Light detection and ranging apparatus

• US 8,120,754 B2
• Filed: 02/19/2009
• Issued: 02/21/2012
• Est. Priority Date: 02/19/2009
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Inventors: Kaehler, Adrian
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): RATCLIFFE, LUKE D
• Application Number:
  US12/389,065
• Publication Number:
  US 20100208235A1
• Time in Patent Office: 1,097 Days
• Field of Search: 356 301- 315, 356 401- 41, 356 501- 515, 356 6- 22, 356/28, 356/28.5
• US Class Current: 356/5.01
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 7/4812 transmitted and received beams following a coaxial path
• CPC Class Codes: G01S 7/4817 relating to scanning

Abstract

A light detection and ranging (LIDAR) apparatus is provided that employs one or more additional reflectors to reflect and redirect the light beam transmission pulses from a scanning fan assembly to a given area of interest. The one or more additional reflectors provide additional resolution for detecting a detectable object. The one or more additional reflectors can be external or internal to the scanning fan assembly.

Claims

1. A light detection and ranging (LIDAR) apparatus comprising:

a light source that provides light beam transmission pulses;

a scanning fan assembly that directs light beam transmission pulses at each of a given emittance angle over a given angular range;

a detection system that detects light beam return pulses associated with respective light beam transmission pulses and determines a distance of a detectable object associated with the given emittance angle for each emittance angle over the given angular range; and

at least one additional reflector positioned to reflect and redirect the light beam transmission pulses from the scanning fan assembly to a given area of interest;

wherein the scanning fan assembly and the at least one reflector reside in a housing of the apparatus, the at least one reflector being at least one fixed internal mirror mounted within the housing in close proximity to a rotating mirror of the scanning fan assembly and being configured to harvest and redirect light beam transmission pulses to the area of interest external to the housing from the rotating mirror that would otherwise not exit the housing of the LIDAR apparatus;

wherein the at least one fixed internal mirror comprises two fixed internal mirrors recessed within an angle within the housing of the LIDAR apparatus, the two fixed internal mirrors being perpendicular to the scanning plane of the rotating mirror to redirect the harvested light beam transmission pulses to the area of interest.

2. The apparatus of claim 1, wherein the scanning fan assembly resides in a LIDAR unit and the at least one additional reflector further comprises at least one additional external reflector physically coupled to the LIDAR unit and external to a housing of the LIDAR unit.

3. The apparatus of claim 2, wherein the LIDAR unit is further configured to convert angular range data to linear range data based on the shape of the reflector.

4. The apparatus of claim 2, wherein the at least one additional external reflector comprises a parabolic reflector.

5. The apparatus of claim 4, wherein the parabolic reflector is one of a two-dimension and three dimension reflector.

6. The apparatus of claim 4, wherein the LIDAR unit is positioned at a focus of the parabolic reflector and oriented such that a scanning fan of light beam transmission pulses from the scanning fan assembly of the LIDAR unit emanates into the reflector and the centerline of the angular range is coincident with the parabola axis of the reflector.

7. The apparatus of claim 6, wherein the parabolic reflector collimates the scanning fan of light beam transmission pulses with the centerlines of the light beam transmission pulses within the scanning fan of light beam transmission pulses emerging from the parabolic reflector parallel to one another and collimates the individual light beam transmission pulses within the scanning fan of light beam transmission pulses.

8. The apparatus of claim 7, wherein the individual light beam transmission pulses within the scanning fan of light beam transmission pulses are emitted from the parabolic reflector in a gap free manner.

9. The apparatus of claim 6, wherein the LIDAR unit and the parabolic reflector are rigidly connected and configured to be rotated through an angular dimension orthogonal to that of the scanning fan of light beam transmission pulses plane to allow the acquisition of three dimensional range data.

10. The apparatus of claim 1, wherein the at least one fixed internal mirror ensures that all light beam transmission pulses emitted from the rotating mirror emerge from the housing and no beams are wasted due to incidence upon a non-reflective interior of the housing.

11. The apparatus of claim 1, wherein some of the light beam transmission pulses emerge from the housing without incidence upon one of the fixed internal mirrors and other light beam transmission pulses will emerge from the housing only after reflecting from one or both of the fixed mirrors, wherein the light beam transmission pulses that emerge from the housing without incidence are associated with the rotating mirror as a physical rangefinder and the light beam transmission pulses that reflect from one of the fixed mirrors are associated with a virtual rangefinder, such that the location of the virtual rangefinder is symmetric to the position of the physical rangefinder about the plane of the reflecting fixed mirror and along the line normal to the fixed mirror and passing through the physical rangefinder.

12. The apparatus of claim 11, wherein a light beam transmission pulses reflecting from a first fixed internal mirror of the two fixed internal mirrors reflects from a second fixed mirror of the two fixed internal mirrors is associated with a second-order virtual rangefinder located at a position symmetric to the first-order virtual rangefinder about the second fixed internal mirror.

13. A light detection and ranging (LIDAR) apparatus comprising:

means for providing light beam transmission pulses;

means for directing light beam transmission pulses at each of a given emittance angle over a given angular range;

means for detecting light beam return pulses associated with a respective transmission light beam transmission pulse;

means for determining a distance of a detectable object associated with the given emittance angle for each emittance angle over the given angular range; and

means for reflecting and redirecting the light beam transmission pulses from the means for directing light beam transmission pulses to a given area of interest;

wherein the means for directing light beam transmission pulses and the means for reflecting and redirecting reside in a housing of the apparatus, the means for reflecting and redirecting being configured to harvest and redirect light beam transmission pulses to the area of interest external to the housing from the means for directing light beam transmission pulses that would otherwise not exit the housing of the LIDAR apparatus;

wherein individual light beam transmission pulses are emitted from the means for reflecting and redirecting in a gap free manner.

14. The apparatus of claim 13, wherein the means for directing light beam transmission pulses is positioned and oriented with respect to the means for reflecting and redirecting such that a scanning fan of light beam transmission pulses are collimated and the individual light beam transmission pulses within the scanning fan of light beam transmission pulses are collimated.

15. The apparatus of claim 13, wherein the means for reflecting and redirecting ensures that all light beam transmission pulses emitted from the means for directing light beam transmission pulses emerge from the housing and no light beam transmission pulses are wasted due to incidence upon a non-reflective interior of the housing.