol. 15, No. 2, Jul. 1972, pp. 504, 505, "Optical Surface Microtopography
An invention is disclosed for optically determining the position of an object in space, using a single lens for triangulation, wherein an indexing light beam is projected to a lens on one side nonparallel to the optical axis of the lens. The lens focuses the indexing light beam at a known point on the other side of the lens at or near which reflection occurs by the object. Reflected light is captured by the lens and focused toward a photodetector which generates a signal indicating whether reflection occurred at the known point, thus indicating whether the object is present at the known point. If laser light is used, provision is made for, in effect, positioning the laser light source on the optical axis to reduce the effects of laser pointing instabilities. The invention can be used to measure the radii of rotating gas turbine engine rotors.
6 Claims, 6 Drawing Figures