TWI773179B - Optical scanning system - Google Patents

Abstract

An optical scanning system including a laser light source, an optical module, a scanning reflection element and a controller is provided. The laser light source is configured to emit a laser beam. The optical module is located on a light path of the laser beam, and has a first axis and a second axis perpendicular to each other. After the laser beam penetrates the optical module, it is focused on the scanning reflection element on the first axis, and is collimated and transmitted to the scanning reflection element on the second axis. The scanning reflection element reflects the laser beam to an object to be scanned and forms a one-dimensional scanning beam on the object to be scanned. The controller is electrically connected to the scanning reflection element. The controller controls the scanning reflection element to act, so that the one-dimensional scanning beam scans the object to be scanned along a scanning direction.

Description

Optical scanning system

The present invention relates to an optical system, and in particular to an optical scanning system.

LiDAR (Light (Laser) Detection And Ranging, LiDAR) is an optical remote sensing technology that measures parameters such as target distance by irradiating a beam of light, usually a pulsed laser, to the target. Optical radar can measure the distance with high precision, identify the shape of the object and build a 3D geographic information model around it. It has the advantages of high distance measurement, high precision, and high recognition. It is not affected by environmental brightness and can sense day and night. Measure the shape, distance and other information of surrounding obstacles, and build a 3D geographic information model. Lidar has applications in surveying and mapping, archaeology, geography, geomorphology, earthquakes, forestry, remote sensing, and atmospheric physics. In addition, this technology is also used in specific applications such as airborne laser mapping, laser altimetry, and lidar contour drawing.

In the field of autonomous cars, the sensing system must be able to accurately detect targets within 100-200 meters in various environments. Therefore, LiDAR is an essential sensor for autonomous driving currently under development. one.

According to the laser scanning method, optical radar can be divided into Flash, 2D Raster-Scan, 1D Line-Scan. The scanning method of Flash LiDAR is like the flash of a camera, illuminating an entire screen at the same time; the scanning method of 2D Raster-Scan LiDAR is like a CRT display, and the light spots emitted by the laser light source are raster scanned to form a surface; 1D Line-Scan LiDAR It is to first expand the light source into a one-dimensional line, and then scan the other dimension to reach a surface. The advantage of Flash LiDAR is fast scanning speed, but the disadvantage is short detection distance; 2D Raster-Scan LiDAR is opposite to Flash LiDAR, the advantage is long detection distance, but the disadvantage is slow scanning speed; the characteristics of 1D Line Scan LiDAR are somewhere in between.

The 1D Line-Scan LiDAR module products currently launched in the market basically have two different implementations.

The first embodiment is as follows. The light source is a laser array light source that emits light in a vertical arrangement, and the laser light source is an XY asymmetric optical element (usually a cylindrical lens is used), which laterally expands the "point" emitted by each laser light source into a "line". The horizontal "line" is matched with the vertically arranged laser array light source to scan a surface. The most important part of the light-receiving part is to use a photodiode array sensor arranged horizontally, with a receiving lens (Receiver Lens), to receive the reflected scattered light irradiating each "line" on the target to the sensor. superior.

The second embodiment is as follows. The collimated laser light (spot) emitted by the laser diode is scanned laterally into a "line" by the MEMS micro-mirror, and then the lateral The "lines" are drawn lengthwise into a face. The light-receiving part adopts a photodiode array sensor arranged vertically, and is matched with a receiving lens to irradiate the light of each "line" on the target. The reflected scattered light is received on the sensor.

However, the light source of the first embodiment uses a laser array, so the cost is relatively high; the light source of the second embodiment uses a laser diode, which can effectively reduce the cost, but further optimization of the optical structure is still required.

The "prior art" paragraph is only used to help understand the present disclosure, so the content disclosed in the "prior art" paragraph may contain some that do not constitute the prior art known to those with ordinary skill in the art. The content disclosed in the "prior art" paragraph does not represent the content or the problem to be solved by one or more embodiments of the present invention, and has been known or recognized by those with ordinary knowledge in the technical field before the application of the present invention.

The present invention provides an optical scanning system with simple optical structure and low cost.

An optical scanning system according to an embodiment of the present invention includes a laser light source, an optical module, a scanning reflection element, and a controller. The laser light source is used for emitting a laser beam. The optical module is located on the light path of the laser beam and has a first axis and a second axis that are perpendicular to each other. After penetrating the optical module, the laser beam is focused on the scanning reflection element along the first axis, and is collimated and transmitted to the scanning reflection element along the second axis. The scanning reflection element reflects the laser beam to an object to be scanned and forms a one-dimensional scanning beam on the object to be scanned. The controller is electrically connected to the scanning reflection element. The controller controls the scanning reflection element to act, so that the one-dimensional scanning beam scans along a scanning direction Scan the object to be scanned.

According to an embodiment, in the above-mentioned optical scanning system, the laser light source includes a vertical resonant cavity surface-emitting laser or an edge-emitting laser.

According to an embodiment, in the above-mentioned optical scanning system, the scanning reflective element includes a MEMS mirror, a scanning galvanometer or a scrolling camera.

According to an embodiment, in the above-mentioned optical scanning system, the laser light source is a single laser diode.

According to an embodiment, in the above-mentioned optical scanning system, the one-dimensional scanning light beam forms a strip-shaped light spot on the plane of the object to be scanned, and the long side of the strip-shaped light spot is perpendicular to the scanning direction.

According to an embodiment, the above-mentioned optical scanning system further includes: a plurality of sensing elements disposed on the transmission path of the one-dimensional scanning beam reflected by the object to be scanned, and the sensing elements are arranged in an array along the scanning direction.

According to an embodiment, in the above-mentioned optical scanning system, the laser beam emitted from the laser light source has a long axis and a short axis, and in the optical path of the laser beam passing through the optical module, the long axis of the laser beam The short axis is parallel to the first axis of the optical module, and the short axis is parallel to the second axis of the optical module.

According to an embodiment, in the above-mentioned optical scanning system, the long axis of the one-dimensional scanning light beam having the elongated light spot is perpendicular to the scanning direction.

According to an embodiment, in the above-mentioned optical scanning system, the scanning direction is perpendicular to the first axis of the optical module.

According to an embodiment, in the above-mentioned optical scanning system, the optical module package Including: a collimating lens; and a cylindrical lens.

According to an embodiment, in the above-mentioned optical scanning system, the cylindrical lens has a plane axis and a refractive axis, and in the light path of the laser beam passing through the cylindrical lens, the long axis of the laser beam is parallel to the long axis of the cylindrical lens. The refractive axis, and the minor axis is parallel to the plane axis of the lenticular lens.

According to an embodiment, in the above-mentioned optical scanning system, the collimating lens and the lenticular lens are sequentially arranged between the laser light source and the scanning reflective element.

Based on the above, in the optical scanning system of an embodiment of the present invention, since the scanning reflective element reflects the laser beam to the object to be scanned and forms a one-dimensional scanning beam on the object to be scanned, and the controller makes the one-dimensional scanning beam scan along the When scanning the object to be scanned in the direction, the optical scanning system can complete the scanning of an entire screen under a simple optical structure. Therefore, the cost of the optical scanning system in the embodiment of the present invention is low.

100: Optical scanning system

110: Laser light source

112: Glowing Surface

120: Optical module

122: collimating lens

124: Cylindrical lens

130: Scanning Reflective Elements

140: Controller

150: Sensing element

B: Laser beam

C1: Long axis direction

C2: Short axis direction

D1, F: long axis

D2: short axis

E1: The first axis

E2: The second axis

O: object to be scanned

OA: Optical axis

P1: plane axis

P2: Refractive axis

SD: Scanning direction

SB: 1D Scanning Beam

FIG. 1 is a schematic diagram of an optical scanning system according to an embodiment of the present invention.

2A is a schematic diagram of an optical scanning system according to an embodiment of the present invention when the viewing angle is perpendicular to the second axis.

2B is a schematic diagram of an optical scanning system according to an embodiment of the present invention when the viewing angle is perpendicular to the first axis.

FIG. 3 is a schematic diagram of an arrangement of sensing elements of an optical scanning system according to an embodiment of the present invention.

The aforementioned and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the drawings. The directional terms mentioned in the following embodiments, such as: up, down, left, right, front or rear, etc., are only for referring to the directions of the attached drawings. Accordingly, the directional terms used are illustrative and not limiting of the present invention.

FIG. 1 is a schematic diagram of an optical scanning system according to an embodiment of the present invention. Please refer to FIG. 1 , an optical scanning system 100 according to an embodiment of the present invention includes a laser light source 110 , an optical module 120 , a scanning reflection element 130 and a controller 140 .

In this embodiment, the laser light source 110 is used for emitting a laser beam B. As shown in FIG. The laser light source 110 may be a semiconductor laser light source, and may include a Vertical Cavity Surface Emitting Laser (VCSEL) or an Edge Emitting Laser (EEL). In one embodiment, the laser light source 110 can be a single laser diode, so it is beneficial to reduce the overall volume and weight of the optical scanning system 100 and reduce the cost.

In this embodiment, the optical module 120 has an optical axis OA, and the cross section of the laser beam B orthogonal to the optical axis OA has a long axis (the long axis D1 in FIG. 2B ) and a short axis (the long axis D1 in FIG. 2A ) Short-axis D2), wherein, at the light-emitting surface 112 of the laser light source 110, the divergence angle of the laser beam B in the long-axis direction C1 is different from the divergence angle in the short-axis direction C2, but at the cross section orthogonal to the optical axis OA An ellipse is formed, and the long-axis direction C1 and the short-axis direction of the laser beam B emitted from the laser light source 110 at the light-emitting surface 112 C2 is parallel to the short axis and the long axis of the laser beam B in the far field, respectively.

In this embodiment, the optical module 120 is disposed between the laser light source 110 and the scanning reflection element 130 , and includes a collimating lens 122 and a cylindrical lens 124 . The lenticular lens 124 has a plane axis (plano axis, such as the plane axis P1 in FIG. 2A ) and a power axis (power axis, such as the power axis P2 in FIG. 2B ), wherein the plane axis is that the lenticular lens 124 does not have a power axis. The axial direction of the optical power, and the refractive axis is the axial direction of the positive refractive power of the lenticular lens 124 . The collimating lens 122 and the cylindrical lens 124 are sequentially disposed between the laser light source 110 and the scanning reflection element 130 along the optical axis OA.

In this embodiment, the scanning reflective element 130 may include a microelectromechanical system mirror (MEMS mirror), a scanning galvo mirror (galvo mirror) or a scrolling prism.

In this embodiment, the controller 140 includes, for example, a microcontroller unit (Microcontroller Unit, MCU), a central processing unit (central processing unit, CPU), a microprocessor (microprocessor), a digital signal processor (digital signal processor, DSP), programmable controller, programmable logic device (PLD) or other similar devices or combinations of these devices are not limited in the present invention. In addition, in one embodiment, each function of the controller 140 may be implemented as multiple codes. The codes are stored in a memory and executed by the controller 140 . Alternatively, in one embodiment, the functions of controller 140 may be implemented as one or more circuits. The present invention does not limit the implementation of the functions of the controller 140 by means of software or hardware.

2A is a view of the optical scanning system according to an embodiment of the present invention Schematic diagram perpendicular to the second axis. 2B is a schematic diagram of an optical scanning system according to an embodiment of the present invention when the viewing angle is perpendicular to the first axis. Please refer to FIG. 1 , FIG. 2A and FIG. 2B at the same time. In this embodiment, the optical module 120 is located on the optical path of the laser beam B and has a first axis E1 and a second axis E2 that are perpendicular to each other. And the first axis E1 and the second axis E2 are respectively perpendicular to the optical axis OA. In the light path of the laser beam B passing through the optical module 120 , the long axis D1 of the laser beam B is parallel to the first axis E1 of the optical module 120 , and the short axis D2 is parallel to the second axis of the optical module 120 to E2. The laser beam B penetrates the optical module 120 and is focused on the scanning reflection element 130 on the first axis E1. As shown in FIG. 2B , the laser beam B penetrates the optical module 130 and is focused on the second axis E2 The upper collimation is passed to the scanning reflective element 130, as shown in Figure 2A. In detail, in the light path of the laser beam B passing through the cylindrical lens 124, the long axis D1 of the laser beam B is parallel to the refractive axis P2 of the cylindrical lens 124 and the first axis E1 of the optical module 120, And the short axis D2 of the laser beam B is parallel to the plane axis P1 of the cylindrical lens 124 and the second axis E2 of the optical module 120 . The refraction axis P2 of the lenticular lens 124 having a positive refractive power focuses the laser beam B to the scanning reflective element 130 , and the plane axis P1 of the lenticular lens 124 having no refractive power causes the laser beam B to be collimated and delivered to the scanning reflective element 130 . Reflective element 130 .

In this embodiment, the scanning reflection element 130 reflects the laser beam B to an object O to be scanned and forms a one-dimensional scanning beam SB on the object O to be scanned. The controller 140 is electrically connected to the scanning reflective element 130, and controls the scanning reflective element 130 to operate, so that the one-dimensional scanning beam SB scans the object O to be scanned along a scanning direction SD. Among them, the one-dimensional scanning beam SB is a long stripe spot on the plane of the object O to be scanned, and the stripe The long side L of the shaped light spot is perpendicular to the scanning direction SD. Since the laser beam B forms an elongated one-dimensional scanning beam SB on the object O to be scanned instead of an entire screen, the sensing distance of the optical scanning system 100 of the embodiment of the present invention is longer, and the optical scanning system The signal strength received by the optical scanning system 100 is also higher, so that the signal-to-noise ratio of the optical scanning system 100 is improved. Moreover, the manner of controlling the operation of the scanning reflection element 130 to make the one-dimensional scanning beam SB scan the object O to be scanned along the scanning direction SD also makes the scanning speed high, and therefore, the frame rate of the optical scanning system 100 is also improved. . In addition, the one-dimensional scanning beam SB may be an oblong light spot on the plane of the object O to be scanned, and the long side of the oblong light spot is perpendicular to the scanning direction SD.

In this embodiment, the scanning direction SD is perpendicular to the first axis E1 of the optical module 120 , and the scanning direction SD is perpendicular to the short-axis direction C2 of the laser beam B at the light-emitting surface of the laser light source 110 (as shown in FIG. 1 ). shown).

In this embodiment, the long axis F of the one-dimensional scanning light beam SB having a long strip-shaped light spot (or an oblong light spot) is perpendicular to the scanning direction SD.

FIG. 3 is a schematic diagram of an arrangement of sensing elements of an optical scanning system according to an embodiment of the present invention. Please refer to FIG. 3 , in this embodiment, the optical scanning system 100 further includes a plurality of sensing elements 150 . The sensing elements 150 are arranged on the transmission path of the one-dimensional scanning beam SB reflected by the object O to be scanned. The sensing elements 150 are arranged in an array along the scanning direction SD. In this embodiment, the sensing element 150 may be a light sensing device of Complementary Metal-Oxide-Semiconductor (CMOS), charge coupled device (CCD) or photodiode array. components, but the present invention is not limited thereto. Every A sensing element 150 may include a plurality of sensing pixels, for example, the sensing pixels are arranged in a pixel array, wherein the arrangement direction of the sensing pixels is perpendicular to the scanning direction SD.

To sum up, in the optical scanning system of an embodiment of the present invention, the laser beam penetrates the optical module and is focused on the scanning reflection element in the first axis, and is collimated and transmitted to the scanning reflection element in the second axis element. Since the scanning reflective element reflects the laser beam to the object to be scanned and forms a one-dimensional scanning beam on the object to be scanned, and the controller makes the one-dimensional scanning beam scan the object to be scanned along the scanning direction, the optical scanning system can operate under a simple optical structure. , the scanning of an entire screen can be completed. Therefore, the optical scanning system of the embodiment of the present invention has the advantages of high scanning speed and low cost at the same time.

However, the above are only preferred embodiments of the present invention, and should not limit the scope of the present invention, that is, any simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the contents of the description of the invention, All still fall within the scope of the patent of the present invention. In addition, it is not necessary for any embodiment of the present invention or the claimed scope of the present invention to achieve all of the objects or advantages or features disclosed in the present invention. In addition, the abstract part and the title are only used to assist the search of patent documents, and are not used to limit the right scope of the present invention. In addition, terms such as "first" and "second" mentioned in this specification or the scope of the patent application are only used to name the elements or to distinguish different embodiments or scopes, and are not used to limit the number of elements. upper or lower limit.

100: Optical scanning system

110: Laser light source

112: Glowing Surface

120: Optical module

122: collimating lens

124: Cylindrical lens

130: Scanning Reflective Elements

140: Controller

B: Laser beam

C1: Long axis direction

C2: Short axis direction

F: long axis

O: object to be scanned

SD: Scanning direction

SB: 1D Scanning Beam

Claims (11)

An optical scanning system includes: a laser light source, an optical module, a scanning reflection element and a controller; wherein, the laser light source is used to emit a laser beam; the optical module is located at the position of the laser beam The light path has a first axis and a second axis that are perpendicular to each other. After the laser beam penetrates the optical module, it is focused on the scanning reflective element on the first axis, and is on the second axis. collimated upward and transmitted to the scanning reflection element; the scanning reflection element reflects the laser beam to an object to be scanned and forms a one-dimensional scanning beam on the object to be scanned; and the controller is electrically connected to the scanning reflection element , the controller controls the scanning reflection element to act, so that the one-dimensional scanning beam scans the object to be scanned along a scanning direction, wherein the one-dimensional scanning beam is a long stripe spot on the plane of the object to be scanned, and the long The long side of the stripe spot is perpendicular to the scanning direction. The optical scanning system of claim 1, wherein the laser light source comprises a vertical resonant cavity surface-emitting laser or an edge-emitting laser. The optical scanning system of claim 1, wherein the scanning reflective element comprises a MEMS mirror, a scanning galvanometer or a scrolling camera. The optical scanning system according to claim 1, wherein the laser light source is a single laser diode. The optical scanning system according to claim 1, further comprising: a plurality of sensing elements disposed after the one-dimensional scanning beam is reflected by the object to be scanned On the transmission path of , the sensing elements are arranged in an array along the scanning direction. The optical scanning system of claim 1, wherein the laser beam emitted from the laser light source has a long axis and a short axis, and in the optical path of the laser beam passing through the optical module, the The long axis of the laser beam is parallel to the first axis of the optical module, and the short axis is parallel to the second axis of the optical module. The optical scanning system according to claim 1, wherein the long axis of the one-dimensional scanning beam with the elongated light spot is perpendicular to the scanning direction. The optical scanning system of claim 1, wherein the scanning direction is perpendicular to the first axial direction of the optical module. The optical scanning system according to claim 6, wherein the optical module comprises: a collimating lens; and a cylindrical lens. The optical scanning system of claim 9, wherein the lenticular lens has a plane axis and a refractive axis, and in the optical path of the laser beam passing through the lenticular lens, the long axis of the laser beam is parallel to the refractive axis of the lenticular lens, and the short axis is parallel to the plane axis of the lenticular lens. The optical scanning system according to claim 9, wherein the collimating lens and the lenticular lens are sequentially arranged between the laser light source and the scanning reflection element.

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