Method and apparatus for electro-optically determining dimension, location and altitude of objects

• US 4,674,869 A
• Filed: 07/22/1985
• Issued: 06/23/1987
• Est. Priority Date: 04/30/1979
• Status: Expired due to Term

• Current Assignee: LMI Technologies Inc.
• Original Assignee: Diffracto, Ltd. (LMI Technologies Inc.)
• Inventors: Pryor, Timothy R., Pastorius, W. J., Hockley, Bernard, Hageniers, Omer L., Liptay-Wagner, Nick
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US06/757,208
• Time in Patent Office: 701 Days
• Field of Search: 356/1, 356/4, 356/376, 356/377, 356/5, 356/394
• US Class Current: 356/3.06
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G01B 11/2416 of gears optical projection profile comparators G01B9/08
• CPC Class Codes: G01B 11/245 using a plurality of fixed, simultaneously operating transducers G01B11/2408 - G01B11/2425, G01B11/255 take precedence
• CPC Class Codes: G01S 17/46 Indirect determination of position data
• CPC Class Codes: G01S 17/48 Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/481 Constructional features, e.g. arrangements of optical elements
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/491 Details of non-pulse systems

Abstract

A method and apparatus for optically determining the dimension of part surfaces. Particular embodiments describe optical triangulation based coordinate measurement machines capable of accurate measurement of complex surfaces, such as gear teeth and turbine blades. Other embodiments provide highly useful sensors for robot guidance and related purposes. Up to 5 axis sensing capability is provided on surfaces of widely varying form.

Claims

1. Apparatus for determining the countour of a varying contoured surface of an object comprising:

means for positioning an object in an inspection location;

means for projecting a zone of light along a light axis onto the surface of said object;

means for detecting an image of said zone of light, said image detecting means comprising light detector means and optical means for forming an image of said zone of light on said light detector means, said light detector means being located in known position relative to an object in said inspection location, relative to said optical means, and relative to said axis of projected light, said light detector means having an optical axis which is angularly spaced from the axis of said projected light such that the position of said image on said light detector means is dependent on the distance between said zone of light and said light detector means, said light detector means including means for providing an output signal indicative of the location on said detector means of said image of said zone of light;

means for moving said image detecting means relative to an object in said inspection location in a pre-determined theoretical varying path parallel to a desired theoretical varying surface contour of a reference object, such that an object in said inspection location will produce, in said light detector means, output signals characteristic of the contour of the surface of said object as said image detecting means is moved along the theoretical varying path relative to said object;

means for comparing said output signals with reference signals characteristic of said desired theoretical varying surface contour whereby said comparing means provides an indication of the deviation from said theoretical varying surface contour of the contour of an object in said inspection location; and

;

means for determining, from the comparison, the varying contour of a surface of an object in said inspection location.

2. A method for determining the contour of a varying contour surface of an object comprising:

positioning an object in an inspection location;

projecting a zone of light along a light axis onto the surface of said object;

detecting, with image detecting means, an image of said zone of light, said image detecting means comprising light detector means and optical means for forming an image of said zone of light on said light detector means, said light detector means being located in known position relative to an object in said inspection location, relative to said optical means, and relative to said axis of projected light, said light detector means having an optical axis which is angularly spaced from the axis of said projected light such that the position of said image on said light detector means is dependent on the distance between said zone of light and said light detector means, said light detector means including means for providing an output signal indicative of the location on said detector means of said image of said zone of light;

moving said image detecting means relative to said object in said inspection location in a pre-determined theoretical varying path parallel to a theoretical desired varying surface contour of a reference object, such that said object in said inspection location will produce, in said light detector means, output signals characteristic of the contour of the surface of said object as said image detecting means is moved along the theoretical varying path relative to said object;

comparing said output signals with reference signals characteristic of said desired varying surface contour to provide an indication of the deviation from said theoretical varying surface contour of the contour of said object in said inspection location; and

determining, from the comparison, the varying contour of said surface of said object in said inspection location.