Distance determination in a scanned beam image capture device

• US 7,312,879 B2
• Filed: 08/23/2005
• Issued: 12/25/2007
• Est. Priority Date: 08/23/2005
• Status: Active Grant

• Current Assignee: University of Washington
• Original Assignee: University of Washington
• Inventors: Johnston, Richard S.
• Primary Examiner(s): Lauchman, Layla G.
• Assistant Examiner(s): Slomski, Rebecca C.
• Application Number:
  US11/210,465
• Publication Number:
  US 20070081168A1
• Time in Patent Office: 854 Days
• Field of Search: 356/614, 356/621, 356/138, 356/912
• US Class Current: 356/614
• CPC Class Codes: A61B 5/0062 Arrangements for scanning
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: A61B 5/1076 for measuring dimensions inside body cavities, e.g. using catheters A61B3/1005 takes precedence
• CPC Class Codes: G01B 11/026 by measuring distance between sensor and object G01B11/0608 takes precedence
• 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: G01B 11/26 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G02B 26/10 Scanning systems

Abstract

Methods, systems, and devices can determine spatial relationships between a probe and a target surface. Specular reflections from the target surface vary dramatically with small changes in angle between the scanning beam and the target surface, and as the geometry of the beam scanner and light detector of the probe are often known, and as the angle of the light beam projected from a scanner for accurately generating an image, the pattern of spectral light reflected from the light beam directly back to the detector allows the distance between the probe and the target surface, and/or the angular relationship between the probe and the target surface, to be calculated.

Claims

1. A method for determining a spatial relationship between a probe and a target surface, the method comprising:

scanning a beam of light from the probe spatially across the surface;

sensing, with a light detector of the probe, a specular reflection of the light from the surface, the sensed specular reflection comprising specular image signals;

determining a specular reflection pattern from the specular image signals; and

determining a distance between the surface and the probe or an angle between the surface and the probe using at least a geometric characteristic of the specular reflection pattern.

2. The method of claim 1, wherein the probe comprises an endoscope, and wherein the surface comprises a tissue surface within a patient body.

3. The method of claim 1, wherein the beam is oscillated by vibrating an optical fiber with a two-dimensional scan.

4. The method of claim 1, wherein the beam of light comprises an imaging light beam, the probe transmitting imaging signals for imaging the surface in response to diffuse reflection of the light beam from the surface.

5. The method of claim 4, further comprising detecting the specular light and the diffuse light with the detector, and separating specular image signals from display image signals using a brightness threshold, the sensed specular reflection comprising the specular image signals.

6. The method of claim 4, wherein an angular scan magnitude is smaller when measuring the specular reflection than when imaging.

7. The method of claim 1, wherein the distance or angle is determined from an angle of the scanning beam when the specular reflection is sensed.

8. The method of claim 7, further comprising scanning the beam with a scanner, wherein the distance is determined using a scanner/detector distance between the scanner and the detector.

9. The method of claim 8, wherein the scanner/detector distance comprises a distance between a center of the scanner and the detector.

10. The method of claim 8, further comprising sensing the specular reflection with a plurality of light detectors of the probe, and determining a pattern of spectral reflections from the surface as sensed by the plurality of detectors.

11. The method of claim 10, wherein the distance is further determined in response to a spectral reflection pattern size.

12. The method of claim 8, wherein the detector is at a first distance from a center of the scan, and wherein another detector is at a second distance from the center of the scan, the second distance being different than the first distance.

13. The method of claim 1, further comprising determining the angle of the surface relative to the probe using the specular reflection.

14. The method of claim 13, wherein the angle is determined at least in part from a shape of the spectral reflection.

15. The method of claim 14, wherein the shape of the spectral reflection comprises:

a spectral reflection pattern shape within an image received by a pattern of detectors, or

a single spectral reflection outline shape received at a single detector.

16. The method of claim 14, wherein the angle of the surface relative to the probe is measured at a plurality of locations within a field of view of the probe.

17. The method of claim 1, further comprising moving a scanner of the probe from a first location to a second location, the scanning beam of light being transmitted from the scanner, the specular light reflections being measured with the scanner at the first and second locations.

18. The method of claim 17, wherein the scanner is moved between a first measurement at the first location and a second measurement at the second location by moving the probe.

19. The method of claim 18, wherein the processor identifies a datum location for the first measurement, identifies the datum location for the second measurement, and uses the datum location to combine the first and second measurements.

20. The method of claim 17, further comprising imaging the surface with the scanner at the first and second locations and generating a contour map of the surface using at least one of the images or the measured specular reflections.

21. The method of claim of claim 1, wherein the light detector has a non-round light detection surface.

22. The method of claim 1, further comprising generating a plurality of images of the surface from signals transmitted by the detector and averaging the images to enhance accuracy of the distance or angle determination.

23. The method of claim 1, wherein the distance between the surface and the probe is determined using a size of a single spectral reflection received at a single associated detector.

24. A surface measurement system comprising:

a light source for transmitting a beam of light;

a scanner coupled to the light source, the scanner spatially scanning the beam of light over a surface;

a light detector positioned to detect a specular reflected portion of the light from the surface, the detected specular reflection portion comprising specular image signals; and

a processor coupled to the detector, the processor configured to determine;

a specular reflection pattern from the specular image signals; and

a distance between the surface measurement system and the surface, or an angle of the surface relative to the surface measurement system, from at least a geometric characteristic of the specular reflection pattern.

25. The surface measurement system of claim 24, wherein at least the scanner and the light detector are included within an endoscopic probe body.

26. The surface measurement system of claim 24, wherein the scanner comprises an assembly including a fiber and an actuator system for oscillating the fiber in first and second dimensions, the assembly suitable for use in a scanning fiber endoscope system.

27. The surface measurement system of claim 24, wherein the processor comprises a separator module configured to separate the specular reflected light from diffuse reflected light.

28. The surface measurement system of claim 27, further comprising a display coupled to the processor, the display showing an image of the surface generated using the diffuse reflected light.

29. Software for use in a scanned beam imaging system, the system including a scanner configured for spatially scanning a beam of light over a target surface, a detector positioned for detecting reflected light from the surface, the light comprising a specular reflected portion, and the detected specular reflected portion comprising specular image signals, and a processor coupled to the detector, the software comprising a tangible computer readable media comprising machine readable code embodying instructions that, if executed, cause the processor to determine:

a specular reflection pattern from the specular image signals; and

a distance between the system and the surface, or an angle of the surface relative to system, using at least a geometric characteristic of the specular reflection pattern.