Holographic light detection and ranging

1. A light detection and ranging, “LIDAR”, system arranged to scan a scene, the system comprising:

a light source arranged to output light having a first characteristic;

a spatial light modulator, “SLM”, arranged to receive the light from the light source and output spatially-modulated light in accordance with computer-generated holograms represented on the spatial light modulator;

a holographic controller arranged to output a plurality of computer-generated holograms to the spatial light modulator, wherein each computer-generated hologram is arranged to form a corresponding light footprint within the scene and the holographic controller is further arranged to change the position of the light footprint within the scene; and

a light detector arranged to receive light having the first characteristic from the scene and output a light response signal,

wherein the plurality of computer-generated holograms comprise a first computer-generated hologram arranged to form a first light footprint at a first position in the scene and a second computer-generated hologram arranged to form a second light footprint at a second position in the scene, wherein output of the second computer-generated hologram immediately follows output of the first computer-generated hologram, and wherein the first light footprint has a first area and the second light footprint has a second area, wherein the first area is not equal to the second area.

2. A LIDAR system as claimed in claim 1 , wherein the plurality of computer-generated holograms comprise a first plurality of computer-generated holograms arranged to provide a first scan within the scene, and wherein the holographic controller is arranged to receive the light response signal in response to the first scan and determine a second plurality of computer-generated holograms based on a property of the light response signal in response to the first scan.

3. A LIDAR system as claimed in claim 2 wherein the second plurality of computer-generated holograms are arranged to provide a second scan within the scene, wherein the first scan is a scan of a first area of the scene and the second scan is a scan of a second area of the scene.

4. A LIDAR system as claimed in claim 1 wherein the first light footprint has a one-dimensional shape extending in a second direction and the second light footprint has a one-dimensional shape extending in a first direction.

5. A LIDAR system as claimed in claim 1 wherein the light footprint is continuously repositioned so as to scan the light footprint within the scene.

6. A LIDAR system as claimed in claim 1 wherein one or more of the following conditions (1)-(3) is met:

(1) the first light footprint has a first shape and the second light footprint has a second shape, wherein the first shape is different to the second shape;

(2) the first light footprint has a shape having a first orientation and the second light footprint has a shape having a second orientation, wherein the first orientation is different to the second orientation; and

(3) the first position is spatially separated from the second position.

7. A LIDAR system as claimed in claim 1 wherein each computer-generated hologram is a phase-only hologram.

8. A LIDAR system as claimed in claim 1 wherein the spatially modulated light output by the SLM is encoded with a code that is unique to the LIDAR system.

9. A LIDAR system as claimed in claim 8 wherein the spatially modulated light output by the SLM is encoded by modulation of the light amplitude.

10. A LIDAR system as claimed in claim 1 comprising first and second light sources configured to output light of different wavelengths to the SLM.

11. A LIDAR system as claimed in claim 1 wherein the light footprint, or a parameter or element associated with the plurality of computer-generated holograms that form the light footprint, is determined based on a received signal.

12. A LIDAR system as claimed in claim 11 wherein the received signal provides an indication of at least one of: vehicle speed; ambient conditions; weather conditions; traffic conditions and other driving parameters.

13. A LIDAR system as claimed in claim 1 wherein the light footprint, or a parameter associated with the plurality of computer-generated holograms that form the light footprint, is determined so as to focus the light footprint at a distance corresponding to a distance range.

14. A LIDAR system as claimed in claim 1 further comprising an angular magnification system arranged to magnify the angular deflection of the spatially-modulated light from the spatial light modulator, wherein the angular magnification system is arranged to receive the spatially modulated light at a first angle and output the spatially modulated light at a second angle, wherein the second angle is greater than the first angle.

15. A LIDAR system as claimed in claim 1 wherein the first characteristic is amplitude modulation at a first frequency.

16. A LIDAR system as claimed in claim 1 wherein each computer-generated hologram comprises first holographic data defining the size and shape of the light footprint and second holographic data defining the position of the light footprint in the scene.

17. A LIDAR system as claimed in claim 1 wherein the first holographic data comprises a lensing function, and wherein the second holographic data comprises a grating function.

18. A LIDAR system as claimed in claim 1 further comprising a processor arranged to determine a distance of an object in the scene from the LIDAR system by measuring a time difference between output of first spatially-modulated light, corresponding to a first computer-generated hologram of the plurality of computer-generated holograms, and detection of first spatially-modulated light reflected from the object.

19. A LIDAR system as claimed in claim 1 wherein at least one of the SLM and the light detector is located within a lamp unit of a portable device or vehicle.

20. A lamp unit comprising the LIDAR system of claim 1 .

21. A vehicle comprising the LIDAR system of claim 1 .

22. A method for scanning a scene using LIDAR, the method comprising:

providing light having a first characteristic;

receiving the light having the first characteristic on a spatial light modulator;

providing a plurality of computer-generated holograms to the spatial light modulator and representing the plurality of computer-generated holograms on the spatial light modulator,

outputting spatially-modulated light having the first characteristic from the spatial light modulator in accordance with the plurality of computer-generated holograms to provide a light footprint within the scene, the plurality of spatially-modulated holograms changing a position of the light footprint within the scene; and

receiving light having the first characteristic from the scene at a light detector and outputting a light response signal from the light detector,

wherein the plurality of computer-generated holograms comprise a first computer-generated hologram arranged to form a first light footprint at a first position in the scene and a second computer-generated hologram arranged to form a second light footprint at a second position in the scene, wherein output of the second computer-generated hologram immediately follows output of the first computer-generated hologram, and wherein the first light footprint has a first area and the second light footprint has a second area, wherein the first area is not equal to the second area.