Laser radar for three-dimensional scanning

• US 8,681,319 B2
• Filed: 03/19/2012
• Issued: 03/25/2014
• Est. Priority Date: 03/31/2011
• Status: Active Grant

• Current Assignee: Denso PS Corporation (DENSO Corporation)
• Original Assignee: Denso PS Corporation (DENSO Corporation)
• Inventors: Tanaka, Hideyuki, Mitsuno, Yoshiki
• Primary Examiner(s): RATCLIFFE, LUKE D
• Application Number:
  US13/423,656
• Publication Number:
  US 20120249996A1
• Time in Patent Office: 736 Days
• Field of Search: 356 301- 315, 356 401- 41, 356 501- 515, 356 6- 22, 356/28, 356/28.5, 35613901-1391
• US Class Current: 356/4.01
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 7/4817 relating to scanning

Abstract

In a laser radar, a first scanning member scans a laser beam in a virtual plane passing through an axis. A control means controls displacements of the first scanning member to change a scan beam angle in the plane. A second scanning member deflects the scanned laser beam and again scans the deflected laser beam toward an external space. A light collecting means collects reflected light. A driving means rotates both the second scanning member and the light collecting means about the axis. The second scanning member has a deflecting surface to deflect the laser beam. The deflecting surface is formed around the axis and has a plurality of reflecting surfaces coaxially arranged centering on the axis. The reflecting surfaces have different inclinations with respect to a horizontal plane perpendicular to the axis.

Claims

1. A laser radar comprising:

a laser beam generating means for generating a laser beam;

a first scanning member for scanning the laser beam from the laser beam generating means in a virtual plane that passes through a predetermined axis;

a control means for controlling a displacement of the first scanning member so that an angle of the scan beam in the plane is changed;

a second scanning member for deflecting the laser beam scanned by the first scanning member and scanning the deflected laser beam toward an external space, the scan member being rotatable about the axis;

a light detecting means for detecting reflected light that is the laser beam reflected in and returned from the external space;

a light collecting means for collecting the reflected light to the light detecting means, the light collecting means being integrally formed with the second scanning member; and

a driving means for driving and rotating both the second scanning member and the light collecting means about the axis, wherein;

the second scanning member has a deflecting surface arranged on a side on which the laser beam is incident and formed to deflect the laser beam;

the deflecting surface is formed at least in a portion of a region along a circumferential direction of the axis, the deflecting surface being a plurality of reflecting surfaces coaxially arranged centering on the axis; and

the plurality of reflecting surfaces are each formed to have a different inclination with respect to a horizontal plane which is perpendicular to the axis.

2. The laser radar according to claim 1, wherein the deflecting surface is formed into an arc shape or an annular shape to surround the axis.

3. The laser radar according to claim 1, wherein the deflecting surface is formed covering an entire circumferential range around the axis.

4. The laser radar according to claim 3, wherein:

the first scanning member is configured to scan the scan beam along the virtual plane and over a predetermined range including both of positive and negative sides with respect to the axis;

the plurality of reflecting surfaces include a circular reflecting surface at a center portion through which the axis passes and one or more annular reflecting surfaces formed surrounding the circular reflecting surface; and

the one or more annular reflecting surfaces have a step which is perpendicular to the axis and located to cross with the respective reflecting surfaces to enable the reflecting surfaces to share a vertical deflected range of the laser beam deflected by the second scanning member.

5. The laser radar according to claim 3, wherein:

the first scanning member is configured to scan the scan beam along the virtual plane and over a predetermined range including one of positive and negative sides with respect to the axis; and

the plurality of reflecting surfaces include a circular reflecting surface at a center portion through which the axis passes and one or more annular reflecting surfaces formed surrounding the circular reflecting surface.

6. The laser radar according to claim 4, wherein:

the light collecting means has a concave reflecting surface;

the second scanning member is arranged at the concave reflecting surface, being exposed therefrom; and

the different inclinations of the plurality of reflecting surfaces are defined by different curvature radiuses such that a plurality of the laser beams incident at different incident angles from the first scanning member are reflected at desired angles by the second scanning member.

7. The laser radar according to claim 6, wherein the second scanning member is integrally formed with the light collecting means.

8. The laser radar according to claim 7, wherein:

the first scanning member is a mirror that reflects the laser beam from the laser beam generating means;

the control means serves as a means for changing an angle of the mirror in terms of a displacement; and

the light collecting means includes a concave mirror that enables the collected reflected light to enter a light-receiving window of the light detecting means.

9. The laser radar according to claim 8, wherein the control means comprises:

a rotation measuring means for measuring the number of rotations of the driving means;

a determining means for determining whether or not the number of rotations measured by the rotation measuring means has become equal to N (N is a natural number); and

a displacement control means for controlling the displacement of the first scanning member so that, when the number of rotations is determined to have reached N by the determining means, the laser beam from the first scanning member is radiated to reflecting surfaces which are different from those before the number of rotations has reached N.

10. The laser radar according to claim 8, wherein the control means comprises:

a rotation measuring means for measuring the number of rotations of the driving means; and

a displacement control means for controlling the displacement of the first scanning member so that, every time the number of rotations measured by the rotation detecting means is incremented by one, the laser beam from the first scanning member scans over the predetermined scan range along the virtual plane for a plurality of times.

11. The laser radar according to claim 4, wherein the control means comprises:

a rotation measuring means for measuring the number of rotations of the driving means;

a determining means for determining whether or not the number of rotations measured by the rotation measuring means has become equal to N (N is a natural number);

a displacement control means for controlling the displacement of the first scanning member so that, when the number of rotations is determined to have reached N by the determining means, the laser beam from the first scanning member is radiated to reflecting surfaces which are different from those before the number of rotations has reached N; and

a scan control means for allowing the first scanning member to perform scan only within a scan range in a plane which is perpendicular to the axis, the scan range being determined by an angle and a position of each step provided in a circumferential direction of the axis.

12. The laser radar according to claim 4, wherein the control means comprises:

a rotation measuring means for measuring the number of rotations of the driving means;

a displacement control means for controlling the displacement of the first scanning member so that, every time the number of rotations measured by the rotation detecting means is incremented by one, the laser beam from the first scanning member scans over the predetermined scan range along the virtual plane for a plurality of times; and

a scan control means for allowing the first scanning member to perform scan only within a scan range in a plane which is perpendicular to the axis, the scan range being determined by an angle and a position of each step provided in a circumferential direction of the axis.

13. The laser radar according to claim 12, wherein a scan range in the plane which is perpendicular to the axis is equal to or less than 180°

.

14. The laser radar according to claim 1, wherein the control means comprises:

a rotation measuring means for measuring the number of rotations of the driving means;

a determining means for determining whether or not the number of rotations measured by the rotation measuring means has become equal to N (N is a natural number);

a displacement control means for controlling the displacement of the first scanning member so that, when the number of rotations is determined to have reached N by the determining means, the laser beam from the first scanning member is radiated to reflecting surfaces which are different from those before the number of rotations has reached N; and

a scan control means for allowing the first scanning member to perform scan over an entire scan range of 360°

along a circumferential direction of the axis.

15. The laser radar according to claim 1, wherein the control means comprises:

a rotation measuring means for measuring the number of rotations of the driving means;

a displacement control means for controlling the displacement of the first scanning member so that, every time the number of rotations measured by the rotation detecting means is incremented by one, the laser beam from the first scanning member scans over the predetermined scan range along the virtual plane for a plurality of times; and

a scan control means for allowing the first scanning member to is perform scan over an entire scan range of 360°

along a circumferential direction of the axis.

16. The laser radar according to claim 1, wherein:

the light collecting means has a concave reflecting surface;

the second scanning member is arranged at the concave reflecting surface, being exposed therefrom; and

the different inclinations of the plurality of reflecting surfaces are defined by different curvature radiuses such that a plurality of the laser beams incident at different incident angles from the first scanning member are reflected at desired angles by the second scanning member.

17. The laser radar according to claim 1, wherein the second scanning member is integrally formed with the light collecting means.

18. The laser radar according to claim 1, wherein:

the first scanning member is a mirror that reflects the laser beam from the laser beam generating means;

the control means serves as a means for changing an angle of the mirror in terms of a displacement; and

the light collecting means includes a concave mirror that enables the collected reflected light to enter a light-receiving window of the light detecting means.

19. The laser radar according to claim 4, wherein:

the light collecting means has a concave reflecting surface;

the second scanning member is arranged at the concave reflecting surface, being exposed therefrom; and

the different inclinations of the plurality of reflecting surfaces are defined by different curvature radiuses such that a plurality of the laser beams incident at different incident angles from the first scanning member are reflected at desired angles by the second scanning member.

20. The laser radar according to claim 5, wherein:

the light collecting means has a concave reflecting surface;

the second scanning member is arranged at the concave reflecting surface, being exposed therefrom; and

the different inclinations of the plurality of reflecting surfaces are defined by different curvature radiuses such that a plurality of the laser beams incident at different incident angles from the first scanning member are reflected at desired angles by the second scanning member.