United States Patent m
 TELECENTRIC, PARFOCAL, MULTIPLE MAGNIFICATION OPTICAL SYSTEM FOR VIDEOINSPECTION APPARATUS
 Inventor: Albert G. Choate, Rush, N.Y.
 Assignee: Optical Gaging Products, Inc., Rochester, N.Y.
 Appl. No.: 499,870
 Filed: Jul. 10,1995
 Int CI.6 G01J 1/20
 U.S. CI 359/663; 250/201.1
 Field of Search 359/663, 821;
 References Cited
U.S. PATENT DOCUMENTS 5,389,774 2/1995 Gelman et al 250/201.1
FOREIGN PATENT DOCUMENTS 0150846 6/1989 Japan 250/201.1
US005668665A [li] Patent Number: 5,668,665  Date of Patent: Sep. 16, 1997
Primary Examiner—Michael J. Tokar
Assistant Examiner—Richard Hanig
Attorney, Agent, or Firm—Shlesinger, Fitzsimmons &
An objective lens is secured in an afocal mode to a support for movement vertically toward and away from a workpiece. An iUumination collimator fixed on the support above the objective lens projects the image of a reticle downwardly and successively through a second lens assembly, a beamsplitter plate, and coaxially of the objective lens to the workpiece. A combined image of the reticle and workpiece is then projected by the objective lens upwardly onto the beamsplitter, and laterally to a mirror which projects the combined image upwardly along an axis spaced from and parallel to the axis of the objective lens, and through one of several different magnifying lens assemblies to the image detector of a video camera. The magnifying lens assemblies can be selectively indexed one at a time into registry with the camera, and each has a telecentric opening or stop which always registers with the rear focal point of the objective lens each time such assembly is indexed into its operative position.
15 Claims, 3 Drawing Sheets