CN115951329A - MEMS laser radar light collimation annular scanning device and method - Google Patents
MEMS laser radar light collimation annular scanning device and method Download PDFInfo
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Abstract
The invention discloses an MEMS laser radar light collimation annular scanning device which comprises a first collimation unit, a second collimation unit, a micro-electro-mechanical system and a weak convergence unit, wherein the first collimation unit comprises a first conical surface and a second conical surface which are symmetrically arranged, a light hole is formed in the positions, close to a geometric center, of the first conical surface and the second conical surface, an outer side surface is arranged on one side, far away from the light hole, of the first conical surface and the second conical surface, and the second collimation unit comprises a light convergence surface and a calibration surface which are matched with the outer side surface; according to the invention, the angle relation between the first conical surface and the second conical surface and the arrangement of the second collimation unit are utilized to realize the convergence of laser in the vertical direction and the horizontal direction, so that the laser is kept collimated and emitted horizontally, and the annular scanning of the radar is realized by fewer mechanical structures.
Description
Technical Field
The invention relates to the technical field of radar scanning, in particular to a light collimation and circular scanning device and method for an MEMS laser radar.
Background
In recent years, the large-view-field laser radar has a great effect on automatic driving, and a common method for realizing the large-view-field laser radar comprises the step of splicing a plurality of small-view-field laser radars, for example, splicing a 360-degree radar by 3 120-degree view-field laser radars.
The other type of radar system realizes the large field of view circular scanning by rotating a reflecting mirror, which is a typical mechanical scanning type radar, and the reflecting mirror has large volume, slower scanning speed and influence on the service life. The disadvantages of the two types of radar can be overcome by using a micro-electro-mechanical system (hereinafter referred to as MEMS) as a scanning element to perform the circular scanning.
Compared with the prior art [ patent: 202110333307.3 ] MEMS lidar of this technology uses a catadioptric prism piece and a compensator prism that needs to move with the MEMS through a mechanism that rotates at high speed, which causes the same problem as mechanical scanning radars, and furthermore, the catadioptric prism uses a plane and 1 cone, each of which performs 1 reflection, where the reflection on the plane does not satisfy total reflection and the realization of the reflection needs to be performed by plating.
In order to solve the defects of the existing radar, the invention uses an MEMS laser radar light collimation circular scanning device and a method, and particularly invents a first collimation unit and a second collimation unit.
Disclosure of Invention
This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.
The invention is provided in view of the problems that the existing MEMS laser radar needs a compensation prism and reflection needs to be realized by coating.
Therefore, the present invention provides a device and a method for collimating and sweeping light of a MEMS lidar, which aims to: the radar ring scan is achieved with fewer mechanical structures.
In order to solve the technical problems, the invention provides the following technical scheme: a MEMS laser radar light collimation annular scanning device comprises a first collimation unit and a second collimation unit, wherein the first collimation unit comprises a first conical surface and a second conical surface which are symmetrically arranged, a light hole is formed in the position, close to a geometric center, of the first conical surface and the second conical surface, an outer side surface is arranged on one side, away from the light hole, of the first conical surface and the second conical surface, and the second collimation unit comprises a light converging surface and a calibration surface which are matched with the outer side surface; the micro-electro-mechanical system is arranged on one side of the light hole in a matching mode, and a straight line section between the micro-electro-mechanical system and the light hole is a first section; and the weak convergence unit is arranged on one side, deviating from the micro-electromechanical system, of the light hole in a matching manner.
As a preferable scheme of the MEMS lidar optical collimating and ring-scanning device of the present invention, wherein: the plane perpendicular to the first section is a horizontal plane, the first conical surface and the horizontal plane form a first included angle, the second conical surface and the horizontal plane form a second included angle, and the micro electro mechanical system and the horizontal plane form a third included angle.
As a preferable scheme of the MEMS lidar optical collimating and ring-scanning device of the present invention, wherein: the first included angle and the third included angle satisfy the relation:
wherein n is a light refractive index of a material adopted by the optical element to which the first conical surface belongs, and the second included angle and the third included angle satisfy a relation:
A2＝A3
in order to further control the laser beam emitting mode to be horizontal emitting, the first included angle A1 and the third included angle need to be controlled to satisfy the relation:
as a preferable scheme of the MEMS lidar optical collimating and ring-scanning device of the present invention, wherein: and a laser for emitting laser to the first collimating unit is further arranged on the first section, and the laser advancing path passes through the light transmitting hole along the weak convergence unit and reaches the micro-electro-mechanical system.
As a preferable scheme of the MEMS lidar optical collimating and ring-scanning device of the present invention, wherein: and a deep hole diaphragm is further arranged in the laser advancing direction and is arranged on the side of the weak convergence unit, which deviates from the light-transmitting hole, in a matching manner.
As a preferable scheme of the MEMS lidar optical collimating and ring-scanning device of the present invention, wherein: the diameter of the light hole is smaller than the diagonal length of the micro electro mechanical system, and the beam aperture of the laser is smaller than the diagonal length of the micro electro mechanical system; the laser is arranged outside the front focus of the weak convergence unit, the vertical distance of the laser is L, and L is larger than or equal to 1mm and smaller than or equal to 5mm.
Another technical problem to be solved by the present invention is to provide a method for collimating and sweeping the light of the MEMS lidar, which aims to generate the collimated laser by operating the above device.
In order to solve the technical problems, the invention provides the following technical scheme: a MEMS laser radar light collimation ring scanning method adopts the light collimation ring scanning device, and further comprises the following steps:
determining suitable experimental parameters, including selecting materials of the optical elements of the first conical surface and the second conical surface;
calculating the first included angle, the second included angle and the third included angle according to the selected materials, and then calculating the curvatures of the first conical surface and the second conical surface;
setting the size of a light hole of the deep hole diaphragm according to the horizontal direction divergence condition when the laser penetrates through the light hole to reach the micro electro mechanical system, and intercepting a large-angle diaphragm through the deep hole diaphragm;
according to the horizontal direction divergence condition when the laser is reflected by the micro electro mechanical system to reach the first conical surface, setting the curvature of a lens of the weak convergence unit to realize convergence of the divergent light of the laser in the horizontal direction, so as to realize compensation after the laser reaches the first conical surface and is subjected to horizontal divergence;
setting the curvature of a lens of the light converging surface according to the vertical direction divergence condition when the laser passes through the first collimating unit and reaches the second collimating unit, so as to realize convergence of light diverging in the vertical direction of the laser;
and adjusting the calibration surface to provide the arrival position of the laser after one-time interception and two-time convergence so as to obtain the optimal surrounding scanning effect.
As a preferable scheme of the MEMS lidar optical collimating and ring-scanning method of the present invention, wherein: and adjusting the relation between the third included angle and the second included angle, so that the laser energy is transmitted when reaching the second conical surface.
As a preferable scheme of the MEMS lidar optical collimating and ring-scanning method of the present invention, wherein: and adjusting the relation between the third included angle and the first included angle, so that the laser can generate total reflection when reaching the first conical surface.
As a preferable scheme of the MEMS lidar optical collimating and ring-scanning method of the present invention, wherein: in the adjusting process, a third included angle between the micro-electro-mechanical system and the horizontal plane is roughly adjusted, so that the laser reaches the second collimating unit, the vertical height of the second collimating unit is determined, and a moving carrier is provided for the laser;
and then, the first included angle and the second included angle are finely adjusted, so that the direction of the laser after passing through the first collimation unit is parallel to the horizontal direction, and the laser is determined to be in a collimation state by matching with the second collimation unit.
The invention has the beneficial effects that:
according to the invention, the angle relation between the first conical surface and the second conical surface is utilized, and the second collimation unit is arranged, so that the convergence of laser in the vertical direction and the horizontal direction is realized, the laser is kept collimated and horizontally emitted, and the annular scanning of the radar is realized by fewer mechanical structures.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:
FIG. 1 is a schematic view of an angle relationship of the MEMS lidar optical collimating and sweeping device of the present invention.
FIG. 2 is a schematic diagram of a partial structure of a MEMS lidar light collimating and ring-scanning device according to the present invention.
Fig. 3 is a schematic structural diagram of a first collimating unit of the MEMS lidar optical collimating ring scanning device of the present invention.
FIG. 4 is a schematic structural diagram of a deep hole diaphragm and a weak convergence unit of the MEMS laser radar light collimation ring scanning device.
FIG. 5 is a schematic diagram of the overall structure of the MEMS lidar light collimation ring scanning device of the invention.
FIG. 6 is a schematic diagram of the process of laser traveling inside the device in the MEMS lidar optical collimating ring scanning device of the present invention.
FIG. 7 is a schematic diagram of a second unit of the MEMS lidar optical collimating and sweeping device of the present invention
Fig. 8 is a front view of the MEMS lidar optical collimating and sweeping device showing the laser travel path and collimating effect.
Fig. 9 shows the laser travel path and the collimation effect of the MEMS lidar optical collimation ring scanning device in the top view.
FIG. 10 is a simplified device diagram of the MEMS lidar optical collimating ring scanning device of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, embodiments accompanying figures of the present invention are described in detail below.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.
Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
Furthermore, the present invention is described in detail with reference to the drawings, and in the detailed description of the embodiments of the present invention, the cross-sectional view illustrating the structure of the device is not enlarged partially according to the general scale for convenience of illustration, and the drawings are only exemplary and should not be construed as limiting the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.
Example 1
Referring to fig. 1 to 5, for the first embodiment of the present invention, a MEMS lidar light collimating ring scanning apparatus is provided, the apparatus includes a first collimating unit 100, which includes a first tapered surface 101 and a second tapered surface 102 symmetrically disposed, the first tapered surface 101 and the second tapered surface 102 have a light hole 103 near a geometric center, and an outer side surface 104 is disposed on a side of the first tapered surface 101 and the second tapered surface 102 away from the light hole 103.
A second collimating unit 200, including a light converging surface 201 and a collimating surface 202, which are matched with the outer side surface 104; the micro-electro-mechanical system 300 is arranged on one side of the light hole 103 in a matching manner, and a straight line section between the micro-electro-mechanical system 300 and the light hole 103 is a first section Q; and the weak convergence unit 400 is cooperatively arranged on one side of the light hole 103, which is far away from the micro-electromechanical system 300, and the first section Q is further provided with a laser 500 for emitting laser X to the first collimating unit 100.
The first unit 100, the second unit 200, and the weak convergence unit 400 are all rotationally symmetric structures, and a 3D structural view as shown in fig. 5 can be obtained by rotating the cross-sectional profile of fig. 1 around the central axis.
The mems 300 can rotate around the center line of the first section Q as a rotation axis under the driving of a debugged program, and the rotation of the mems 300 cooperates with the first unit 100 to scan the laser beam in the horizontal direction.
The micro electro mechanical system 300 can rotate by taking a straight line where the first section Q is located as an axis in a debugged program, the first collimating unit 100 provides reflection for the laser X, the rotation of the micro electro mechanical system 300 is matched with the first collimating unit 100, the micro electro mechanical system 300 provides light beam scanning after the laser X passes through the light hole 103, and the scanning light beam passes through a light beam emitted by the second collimating unit 200, hits a surrounding object and then is reflected to a detector to form point cloud so as to realize laser radar detection.
In the use, still be provided with the second collimation unit 200 with first collimation unit 100 matched with, second collimation unit 200 encircles and sets up in the outside of first collimation unit 100, no matter what angle deflection is carried out to micro electro mechanical system 300, and second collimation unit 200 homoenergetic is further assembled by micro electro mechanical system 300 reflected laser X to realize better beam collimation effect, and the ray detection distance is farther this moment, and radar resolution ratio is higher.
In this embodiment, in order to achieve more accurate detection effect and longer device lifetime with less material, the following limitations are made on the angular relationship between the first conical surface 101, the second conical surface 102, and the mems 300:
the plane perpendicular to the first section Q is a horizontal plane M, the first conical surface 101 and the horizontal plane M form a first included angle A1, the second conical surface 102 and the horizontal plane M form a second included angle A2, and the mems 300 and the horizontal plane M form a third included angle A3.
The first included angle A1 and the third included angle A3 satisfy the relation:
wherein n is a light refractive index of a material adopted by the optical element to which the first cone 101 belongs, and the second included angle A2 and the third included angle A3 satisfy the relation:
A2＝A3
the laser 500 is disposed outside the front focus of the weak convergence unit 400 at a vertical distance L of 1mm ≦ L ≦ 5mm (since this size is too small, it is not shown in the figure, and the position of the laser 500 is set with the front focus of the actual weak convergence unit 400 as a reference point).
With the above restrictions, the following laser X travel paths are achieved:
on the path of the laser X propagating to the mems 300, the laser X is affected by the weak convergence unit 400 to converge for the first time, and after reaching the reflective surface of the mems 300, the laser X reaches the side of the second conical surface 102 close to the mems 300, which is determined by the rotation direction of the mems 300 at a certain moment.
At this time, the second included angle A2 and the third included angle A3 satisfy the relationship:
A2＝A3
when the laser beam X reaches the second tapered surface 102, the laser beam X is perpendicular to the second tapered surface 102, and the laser beam X is transmitted into the first collimating unit 100, and the optical path direction is hardly changed, so that the incident beam transmittance is highest in the direction. The laser beam passes through the second tapered surface 102 and is incident to the first tapered surface 101, at this time, since (1) the optical refractive index of the first collimating unit 100 is greater than that of the outside; (2) the first included angle A1 and the third included angle A3 satisfy the relation:
the incident angle when the laser beam reaches the first tapered surface 101 satisfies that the first tapered surface 101 totally reflects the laser beam. In order to further control the laser beam emitting mode to be horizontal emitting, the first included angle A1 and the third included angle A3 need to be controlled to satisfy the relation:
in this embodiment, by reasonably controlling the angles, the laser X enters the second tapered surface 102, the beam is almost perpendicular to the second tapered surface 102, the beam transmittance is highest, the laser X enters the first tapered surface 101 and is totally reflected, the beam reflectance is highest, and the high reflectance is achieved without plating a highly reflective optical film, and the laser X exits in a horizontal manner. On the basis of the same MEMS laser circular scanning principle, the device does not have overflow light, and the laser X circular scanning effect is realized by fewer mechanical structures.
Example 2
Referring to fig. 5 to 8, this embodiment is a second embodiment of the present invention, and is intended to make a further supplementary explanation on the collimation effect of the apparatus, and the lidar needs to have very good collimation property of the final output laser beam in order to realize long-distance detection. The divergence angles of lasers, particularly vertical cavity surface lasers (VCSELs) commonly used in laser radars, are large, so that laser output by the lasers needs to be collimated, and the first unit deep hole diaphragm 105 and the weak convergence unit 400 are used for reducing the divergence angles of the laser.
Instead of perfectly collimating the laser beam, a certain slight angle of convergence is maintained. When the laser beam passes through the second tapered surface 102 and the first tapered surface 101, since the tapered surfaces have curvature in the horizontal direction, the laser beam has a certain divergence angle in the horizontal direction when the perfectly collimated laser beam passes through the tapered surfaces, and thus it is necessary to converge the laser beam by a weak convergence unit before the laser beam reaches the tapered surfaces.
As shown in fig. 6, the left side is a 3D view of the process of the laser X traveling inside the device, and the right side is a front view of the process. From the 3D view, it can be seen that if the fully collimated light beam passes through the second tapered surface 102 and then is reflected by the first tapered surface 101, the light beam has a significant divergence in the horizontal direction, while the collimation in the vertical direction is still maintained, and in order to solve this problem, the divergence in the horizontal direction caused by the surface of the first tapered surface 101 is supplemented by a weak convergence unit.
Thus, after compensation by the weak convergence unit 400, the light beam is reflected by the first cone 101 surface, and becomes collimated in the horizontal direction. As can be seen from the front view on the right side of FIG. 6, the fully collimated light beam reflected by the first cone 101 does not diverge or converge vertically, which means that the first cone 101 only affects the divergence or convergence of the light beam in the horizontal direction, but not in the vertical direction.
After the weak convergence unit is introduced, the light beam starts to have certain convergence after passing through the weak convergence unit, and is converged to a small light spot after passing through a section of propagation optical path, so that the light beam starts to diverge after continuously propagating. The surface of the first cone 101 only affects the divergence or convergence of the light beam in the horizontal direction, but not the divergence or convergence in the vertical direction, so that the light beam propagates to the first cone 101 from the weak convergence unit 400, has propagated a relatively long optical path, and has a certain divergence in the vertical direction.
Aiming at the unresolved divergence of the laser beam in the vertical direction, the second unit 200 arranged around the outer side of the first unit 100 comprises a light converging surface 201 and a second unit outer side surface 202, the light converging surface 201 has a curvature in the vertical direction, and the convergence of the laser beam in the vertical direction is realized through the light converging surface 201. The laser beam passes through the weak convergence unit 400, the second conical surface 102 and the first conical surface 101, converges in the vertical direction and then diverges, the convergence surface 201 compensates for the divergence in the vertical direction, so that the collimation of the laser in the vertical direction is realized, and the outer side surface 202 of the second unit realizes the outward transmission of the laser beam.
In fig. 7, the upper drawing is a front view of the second unit 200, the lower drawing is a plan view of the second unit 200, and it can be seen from the plan view that the horizontal curvature radii of the two surfaces, i.e., the converging surface 201 and the second unit outer side surface 202, of the second unit 200 are R h1 R h2 The thickness between the two faces is very thin so R h1 R h2 The focal power is very small, seen in the horizontal direction, almost zero, and the convergence and divergence of the light rays in the horizontal direction after passing through the two surfaces are basically unchanged.
It can be seen from the front view that the vertical curvature radii of the two surfaces, i.e., the converging surface 201 and the outer side surface 202 of the second unit 200 are respectively R v1 And R v2 Wherein R is v2 Has an infinite radius, that is, the curvature of the surface 202 in the vertical direction is zero, and the converging surface 201 and the outer side surface 202 in the vertical direction correspond to a circular convex lens, which has a converging or diverging effect on light in the vertical direction. In short, the second unit only changes the convergence or divergence of the light beam in the vertical direction, and has no influence on the convergence or divergence of the light beam in the horizontal direction.
The laser beam is emitted from the outer side surface of the first unit 104, the good collimation performance is kept in the horizontal direction, and the laser beam is diverged after passing through a long optical path due to the influence of the weak convergence unit 400 in the vertical direction, so that the second unit 200 only provides convergence in the vertical direction for the laser beam to compensate the divergence of the weak convergence unit 400 to the laser beam after passing through the long optical path, and the vertical direction is also collimated. Finally, the laser beam is well collimated in both directions after exiting from the second unit 202 face.
In order to achieve better collimation effect of the laser beam, the deep hole diaphragm 105 which is arranged on the side, away from the light transmission hole 103, of the weak convergence unit 400 is provided in a matching mode, so that the laser beam with a larger angle emitted by the laser 500 can be directly absorbed, in order to enable the device to be more reasonable, on a laser beam propagation path, the diameter of the light transmission hole 103 is smaller than the diagonal length of the micro-electro-mechanical system 300, and the beam caliber of the laser beam is smaller than the diagonal length of the micro-electro-mechanical system 300.
In this embodiment, the weak convergence system may be a spherical lens, an aspherical lens, or a spherical lens group (2-4 pieces), an aspherical lens group (2-4 pieces), or a lens group (2-4 pieces) in which a spherical surface and an aspherical surface are mixed. The inner surface and the outer surface of the deep hole diaphragm are coated in black and used for absorbing large-angle light emitted by the laser.
The rest of the structure is the same as that of embodiment 1.
Example 3
With reference to fig. 1 to 10, a third embodiment of the present invention provides a method for performing a light collimation annular scanning on a MEMS lidar, where the imaging method employs the above light collimation annular scanning apparatus, and further includes the following steps:
suitable experimental parameters are determined, including the selection of the material of the tapered lens, typically glass or plastic, from the first tapered surface 101 and the second tapered surfaces 102 and 103 and the first unit outer side surface 104, to determine the thickness of the tapered lens edge and the maximum aperture.
The angle A3 of the MEMS to the horizontal, which is typically 5-8 degrees, is selected so that the 1 st included angle A1 can be determined.
Then, according to the following formula of the condition for controlling the horizontal emission of the laser beam, the 1 st included angle A1 is determined
The value range of the second included angle A2 is calculated according to the following formula,
A 2＝A3
the tapered lens constituted by the first tapered surface 101 and the second tapered surfaces 102 and 103 and the first unit outer side surface 104 can be determined based on the above conditions.
Setting the aperture size of the deep hole diaphragm 105 according to the horizontal divergence condition of the laser X when the laser X passes through the light hole 103 and reaches the micro electro mechanical system 300, and intercepting the large-angle diaphragm through the deep hole diaphragm 105;
according to the horizontal direction divergence situation when the laser X is reflected by the micro electro mechanical system 300 to reach the first conical surface 101, the lens curvature of the weak convergence unit 400 is optimized, the convergence of the divergent light in the horizontal direction of the laser X is realized, and the horizontal divergence when the laser X reaches the first conical surface 101 is compensated;
the curvatures of the first conical surface 101 and the second conical surface 102 are finely adjusted to realize the collimation emission of the laser X in the horizontal direction, the relationship between the third included angle A3 and the second included angle A2 is adjusted to ensure that the laser X can be transmitted when reaching the second conical surface 102,
the relation between the third included angle A3 and the first included angle A1 is adjusted, so that the laser X can be totally reflected when reaching the first conical surface 101.
According to the vertical divergence situation when the laser X passes through the first collimating unit 100 and reaches the second collimating unit 200, the lens curvature of the light converging surface 201 is set, so that the divergent light in the vertical direction of the laser X is converged;
the calibration surface 202 is adjusted to provide the arrival position of the laser X after one interception and two convergence, so as to obtain the best surrounding scanning effect.
In the adjusting process, a third included angle A3 between the micro electro mechanical system 300 and the horizontal plane is roughly adjusted, so that the laser X reaches the second collimating unit 200, the vertical height of the second collimating unit 200 is determined, and a moving carrier is provided for the laser X;
and then, by fine-tuning the first included angle A1 and the second included angle A2, the direction of the laser X after passing through the first collimating unit 100 is parallel to the horizontal direction, and the laser X is determined to be in a collimating state by matching with the second collimating unit 200.
With reference to fig. 1 to 10, by focusing on the traveling path of the laser X, the structure of the apparatus and the beneficial effects obtained by the apparatus are known, for convenience of description, it is specified that the direction of the first section Q is vertical, the position of the laser 500 is upward, the position of the mems 300 is downward, the laser X is projected downward by the downward laser 500, and first reaches the deep hole diaphragm 105, the deep hole diaphragm 105 intercepts the large-angle diaphragm, at this time, the laser X reaches the weak convergence unit 400, and the weak convergence unit 400 converges the laser X, so as to keep the laser X collimated.
The micro electro mechanical system 300 is controlled by a software part to rotate by taking a straight line where the first section Q is located as an axis, at a certain moment, the laser X reaches the micro electro mechanical system 300 and is reflected and reaches the lower surface of the second conical surface 102, the laser X is transmitted into the first collimating unit 100 and reaches the first conical surface 101 at the original incident angle, the incident angle when the laser X reaches the first conical surface 101 is enough to meet the requirement that the first conical surface 101 totally reflects the laser X, and the emitting mode of the laser X is horizontal emitting.
At this time, the laser X reaches the second collimating unit 200, the light converging surface 201 converges the laser X again, the collimation of the laser X is maintained, the laser X passes through the collimating surface 202 to be collimated and is projected outwards, in the dynamic process, the micro electro mechanical system 300 rotates by taking the straight line where the first section Q is located as an axis, the reaching position of the laser X changes along with the rotation of the micro electro mechanical system 300, and the light beam projected by the second collimating unit 200 is projected to the surrounding object and then reflected to the detector to form point cloud so as to realize the laser radar detection.
In this process, for the horizontal divergence of the laser X when the laser X reaches the first conical surface 101, the weak convergence unit 400 converges the laser X in advance, so as to realize the divergence compensation of the laser X when the laser X reaches the first conical surface 101, and realize the horizontal collimation emission of the laser X.
In order to solve the problem that if the completely collimated light beam passes through the second conical surface 102 and then is reflected by the first conical surface 101, the light beam is obviously diverged in the horizontal direction, and the collimation is still kept in the vertical direction, the horizontal divergence caused by the surface of the first conical surface 101 is supplemented by a weak convergence unit. After the compensation of the weak convergence unit 400, the light beam is reflected by the first cone surface 101, and then becomes collimated in the horizontal direction.
The fact that the fully collimated light beam does not diverge or converge in the vertical direction after being reflected by the first conical surface 101 means that the first conical surface 101 only affects the divergence or convergence of the light beam in the horizontal direction, and does not affect the divergence or convergence in the vertical direction. After the weak convergence unit is introduced, the light beam starts to have certain convergence after passing through the weak convergence unit, and converges to a small light spot after passing through a section of propagation optical path, so that the light beam starts to diverge after continuously propagating. The surface of the first cone 101 only affects the divergence or convergence of the light beam in the horizontal direction, but not the divergence or convergence in the vertical direction, so that the light beam propagates to the first cone 101 from the weak convergence unit 400, has propagated a relatively long optical path, and has a certain divergence in the vertical direction.
Aiming at the unresolved divergence of the laser beam in the vertical direction, the second unit 200 arranged around the outer side of the first unit 100 comprises a light converging surface 201 and a second unit outer side surface 202, the light converging surface 201 has a curvature in the vertical direction, and the convergence of the laser beam in the vertical direction is realized through the light converging surface 201. The laser beam firstly converges on a line in the vertical direction through the weak convergence unit 400, the second conical surface 102 and the first conical surface 101, then diverges, and the divergence in the vertical direction is compensated through the convergence surface 201, so that the collimation of the laser in the vertical direction is realized, and the outward transmission of the laser beam is realized through the outer side surface 202 of the second unit.
The laser beam is emitted from the outer side surface of the first unit 104, the good collimation performance is kept in the horizontal direction, and the laser beam is diverged after passing through a long optical path due to the influence of the weak convergence unit 400 in the vertical direction, so that the second unit 200 only provides convergence in the vertical direction for the laser beam to compensate the divergence of the weak convergence unit 400 to the laser beam after passing through the long optical path, and the vertical direction is also collimated. Finally, the laser beam is well collimated in both directions after exiting the face of the second unit 202.
The system only needs MEMS to rotate to realize 360-degree scanning around in the scanning process, the whole system does not need any optical element to rotate, and the system is small in size, simple in structure, long in service life, light in material and small in difficulty in realizing rotary scanning.
On the other hand, the angles of the first conical surface 101 and the second conical surface 102 are set, so that the laser beam can transmit through the second conical surface 102 at high transmittance, total reflection is generated on the first conical surface 101, coating on the conical surface 101 is not needed, the coating process is simplified, the laser beam can horizontally exit through the outer side surface of the first unit only through one-time transmission and one-time reflection, the reflection and refraction times are few, and the light efficiency is high.
In the MEMS laser radar, in order to keep collimation of laser, a weak convergence unit 400 and a second collimation unit 200 are arranged to realize convergence of laser divergence, and the weak convergence unit 400 and the second collimation unit 200 are matched with each other to realize that laser X keeps collimation in the vertical direction and the horizontal direction and is horizontally emitted.
To further simplify the device, the biconic lens of the first unit may be integrated with the second unit, as shown in fig. 10.
It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (10)
1. The utility model provides a device is swept to MEMS laser radar light collimation ring which characterized in that: comprises the steps of (a) preparing a substrate,
the first collimation unit (100) comprises a first conical surface (101) and a second conical surface (102) which are symmetrically arranged, a light hole (103) is formed in the positions, close to the geometric center, of the first conical surface (101) and the second conical surface (102), an outer side surface (104) is arranged on one side, far away from the light hole (103), of the first conical surface (101) and the second conical surface (102),
a second collimating unit (200) comprising a light converging surface (201) and a collimating surface (202) cooperating with said outer side surface (104);
the micro-electro-mechanical system (300) is arranged on one side of the light hole (103) in a matching mode, and a straight line section between the micro-electro-mechanical system (300) and the light hole (103) is a first section (Q); and the number of the first and second groups,
and the weak convergence unit (400) is arranged on one side of the light hole (103) departing from the micro-electromechanical system (300) in a matching manner.
2. The MEMS lidar light-collimating ring-scan apparatus of claim 1, wherein: the first section (Q) vertical plane is a horizontal plane (M), the first conical surface (101) and the horizontal plane (M) form a first included angle (A1), the second conical surface (102) and the horizontal plane (M) form a second included angle (A2), and the micro electro mechanical system (300) and the horizontal plane (M) form a third included angle (A3).
3. The MEMS lidar light-collimating ring-scan apparatus of claim 2, wherein: the first included angle (A1) and the third included angle (A3) satisfy the relation:
wherein n is a light refractive index of a material adopted by the optical element to which the first conical surface (101) belongs, and the second included angle (A2) and the third included angle (A3) satisfy the relation:
A2＝A3
in order to further control the laser beam emitting mode to be horizontal emitting, the first included angle (A1) and the third included angle (A3) need to be controlled to satisfy the relation:
4. the MEMS lidar light-collimating ring-scan apparatus of claim 2 or 3, wherein: the first section (Q) is also provided with a laser (500) for emitting laser (X) to the first collimating unit (100), and the travel path of the laser (X) passes through the light hole (103) along the weak convergence unit (400) and reaches the micro-electromechanical system (300).
5. The MEMS lidar light-collimating ring-scan apparatus of claim 4, wherein: and a deep hole diaphragm (105) is further arranged in the advancing direction of the laser (X), and the deep hole diaphragm (105) is arranged on the side, deviating from the light hole (103), of the weak convergence unit (400) in a matching manner.
6. The MEMS lidar light-collimating ring-scan apparatus of claim 5, wherein: the diameter of the light hole (103) is smaller than the diagonal length of the micro-electro-mechanical system (300), and the beam aperture of the laser (X) is smaller than the diagonal length of the micro-electro-mechanical system (300);
the laser (500) is arranged outside the front focus of the weak convergence unit (400), the vertical distance of the laser is L, and L is larger than or equal to 1mm and smaller than or equal to 5mm.
7. A MEMS laser radar light collimation annular scanning method is characterized in that: a MEMS lidar light-collimating ring scanning apparatus employing any of claims 1-6, comprising:
determining suitable experimental parameters, including selecting materials of the first tapered surface (101) and the second tapered surface (102);
calculating the first included angle (A1), the second included angle (A2) and the third included angle (A3) according to the selected material, and then calculating the curvatures of the first conical surface (101) and the second conical surface (102);
setting the size of a light hole of the deep hole diaphragm (105) according to the horizontal direction divergence condition when the laser (X) penetrates through the light hole (103) to reach the micro-electro-mechanical system (300), and intercepting a large-angle diaphragm through the deep hole diaphragm (105);
according to the horizontal direction divergence situation when the laser (X) is reflected by the micro-electro-mechanical system (300) and reaches the first conical surface (101), the curvature of a lens of the weak convergence unit (400) is set, the convergence of the divergent light in the horizontal direction of the laser (X) is realized, and therefore the compensation after the laser (X) reaches the first conical surface (101) and is subjected to horizontal divergence is realized;
according to the vertical direction divergence situation when the laser (X) passes through the first collimation unit (100) and reaches the second collimation unit (200), setting the lens curvature of the light converging surface (201) to realize the convergence of the divergent light in the vertical direction of the laser (X);
and adjusting the calibration surface (202) to provide the arrival position of the laser (X) after one interception and two convergence so as to obtain the optimal surrounding scanning effect.
8. The MEMS lidar light-collimating ring scan method of claim 7, wherein: adjusting the relationship of the third angle (A3) to the second angle (A2) such that the laser light (X) is highest in transmissivity through the second tapered surface (102).
9. The MEMS lidar light-collimating ring scan method of claim 8, wherein: and adjusting the relation between the third included angle (A3) and the first included angle (A1) to enable the laser (X) to be subjected to total reflection when reaching the first conical surface (101).
10. The MEMS lidar light-collimating ring scan method of claim 9, wherein: in the adjusting process, a third included angle (A3) between the micro-electro-mechanical system (300) and the horizontal plane is roughly adjusted, so that the laser (X) reaches the second collimation unit (200), the vertical height of the second collimation unit (200) is determined, and a traveling carrier is provided for the laser (X);
and then, the direction of the laser (X) after passing through the first collimation unit (100) is parallel to the horizontal direction by finely adjusting the first included angle (A1) and the second included angle (A2), and the laser (X) is determined to be in a collimation state by matching with the second collimation unit (200).
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| CN117518131A (en) * | 2023-11-07 | 2024-02-06 | 无锡微视传感科技有限公司 | 360-degree scanning laser radar optical system and scanning method based on annular prism |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117518131A (en) * | 2023-11-07 | 2024-02-06 | 无锡微视传感科技有限公司 | 360-degree scanning laser radar optical system and scanning method based on annular prism |
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