Optical systems and laser ranging equipment

Abstract

This application provides an optical system and a laser ranging device. The optical system includes: a transmitting unit (210) for emitting a laser beam; a beam shaping unit (220) for shaping the laser beam so that it first converges and then diffuses to form a linear laser; a perforated mirror (230) with the aperture located at the convergence point of the laser beam, the perforated mirror (230) for reflecting the laser echo of the linear laser; and a receiving unit (240) for receiving the laser echo from the perforated mirror (230), which helps to reduce the energy loss of the laser echo during laser reception.

Description

Technical Field

[0001] This application relates to the field of optical technology, specifically to an optical system and a laser ranging device. Background Technology

[0002] Currently, laser optical systems can be broadly classified into two categories: coaxial optical systems and paraxial optical systems. In coaxial optical systems, some optical components can be shared during both laser emission and laser reception. Therefore, coaxial optical systems have advantages such as low cost and small size.

[0003] In a traditional coaxial optical system, a spot laser beam emitted by the transmitting unit passes through an aperture in a perforated mirror to scan objects within the target area. Correspondingly, the laser echo reflected back from the object can be reflected by the perforated mirror to the receiving unit. However, this coaxial optical system is only suitable for spot laser beams with a small divergence angle. If applied to linear lasers with a large divergence angle, the aperture in the perforated mirror needs to be enlarged to allow the linear laser to pass through. This reduces the reflection area of ​​the perforated mirror, and some of the laser echo cannot be reflected back to the receiving unit, leading to increased energy loss of the laser echo during laser reception. Summary of the Invention

[0004] In view of this, embodiments of this application aim to provide an optical system and a laser ranging device to reduce the energy loss of laser echo during laser reception.

[0005] A first aspect provides an optical system comprising: a transmitting unit 210 for emitting a laser beam; a beam shaping unit 220 for shaping the laser beam such that the laser beam first converges and then diffuses to form a linear laser; a perforated mirror 230, the perforation of which is located at the convergence point of the laser beam, the perforated mirror 230 for reflecting the laser echo of the linear laser; and a receiving unit 240 for receiving the laser echo from the perforated mirror 230.

[0006] In one possible implementation, the beam shaping unit 220 includes: a collimating lens 410 for collimating the laser beam emitted by the emitting unit 210; and a cylindrical lens 420 for focusing and then diffusing the collimated laser beam to form the linear laser beam.

[0007] In one possible implementation, the beam shaping unit 220 includes: a collimating lens 510 for collimating the laser beam emitted by the emitting unit; and a diffractive optical element 520 for focusing and then diffusing the collimated laser beam to form the linear laser.

[0008] In one possible implementation, the beam shaping unit 220 includes a diffractive optical element 610 for collimating the laser beam emitted by the emitting unit 210, and then converging and diffusing the collimated laser beam to form the linear laser.

[0009] In one possible implementation, the laser optical system includes a plurality of the emitting units 810, each of the emitting units 810 emitting a laser beam to form a plurality of the linear laser beams.

[0010] In one possible implementation, a plurality of the linear lasers are arranged in a direction perpendicular to the direction in which the linear lasers extend.

[0011] In one possible implementation, laser beams emitted by multiple emission units are converged and diffused through the same optical element.

[0012] In one possible implementation, the laser optical system further includes a scanning unit for receiving the linear laser and deflecting the propagation direction of the linear laser to scan objects within a target range.

[0013] In one possible implementation, the response region of the receiving unit 240 to the laser echo is a linear region.

[0014] In one possible implementation, the linear laser has a vertical divergence angle of 20 to 60 degrees and a horizontal divergence angle of 0.1 to 2 degrees; or the linear laser has a horizontal divergence angle of 60 to 120 degrees and a vertical divergence angle of 0.1 to 2 degrees.

[0015] In a second aspect, a laser ranging device is provided, comprising: an optical system 1610 as described in any possible implementation of the first aspect, for emitting a linear laser toward a target and receiving a laser echo of the linear laser; and a processing unit 1620 for determining the distance to the target based on the laser echo.

[0016] This application provides an optical path scheme in which a laser beam is focused by a beam shaping unit to pass through the hole in a perforated mirror and then diffused to form a linear laser beam. This helps to reduce the energy loss of the laser echo during laser reception. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a traditional coaxial optical system.

[0018] Figure 2 This is a schematic diagram of an optical system according to an embodiment of this application.

[0019] Figure 3This is a schematic diagram of a linear laser according to an embodiment of this application.

[0020] Figure 4 This is a schematic diagram of the optical path of the beam shaping unit according to an embodiment of this application.

[0021] Figure 5 This is a schematic diagram of the optical path of a beam shaping unit according to another embodiment of this application.

[0022] Figure 6 This is a schematic diagram of the optical path of a beam shaping unit according to another embodiment of this application.

[0023] Figure 7 This is a schematic diagram showing the arrangement of multiple transmitting units according to an embodiment of this application.

[0024] Figure 8 This is a schematic diagram of the optical path between multiple transmitting units and beam shaping units in an embodiment of this application.

[0025] Figure 9 This is a schematic diagram of the optical path between multiple transmitting units and a beam shaping unit according to another embodiment of this application.

[0026] Figure 10 This is a schematic diagram of the optical path between multiple transmitting units and a beam shaping unit according to another embodiment of this application.

[0027] Figure 11 This is a schematic diagram of the scanning area of ​​the linear laser after being deflected by the scanning unit in an embodiment of this application.

[0028] Figure 12 This is a schematic diagram of the scanning area of ​​the linear laser after being deflected by the scanning unit in another embodiment of this application.

[0029] Figure 13 This is an illustration of the effect of using a scanning galvanometer to deflect the diffused linear laser beam according to an embodiment of this application.

[0030] Figure 14 This is an illustration of the effect of using a polyhedral mirror to deflect the diffused linear laser beam according to an embodiment of this application.

[0031] Figure 15 This is a schematic diagram of an optical system according to another embodiment of this application.

[0032] Figure 16 This is a schematic diagram of a laser ranging device according to an embodiment of this application. Detailed Implementation

[0033] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0034] To facilitate understanding this application, let's first combine... Figure 1 This section introduces traditional coaxial optical systems. Figure 1 This is a schematic diagram of a traditional coaxial optical system. Figure 1 The coaxial optical system 100 shown includes a transmitting unit 1, a perforated mirror 2, a scanning unit 3, and a receiving unit 4.

[0035] In a conventional coaxial optical system 100, the emitting unit 1 emits a spot laser beam with a small divergence angle in all directions. This laser beam can easily pass through the aperture in the perforated mirror 2 and be deflected by the scanning unit 3 to scan the object 5 within the target range. Correspondingly, the laser echo reflected back from the object 5 is deflected by the scanning unit 3, transmitted to the perforated mirror 2, and finally reflected by the perforated mirror 2 to the receiving unit 4.

[0036] With technological advancements, it has been discovered that linear lasers have a larger divergence angle compared to spot laser beams, or in other words, a larger scanning area. Therefore, linear lasers are a superior choice for laser scanning and laser ranging applications.

[0037] As mentioned above, while maintaining the low cost and small size of coaxial optical systems, the field of view of the optical system can be increased by using linear lasers. Therefore, applying linear lasers to coaxial optical systems is a future development trend for optical systems.

[0038] However, because linear lasers have a large divergence angle, in order for the linear laser to pass through the hole in the perforated lens during the laser emission process, the hole in the perforated mirror needs to be enlarged. This inevitably reduces the reflection area of ​​the perforated mirror, and some of the laser echo can no longer be reflected to the receiving unit through the perforated mirror, resulting in increased energy loss of the laser echo during laser reception.

[0039] Therefore, in order to avoid the above problems, this application provides an optical path scheme that shapes the laser beam by means of a beam shaping unit, so that the laser beam first converges and passes through the hole of the perforated mirror, and then diffuses to form a linear laser. In this way, there is no need to enlarge the hole in the perforated mirror, which helps to reduce the energy loss of the laser echo during laser reception.

[0040] The following text combines Figure 2 The optical system of the present application is described. Figure 2 This is a schematic diagram of an optical system according to an embodiment of this application. Figure 2 The optical system shown includes a transmitting unit 210, a beam shaping unit 220, a perforated mirror 230, and a receiving unit 240.

[0041] The emitting unit 210 may be, for example, a laser for emitting a laser beam.

[0042] The beam shaping unit 220 is used to shape the laser beam so that the laser beam is first focused and then diffused to form a linear laser beam.

[0043] In some embodiments, the beam shaping unit 220 may include a cylindrical lens or a diffractive optical element (DOE). For specific optical path diagrams, please refer to the relevant descriptions of Schemes 1 to 6 below. For the sake of brevity, they will not be described in detail here.

[0044] The aforementioned linear lasers typically diverge at a large angle in one direction and at a smaller angle in another direction; for example, see [reference needed]. Figure 3 A linear laser can have a vertical divergence angle of 20–60 degrees and a horizontal divergence angle of 0.1–2 degrees. For example, a linear laser can have a horizontal divergence angle of 60–120 degrees and a vertical divergence angle of 0.1–2 degrees.

[0045] The perforated mirror 230 is used to reflect the laser echo of a linear laser.

[0046] The aforementioned perforated reflector 230 is positioned such that the hole of the perforated reflector 230 is located at the convergence point of the laser beam, meaning that the converged laser beam can pass through the hole of the perforated reflector 230.

[0047] The receiving unit 240 is used to receive laser echoes from the perforated mirror 230.

[0048] Optionally, the response area of ​​the receiving unit 240 to the laser echo can be a linear area to facilitate the reception of linear laser echoes. Of course, the response area can also be a surface area, and this embodiment does not specifically limit this.

[0049] In this embodiment, the specific structure of the beam shaping unit 220 is not limited. The specific structure of the beam shaping unit 220 differs depending on whether there is a single transmitting unit or multiple transmitting units. The following description, using Schemes 1 to 3 as examples, first introduces the specific structure of the beam shaping unit 220 in the case of a single transmitting unit.

[0050] Option 1: The beam shaping unit 220 may include a collimating lens 410 and a cylindrical lens 420. See the detailed optical path diagram below. Figure 4 .

[0051] The collimating lens 410 is used to collimate the laser beam emitted by the emitting unit 210. The cylindrical lens 420 is used to converge and then diffuse the collimated laser beam to form a linear laser beam.

[0052] Option 2: The beam shaping unit 220 mentioned above may include a collimating lens 510 and a DOE 520. See the detailed optical path diagram below. Figure 5 .

[0053] The collimating lens 510 is used to collimate the laser beam emitted by the emitting unit 210. The DOE 520 is used to converge and then diffuse the collimated laser beam to form a linear laser beam.

[0054] Option 3: Since some DOEs integrate collimation functionality, the collimating lens 510 in Option 2 can be directly implemented by the DOE. That is, the beam shaping unit 220 can include a DOE 610. See the detailed optical path diagram for more information. Figure 6 .

[0055] The DOE 610 is used to collimate the laser beam emitted by the emitting unit 210, and then converge and diffuse the collimated laser beam to form the linear laser.

[0056] In order to increase the irradiance of the linear laser on the object and improve the ranging capability and accuracy of the optical system, embodiments of this application may also employ multiple emitting units to emit laser beams respectively, thereby forming multiple linear lasers.

[0057] Accordingly, in order to allow multiple linear laser beams to pass through the perforated mirror, multiple small holes can be set on a single perforated mirror. In this way, the laser beams emitted by multiple emitting units can be converged and then pass through their respective holes before being diffused to form linear laser beams. Of course, in the embodiments of this application, multiple perforated mirrors can also be directly set to converge and diffuse the laser beams emitted by multiple emitting units respectively.

[0058] Optionally, to expand the scanning range of the linear laser, the aforementioned plurality of emitting units can be arranged in a direction perpendicular to the extension direction of the linear laser line, see [reference needed]. Figure 7 Alternatively, in other embodiments, the plurality of emitting units described above can be arranged in any manner, for example, along the direction of the linear laser line.

[0059] The following describes the optical path diagrams between the multiple emitting units 810 and the beam shaping unit 220 in embodiments of this application, with reference to embodiments four to six. In embodiments four to six, in order to reduce the cost of the optical system, the same optical element can be used to converge and diffuse the laser beams emitted by the multiple emitting units 810. Optionally, in other embodiments, each linear laser beam may correspond to its own optical element.

[0060] It should be noted that in the above-described scheme of using the same element to converge and diffuse the laser beam, the same optical element or different optical elements can be used to collimate the laser beam emitted by each emitting unit 810. This application embodiment does not limit this.

[0061] Option 4 uses N collimating lenses and 1 cylindrical lens to shape the laser beams emitted by N emitting units, where N ≥ 2 and N is a positive integer.

[0062] See Figure 8 N emitting units 810 emit laser beams respectively, and N collimating lenses 820 collimate the received laser beams respectively. The collimated laser beams are first converged and then diffused by cylindrical lenses 830 to form a linear laser.

[0063] Option 5 uses M collimating lenses and 1 DOE to shape the laser beams emitted by M transmitting units, where M ≥ 2 and M is a positive integer.

[0064] See Figure 9 M emitting units 910 emit laser beams respectively, and M collimating lenses 920 collimate the received laser beams respectively. The collimated laser beams are first converged and then diffused by DOE 930 to form a linear laser.

[0065] Option 6: For a DOE that integrates collimation function, K emitting units can share 1 DOE to collimate and shape the laser beam, where K ≥ 2 and K is a positive integer.

[0066] See Figure 10 K emitting units 1010 emit laser beams respectively. The laser beams emitted by the K emitting units 1010 are collimated and shaped by a DOE 1020, so that the laser beams emitted by the K emitting units 1010 first converge and then diffuse to form a linear laser.

[0067] In this embodiment, to obtain a larger scanning area, a scanning unit can be added to the optical system to deflect the propagation direction of the linear laser. Optionally, the deflection direction of the scanning unit on the linear laser can be perpendicular to the line direction of the linear laser. For example, see... Figure 11 When the linear laser beam is perpendicular, the deflection direction can be horizontal, thus expanding the horizontal scanning area. For example, see... Figure 12 When the direction of the linear laser is horizontal, the deflection direction of the linear laser can be vertical, thus expanding the scanning area of ​​the linear laser in the vertical direction.

[0068] In some embodiments, the scanning unit may include a scanning galvanometer, a polyhedral mirror, etc. Figure 13 The image shows the effect of deflecting the diffused linear laser beam using a scanning galvanometer 1310. Figure 13 During the process, as the scanning galvanometer 1310 vibrates, the deflection direction of the linear laser changes to form a surface scan.

[0069] Figure 14 The image shows the effect of deflecting the diffused linear laser light using a polyhedral mirror 1410. Figure 14 In this process, as the polyhedral mirror 1410 rotates (e.g., clockwise as shown in the illustration), the deflection direction of the linear laser changes to form a surface scan.

[0070] To facilitate understanding of the embodiments of this application, the beam shaping unit and scanning galvanometer described in Scheme 1 above are used as examples below, combined with... Figure 15 This application describes an optical system according to embodiments of the present application. It should be understood that... Figure 15 The optical system shown can also employ any of the beam shaping units shown in Schemes 2 through 6. It should also be understood that... Figure 15 Other scanning units, such as polyhedral mirrors, can also be used in the optical system shown.

[0071] Figure 15 The optical system shown includes a transmitting unit 1510, a collimating lens 1520, a cylindrical lens 1530, a perforated mirror 1540, a scanning galvanometer 1550, and a receiving unit 1560, wherein the perforation of the perforated mirror 1540 is located at the convergence point of the laser beam. The functions of the above components in the optical system are described below.

[0072] The transmitting unit 1510 is used to emit a laser beam.

[0073] Collimating lens 1520 is used to collimate the laser beam emitted by emitting unit 1510.

[0074] Cylindrical lens 1530 is used to converge and then diffuse the straightened laser beam to form a linear laser beam. The converged laser beam diffuses after passing through the aperture of the perforated mirror 1540.

[0075] The scanning galvanometer 1550 is used to deflect the projection direction of the linear laser to form a surface scan.

[0076] The perforated mirror 1540 is used to reflect the laser echo of a linear laser.

[0077] The receiving unit 1560 is used to receive laser echoes from the perforated mirror 1540.

[0078] The above text combined Figures 2 to 15 The optical system described can be applied to laser ranging devices (e.g., lidar). Figure 16 This is a schematic diagram of a laser ranging device according to an embodiment of this application. Figure 16 The laser ranging device 1600 shown includes any of the optical systems 1610 and processing units 1620 described above.

[0079] The optical system 1610 is used to emit a linear laser toward a target and to receive the laser echo of the linear laser.

[0080] The processing unit 1620 is used to determine the distance of the target object based on the laser echo.

[0081] Optionally, the processing unit 1620 is used to compare the transmission parameters of the laser beam emitted by the transmitting unit 1510 with the reception parameters of the laser beam received by the receiving unit 1560 to determine the distance to the target.

[0082] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An optical system characterized by comprising: The optical system comprises: a transmitting unit (210) for transmitting a laser beam; a beam shaping unit (220), which comprises: a collimating lens (410) for collimating the laser beam transmitted by the transmitting unit (210); a cylindrical lens (420) or a diffractive optical element (610) for converging and then diffusing the collimated laser beam to form a linear laser beam; a hole mirror (230) with a hole located at the convergence of the light rays of the laser beam, the hole mirror (230) being used for reflecting a laser echo of the linear laser beam; a receiving unit (240) for receiving the laser echo from the hole mirror (230).

2. The optical system of claim 1, wherein The optical system comprises a plurality of the transmitting units (810), each of which transmits a laser beam to form a plurality of linear laser beams.

3. The optical system of claim 2, wherein, The plurality of linear laser beams are arranged in a direction perpendicular to the direction of the linear lines of the linear laser beams.

4. The optical system of claim 2, wherein The laser beams transmitted by the plurality of transmitting units (810) are converged and diffused by the same optical element.

5. The optical system of claim 1, wherein The optical system further comprises: a scanning unit for receiving the linear laser beams and deflecting the propagation direction of the linear laser beams to scan objects in a target range.

6. The optical system of claim 1, wherein The response area of the receiving unit (240) to the laser echo is a linear area.

7. The optical system of claim 1, wherein, The linear laser beam has a divergence angle of 20-60 degrees in the vertical direction and a divergence angle of 0.1-2 degrees in the horizontal direction; or The linear laser beam has a divergence angle of 60-120 degrees in the horizontal direction and a divergence angle of 0.1-2 degrees in the vertical direction.

8. A laser ranging device, characterized by, The optical system (1610) according to any one of claims 1-7 is used for transmitting a linear laser beam toward a target object and receiving a laser echo of the linear laser beam; a processing unit (1620) for determining the distance of the target object according to the laser echo. ​

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