Stray light filter structures for lidar detector array

Patent metadata

Field	Value
Publication number	US-2024103138-A1
Application number	US-202318374620-A
Country	US
Kind code	A1
Filing date	Sep 28, 2023
Priority date	Sep 28, 2022
Publication date	Mar 28, 2024
Grant date	—

Abstract

Embodiments of the present disclosure provide stray light filter structures in light detection and ranging (LiDAR) systems to attenuate stray light and reduce unwanted scattering. In some embodiments, a micro lens array is used together with a pinhole array to block stray light in the optical path just prior to the photodetector. In some embodiments, a bandpass optical filter is used in the optical path prior to the microlens array. In other embodiments, a slit filter is used further upstream in the optical path to block unwanted stray light and allow returning signal light to pass to imaging optics that provide a returning signal light image at a photodetector. In some embodiments, the imaging optics include a collimating lens and a focusing lens. In some embodiments, an optical bandpass filter is positioned on the optical path between the collimating lens and the focusing lens to reject light that is outside of a an expected wavelength range for returning signal light. These and other embodiments and details are further disclosed herein.

First claim

1 . A light ranging and detection (LiDAR) system comprising:
a collection lens configured to receive return signal light and stray light; a photodetector; and a return optical path from the collection lens to the photodetector including one or more stray light filtering structures, the stray light filtering structures comprising:
a slit filter comprising a light-blocking material surrounding a slit-shaped aperture, the slit-shaped aperture being dimensioned and positioned on the optical path relative to the collection lens such that light received at the collection lens having an angle of incidence expected for return signal light passes through the slit-shaped aperture and light received at the collection lens having an angle of incidence consistent with stray light is attenuated by the light-blocking material; and
a bandpass filter configured to pass light in a wavelength range expected for the return signal light and attenuate light having a wavelength outside of a wavelength range expected for the return signal light.

2 . The system of claim 1 wherein the bandpass filter is disposed on the optical path between the slit filter and the photodetector.

3 . The system of claim 2 wherein the optical path further comprises:
a collimating lens disposed between the slit filter and the bandpass filter; and
a focusing lens disposed between the bandpass filter and the photodetector.

4 . The system of claim 1 wherein the photodetector comprises an array of photodetector cells and the optical path further comprises:
a microlens array between the focusing lens and the array of photodetector cells, the microlens array comprising a plurality of respective lenslets positioned and configured to direct light from the focusing lens to respective photodetector cells of the array of photodetector cells.

5 . The system of claim 1 wherein the photodetector comprises an array of photodetector cells.

6 . The system of claim 5 wherein the array of photodetector cells has a cross-sectional area that is larger than a cross-sectional area of the slit-shaped aperture.

7 . The system of claim 3 wherein the collection lens, the collimating lens, the slit filter and the focusing lens are configured and are positioned on the optical path relative to each other and relative to the photodetector such that an image of light passing through the slit-shaped aperture formed at the photodetector has an area that is larger than a cross-sectional area of the slit-shaped aperture.

8 . The system of claim 1 wherein the slit-shaped aperture is rectangular with width that is substantially less than a length, the width being in a range of 3 μm to 7 μm and a length in a range of 1 mm-5 mm.

9 . The system of claim 8 wherein the length is in a range of 1 mm-5 mm.

10 . The system of claim 1 wherein the optical path further comprises a folding mirror positioned between the collection lens and the slit filter.

11 . The system of claim 1 implemented in a LiDAR system further comprising:
a laser source system comprising a laser source and transmission optics configured to direct outgoing laser light on a transmission optical path that is substantially separated from the collection lens and from a receiving optical path that includes the collection lens.

12 . The system of claim 11 wherein the transmission optics comprise:
a first transmission folding mirror;
a second transmission folding mirror;
a third folding mirror; and
a rotating polygon mirror.

13 . The system of claim 12 wherein the transmission optics further comprise:
a first collimating lens disposed between the laser source and the first transmission folding mirror; and
a second collimating lens disposed between the first transmission folding mirror and the second transmission folding mirror.

14 . The system of claim 13 wherein the first collimating lens is a fast-axis collimating lens and the second collimating lens is a slow-axis collimating lens.

15 . The system of claim 12 wherein the third folding mirror is positioned to receive return signal light from a facet of the rotating polygon mirror and direct it to the collection lens.

16 . The system of claim 12 wherein the first transmission folding mirror is oriented substantially parallel to an orientation of the second transmission folding mirror.

17 . A vehicle comprising a LiDAR system in accordance with claim 1 .

18 . A vehicle comprising a LiDAR system in accordance with claim 3 .

19 . A vehicle comprising a LiDAR system in accordance with claim 12 .

Assignees

• Innovusion Inc

Inventors

• Li Yufeng
• Wang Haosen
• Li Yimin
• Bao Junwei
• Meng Ching-Ling

Classifications

• G01S7/4816 Primary

  of receivers alone · CPC title

• G01S7/4814

  of transmitters alone · CPC title

• G01S17/89

  for mapping or imaging · CPC title

• G01S17/931

  of land vehicles · CPC title

• G01S7/4817

  relating to scanning · CPC title