High precision three dimensional mapping camera

• US 6,424,735 B1
• Filed: 12/11/2000
• Issued: 07/23/2002
• Est. Priority Date: 12/02/1998
• Status: Expired due to Term

• Current Assignee: Electro Scientific Industries Incorporated (MKS Instruments Incorporated)
• Original Assignee: Daniel Freifeld
• Inventors: Freifeld, Daniel
• Primary Examiner(s): MEHTA, BHAVESH M
• Application Number:
  US09/734,229
• Time in Patent Office: 589 Days
• Field of Search: 382/151, 382/154, 382/141, 348/86, 348/87, 348/92, 356/3, 356/3.01, 356/3.1, 356/3.13
• US Class Current: 382/154
• CPC Class Codes: G01B 11/2518 Projection by scanning of the object
• CPC Class Codes: G06V 10/12 Details of acquisition arrangements; Constructional details thereof
• CPC Class Codes: G06V 2201/12 Acquisition of 3D measurements of objects

Abstract

An optical imaging apparatus comprising a linear array-based camera, using a positional encoding technique highly insensitive to transient and steady state mechanical tolerances in the mechanical scanning system, with the capacity to capture a three dimensional image of a part with enough precision to allow accurate measurements of the part'"'"'s features to be made.

Claims

1. An optical imaging apparatus having focusing optics, with an optical axis, for sending light emitted from an object under observation placed within the field of view of said optical imaging apparatus along said optical axis from said object under observation to be focused on a focal plane, said optical imaging apparatus comprising:

(a) a linear array of detectors, said linear array of detectors comprising at least one light sensitive element, said light sensitive element being positioned in said focal plane, said light sensitive element outputting an image of a portion of said object under view;

(b) a platform configured and dimensioned to support said object under observation in a known position with respect to said platform;

(c) a first moveable mounting responsive to vertical mechanical drive forces to move said platform relative to said optical imaging apparatus to a desired horizontal and vertical position;

(d) a motor having a vertical drive member for applying a vertical drive force to said movable mounting;

(e) a light source emitting light onto said object under observation;

(f) a vertical position transmitting device coupled to said platform and having the ability to transmit positional data relative to said platform;

(g) a computer receiving vertical positional data from said vertical position transmitting device, said computer using said vertical positional data to calculate the position of said object under observation with respect to said at least one light sensitive element, said computer using image data output by said at least one light sensitive element and positional data output by said vertical position transmitting device to generate a three dimensional image.

2. An optical imaging apparatus as in claim 1, wherein said focusing optics are telecentric.

3. An optical imaging apparatus as in claim 1, wherein said three dimensional image is generated by said computer combining image data output by said at least one light sensitive element at various vertical positions.

4. An optical imaging apparatus as in claim 1, wherein said focusing optics comprise a lens with a high numerical aperture.

5. An optical imaging apparatus as in claim 1, wherein said light source comprises four linear illuminators spaced at 90 degree intervals around said object.

6. An optical imaging apparatus having focusing optics with an optical axis, for sending light emitted from an object under observation placed within the field of view of said optical imaging apparatus along said optical axis from said object under observation to be focused on a focal plane, said optical imaging apparatus comprising:

(a) a linear array of detectors, said linear array of detectors comprising at least one light sensitive element, said light sensitive element being positioned in said focal plane, said light sensitive element outputting an image of a portion of said object under view;

(b) a support structure configured and dimensioned to support said focusing optics and said linear array of detectors in a known position with respect to said support structure;

(c) a platform configured and dimensioned to support said object under observation in a known position with respect to said platform;

(d) a first moveable mounting responsive to horizontal mechanical drive forces to move said platform to a desired horizontal position relative to said optical imaging apparatus;

(e) a horizontal motor having a horizontal drive member for applying a horizontal drive force to said first movable mounting;

(f) a second moveable mounting responsive to vertical mechanical drive forces to move said support structure to a desired vertical position;

(g) a vertical motor having a vertical drive member for applying a vertical drive force to said second movable mounting;

(h) a light source emitting light onto said object under observation;

(i) a horizontal position transmitting device coupled to said platform and having the ability to transmit positional data on said platform;

(j) a vertical position transmitting device coupled to said support structure and having the ability to transmit positional data on relative to said support structure;

(k) a computer receiving horizontal positional data from said horizontal position transmitting device and receiving vertical positional data from said vertical position transmitting device, said computer using said horizontal and said vertical positional data to calculate the position of said object under observation with respect to said at least one light sensitive element, said computer using image data output by said linear array and positional data output by said horizontal position transmitting device and vertical position transmitting device to generate a three dimensional image.

7. A method of generating a three dimensional image using an optical imaging apparatus having focusing optics and a linear array of detectors which capture an image of an object placed on a platform within the field of view of said linear array of detectors, said at least one light sensitive element having a direction of movement vertically away from a first point and towards a second point, said focusing optics having an optical axis orthogonal to said direction of movement, said method comprising the steps of:

a) signaling said at least one light sensitive element to capture a first image of said object, said first image having areas in focus and out of focus;

b) moving said at least one light sensitive element a known distance in the direction of said second point;

c) signaling said at least one light sensitive element to capture a second image of said object, said second image having areas in focus and out of focus, said second image not being the same as the first image;

d) moving said at least one light sensitive element a known distance in the direction of said second point;

e) signaling said at least one light sensitive element to capture a third image of said object, said third image having areas in focus and out of focus; and

f) moving said object to subsequent positions in the direction of said second point and signaling subsequent captures of subsequent image of said object, each of said subsequent captures containing areas in focus and out of focus.

8. A method as in claim 7, wherein said optical imaging apparatus comprises a lens having a numerical aperture of NA 0.2 or higher.

9. A method of imaging an object in three dimensions comprising the steps of:

(a) imaging a portion of said object on a plurality of light sensitive elements forming an array, said imaging being done with focusing optics in a first focal position to project a first image on said array said first focusing optics defining a focal surface at a position in space relative to said focusing optics, said focal surface comprising a plurality of first points, each of said first points corresponding to a light sensitive element in said array, the position of each of said first points relative to its respective light sensitive element being known where said image is in focus at said respective light sensitive element, said position when said image is in focus comprising associated position information;

(b) imaging said portion of said object on said array with said imaging being effected with said focusing optics in a second focal position to project a second image on said array;

(c) imaging said portion of said object on said array with said imaging being effected with said focusing optics in additional focal position to project additional image on said array;

(d) comparing said first, second and additional images to determine which sub-portions of said first, second and additional image are most in focus image sub-portions;

(e) for each point in said portion of said object, selecting and associating all of said most in focus image sub-portions to generate an in focus image of said portion of said object with said image portions defining a contour defined by said associated position information;

f) repeating steps (a), (b), (c), (d) and (e) to generate a final image.

10. A method of imaging an object in three dimensions as claimed in claim 9 wherein said partial array is a linear array.

11. A method of imaging an object in three dimensions as claimed in claim 9 wherein said partial ARRAY is an area array.

12. A method of imaging an object in three dimensions as claimed in claim 9 wherein an image is in focus when contrast is at a maximum.

13. A method of imaging an object in three dimensions as claimed in claim 9 wherein at least one portion comprises multiple portions imaged simultaneously.

14. A method of generating a three dimensional image of an object as claimed in claim 9 wherein said object moves and said light sensitive elements remains stationary.

15. A method of generating a three dimensional image of an object as claimed in claim 9 wherein said light sensitive elements move and said object remains stationary.

16. A method of generating a three dimensional image of an object as claimed in claim 9 wherein said light sensitive elements and said object move.

17. A method of generating a three dimensional image of an object as claimed in claim 9 wherein said object moves horizontally and said optical axis remains stationary.

18. A method of generating a three dimensional image of an object as claimed in claim 9 wherein said optical axis move horizontally and said object remains stationary.

19. A method of generating a three dimensional image of an object as claimed in claim 9 wherein said optical axis and said object move horizontally.

20. A method of generating a three dimensional image of an object as claimed in claim 9 wherein said focal surface can be altered by said focusing optics such that said image of said portion of said object can be magnified or reduced.

21. A method of generating a three dimensional image of an object as claimed in claim 9 further comprising generating measurement information from said image.