Assembly comprising a pocket 3-D scanner

• US 6,118,518 A
• Filed: 02/24/1999
• Issued: 09/12/2000
• Est. Priority Date: 02/24/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Hobbs, Philip C. D.
• Primary Examiner(s): Kim, Robert H.
• Application Number:
  US09/256,535
• Time in Patent Office: 566 Days
• Field of Search: 356/4.09, 356/345, 356/349, 356/358
• US Class Current: 356/4.09
• CPC Class Codes: G01B 11/00 Measuring arrangements characterised by the use of optical techniques
• CPC Class Codes: G01B 2290/45 Multiple detectors for detecting interferometer signals
• CPC Class Codes: G01B 2290/65 Spatial scanning object beam
• CPC Class Codes: G01B 2290/70 Using polarization in the interferometer
• CPC Class Codes: G01B 9/02003 using beat frequencies
• CPC Class Codes: G01B 9/02004 using frequency scans
• CPC Class Codes: G01S 17/08 for measuring distance only indirect measurement G01S17/46; active triangulation systems G01S17/48
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/89 for mapping or imaging

Abstract

An assembly comprising a 3-D scanner and suitable for capturing at least one of objects, or textures, or documents. The assembly preferably can be developed as a pocket page scanner having dimensions approximately the size of a chalkboard eraser. The assembly preferably utilizes an alignment-insensitive diode laser interferometer. In operation, the assembly enables a user to scan any page-sized area in e.g., a half of second, store a hundred or so of them, then play them back into a PC infrared port for OCR, printing, archival storage, or further processing.

Claims

1. An assembly comprising:

(1) a laser for producing an optical beam that can be modulated so as to enable time-of-flight ranging;

(2) a subrange scanner positioned so that it can deviate the path of the optical beam; and

(3) an interferometer, configured so that when it receives at least a portion of the optical beam from the subrange scanner, it can subdivide it to produce transmit and local oscillator beams, and combine the local oscillator beam with at least a portion of an appropriately directed received beam, if present, to produce a combined beam.

2. An assembly comprising:

(1) a laser for producing an optical beam that can be modulated so as to enable time-of-flight ranging;

(2) an interferometer, configured so that when it receives at least a portion of the optical beam from the laser, it can subdivide it to produce transmit and local oscillator beams, and combine the local oscillator beam with at least a portion of an appropriately directed received beam, if present, to produce a combined beam;

(3) a scanner, that can deflect at least a portion of the transmit beam between set angular limits;

(4) an optical detector, configured so as to intercept at least a portion of the combined beam and produce an electrical signal containing range or beam strength information; and

(5) a subrange scanner which deviates the path of the transmit beam.

3. An assembly according to claim 2, in which the subrange scanner can be controlled so as to reduce a scan position error due to the scanner.

4. An assembly according to claim 2, in which the scanner can produce a raster pattern.

5. An assembly according to claim 4, in which the subrange scanner can produce a dither in the frame scan direction, at a rate faster than either the line or frame scan rates of the scanner.

6. An assembly according the claim 5, in which the subranges in adjacent scan lines can overlap.

7. An assembly according to claim 5, in which the measurement data from some of the overlapping portions can be compared, and the spatial relationship between the overlapped sections estimated by comparing these data.

8. An assembly according to claim 5, in which the measurement data from some of the overlapping portions can be compared, to estimate a relative motion component between the assembly and the object surface.

9. An assembly comprising:

(1) a laser for producing an optical beam that can be modulated so as to enable time-of-flight ranging;

(2) an interferometer, configured so that when it receives at least a portion of the optical beam from the laser, it can subdivide it to produce transmit and local oscillator beams, and combine the local oscillator beam with at least a portion of an appropriately directed received beam, if present, for producing a combined beam;

(3) a scanner that can deflect at least a portion of the transmit beam between set angular limits;

(4) an optical detector, configured so that if a combined beam is present, it can intercept at least a portion of the combined beam, and produce an electrical signal containing range or beam strength information; and

(5) a signal processor that can receive the electrical signal and can produce outputs corresponding to combined beam strength and a range between the assembly and an object surface;

(6) a subrange scanner for deviating the path of the transmit beam.

10. An assembly according to claim 9, wherein the subrange scanner is disposed so that the optical beam encounters it before it encounters the interferometer.

11. An assembly according to claim 9, wherein the subrange scanner includes a diffraction grating for deflecting the transmit beam in response to a change in its wave length.

12. An assembly according to claim 11, wherein the laser comprises a diode laser.

13. An assembly according to claim 12, wherein the laser can operate with a duty cycle above 5%.

14. An assembly according to claim 12, wherein the laser can be tuned by varying a bias current.

15. An assembly according to claim 14, wherein the bias current comprises a component of the injection current of the laser.

16. An assembly according to claim 14, wherein the bias current variation waveform can be ramp-shaped over at least a portion of its cycle.

17. An assembly according to claim 14, wherein the bias current variation waveform can be staircase-shaped over at least a portion of its cycle.

18. An assembly according to claim 14, wherein the bias current variation waveform can be shaped like a staircase with tilted treads over at least a portion of its cycle.

19. An assembly according to claim 14, wherein the shape of the bias current variation wave-form can be controlled for reducing the variations in total optical dose across the scan range.

20. An assembly according to claim 9, wherein the range information enables control of the state of focus of the transmit beam.

21. An assembly according to claim 9, wherein the range information enables control of the angular limits of the scan, for making the range more nearly perpendicular to an object surface.

22. An assembly according to claim 9, wherein the range information enables control of a distance between the assembly and an object surface.

23. An assembly according to claim 9, wherein the range information enables correction of variations in a distance between the assembly and an object surface.

24. An assembly according to claim 9, wherein the range information enables estimation of the viewing perspective of an object surface as seen from the assembly.

25. An assembly according to claim 9, wherein the range information enables correction of variations in viewing perspective of an object surface as seen from the assembly.

26. An assembly according to claim 9, wherein the signal processor can use a measurement of a beat frequency between the local oscillator and received beams for measuring the time-of-flight of the received beam.

27. An assembly according to claim 26, wherein the signal processor can use a measurement of the strength of a beat signal between the local oscillator and received beams for measuring the strength of the received beam.

28. An assembly according to claim 9, wherein the signal processor comprises a filter for rejecting changes in the baseline of the beat signal and undesired amplitude modular of the optical beam.