Three-dimensional scanning laser radar based on MEMS micromirror

Abstract

The invention relates to the technical field of laser detection, in particular to a three-dimensional scanning laser radar based on an MEMS micromirror, which comprises a base, a scanning module, a control module, a transmitting module and a receiving module, and is characterized in that the scanning module performs 360-degree rotary scanning in the horizontal direction and provides an angle orientation in the horizontal direction; the transmitting module continuously scans and transmits laser beams in the vertical direction, the receiving module detects and processes echoes, and the control module controls transmitting of the transmitting module, receiving of the receiving module and scanning of the scanning module. And the point cloud array of the environment to be measured is obtained according to the transmitting pitch angle information of the transmitting module, the horizontal rotation angle information of the scanning module and the corresponding distance between the laser radar and the target object. The laser radar based on the MEMS micromirror is compact in structure, and the size and the weight of the laser radar are reduced.

Description

[0001] This application is a divisional application of the original invention entitled A three-dimensional scanning laser radar based on MEMS micromirrors. The application date of the original application is March 14, 2018, and the application number is 201810207854.5. Technical Field

[0002] The present invention relates to the field of laser detection technology, and in particular to a three-dimensional scanning laser radar based on a MEMS micromirror. Background Art

[0003] Laser scanning ranging radar can be used to detect the position, contour and speed of the target. The application field of laser ranging radar is gradually expanding, including precise measurement, navigation positioning, safe obstacle avoidance, and it has begun to be applied to unmanned driving technology. Laser scanning radar transmits the emitted laser beam through rotation scanning to form a scanning cross section, thereby testing the characteristic information of the object to be tested. At present, the three-dimensional scanning laser radar has multi-layer scanning in the vertical direction, 360° in the horizontal direction, and can reach 40° in the vertical direction. It can well reflect the characteristic information of the object to be tested and is suitable for many fields, such as unmanned driving navigation and shape contour detection.

[0004] At present, 3D scanning laser radars mostly use multi-line scanning, that is, multiple laser tubes are used for sequential transmission. The structure is that multiple laser tubes are arranged vertically, and there is a certain angle between each laser tube. The vertical transmission field of view is 30-40°. The receiving module receives at the corresponding angle. Each receiving detector corresponds to an emission angle. The structure is that the receiving module and the transmitting module are arranged symmetrically on both sides, and a reflector is used inside to turn the light path. Then it rotates in the horizontal direction to achieve 3D scanning ranging. In order to meet the requirements of quickly obtaining scanning test information and collecting more feature information to increase the dot matrix pixels, the multi-line laser radar controls multiple transmitting diodes to transmit sequentially in the vertical direction, and installs the same number of receiving detectors corresponding to the multiple transmitting diodes, resulting in an increase in the vertical volume, increased power consumption and heat dissipation, and high costs, which restricts the development of multi-line laser radars. Summary of the invention

[0005] Based on the above problems, the purpose of the present invention is to provide a three-dimensional scanning laser radar based on MEMS micromirrors. The present invention adopts the following technical solutions:

[0006] The present invention provides a three-dimensional scanning laser radar based on a MEMS micromirror, comprising:

[0007] A scanning module, wherein the scanning module is arranged on the base, and the scanning module performs 360° rotation scanning in the horizontal direction and provides an angular orientation in the horizontal direction;

[0008] A transmitting module, wherein the transmitting module is arranged on the scanning module, and the transmitting module continuously scans and transmits a laser beam in a vertical direction;

[0009] A receiving module, wherein the receiving module is arranged on the scanning module, the receiving module is arranged on one side of the transmitting module, the receiving module detects and processes echoes, and the scanning field of view of the transmitting module in the vertical direction corresponds to the receiving field of view of the receiving module in the vertical direction;

[0010] A control module, wherein the control module controls the transmission of the transmitting module, the reception of the receiving module and the scanning of the scanning module, and obtains a point cloud array of the environment to be measured according to the transmission pitch angle information of the transmitting module, the horizontal rotation angle information of the scanning module and the corresponding distance between the laser radar and the target object.

[0011] Preferably, the receiving module includes a receiving lens, a light guiding element and a receiving detector; the receiving lens includes 3 or 4 lenses, and the light guiding element is arranged between the receiving lens and the receiving detector; the receiving lens couples the received light to the receiving detector through the light guiding element.

[0012] Preferably, the length of the light guide element ranges from 5 mm to 20 mm;

[0013] The front port of the light guide element is provided with a slit aperture, the length of which ranges from 5 mm to 20 mm, and the width of which ranges from 3 um to 300 um;

[0014] The rear port of the light guide element is provided with a slit aperture, the length of which ranges from 0.5 mm to 20 mm, and the width of which ranges from 5 um to 300 um.

[0015] Preferably, the light-guiding element is made of a component composed of multiple hard optical fibers, and each of the hard optical fibers is wrapped with a low-refractive-index material on the outside, or the light-guiding element is made of the same high-refractive-index light-transmitting material, and its outer side is wrapped with a low-refractive-index material.

[0016] Preferably, the front port of the light guiding element is located at the image plane of the receiving lens, the rear port of the light guiding element is aligned with and in close contact with the photosensitive surface of the receiving detector, the aperture ratio of the front port and the rear port of the light guiding element is the ratio between the image plane size of the receiving lens and the photosensitive surface size of the receiving detector, and the shape of the light guiding element is a compound parabola.

[0017] Preferably, a slit aperture is provided on the photosensitive surface of the receiving detector, with a length ranging from 0.5 mm to 20 mm and a width ranging from 3 um to 300 um.

[0018] Preferably, the receiving detector is an APD array or an MPPC array.

[0019] Preferably, the transmitting module includes at least one semiconductor laser, an elliptical cylindrical lens group, a beam combiner, a prism pair, a microlens array, a right-angle prism, a MEMS micromirror and a transmitting circuit, the elliptical cylindrical lens group is arranged at the emission outlet of the semiconductor laser, the MEMS micromirror is arranged opposite to the right-angle prism, the microlens array and the prism pair are arranged between the right-angle prism and the beam combiner, the microlens array is close to the right-angle prism, and the prism pair is close to the beam combiner.

[0020] Preferably, the semiconductor laser and the elliptical cylindrical lens group have the same optical axis, and the right-angle prism reflects the light spot at the center of the MEMS micromirror.

[0021] Preferably, it comprises an outer cover, which is arranged on the periphery of the transmitting module and the receiving module; the outer cover is in the shape of a cylinder, made of thermoplastic plastic that transmits infrared light, and coated on the outer surface with a narrow-band absorber that transmits the emission wavelength.

[0022] Compared with the prior art, the beneficial technical effects of the present invention are:

[0023] The three-dimensional scanning laser radar based on MEMS micromirrors provided by the present invention comprises a base, a scanning module, a control module, a transmitting module and a receiving module, wherein the scanning module performs 360° rotation scanning in the horizontal direction and provides an angular orientation in the horizontal direction, the transmitting module continuously scans and transmits a laser beam in the vertical direction, the receiving module detects and processes echoes, the control module controls the transmission of the transmitting module, the reception of the receiving module and the scanning of the scanning module, and obtains a point cloud array of the environment to be measured according to the transmission pitch angle information of the transmitting module, the horizontal rotation angle information of the scanning module and the corresponding distance between the laser radar and the target object. The three-dimensional scanning laser radar based on MEMS micromirrors provided by the present invention has a compact structure and reduces the volume and weight of the laser radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] Figure 1 A schematic diagram of the specific structure of a three-dimensional scanning laser radar based on a MEMS micromirror provided in the first embodiment of the present invention;

[0026] Figure 2 A schematic diagram of the transmission optical path of a three-dimensional scanning laser radar based on a MEMS micromirror provided in Example 1 of the present invention;

[0027] Figure 3A schematic diagram of the receiving optical path of a three-dimensional scanning laser radar based on a MEMS micromirror provided in Example 1 of the present invention;

[0028] Figure 4 A schematic diagram of the slit apertures at the front and rear ends of the light guide element provided in the first embodiment of the present invention;

[0029] Figure 5 Schematic diagram of the slit aperture on the photosensitive surface of the receiving detector provided in Embodiment 1 of the present invention.

[0030] Explanation of the reference numerals: 1. base; 2. scanning module; 3. transmitting module; 301. semiconductor laser; 302. elliptical cylindrical lens group; 303. beam combiner; 304. prism pair; 305. microlens array; 306. right-angle prism; 307. MEMS micromirror; 4. receiving module; 401. receiving lens; 402. light-guiding element; 403. receiving detector; 5. outer cover. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0032] Figure 1 The specific structural diagram of the three-dimensional scanning laser radar based on the MEMS micromirror 307 provided in the first embodiment of the present invention. Figure 1 As shown, the three-dimensional scanning laser radar based on the MEMS micromirror 307 provided in this embodiment includes a base 1, a scanning module 2, a control module, a transmitting module 3 and a receiving module 4. The scanning module 2 is arranged on the base 1, and the scanning module 2 performs 360° rotation scanning in the horizontal direction and provides an angular orientation in the horizontal direction. The transmitting module 3 and the receiving module 4 are arranged on the scanning module 2, and the receiving module 4 is arranged on one side of the transmitting module 3. The transmitting module 3 continuously scans and transmits a laser beam in the vertical direction, and the receiving module 4 detects and processes echoes. The scanning field of view of the transmitting module 3 in the vertical direction corresponds to the receiving field of view of the receiving module 4 in the vertical direction. The transmitting module 3 and the receiving module are fixed on the scanning module 2 and rotate with the scanning module 2. The three-dimensional scanning laser radar based on the MEMS micromirror 307 provided in this embodiment has a compact structure, which reduces the volume and weight of the laser radar.

[0033] like Figure 1As shown, the control module controls the emission of the emission module 3, the reception of the receiving module 4 and the scanning of the scanning module 2, and obtains the point cloud array of the environment to be measured according to the emission pitch angle information of the emission module 3, the horizontal rotation angle information of the scanning module 2 and the corresponding distance between the laser radar and the target object, and the outer cover 5 is arranged on the periphery of the emission module 3 and the receiving module 4. The outer cover 5 plays a protective role at the top, and the base 1 plays a supporting role at the bottom. The three-dimensional scanning laser radar based on the MEMS micromirror 307 provided in this embodiment has a compact structure, which reduces the volume and weight of the laser radar.

[0034] Figure 2 Schematic diagram of the transmission light path of the three-dimensional scanning laser radar based on the MEMS micromirror 307 provided in the first embodiment of the present invention. Figure 2 As shown, the transmitting module 3 includes at least one semiconductor laser 301, an elliptical cylindrical lens group 302, a beam combiner 303, a prism pair 304, a microlens array 305, a right-angle prism 306, a MEMS micromirror 307 and a transmitting circuit. The elliptical cylindrical lens group 302 is arranged at the emission outlet of the semiconductor laser 301, the MEMS micromirror 307 is arranged opposite to the right-angle prism 306, the microlens array 305 and the prism pair 304 are arranged between the right-angle prism 306 and the beam combiner 303, the microlens array 305 is close to the right-angle prism 306, and the prism pair 304 is close to the beam combiner 303. The scanning laser of the semiconductor laser 301 first passes through the elliptical cylindrical lens group 302, then is combined by the beam combiner 303, first passes through the prism pair 304, then passes through the microlens array 305 for spot homogenization, then the light path is deflected by the right-angle prism 306, and finally irradiates the MEMS micromirror 307 for scanning and emission.

[0035] Figure 3 Schematic diagram of the receiving optical path of the three-dimensional scanning laser radar based on the MEMS micromirror 307 provided in the first embodiment of the present invention. Figure 3 As shown, the receiving module 4 includes a receiving lens 401, a light guide element 402 and a receiving detector 403. The receiving lens 401 includes 3 or 4 lenses. The light guide element 402 is arranged between the receiving lens 401 and the receiving detector 403. The length of the light guide element 402 ranges from 5 mm to 20 mm. The three-dimensional scanning laser radar based on the MEMS micromirror 307 provided in this embodiment has a compact structure, which reduces the volume and weight of the laser radar.

[0036] Figure 4 Schematic diagram of the slit apertures at the front and rear ends of the light guide element 402 provided in the first embodiment of the present invention. Figure 4As shown, the front port of the light guide element 402 is provided with a slit aperture, with a length ranging from 5mm to 20mm and a width ranging from 3um to 300um. In practice, the rear port of the light guide element 402 is provided with a slit aperture, with a length ranging from 0.5mm to 20mm and a width ranging from 5um to 300um. Figure 5 Schematic diagram of the slit aperture on the photosensitive surface of the receiving detector 403 provided in the first embodiment of the present invention. Figure 5 As shown, the photosensitive surface of the receiving detector 403 is provided with a slit aperture, the length of which ranges from 0.5 mm to 20 mm, and the width of which ranges from 3 um to 300 um.

[0037] like Figure 3 As shown, the semiconductor laser 301 and the elliptical cylindrical lens group 302 have the same optical axis, and the right-angle prism 306 reflects the light spot at the center of the MEMS micromirror 307. The receiving lens 401 couples the received light to the receiving detector 403 through the light-guiding element 402, and the receiving detector 403 is an APD array or an MPPC array. The light-guiding element 402 is processed by a component composed of a plurality of hard optical fibers, and each of the hard optical fibers is wrapped with a low-refractive index material on the outside, or the light-guiding element 402 is processed by the same high-refractive index light-transmitting material, and the outside is wrapped with a low-refractive index material. The three-dimensional scanning laser radar based on the MEMS micromirror 307 provided in this embodiment has a compact structure, which reduces the volume and weight of the laser radar.

[0038] In this embodiment, the front port of the light guide element 402 is located at the image plane of the receiving lens 401, the rear port of the light guide element 402 is aligned with and close to the photosensitive surface of the receiving detector 403, the aperture ratio of the front port and the rear port of the light guide element 402 is the ratio between the image plane size of the receiving lens 401 and the photosensitive surface size of the receiving detector 403, and the shape of the light guide element 402 is a compound parabola. The outer cover 5 is in the shape of a cylinder, made of thermoplastic plastic that transmits infrared light, and the outer surface is coated with a narrow-band absorber that transmits the emission wavelength. The outer cover 5 plays a protective role at the top, and the base 1 plays a supporting role at the bottom.

[0039] The three-dimensional scanning laser radar based on the MEMS micromirror 307 provided in this embodiment includes a base 1, a scanning module 2, a control module, a transmitting module 3 and a receiving module 4. The scanning module 2 performs 360° rotation scanning in the horizontal direction and provides an angular orientation in the horizontal direction. The transmitting module 3 continuously scans and transmits a laser beam in the vertical direction. The receiving module 4 detects and processes echoes. The control module controls the transmission of the transmitting module 3, the reception of the receiving module 4 and the scanning of the scanning module, and obtains a point cloud array of the environment to be measured according to the transmission pitch angle information of the transmitting module 3, the horizontal rotation angle information of the scanning module 2 and the corresponding distance between the laser radar and the target object. The receiving module 4 includes a receiving lens 401, a light guide element 402 and a receiving detector 403. The receiving lens 401 includes 3 or 4 lenses, and the light guide element 402 is arranged between the receiving lens 401 and the receiving detector 403. The three-dimensional scanning laser radar based on the MEMS micromirror 307 provided in this embodiment has a compact structure, which reduces the volume and weight of the laser radar.

[0040] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A three-dimensional scanning laser radar based on MEMS micromirrors, characterized in that: include: A scanning module (2), wherein the scanning module (2) is arranged on the base (1), and the scanning module (2) performs 360° rotation scanning in the horizontal direction and provides an angular orientation in the horizontal direction; An emitting module (3), the emitting module (3) being arranged on the scanning module (2), and the emitting module (3) continuously scans and emits a laser beam in a vertical direction; a receiving module (4), the receiving module (4) being arranged on the scanning module (2), the receiving module (4) being arranged on one side of the transmitting module (3), the receiving module (4) detecting and processing echoes, the scanning field of view of the transmitting module (3) in the vertical direction corresponding to the receiving field of view of the receiving module (4) in the vertical direction; A control module, wherein the control module controls the transmission of the transmitting module (3), the reception of the receiving module (4) and the scanning of the scanning module (2), and obtains a point cloud array of the environment to be measured according to the transmission pitch angle information of the transmitting module (3), the horizontal rotation angle information of the scanning module (2) and the corresponding distance between the laser radar and the target object.

2. The three-dimensional scanning laser radar based on MEMS micromirror according to claim 1, characterized in that: The receiving module (4) comprises a receiving lens (401), a light-guiding element (402) and a receiving detector (403); the receiving lens (401) comprises three or four lenses, and the light-guiding element (402) is arranged between the receiving lens (401) and the receiving detector (403); the receiving lens (401) couples the received light to the receiving detector (403) through the light-guiding element (402).

3. The three-dimensional scanning laser radar based on MEMS micromirror according to claim 2, characterized in that: The length of the light guide element (402) ranges from 5 mm to 20 mm; The front port of the light guide element (402) is provided with a slit aperture, the length of which ranges from 5 mm to 20 mm, and the width of which ranges from 3 um to 300 um; The rear port of the light-guiding element (402) is provided with a slit aperture, the length of which ranges from 0.5 mm to 20 mm, and the width of which ranges from 5 um to 300 um.

4. The three-dimensional scanning laser radar based on MEMS micromirror according to claim 2, characterized in that: The light-guiding element (402) is processed from an element composed of multiple hard optical fibers, and each of the hard optical fibers is wrapped with a low-refractive-index material on the outside, or the light-guiding element is processed from the same high-refractive-index light-transmitting material, and its outer side is wrapped with a low-refractive-index material.

5. The three-dimensional scanning laser radar based on MEMS micromirror according to claim 2, characterized in that: The front port of the light-guiding element (402) is located on the image plane of the receiving lens (401), the rear port of the light-guiding element (402) is aligned with and closely attached to the photosensitive surface of the receiving detector (403), the aperture ratio of the front port and the rear port of the light-guiding element (402) is the ratio between the image plane size of the receiving lens (401) and the photosensitive surface size of the receiving detector (403), and the shape of the light-guiding element (402) is a compound parabola.

6. The three-dimensional scanning laser radar based on MEMS micromirror according to claim 2, characterized in that: The photosensitive surface of the receiving detector (403) is provided with a slit aperture, the length of which ranges from 0.5 mm to 20 mm, and the width of which ranges from 3 um to 300 um.

7. The three-dimensional scanning laser radar based on MEMS micromirror according to claim 2, characterized in that: The receiving detector (403) is an APD array or an MPPC array.

8. The three-dimensional scanning laser radar based on MEMS micromirror according to claim 1, characterized in that: The transmitting module (3) comprises at least one semiconductor laser (301), an elliptical cylindrical lens group (302), a beam combining mirror (303), a prism pair (304), a microlens array (305), a right-angle prism (306), a MEMS micromirror (307) and a transmitting circuit; the elliptical cylindrical lens group (302) is arranged at the transmitting outlet of the semiconductor laser (301); the MEMS micromirror (307) and the right-angle prism (306) are arranged opposite to each other; the microlens array (305) and the prism pair (304) are arranged between the right-angle prism (306) and the beam combining mirror (303); the microlens array (305) is close to the right-angle prism (306); and the prism pair (304) is close to the beam combining mirror (303).

9. The three-dimensional scanning laser radar based on MEMS micromirror according to claim 8, characterized in that: The semiconductor laser (301) and the elliptical cylindrical lens group (302) have the same optical axis, and the right-angle prism (306) reflects the light spot at the center of the MEMS micromirror (307).

10. The three-dimensional scanning laser radar based on MEMS micromirror according to claim 1, characterized in that: It comprises an outer cover (5), which is arranged on the periphery of the transmitting module (3) and the receiving module (4); the outer cover (5) is in the shape of a cylinder, made of thermoplastic plastic that transmits infrared light, and coated on the outer surface with a narrow-band absorbent that transmits the emission wavelength.

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