Micromirror scanning optical system

Abstract

The application discloses a kind of micro mirror scanning optical systems.This micro mirror scanning optical system includes: for emitting probe light signal emission optical unit;Emission optical unit includes sequentially arranged light source subunit, scanning mirror and diffraction subunit along the propagation direction of light;Light source subunit is used to emit light beam;Scanning mirror is used to rotate under the action of driving force, to change the propagation direction of light beam, and carry out one-dimensional scanning;Diffraction subunit is used to shape light beam in the direction perpendicular to scanning direction, and form the probe light signal with the set field angle value.The technical scheme of the application, by the cooperation of scanning mirror and diffraction mirror, can form larger scanning field of view in two directions perpendicular to each other, avoid the problem that the overall cost of system is higher caused by the need of multiple scanning mirrors or multiple light source subunits splicing in the existing micro mirror scanning optical system, and reduce the cost of micro mirror scanning optical system.

Description

Technical Field

[0001] The present invention relates to the field of laser ranging technology, and in particular to a micromirror scanning optical system. Background Technology

[0002] With the rapid development of semiconductor technology, information technology, and optical communication technology, another important direction in the development of Micro-Electro-Mechanical Systems (MEMS) is their integration with optics, known as Micro-Opto-Electro-Mechanical Systems (MOEMS). MOEMS are micro-opto-electro-mechanical devices and systems realized using microfabrication technology. Optical elements (such as lenses, mirrors, or gratings) within these systems, under the action of microelectronic or micromechanical devices, can control the convergence, reflection, or diffraction of light beams, thereby achieving functions such as switching, attenuation, scanning, or imaging. MEMOS scanning mirrors typically refer to scanning mirrors that deflect under the action of driving forces (including electrostatic, electromagnetic, electrothermal, and piezoelectric actuation), thereby changing the exit angle of the light beam. Compared to traditional optical scanning methods that use motors to drive mirrors, MOMES scanning mirrors are smaller, lighter, consume less power, and have a faster dynamic response. Furthermore, MOMES scanning mirrors also possess the advantages common to MEMS devices, such as ease of large-scale mass production and lower cost.

[0003] However, current scanning mirror scanning optical systems have a small scanning field of view. To achieve a large scanning field of view, it is usually necessary to splice together multiple scanning mirrors or multiple light source sub-units, which results in high costs. Summary of the Invention

[0004] This invention provides a micromirror scanning optical system that can increase the scanning field of view, thereby reducing the cost of micromirror scanning optical systems with a large scanning field of view.

[0005] In a first aspect, embodiments of the present invention provide a micromirror scanning optical system, the system comprising: an emitting optical unit for emitting a probe light signal;

[0006] The emitting optical unit includes a light source subunit, a scanning mirror, and a diffraction subunit arranged sequentially along the direction of light propagation;

[0007] The light source subunit is used to emit a light beam;

[0008] The scanning mirror is used to rotate under the action of driving force, thereby changing the propagation direction of the light beam and performing one-dimensional scanning;

[0009] The diffraction sub-unit is configured to shape the light beam in a direction perpendicular to the scanning direction to form the probe light signal with a set field of view angle value.

[0010] Further, the emission optical unit further comprises a collimation sub-unit.

[0011] The collimation sub-unit is located in an optical path between the light source sub-unit and the scanning mirror.

[0012] The collimation sub-unit is configured to collimate the light beam emitted by the light source sub-unit and irradiate the collimated light beam to a reflecting surface of the scanning mirror.

[0013] Further, the collimation sub-unit comprises a cylindrical mirror and a collimation lens.

[0014] The cylindrical mirror is configured to adjust a divergence degree of the light beam in a first direction so that the adjusted light beam has consistent divergence degrees in the first direction and a second direction perpendicular to the first direction.

[0015] The collimation lens is configured to collimate the light beam adjusted by the cylindrical mirror.

[0016] Further, the collimation lens is a spherical lens group or an aspherical lens group.

[0017] Further, the scanning mirror has an elliptical shape, and a length A of a major axis of the elliptical shape ranges from 1 mm to 4 mm, and a length B of a minor axis of the elliptical shape ranges from 1 mm to 4 mm.

[0018] Further, the scanning mirror has a circular shape, and a diameter D of the circular shape ranges from 1 mm to 4 mm.

[0019] Further, the diffraction sub-unit comprises a diffraction mirror.

[0020] Further, the diffraction mirror is configured to shape the light beam irradiated thereon into a light beam with a field of view angle of 20 degrees in a direction perpendicular to the scanning direction.

[0021] Further, the light source sub-unit is a semiconductor laser, a fiber laser, a gas laser, or a solid-state laser.

[0022] Further, the micromirror scanning optical system further comprises a receiving optical unit.

[0023] The receiving optical unit is configured to receive a to-be-measured light signal reflected by a target object.

[0024] Further, the receiving optical unit comprises, in sequence along a light propagation direction, a receiving lens sub-unit, a filtering sub-unit, and a receiving detector sub-unit.

[0025] The receiving lens subunit is configured to shape and focus the to-be-measured light signal reflected by the target object to the receiving detector subunit.

[0026] The light filtering subunit is configured to filter out light signals of other wavelengths through the detection light signal.

[0027] The receiving detector subunit is configured to detect the to-be-measured light signal after shaping and focusing.

[0028] The receiving lens subunit is configured to shape and focus the to-be-measured light signal into a light beam consistent with the shape and size of the receiving detector subunit.

[0029] Further, the receiving lens subunit includes a spherical lens group or an aspherical lens group.

[0030] Further, the light filtering subunit includes a light filter.

[0031] Further, the receiving detector subunit includes a multi-channel avalanche photodiode.

[0032] Further, the multi-channel avalanche photodiode is rectangular, with a long side of 12 mm in length and a short side of 5 mm in length.

[0033] Further, the receiving lens subunit includes a focusing lens group and a cylindrical lens.

[0034] The focusing lens group is configured to focus the to-be-measured light signal to the multi-channel avalanche photodiode.

[0035] The cylindrical lens is configured to shape the to-be-measured light signal, so that the spot length of the shaped to-be-measured light signal is equal to the length of the long side of the multi-channel avalanche photodiode, and the spot width of the shaped to-be-measured light signal is not greater than 88% of the length of the short side of the multi-channel avalanche photodiode.

[0036] In a second aspect, an embodiment of the present application provides a laser radar, which includes the micro-mirror scanning optical system provided in the first aspect.

[0037] The embodiment of the present application provides a micro-mirror scanning optical system, which comprises a transmitting optical subunit for transmitting a probe light signal, the transmitting optical subunit comprises a light source subunit, a scanning mirror and a diffraction subunit arranged in sequence along the propagation direction of light; the propagation direction of the light beam can be changed by rotating the scanning mirror under the action of a driving force, and the angle of the rotation of the scanning mirror determines the relative size of the angle of deflection of the propagation direction of the light beam relative to the propagation direction of the light beam incident to the front of the scanning mirror, so that one-dimensional scanning can be realized by the rotation of the scanning mirror; meanwhile, the light beam after passing through the scanning mirror is incident to the diffraction subunit, the light beam is shaped in the direction perpendicular to the scanning direction by the diffraction subunit, and the probe light signal with a set field of view angle value is formed. Therefore, by cooperation of the scanning mirror and the diffraction mirror, a larger scanning field of view can be formed, the problem of high cost caused by splicing of multiple scanning mirrors or multiple light source subunits is avoided, and the cost of the micro-mirror scanning optical system is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0039] Figure 1 is a light path schematic diagram of a transmitting optical unit provided by the embodiment of the present application;

[0040] Figure 2 is a light path schematic diagram of another transmitting optical unit provided by the embodiment of the present application;

[0041] Figure 3 is a light path schematic diagram of still another transmitting optical unit provided by the embodiment of the present application;

[0042] Figure 4 is a scanning range schematic diagram of a transmitting optical unit provided by the embodiment of the present application;

[0043] Figure 5 is a light path schematic diagram of still another transmitting optical unit provided by the embodiment of the present application;

[0044] Figure 6 is a structure schematic diagram of a collimating subunit provided by the embodiment of the present application;

[0045] Figure 7 is a structure schematic diagram of a receiving optical unit provided by the embodiment of the present application;

[0046] Figure 8This is a schematic diagram of the detection range of a receiving optical unit provided in an embodiment of the present invention;

[0047] Figure 9 This is a schematic diagram of the structure of a multi-channel avalanche photodiode provided in an embodiment of the present invention;

[0048] Figure 10 This is a schematic diagram of the structure of a receiving lens subunit provided in an embodiment of the present invention. Detailed Implementation

[0049] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0050] The micromirror scanning optical system provided in this invention can be applied to laser ranging. Using this optical system and based on the time-of-flight method, the optical path is obtained by calculating the time difference between the emission and return of the modulated laser, thereby acquiring the distance information of the target object. This micromirror scanning optical system includes an emitting optical unit for emitting a probe light signal. Figure 1 This is a schematic diagram of the optical path of a transmitting optical unit provided in an embodiment of the present invention. See also: Figure 1 The emitting optical unit includes a light source subunit 10, a scanning mirror 20, and a diffraction subunit 30 arranged sequentially along the direction of light propagation. The light source subunit 10 is used to emit a light beam. The scanning mirror 20 is used to rotate under the action of a driving force, thereby changing the direction of light propagation and performing one-dimensional scanning. The diffraction subunit 30 is used to shape the light beam in a direction perpendicular to the scanning direction to form a probe light signal with a set field of view angle value.

[0051] The light beam emitted by the light source subunit 10 can be a modulated laser beam with a specific frequency (wavelength) and phase.

[0052] Optionally, the light source subunit 10 can be a semiconductor laser, fiber laser, gas laser, or solid-state laser. For example, the light source subunit 10 can be a high-power nanosecond-level pulsed semiconductor laser in the infrared band (a semiconductor laser, also known as a laser diode, is a laser that uses semiconductor material as its working medium).

[0053] The scanning mirror 20 can be a MEMS micro-mirror. The driving force for driving the MEMS micro-mirror to rotate for one-dimensional scanning mainly includes four types: electrostatic driving, electromagnetic driving, electrothermal driving and piezoelectric driving. Compared with the conventional scanning mode of rotating a large-size mirror by a motor, the embodiment of the present application provides the driving force for driving the MEMS micro-mirror to rotate, which is small in size, light in weight, low in power consumption and fast in dynamic response speed, and also has the characteristics of easy batch production and low cost.

[0054] Generally, the greater the angle at which the MEMS micro-mirror can rotate, the greater the scanning range of the emission optical unit. The greater the size of the MEMS micro-mirror, on the one hand, can reflect all the outlet light spots (the light spots formed by the light beams emitted by the light source sub-unit 10 on the reflecting surface of the MEMS micro-mirror) to avoid energy loss, and on the other hand, the greater the outlet light spot is easier to collimate, so that the intensity of the strong light beam ensures that the intensity of the emitted signal is high, thereby making the accuracy of laser ranging higher and the measurable distance farther.

[0055] Exemplarily, Figure 2 is another optical path schematic diagram of the emission optical unit provided by the embodiment of the present application, Figure 3 is still another optical path schematic diagram of the emission optical unit provided by the embodiment of the present application. In combination with Figures 1-3 , the scanning mirror 20 is a one-dimensional MEMS micro-mirror, and the angle at which the scanning mirror 20 can rotate determines the scanning angle range of the emission optical unit. Exemplarily, based on the directions shown in Figure 1 and Figure 2 , the scanning mirror 20 rotates clockwise by 10 degrees, and then the light beam reflected by the scanning mirror 20 rotates clockwise by 20 degrees. Exemplarily, based on the directions shown in Figure 1 and Figure 3 , the scanning mirror 20 rotates counterclockwise by 10 degrees, and then the light beam reflected by the scanning mirror 20 rotates counterclockwise by 20 degrees. Exemplarily, the scanning angle range of the scanning mirror 20 is 10-50 degrees adjustable, that is, the angle at which it can rotate is 40 degrees, and then the light beam of the emission optical unit can realize 80-degree scanning.

[0056] It should be noted that the specific values of the above angles are only exemplary descriptions of the micro-mirror scanning optical system provided by the embodiment of the present application, and are not limiting.

[0057] The diffraction sub-unit 30 can shape the point light source into a line light source. In the embodiment of the present application, the diffraction sub-unit 30 shapes the light beam in the direction perpendicular to the scanning direction, that is, the emission optical unit scans in two mutually perpendicular directions.

[0058] Optionally, the diffraction sub-unit 30 can include a diffraction mirror.

[0059] Optionally, the diffraction mirror is used to shape the light beam irradiated thereon into a light beam with a field angle of 20 degrees in a direction perpendicular to the scanning direction.

[0060] Therefore, the emission optical unit can form a scanning field of view of 80 degrees*20 degrees.

[0061] An exemplary embodiment of the present application is shown in the following table 1. Figure 4 is a schematic diagram of a scanning range of an emission optical unit provided by an embodiment of the present application. Referring to Figure 4 The light beam reflected by the scanning mirror 20 is shaped by the diffraction subunit 30 to form a two-dimensional scanning field of view with an alpha angle of 20 degrees and a theta angle of 80 degrees.

[0062] An exemplary embodiment of the present application is shown in the following table 1.

[0063] Table 1: Comparison of parameters of different schemes

[0064]

[0065] In the table 1, scheme one is a scheme provided by an embodiment of the present application for realizing two-dimensional field of view scanning by using a one-dimensional MEMS micro-mirror combined with a diffraction mirror, and scheme two is a scheme for realizing two-dimensional field of view scanning by using a two-dimensional MEMS micro-mirror. The horizontal angle is a scanning angle realized by rotation of the one-dimensional MEMS micro-mirror, and the vertical angle is a scanning angle realized by diffraction shaping of the diffraction mirror.

[0066] As can be seen from the comparison in table 1, to realize the same scanning field of view, scanning point number, angular resolution and frame refresh rate, the emission frequency of the light source subunit 10 used in the scheme of the one-dimensional MEMS micro-mirror combined with the diffraction mirror provided by an embodiment of the present application is 12000 Hz, and the emission frequency of the light source subunit 10 used in the scheme of the two-dimensional MEMS micro-mirror is 768000 Hz. Exemplarily, the emission frequency of an existing semiconductor laser with a wavelength of 905 nm is about 100000 Hz at most. Obviously, the scheme of the two-dimensional MEMS micro-mirror cannot realize the above parameters using one semiconductor laser, and multiple lasers must be used for splicing.

[0067] It should be noted that the above parameters shown in table 1 are only exemplary for comparison between scheme one and scheme two, and are not a limitation of the micro-mirror scanning optical system provided by an embodiment of the present application.

[0068] The micro mirror scanning optical system provided by the embodiment of the present application utilizes a one-dimensional MEMS micro mirror combined with a diffraction mirror, and has the advantages that the required semiconductor laser has a low emission frequency, and the horizontal scanning field of view is determined only by the one-dimensional MEMS micro mirror, and the larger the scanning field of view angle of the one-dimensional MEMS micro mirror, the larger the horizontal scanning field of view of the emission optical unit, that is, the larger the horizontal scanning field of view of the micro mirror scanning optical system, and the horizontal scanning field of view is not affected by other optical systems or other factors in the optical system. Meanwhile, the micro mirror scanning optical system provided by the embodiment of the present application can realize a larger scanning field of view and higher angle resolution without the need for splicing multiple light source subunits (lasers), thereby saving costs.

[0069] Optionally, Figure 5 is another schematic diagram of an optical path of an emission optical unit provided by the embodiment of the present application. Referring to Figure 5 The emission optical unit further includes a collimation subunit 40, which is located in the optical path between the light source subunit 10 and the scanning mirror 20, and is configured to collimate the light beam emitted by the light source subunit 10 and irradiate the collimated light beam to the reflecting surface of the scanning mirror 20.

[0070] In the embodiment, the light beam emitted by the light source subunit 10 is a divergent light beam, and the collimation subunit 40 collimates the divergent light beam emitted by the light source subunit 10 to form a parallel light beam, which is then irradiated to the reflecting surface of the scanning mirror 20, thereby avoiding energy loss and improving the intensity of the signal of the light beam emitted by the emission optical unit.

[0071] Optionally, the scanning mirror 20 is in the shape of an ellipse, and the length A of the long axis of the ellipse is in the range of 1mm≤A≤4mm, and the length B of the short axis of the ellipse is in the range of 1mm≤B≤4mm.

[0072] Optionally, the scanning mirror 20 is in the shape of a circle, and the diameter D of the circle is in the range of 1mm≤D≤4mm.

[0073] In the embodiment, the size of the scanning mirror 20 is small, and the light beam is collimated by the collimation subunit 40, so that the size of the light spot irradiated to the scanning mirror is small, thereby avoiding the waste of light beam energy. For example, the size of the light spot of the light beam collimated by the collimation subunit 40 is smaller than the above-mentioned mirror size of the scanning mirror 20, so that the light spot can fall on the mirror surface of the scanning mirror 20 and be reflected by the scanning mirror 20.

[0074] Optionally, Figure 6 is a structural schematic diagram of a collimation subunit provided by the embodiment of the present application. Referring to Figure 6The collimation sub-unit 40 comprises a cylindrical lens 401 and a collimation lens 402. The cylindrical lens 401 is used to adjust the divergence of the light beam in the first direction, so that the adjusted light beam has the same divergence in the first direction and the second direction which are perpendicular to each other. The collimation lens 402 is used to collimate the light beam adjusted by the cylindrical lens.

[0075] The wavelength range of each lens is matched with the wavelength range of the light source sub-unit. For example, if the light source sub-unit is a semiconductor laser with a wavelength of 905 nm, the cylindrical lens 401 and the collimation lens 402 are also lenses with a wavelength of 905 nm.

[0076] The divergence angles of the light beam emitted by the light source sub-unit in the first direction and the second direction are usually quite different. Therefore, the divergence angle of at least one direction is adjusted by the cylindrical lens 401 first, so that the divergence angles of the light beam in the two directions are similar. Then the collimation lens 402 is used to collimate the light beam, so that the light beam emitted by the light source sub-unit can be well collimated in the fast axis direction and the slow axis direction, thereby making the energy of the collimated light beam more concentrated.

[0077] For example, the divergence angle of the light beam emitted by the light source sub-unit in the first direction is 25 degrees, and the divergence angle in the second direction is 8-9 degrees, which are quite different. In this case, in the collimation sub-unit 40, the divergence angle of the light beam in the second direction is first adjusted by the cylindrical lens 401 to about 25 degrees, and then the collimation lens 402 is used to collimate the adjusted light beam to form a parallel light beam, which forms a point spot on the reflecting surface of the scanning mirror. For example, the diameter of the collimated spot size is less than 2 mm, and the divergence angle of the light beam is 0.15 mrad.

[0078] It should be noted that the specific values of the divergence angle and the spot size are only exemplary descriptions of the micromirror scanning optical system provided in the embodiment of the present application, and are not limited.

[0079] Optionally, the collimation lens is a spherical lens group or an aspherical lens group.

[0080] The collimation lens can only collimate the divergent light beam into a parallel light beam. The specific composition of the collimation lens is not limited in the present application.

[0081] Optionally, the micromirror scanning optical system further comprises a receiving optical unit, which is used to receive the to-be-measured light signal reflected by the target object.

[0082] Thus, by comparing the information of the to-be-measured light signal received by the receiving optical unit with the information of the light signal emitted by the emitting optical unit, the distance value of the target object can be obtained.

[0083] Optionally, Figure 7 is a structural schematic diagram of a receiving optical unit provided by an embodiment of the present application. Referring to Figure 7 , the receiving optical unit comprises, in sequence along the propagation direction of light, a receiving lens subunit 50, a filter subunit 60, and a receiving detector subunit 70; the receiving lens subunit 50 is configured to shape and focus the to-be-measured light signal reflected by the target object to the receiving detector subunit 70; the filter subunit 60 is configured to pass the probe light signal and filter out light signals of other wavelengths; the receiving detector subunit 70 is configured to detect the to-be-measured light signal after shaping and focusing; wherein the shape of the receiving detector subunit 70 is rectangular, and the receiving lens subunit 50 is configured to shape and focus the to-be-measured light signal into a light beam consistent with the shape and size of the receiving detector subunit.

[0084] In the present embodiment, the receiving optical unit is provided with the receiving detector subunit 70 in the shape of a rectangle, so that the to-be-measured light signal reflected by the target object at different angles in the vertical direction can be received simultaneously.

[0085] Optionally, Figure 8 is a schematic diagram of the detection range of a receiving optical unit provided by an embodiment of the present application. Referring to Figure 8 , the receiving detector subunit 70 can detect the to-be-measured light signal reflected by the target object under different scanning fields of view, corresponding to the scanning range of the transmitting optical unit shown in Figure 4 .

[0086] Optionally, the receiving detector subunit comprises a multi-channel avalanche photo diode.

[0087] In the present embodiment, the multi-channel avalanche photo diode can receive the to-be-measured light signal at different angles in the vertical direction, and the number of channels of the multi-channel avalanche diode is equal to the number of angles in the vertical direction that can be distinguished. In combination with the parameters shown in Table 1, the number of channels of the multi-channel avalanche diode is set to 64, so that the number of scanning points in the vertical direction is 64. At the same time, the placement direction of the multi-channel avalanche diode corresponds to the vertical field of view of the receiving field of view.

[0088] Optionally, Figure 9 is a structural schematic diagram of a multi-channel avalanche photo diode provided by an embodiment of the present application. Referring to Figure 9 , the length E of the multi-channel avalanche photo diode in the vertical direction is 12 mm, and the length F of the multi-channel avalanche photo diode in the horizontal direction is 5 mm.

[0089] It should be noted that, Figure 9The structure of the multi-channel avalanche photodiode is only exemplarily shown, but is not limited to the embodiments of the present application.

[0090] Continuing to refer to Figure 7 The receiving lens subunit 50 plays two roles, one is to focus the light beams incident thereon, so that the spot of the to-be-measured light signal irradiated to the receiving detector subunit 70 is small and the energy is more concentrated, thereby improving the measurement accuracy; the other is to shape the light beams incident thereon, so that the shape and size of the spot of the to-be-measured light signal irradiated to the receiving detector subunit 70 are consistent with the shape and size of the receiving detector subunit 70, thereby the to-be-measured light signal at different vertical field angles in the vertical direction can be distinguished.

[0091] Optionally, the receiving lens subunit comprises a spherical mirror group or an aspherical mirror group.

[0092] The receiving lens subunit can only realize the role of shaping and focusing the to-be-measured light signal, and the specific composition thereof is not limited in the embodiments of the present application.

[0093] Optionally, the receiving lens subunit comprises a focusing lens group and a cylindrical mirror; the focusing lens group is used for focusing the to-be-measured light signal to the multi-channel avalanche photodiode; and the cylindrical mirror is used for shaping the to-be-measured light signal, so that the length of the spot of the shaped to-be-measured light signal is equal to the length of the long side of the multi-channel avalanche photodiode, and the width of the spot of the shaped to-be-measured light signal is not greater than 88% of the length of the short side of the multi-channel avalanche photodiode.

[0094] In this way, the light beam passing through the focusing lens group is more concentrated in intensity, and then the light beam with the concentrated intensity is shaped by the cylindrical mirror and irradiated to the receiving detector subunit, so that the to-be-measured light signal at each angle in the vertical direction can be detected.

[0095] Exemplarily, Figure 10 is a structural schematic diagram of a receiving lens subunit provided by the embodiments of the present application. Referring to Figure 10 The receiving lens subunit 50 comprises a spherical mirror 501, a cylindrical mirror double-cemented lens 502, a cylindrical mirror 503 and a cylindrical mirror 504. The equivalent focal length of the receiving lens subunit 50 is 4.3 mm, the back focal length is 5 mm, the clear aperture is 5 mm, and the total optical length is 29 mm. The light beam passing through the receiving lens subunit 50 is irradiated to the receiving detector subunit 70. The spot received by the receiving detector subunit 70 is a rectangular spot, and the length of the spot is consistent with the length of the receiving detector subunit 70. Exemplarily, in combination with Figure 9That is, the length of the light spot is 12 mm, so that the 12 mm long light spot is received by the 64 channels of the multi-channel avalanche diode; the light spot width (i.e., the half image height in the horizontal direction) is at most 2.2 mm, so that the light spot of the to-be-measured optical signal is all on the detection surface of the multi-channel avalanche diode.

[0096] Exemplarily, the relationship between the half image height of the light spot received by the detection surface of the multi-channel avalanche diode and the horizontal field of view angle obtained by optical software simulation is shown in Table 2.

[0097] Table 2 Relationship between half image height and horizontal field of view angle

[0098] Field of view angle (degrees) 0 10 20 30 Half image height (mm) 0 0.731 1.444 2.125

[0099] In Table 2, the horizontal field of view angle is variable in the range of 0 degrees to ± 30 degrees, so that the size of the half image height in the range of 0 degrees to 30 degrees can represent the size of the half image height in the entire horizontal field of view angle range, and the size of the half image height increases with the increase of the angle value of the horizontal field of view angle. Therefore, the half image height shown in Table 2 meets the design requirement that the light spot width (i.e., the half image height in the horizontal direction) is at most 2.2 mm.

[0100] Continuing to refer to Figure 7 In particular, in a strong light environment, the intensity of the noise signal in the light signal incident on the light filtering sub-unit 60 is large, and this noise signal with large intensity is filtered out by the light filtering sub-unit 60, so that the intensity of the detection light signal incident on the detector sub-unit is relatively increased, thereby improving the signal-to-noise ratio. When the optical system is applied to laser ranging, the detection distance of the ranging system can be increased.

[0101] Optionally, the light filtering sub-unit comprises a filter.

[0102] Exemplarily, when the wavelength of the light beam emitted by the light source sub-unit is 905 nm, the filter can only pass light with a wavelength of 905 nm and filter out light with other wavelengths, thereby improving the signal-to-noise ratio.

[0103] The embodiment of the present application also provides a laser radar comprising the micro-mirror scanning optical system shown in the above embodiments. Therefore, the laser radar provided by the embodiment of the present application has the technical effects of the micro-mirror scanning optical system, which will not be described here again.

[0104] For example, the laser radar is a MEMS solid-state laser ranging radar. The laser radar comprises the micro-mirror scanning optical system as described above, and further comprises a signal processing unit for processing the light signal to be measured and the light signal emitted by the emission optical unit to obtain the distance value of the target object. For example, the laser radar can be used for detecting the target object within 200 meters. This is only an example description and is not limited.

[0105] It should be noted that the above only describes the preferred embodiments of the present application and the principles of the applied technology. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and those skilled in the art can make various obvious changes, re-adjustments and substitutions without departing from the scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A micro-mirror scanning optical system characterized by comprising: Comprise: The emission optical unit for emitting the probe light signal; the emission optical unit comprises light source subunit, scanning mirror and diffraction subunit arranged in turn along the propagation direction of light; the light source subunit is used for emitting light beam; the scanning mirror is used for rotating under the action of driving force, thereby changing the propagation direction of the light beam, and one-dimensional scanning is carried out; the scanning mirror realizes horizontal direction scanning relative to the body of laser radar; the diffraction subunit is used for shaping the light beam in the direction perpendicular to the scanning direction, forming the probe light signal with the set field of view angle value; the diffraction subunit realizes vertical direction scanning relative to the body of laser radar; further comprising receiving optical unit; the receiving optical unit is used for receiving the to-be-measured light signal reflected by the target object; the emission optical unit further comprises collimation subunit; the collimation subunit is located in the optical path between the light source subunit and the scanning mirror; the collimation subunit is used for collimating the light beam emitted by the light source subunit, and irradiating the collimated light beam to the reflecting surface of the scanning mirror; The collimation subunit comprises cylindrical mirror and collimation lens; the cylindrical mirror is used for adjusting the divergence degree of the light beam in the first direction, so that the divergence degree of the adjusted light beam in the mutually perpendicular first direction and second direction is consistent; The collimation lens is used for collimating the light beam adjusted by the cylindrical mirror.

2. The micro-mirror scanning optical system according to claim 1, characterized in that, The collimation lens is spherical lens group or aspherical lens group.

3. The micro-mirror scanning optical system according to claim 1, wherein The shape of the scanning mirror is elliptical, the length A of the major axis of the elliptical shape is in the range of 1mm≤A≤4mm, and the length B of the minor axis is in the range of 1mm≤B≤4mm.

4. The micro-mirror scanning optical system of claim 1, wherein The shape of the scanning mirror is circular, and the diameter D of the circular shape is in the range of 1mm≤D≤4mm.

5. The micro-mirror scanning optical system of claim 1, wherein, The diffraction subunit comprises diffraction mirror.

6. The micro-mirror scanning optical system according to claim 5, wherein The diffraction mirror is used for shaping the light beam irradiated thereon into a light beam with a field of view angle of 20 degrees in the direction perpendicular to the scanning direction.

7. The micro-mirror scanning optical system according to claim 1, wherein The light source subunit is semiconductor laser, fiber laser, gas laser or solid laser.

8. The micro-mirror scanning optical system according to claim 7, wherein, The receiving optical unit comprises receiving lens subunit, optical filtering subunit and receiving detector subunit arranged in turn along the propagation direction of light; the receiving lens subunit is used for shaping and focusing the to-be-measured light signal reflected by the target object to the receiving detector subunit; the optical filtering subunit is used for filtering out other wavelength light signals through the probe light signal; the receiving detector subunit is used for detecting the to-be-measured light signal after shaping and focusing; wherein, the shape of the receiving detector subunit is rectangular, and the receiving lens subunit is used for shaping and focusing the to-be-measured light signal into a light beam consistent with the shape and size of the receiving detector subunit.

9. The micro-mirror scanning optical system of claim 8, wherein, The receiving lens subunit comprises spherical mirror group or aspherical mirror group.

10. The micro-mirror scanning optical system of claim 8, wherein, The optical filtering subunit comprises optical filter.

11. The micro-mirror scanning optical system of claim 8, wherein, The receiving detector subunit comprises multi-channel avalanche photodiode.

12. The micro-mirror scanning optical system of claim 11, wherein, The multi-channel avalanche photodiode is rectangular, the length E of the long side of the rectangle is 12mm, and the length F of the short side is 5mm.

13. The micro-mirror scanning optical system of claim 12, wherein, The receiving lens subunit comprises a focusing lens group and a cylindrical lens; the focusing lens group is used for focusing the to-be-tested optical signal to the multi-channel avalanche photodiode; The cylindrical lens is used for shaping the to-be-tested optical signal, so that the spot length of the shaped to-be-tested optical signal is equal to the length of the long side of the multi-channel avalanche photodiode, and the spot width of the shaped to-be-tested optical signal is not greater than 88% of the length of the short side of the multi-channel avalanche photodiode.

14. A lidar, characterized by A micro-mirror scanning optical system comprising the micro-mirror scanning optical system of any one of claims 1-13.

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