Apparatus for measuring the curvature of a surface using moveable reflecting and focusing elements

• US 5,589,940 A
• Filed: 12/21/1994
• Issued: 12/31/1996
• Est. Priority Date: 12/21/1994
• Status: Expired due to Term

• Current Assignee: Raytheon Canada Limited (Rtx Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Hollmann, Joerg W.
• Primary Examiner(s): Gonzalez, Frank
• Assistant Examiner(s): VIERRA EISENBERG, JASON D
• Application Number:
  US08/361,260
• Time in Patent Office: 741 Days
• Field of Search: 356/375, 356/376, 356/431, 250/201.2, 250/201.4, 250/201.6, 250/201.9, 250/559.39, 250/559.06, 250/559.38, 250/559.49
• US Class Current: 356/624
• CPC Class Codes: G01B 11/255 for measuring radius of curvature measuring diameter G01B11/08

Abstract

A curvature measuring device (10) for measuring the curvature of an object (14) without contacting object (14) includes a moveable frame (20) and a reflector (28) for reflecting light incident thereupon. A reflector (28) is connected and rotatable with respect to moveable frame (20). An electro-optical device (42) is connected and moveable with respect to moveable frame (20). Electrooptical device (42) includes a light transceiver (52) for transmitting an incident beam of light (54) onto reflector (28) and for receiving a reflected beam of light (56) reflected by reflector (28). Electro-optical device (42) generates a focus signal related to a degree that reflected beam of light (56 ) is received by electro-optical device (42). A controller (90) calculates the curvature of object (14 ) by adjusting a position of moveable frame (20), an angular position of reflector (28), and focus position of electro-optical device (42). Light transceiver (42) can include a bifurcated fiber optic cable have a first bundle coupled to a light emitting diode and a second bundle coupled to a photodiode. The controller (90) aligns incident beam of light (54) to form a 90° angle with surface (12) of object (14). Controller (90) employs a focus signal generated by the electro-optical device (42) in a closed-loop fashion to adjust a frame positioning device (22), an angular positioning device (30), and a focus positioning device (40).

Claims

1. Apparatus for measuring the curvature of a surface of an object at a first position on the surface comprising:

a frame;

means for moving said frame relative to said object to provide a frame position signal;

light source means for providing incident light;

means disposed adjacent to said light source means for focussing said incident light said focussing means including means for transmitting light onto said reflecting means and means for receiving return light from said reflecting means and for transmitting return light to said light source means to provide a focus signal;

means disposed adjacent to said focussing means for reflecting said incident light onto said surface and for reflecting return light from said surface to said focussing means;

means for rotating said reflecting means to provide an angle position signal for the reflecting means;

means for moving said focussing means to provide a focus position signal; and

control means including a processor means for receiving said frame position signal, said angle position signal, said focus position signal, and said focus signal to calculate the curvature of said surface at said first position.

2. The apparatus of claim 1 said control means further comprising means for generating control signals for causing movement of at least one of said rotating means and said focussing means prior to the calculation of curvature at the position.

3. The apparatus of claim 2 wherein said means for transmitting light and said means for receiving and transmitting return reflected light comprise a single fiber optic bundle coupled between said control means and said reflecting means.

4. The apparatus of claim 1, said control means further comprising means for generating control signals for causing a series of movements of said frame moving means to calculate curvature for an entire surface.

5. The apparatus of claim 1 further comprising a fixture for receiving said object and means for moving said fixture relative to said reflecting means.

6. The apparatus of claim 1 wherein said light source means comprises a light emitting diode controlled by said control means.

7. The apparatus of claim 1 wherein said focussing means comprises at least one lens.

8. The apparatus of claim 1 wherein said reflecting means is rotated such that incident light is reflected onto said surface at a plurality of angles of incidence with respect to said surface.

9. The apparatus of claim 8 wherein at least one of said angles of incidence is 90°

.

10. The apparatus of claim 1 wherein said control means uses a peak in said focus signal to control the movement of at least one of said focussing means and said rotating means.

11. The apparatus of claim 1, said apparatus being disposed in noncontact physical relationship with respect to the surface of said object.

12. Method for measuring the curvature of a surface of an object at a first position on the surface comprising:

providing a frame;

moving said frame relative to said object to provide a frame position signal;

providing incident light;

providing reflecting means;

reflecting said incident light onto said surface and receiving return light reflected by said surface using said reflecting means;

moving said reflecting means to provide an angle position signal for the reflecting mechanism;

providing focussing means;

focussing light onto said reflecting means using said focussing means, said focussing step including transmitting light onto said reflecting means and receiving and transmitting return reflected light to provide a focus signal;

moving said focussing means to provide a focus position signal; and

processing said frame position signal, said angle position signal, said focus position signal, and said focus signal to calculate the curvature of said surface at said first position.

13. The method of claim 12 further comprising the step of generating control signals to cause at lease one of said rotating steps and said focussing steps to occur prior to the calculation of curvature at the position.

14. The method of claim 13 wherein said steps of transmitting light and receiving and transmitting return reflected light include using a single fiber optic bundle.

15. The method of claim 12, further comprising the step of generating control signals to cause a series of movements of said frame moving means to calculate curvature for the entire said surface.

16. The method of claim 12 further comprising the steps of providing a fixture for receiving said object and moving said fixture relative to said reflecting means.

17. The method of claim 12 wherein said step of providing a light source comprises providing a light emitting diode controlled by said control means.

18. The method of claim 12 wherein said focussing steps includes using at least one leans.

19. The method of claim 12 further comprising moving said reflecting means such that incident light is reflected onto said surface at a plurality of angles of incidence with respect to said surface.

20. The method of claim 19 wherein at least one of said angles of incidence is 90°

.

21. The method of claim 12 said processing step using a peak in said focus signal to control at lease one of said focussing steps and rotating steps.

22. The method of claim 12 said apparatus being disposed in noncontact physical relationship with respect to the surface of said object.