LARGE SCALE METROLOGY APPARATUS AND METHOD

• US 20120050752A1
• Filed: 08/22/2011
• Published: 03/01/2012
• Est. Priority Date: 08/24/2010
• Status: Abandoned Application

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: NOVAK, W. THOMAS, SMITH, DANIEL G.
• Application Number:
  US13/214,684
• Publication Number:
  US 20120050752A1
• Time in Patent Office: Days
• US Class Current: 356/623
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01S 17/00 Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49

Abstract

A metrology system that uses multiple rotating receiving heads and either (i) photo-emitting targets or (ii) passive retro-reflector targets. In either case, each receiver head includes a pair of slit-shaped field view collectors, at opposing degrees, relative to the axis of rotation of the head. As each head rotates, radiation either generated by or reflected off the targets, passes through slit-shaped field view collectors and onto photo-detectors. A signal processor couple to each of the rotating heads determines the relative position and height of each of the targets based on the signals generated by the photo-detectors.

Claims

1. A system, comprising:

a plurality of targets configured to each be positioned at first locations within a predetermined volume;

a plurality of photo-detecting heads configured to each be positioned at second locations within the predetermined volume, each of the photo-detecting heads configured to rotate within the predetermined volume and receive radiation from the plurality of targets; and

a signal processor configured to determine the relative position and height of the plurality of targets within the predetermined area based on signals generated by the plurality of rotating photo-detecting heads in response to radiation received from the plurality of targets respectively.

2. The system of claim 1, wherein each of the plurality of photo-detecting heads comprises:

a pair of slit-shaped field view collectors; and

a pair of photo-detectors positioned to receive light passing through the pair of slit-shaped field view collectors.

3. The system of claim 2, wherein each pair of the photo-detectors is configured to generate a plurality of pulsed pair of signals.

4. The system of claim 3, wherein each of the plurality of pulsed pair signals is generated, per each revolution of the rotating heads, for each of the plurality of targets in the predetermined volume respectively.

5. The system of claim 4, wherein the signal processor is further configured to generate, for each of the plurality of pulsed pair signals, the following:

(i) an elevation for the corresponding target based on the elapsed time between the pulsed pair signals; and

(ii) an azimuth of the corresponding target from the timing of the pulsed pair signals relative to the rotational position of the photo-detecting head that generated the pulsed pair signal.

6. The system of claim 5, wherein the signal processor is further configured to generate a plurality of direction lines from the plurality of pulsed pair signals.

7. The system of claim 6, wherein the signal processor is further configured to:

(i) ascertain the direction lines that intersect; and

(ii) determine the relative position of the plurality of targets based on the ascertained intersections.

8. The system of claim 7, wherein determining the relative position further comprises one of the following:

(i) determining the relative position of the plurality of targets in the volume in two dimensions; and

(ii) determining the relative position of the plurality of targets in the volume in three dimensions.

9. The system of claim 1, wherein the targets are photo-emitting targets.

10. The system of claim 9, wherein the photo-emitting targets include first and second photo-emitters laterally spaced apart.

11. The system of claim 10, wherein the first and the second photo-emitters use radiation from LEDs.

12. The system of claim 9, wherein each of the photo-emitting targets generate radiation 360 degrees around each target respectively.

13. The system of claim 9, wherein each of the photo-emitting targets generate radiation having an elevation ranging from +/−

10 to +/−

60 degrees.

14. The system of claim 1, wherein the targets are passive-reflective targets.

15. The system of claim 14, wherein each of the passive-reflective targets includes a first reflective surface and a second reflective surface.

16. The system of claim 15, wherein the second reflective surface consists of one of the following:

a mirror, a corner cube or a surface coated with a reflective material, or an array of retro-reflecting elements.

17. The system of claim 15, wherein the first and the second reflective surfaces are contained within a transparent spherical window.

18. The system of claim 14, wherein each of the passive reflective targets comprise at least one sphere covered with a retro-reflective material.

19. The system of claim 1, wherein the photo-detecting heads are each configured to generate two fan beams to illuminate the predetermined volume.

20. The system of claim 19, wherein the fan beams rotate 360 degrees around each photo-detecting head respectively.

21. The system of claim 19, wherein the fan-out beams have an elevation ranging from +/−

5 to +/−

75 degrees respectively.

22. The system of claim 10, further comprising a master controller for selectively activating or deactivating the photo-emitting targets.

23. The system of claim 1, further comprising a master controller configured to calibrate the system by determining the location of the plurality of photo-detecting heads within the predetermined area.