Mems actuated alvarez lens for tunable beam spot size in lidar

Abstract

Embodiments of the disclosure provide a transmitter containing a tunable collimation lens, an optical sensing system containing the same, and an optical sensing method using the same. For example, the optical sensing system includes an optical source configured to emit optical signals. The optical sensing system further includes a tunable collimation lens configured to dynamically collimate the optical signals emitted by the optical source to varying divergences. The optical sensing system additionally includes a steering device configured to steer the tuned optical signals output from the tunable collimation lens toward an environment surrounding the optical sensing system. The optical sensing system additionally includes a receiver configured to receive the optical signals returning from the environment.

What is claimed is: 
     
         1 . An optical sensing system, comprising:
 an optical source, configured to emit a series of optical signals;   a tunable collimation lens, configured to dynamically collimate the optical signals emitted by the optical source to varying divergences;   a steering device, configured to steer the tuned optical signals output from the tunable collimation lens toward an environment surrounding the optical sensing system; and   a receiver, configured to receive the optical signals returning from the environment.   
     
     
         2 . The optical sensing system of  claim 1 , wherein, to dynamically collimate the received optical signals to the varying divergences, the tunable collimation lens is configured to:
 tune the emitted optical signals to a first divergence towards a first object, in the environment, at a first distance away from the optical sensing system; or   tune the emitted optical signals to a second divergence towards a second object, in the environment, at a second distance away from the optical sensing system,   wherein the second distance is larger than the first distance and the second divergence is smaller than the first divergence.   
     
     
         3 . The optical sensing system of  claim 1 , wherein the tunable collimation lens comprises a pair of identical Alvarez lenses arranged in tandem. 
     
     
         4 . The optical sensing system of  claim 3 , wherein each of the pair of Alvarez lenses comprises a curved freeform surface and a planar surface opposite the curved freeform surface. 
     
     
         5 . The optical sensing system of  claim 4 , wherein the curved freeform surfaces of the pair of Alvarez lenses complement each other when the pair of Alvarez lenses are aligned along an optical axis. 
     
     
         6 . The optical sensing system of  claim 3 , wherein at least one of the pair of Alvarez lenses is movable along a direction perpendicular to a direction of the optical signals. 
     
     
         7 . The optical sensing system of  claim 6 , wherein a movement of the at least one movable Alvarez lens causes a divergence of each optical signal output from the tunable collimation lens to be tuned to a predefined divergence. 
     
     
         8 . The optical sensing system of  claim 6 , wherein the at least one movable Alvarez lens is fixed between a pair of comb drives. 
     
     
         9 . The optical sensing system of  claim 8 , wherein a movement of the at least one movable Alvarez lens is controlled by a MEMS actuator of the pair of the comb drives. 
     
     
         10 . The optical sensing system of  claim 7 , wherein the pair of Alvarez lenses are disposed at a predefined distance apart, such that there is no touch between the pair of Alvarez lenses during the movement of the at least one movable Alvarez lens. 
     
     
         11 . The optical sensing system of  claim 1 , wherein the receiver comprises a plurality of photodiodes arranged in a one-dimensional or two-dimensional array. 
     
     
         12 . An optical sensing method, comprising:
 emitting, by an optical source of an optical sensing system, a series of optical signals;   dynamically collimating, by a tunable collimation lens of the optical sensing system, the emitted optical signals to varying divergences;   steering, by a steering device of the optical sensing system, the tuned optical signals toward an environment surrounding the optical sensing system; and   receiving, by a receiver of the optical sensing system, the optical signals returning from the environment.   
     
     
         13 . The optical sensing method of  claim 12 , wherein dynamically collimating the emitted optical signals to varying divergences comprises:
 tuning the emitted optical signals to a first divergence towards a first object, in the environment, at a first distance away from the optical sensing system; or   tuning the emitted optical signals to a second divergence towards a second object, in the environment, at a second distance away from the optical sensing system,   wherein the second distance is larger than the first distance and the second divergence is smaller than the first divergence.   
     
     
         14 . A transmitter for an optical sensing system, comprising:
 an optical source, configured to emit a series of optical signals;   a tunable collimation lens, configured to dynamically collimate the optical signals emitted by the optical source to varying divergences; and   a steering device, configured to steer the tuned optical signals output from the tunable collimation lens toward an environment surrounding the transmitter.   
     
     
         15 . The transmitter of  claim 14 , wherein, to dynamically collimate the received optical signals to the varying divergences, the tunable collimation lens is configured to:
 tune the emitted optical signals to a first divergence towards a first object, in the environment, at a first distance away from the optical sensing system; or   tune the emitted optical signals to a second divergence towards a second object, in the environment, at a second distance away from the optical sensing system,   wherein the second distance is larger than the first distance and the second divergence is smaller than the first divergence.   
     
     
         16 . The transmitter of  claim 14 , wherein the tunable collimation lens comprises a pair of identical Alvarez lenses arranged in tandem. 
     
     
         17 . The transmitter of  claim 16 , wherein each of the pair of Alvarez lenses comprises a curved freeform surface and a planar surface opposite the curved freeform surface. 
     
     
         18 . The transmitter of  claim 17 , wherein the curved freeform surfaces of the pair of Alvarez lenses complement each other when the pair of Alvarez lenses are aligned along an optical axis. 
     
     
         19 . The transmitter of  claim 16 , wherein at least one of the pair of Alvarez lenses is movable along a direction perpendicular to a direction of the optical signals. 
     
     
         20 . The transmitter of  claim 19 , wherein a movement of the at least one movable Alvarez lens causes a divergence of each optical signal output from the tunable collimation lens to be tuned to a predefined divergence.