CN-109870825-B - Collimation system and laser radar based on MEMS galvanometer

Abstract

The invention provides a collimation system and a laser radar based on MEMS (micro-electromechanical system) vibrating mirrors, wherein the collimation system based on the MEMS vibrating mirrors comprises a laser emitting unit, a front beam shaping unit, a MEMS vibrating mirror scanning unit and a rear collimation unit, wherein the laser emitting unit is used for emitting modulated laser beams, the front beam shaping unit is used for shaping laser emitted by the laser emitting unit, the MEMS vibrating mirror scanning unit is used for carrying out field scanning on an object plane to be detected after carrying out resonance reflection on the beam shaped by the front beam shaping unit by using the MEMS vibrating mirrors, and the rear collimation unit is used for carrying out secondary shaping on the beam reflected by the MEMS vibrating mirror scanning unit so that the optical path lengths of an edge beam and a center beam deflected by the MEMS vibrating mirrors are equal at an entrance pupil of the rear collimation unit. The collimation system based on the MEMS galvanometer can improve the energy coupling efficiency of the system, reduce the divergence angle of light beams and the volume of the system, and enable the distance measurement capability of a central view field and an edge view field to be uniform and consistent.

Inventors

• TONG JIAN
• QU ZHIWEI
• CHEN JIA

Assignees

• 北京万集科技股份有限公司

Dates

Publication Date

20260508

Application Date

20171201

Claims (9)

1. 1. A MEMS galvanometer based collimation system comprising: a laser emitting unit for emitting a modulated laser beam; the front beam shaping unit is used for shaping the laser emitted by the laser emitting unit so that the beam in the fast axis direction is collimated and shaped into parallel light, and the beam in the slow axis direction forms a converging beam; The MEMS galvanometer scanning unit is used for scanning the field of view of the object plane to be detected after carrying out resonance reflection on the light beam shaped by the front beam shaping unit by utilizing the MEMS galvanometer; The rear collimation unit comprises a toric mirror, wherein the toric mirror is used for secondarily shaping the light beam reflected by the MEMS galvanometer scanning unit, so that the optical path of the edge light beam deflected by the MEMS galvanometer is equal to that of the center light beam at the entrance pupil of the rear collimation unit, and the divergence angle of the light spot at the center view field is consistent with that of the edge view field.
2. 2. The system of claim 1, wherein the laser emitting unit comprises a semiconductor laser and a semiconductor laser driving unit for modulating a light beam emitted by the semiconductor laser.
3. 3. The system of claim 1, wherein the front-end beam shaping unit comprises a shaping lens for shaping the beam of light emitted by the laser emitting unit.
4. 4. A system according to claim 3, wherein the shaping lens consists of at least one aspherical or freeform lens or a plurality of plain lenses.
5. 5. The system of claim 3, wherein the front-end beam shaping unit further comprises a microlens encapsulated at the beam exit of the laser emitting unit for preliminary shaping of the beam emitted by the laser emitting unit.
6. 6. The system of claim 3 or 4, wherein the front beam shaping unit further comprises a field stop, and the field stop is used for limiting the beam spot size after shaping, so that the emergent beam can be totally incident on the MEMS galvanometer and redundant stray light is intercepted.
7. 7. The system of claim 1, wherein the MEMS galvanometer scanning unit comprises a MEMS galvanometer scanning component and a MEMS scanning driving component, wherein the MEMS scanning driving component is used for driving and controlling the MEMS galvanometer scanning component, and the driving mode of the MEMS scanning driving component comprises one or more of piezoelectric driving, electrothermal driving, electrostatic driving and electromagnetic driving.
8. 8. The system of claim 7, wherein the MEMS galvanometer scanning component is comprised of a single or multiple MEMS galvanometer array that respectively scans and reflects the shaped beam in accordance with a corresponding scan drive signal.
9. 9. A lidar comprising a MEMS galvanometer-based collimation system as defined in any one of claims 1 to 8.

Description

Collimation system and laser radar based on MEMS galvanometer Technical Field The invention relates to the technical field of laser radars, in particular to a collimation system based on an MEMS vibrating mirror and the laser radar. Background The laser radar technology is one of key core technologies of unmanned automobiles, has the advantages of high ranging accuracy, quick response, strong directivity, no influence of ground clutter and the like, can effectively provide information required by a vehicle decision-making and control system, and becomes the most effective scheme for sensing the unmanned environment at present. At present, when the laser radar technology is used for detection, a mechanical rotating device is generally used, a plurality of emitting lasers and a plurality of receiving detectors are used for realizing multi-line scanning, the lasers are placed on a rotating table capable of rotating at a constant speed, and meanwhile, the lasers are controlled to emit laser beams to scan target objects and correspondingly record azimuth information, so that the scanning frequency is low and the angular resolution is poor, the system structure is complex, and the overall stability of the system is influenced. With respect to the above problems, there is a continuous search for a lidar with high stability, high resolution and simple structure, and thus, MEMS-based lidars have been gradually developed. MEMS-based lidar suffers from a number of problems, one of which is the critical issue with respect to the energy coupling efficiency and the size of the outgoing spot of the transmitting system. The mirror surface size of the MEMS galvanometer cannot be too large because the MEMS galvanometer is required to realize higher vibration frequency, and the mirror surface size of the common MEMS galvanometer is a circle with the diameter of 1mm to 2 mm. The laser emitted by the laser device is usually required to perform collimation and shaping on the light beam, but the caliber size of a light spot after collimation and shaping is much larger than the mirror surface size of the MEMS galvanometer, and the light spot cannot be totally emitted on the MEMS galvanometer, so that the energy coupling efficiency of the system is low, and the ranging capability of the MEMS-based laser radar is greatly reduced. Therefore, a solid laser with better beam quality is adopted as a light source in the market at present, so that higher energy coupling efficiency is ensured. However, since the solid-state laser needs a refrigeration system, the size and the volume are large, which results in a large size of the whole laser radar system, and the cost of the solid-state laser is relatively high, the scheme reduces the applicability of the product. The laser radar based on MEMS requires small size, generally a semiconductor laser with higher cost performance is adopted, but the inherent astigmatism of the semiconductor laser leads to that the luminous surfaces of the fast axis and the slow axis are not on the same plane, and when the collimation and the shaping of the optical path are carried out, the beam collimation and the shaping of the fast axis and the slow axis cannot be carried out simultaneously, so that the divergence of light spots at a distance can be caused, the ranging capability is insufficient, and the resolution of the system is low. Disclosure of Invention Aiming at the defects in the prior art, the invention provides a collimation system and a laser radar based on an MEMS vibrating mirror, which can improve the energy coupling efficiency of the system, reduce the beam divergence angle and enable the ranging capability of a central view field and an edge view field to be uniform and consistent. In order to achieve the above purpose, the present invention provides the following technical solutions: in a first aspect, the present invention provides a MEMS galvanometer based collimation system comprising: a laser emitting unit for emitting a modulated laser beam; The front beam shaping unit is used for shaping the laser emitted by the laser emitting unit; The MEMS galvanometer scanning unit is used for scanning the field of view of the object plane to be detected after carrying out resonance reflection on the light beam shaped by the front beam shaping unit by utilizing the MEMS galvanometer; and the rear collimation unit is used for carrying out secondary shaping on the light beam reflected by the MEMS galvanometer scanning unit, so that the optical path length of the edge light beam deflected by the MEMS galvanometer is equal to that of the center light beam at the entrance pupil of the rear collimation unit. Preferably, the rear collimation unit comprises a toric mirror; the toric mirror is used for carrying out secondary shaping on the light beam reflected by the MEMS galvanometer scanning unit, so that the optical path of the edge light beam deflected by the MEMS galvanometer is equal to the optical path