US 11,940,758 B2
Light detection and ranging
Alexander Cole, Milton Keynes (GB)
Assigned to Envisics Ltd, Milton Keynes (GB)
Filed by Envisics Ltd, Milton Keynes (GB)
Filed on May 14, 2021, as Appl. No. 17/320,516.
Application 17/320,516 is a continuation in part of application No. 17/179,148, filed on Feb. 18, 2021.
Claims priority of application No. 2002276 (GB), filed on Feb. 19, 2020.
Prior Publication US 2021/0286319 A1, Sep. 16, 2021
Int. Cl. G03H 1/22 (2006.01); G01S 7/4865 (2020.01); G01S 17/88 (2006.01)
CPC G03H 1/2202 (2013.01) [G01S 7/4865 (2013.01); G01S 17/88 (2013.01); G03H 2001/2244 (2013.01)] 22 Claims
OG exemplary drawing
 
1. A light detection and ranging, “LiDAR”, system arranged to make time of flight measurements of a scene, the LiDAR system comprising:
a holographic projector comprising: a spatial light modulator arranged to display light modulation patterns, each light modulation pattern comprising a hologram and grating function having a periodicity; a light source arranged to illuminate each displayed light modulation pattern in turn; and a projection lens arranged to receive spatially modulated light from the spatial light modulator and project a structured light pattern corresponding to each hologram onto a respective replay plane, wherein the position of the structured light pattern on the replay plane is determined by the periodicity of the corresponding grating function;
wherein there is a spatial separation between the spatial light modulator and the array of detection elements, such that they have two different respective lines of sight of a target, within the scene;
a detector comprising an array of detection elements and an imaging lens arranged such that each detection element receives light from a respective sub-area of the holographic replay plane, wherein the sub-areas collectively define a field of view of the detector on the replay plane; and
a system controller arranged to receive distance information related to the scene and output to the holographic projector a control signal corresponding to the distance information, wherein the holographic projector is arranged to use the control signal to determine a parameter for projection of a subsequent structured light pattern;
wherein the parameter is indicative of a subsequent grating function that should be selected, for combination with a hologram, to ensure that the resulting structured light pattern, corresponding to that subsequent grating function, will be located within the detector's field of view on the replay plane.