Apparatus and methods for obtaining multi-dimensional spatial and spectral data with LIDAR detection

• US 8,599,367 B2
• Filed: 08/04/2010
• Issued: 12/03/2013
• Est. Priority Date: 08/04/2010
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Alliant Techsystems Incorporated (Northrop Grumman Corporation)
• Inventors: Canham, John S.
• Primary Examiner(s): RATCLIFFE, LUKE D
• Application Number:
  US12/850,536
• Publication Number:
  US 20120182541A1
• Time in Patent Office: 1,217 Days
• Field of Search: 356 301- 515, 356 6- 22, 356/28, 356/28.5
• US Class Current: 356/5.01
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• CPC Class Codes: G01J 2003/2826 Multispectral imaging, e.g. filter imaging
• CPC Class Codes: G01J 3/2823 Imaging spectrometer
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G01S 7/4802 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01S 7/4816 of receivers alone
• CPC Class Codes: G01S 7/486 Receivers

Abstract

A Light Detection and Ranging (LIDAR) apparatus comprises a laser generator configured to generate an output laser signal toward a target area, at least one detector configured as an array of light sensitive elements, the array including a plurality of rows and columns of the light sensitive elements, and at least one wavelength dispersion element positioned in a return path of a returning laser signal returning from the target area. The at least one wavelength dispersion element is configured to separate wavelengths of the returning laser signal onto the plurality of rows and columns of the array, wherein the plurality of columns of the array are associated with the separated wavelengths that correspond with a position along a row of the array, the position along the row of the array corresponding with a spatial position of the target area along a first axis. Methods for scanning a target area and obtaining spectral and spatial data are disclosed herein.

Claims

1. A Light Detection and Ranging (LIDAR) apparatus, comprising:

a laser generator configured to generate an output laser signal toward a target area;

at least one detector configured as an array of light sensitive elements, the array including a plurality of rows and columns of light sensitive elements;

at least one wavelength dispersion element positioned in a return path of a returning laser signal returning from the target area, the at least one wavelength dispersion element configured to separate wavelengths of the returning laser signal onto the plurality of rows and columns of the array, wherein the columns of the plurality of columns of the array are associated with the separated wavelengths that correspond with a position along a row of the array, the position along the row of the array corresponding with a spatial position of the target area along a first axis; and

a processor including control logic configured to calculate three-dimensional (3D) spatial data and combine the 3D spatial data with spectral data including the separated wavelengths, wherein the 3D spatial data includes;

data associated with the first axis;

data associated with a second axis based, at least in part, on a position in a direction of movement of the at least one detector; and

data associated with a third axis based, at least in part, on a time conversion of a time interval between reception of the returning laser signal and generation of the output laser signal.

2. The LIDAR apparatus of claim 1, wherein the rows of the plurality of rows of the array are oriented in a direction orthogonal to a direction of movement of the at least one detector.

3. The LIDAR apparatus of claim 1, wherein the at least one wavelength dispersion element is configured to pass one of Raman data and Rayleigh data to the at least one detector and the spectral data includes at least one of Raman data and Raleigh data obtained from the returning laser signal.

4. The LIDAR apparatus of claim 1, further comprising:

at least one additional detector configured as an additional array of light sensitive elements, the additional array including a plurality of additional rows and columns of light sensitive elements; and

at least one additional wavelength dispersion element associated with the at least one detector, wherein the at least one additional wavelength dispersion element is configured to separate the returning laser signal into a column of separated wavelengths associated with a position of a row in a direction perpendicular to a direction of the at least one additional detector.

6. The LIDAR apparatus of claim 4, wherein the at least one detector and the at least one additional detector are Flash LIDAR detectors.

7. The LIDAR apparatus of claim 4, wherein the at least one wavelength dispersion element and the at least one additional wavelength dispersion element each includes at least one diffraction grating.

8. The LIDAR apparatus of claim 1, further comprising optics configured to convert the returning laser signal from one form to a linear distribution of light.

9. The LIDAR apparatus of claim 8, wherein the optics include a parabolic reflector.

5. A Light Detection and Ranging (LIDAR) apparatus, comprising:

a laser generator configured to generate an output laser signal toward a target area;

at least one detector configured as an array of light sensitive elements, the array including a plurality of rows and columns of light sensitive elements;

at least one wavelength dispersion element positioned in a return path of a returning laser signal returning from the target area, the at least one wavelength dispersion element configured to separate wavelengths of the returning laser signal onto the plurality of rows and columns of the array, wherein the columns of the plurality of columns of the array are associated with the separated wavelengths that correspond with a position along a row of the array, the position along the row of the array corresponding with a spatial position of the target area along a first axis;

at least one additional detector configured as an additional array of light sensitive elements, the additional array including a plurality of additional rows and columns of light sensitive elements; and

at least one additional wavelength dispersion element associated with the at least one additional detector, wherein the at least one additional wavelength dispersion element is configured to separate the returning laser signal into a column of separated wavelengths associated with a position of a row in a direction perpendicular to a direction of the at least one additional detector;

wherein the at least one wavelength dispersion element is configured to pass one of Raman data and Rayleigh data to the at least one detector, and the at least one additional wavelength dispersion element is configured to pass the other one of Raman data and Rayleigh data to the at least one additional detector.

10. A method for obtaining hyper-spectral imaging data correlated with spatial data, the method comprising:

generating, with a laser generator, a first output laser signal toward a target area;

receiving, with at least one detector, a first returning laser signal from the target area;

dispersing, with at least one wavelength dispersion element, the first returning laser signal into a plurality of wavelengths within a field of view of an array of detector elements to be detected thereby, wherein a column of the array views the plurality of wavelengths that correspond to a spatial location of the target area in a first axis; and

calculating, with a processor, three-dimensional (3D) spatial data and combining the 3D spatial data with spectral data including the separated wavelengths, wherein the 3D spatial data includes;

data associated with the first axis;

data associated with a second axis based, at least in part, on a position in a direction of movement of the at least one detector; and

data associated with a third axis based, at least in part, on a time conversion of a time interval between reception of the returning laser signal and generation of the output laser signal.

11. The method of claim 10, further comprising:

generating at least one second output laser signal toward the target area at a different location from the first output laser signal;

receiving at least one second returning laser signal from the target area; and

dispersing the at least one second returning laser signal into a plurality of wavelengths within the field of view of the array of detector elements, wherein a column of the array views the plurality of wavelengths that correspond to a spatial location of the target area in the first axis.

12. The method of claim 10, further comprising arranging data as a multi-dimensional data cube including spectral data and spatial data, wherein the spectral data includes data corresponding to the plurality of wavelengths detected by the array of detector elements, and the spatial data includes data corresponding to locations on the first axis, the second axis, and the third axis when the respective spectral data is detected.

13. The method of claim 10, further comprising directing a Raman component of the first returning laser signal to the array of detector elements and directing a Rayleigh component of the first returning laser signal to another array of detector elements.

14. The method of claim 10, further comprising optically converting the first returning laser signal from one form to a linear distribution of light.

15. The method of claim 10, wherein calculating the 3D spatial data includes:

determining an x-component of the spatial location by correlating locations in rows of the array of detector elements with the first axis of the target area;

determining a z-component of the spatial location by correlating a time delay of the returning laser signal with the third axis of the target area in a direction of propagation for the returning laser signal; and

determining a y-component of the spatial location by correlating a location of the LIDAR detector array with the second axis of the target area.

16. The method of claim 10, further comprising scanning the target area with the first output laser signal over a plurality of scan steps at different locations along the second axis of the target area, wherein each of the generating the first output laser signal, the receiving the first returning laser signal, and the dispersing the first returning laser signal are included in each scan step of the plurality of scan steps.

17. The method of claim 16, wherein generating a first output laser signal toward the target area comprises generating the first output laser signal toward the target area by transmitting the first laser output signal along the third axis of the target area.

18. A method for obtaining hyper-spectral imaging data correlated with spatial data, the method comprising:

generating, with a laser generator, a first output laser signal toward a target area;

receiving, with at least one detector, a first returning laser signal from the target area;

dispersing, with at least one wavelength dispersion element, the first returning laser signal into a plurality of wavelengths within a field of view of an array of detector elements to be detected thereby, wherein a column of the array views the plurality of wavelengths that correspond to a spatial location of the target area in a first axis; and

scanning the target area with the first output laser signal over a plurality of scan steps at different locations along a y-axis of the target area, wherein each of the generating the first output laser signal, the receiving the first returning laser signal, and the dispersing the first returning laser signal are included in each scan step of the plurality of scan steps;

wherein generating a first output laser signal toward the target area comprises generating the first output laser signal toward the target area by transmitting the first laser output signal along a z-axis of the target area; and

wherein each scan step further includes;

time-gating at least one detector at time intervals after transmitting the output laser signal; and

detecting the plurality of wavelengths during the time intervals, wherein the at least one detector receives a spectrum of the plurality of wavelengths into columns of an array of detectors of the at least one detector, the columns corresponding to different locations along an x-axis of the target area.