Coaxial laser distance measuring device

Abstract

The embodiment of the present application discloses a coaxial laser ranging device, which includes: a laser, a focusing lens, a reflector with a hole, a first receiving lens and a detector, wherein the laser, the focusing lens, the hole portion of the reflector with a hole and the first receiving lens are located on the same optical axis; wherein the laser is used to emit laser light; the focusing lens is used to focus the laser light so as to focus the laser light through the hole portion of the reflector with a hole to the first receiving lens; the first receiving lens is used to collimate the laser light and direct the collimated laser light to a target, and receive the echo laser light reflected by the target, and then direct the echo laser light to an area other than the hole portion of the reflector with a hole; the reflector with a hole is used to transmit the received echo laser light to the detector; the detector is used to realize ranging according to the received echo laser light. The embodiment of the present application is used to realize a low-cost and high-precision coaxial laser ranging device.

Description

Technical Field

[0001] The present application relates to the technical field of laser ranging, and in particular to a coaxial laser ranging device. Background Art

[0002] The measurement accuracy of existing distance measuring instruments is restricted by the energy of the light spot. In particular, the laser power emitted by civilian lasers is strictly limited and must not cause harm to human life and health. When using lasers for long-distance distance measurement, whether it is direct observation of the light spot image measurement or detection of the round-trip time of the light wave for calculation, the higher the light spot energy density and total energy, the more beneficial it is for precise distance measurement. The coaxial laser rangefinder has the characteristics of unified global coordinates. Compared with the non-coaxial design, it simplifies the coordinate calibration steps, reduces the calibration error, and improves the measurement accuracy. According to the Rahe invariant of basic optical theory, for a certain laser, the smaller the width of the collimated light beam, the larger the divergence angle, and the faster the energy density decreases during the light spot transmission; the higher the collimation of the laser beam, the wider the output beam. Using a laser transceiver system with a hole reflector, the smaller the hole, the larger the echo energy receiving area, and the higher the energy utilization rate. However, because the divergence angle increases and the beam energy density decreases, the two contradict each other and it is difficult to achieve long-distance measurement. Therefore, due to the serious energy loss defect of the traditional coaxial design, most detection devices including laser ranging use non-coaxial design. Non-coaxial design requires unifying multiple local coordinates into global coordinates, and the coordinate calibration is complicated. It is difficult to reach the millimeter level in long-distance (hundred-meter level) ranging. The hardware (such as optical system) and software (such as coordinate calibration, conversion and compensation algorithms) of a few solutions (such as total stations) are very complicated, making the equipment that meets the measurement accuracy requirements expensive. Therefore, how to improve the realization of low-cost and high-precision coaxial laser ranging devices needs to be solved urgently. Summary of the invention

[0003] The embodiment of the present application provides a coaxial laser ranging device, which can realize a low-cost and high-precision coaxial laser ranging device.

[0004] The embodiment of the present application provides a coaxial laser ranging device, which comprises: a laser, a focusing lens, a reflector with a hole, a first receiving lens and a detector, wherein the laser, the focusing lens, the hole portion of the reflector with a hole and the first receiving lens are located on the same optical axis; wherein,

[0005] The laser is used to emit laser light;

[0006] The focusing lens is used to focus the laser so as to focus the laser onto the first receiving lens through the hole of the perforated reflector;

[0007] The first receiving lens is used to collimate the laser, direct the collimated laser toward a target, receive the echo laser reflected by the target, and direct the echo laser toward an area of ​​the perforated reflector other than the hole;

[0008] The perforated reflector is used to transmit the received echo laser to the detector;

[0009] The detector is used to measure the distance according to the received echo laser.

[0010] The implementation of the embodiments of the present application has the following beneficial effects:

[0011] It can be seen that the coaxial laser ranging device described in the embodiment of the present application includes: a laser, a focusing lens, a reflector with a hole, a first receiving lens and a detector, and the laser, the focusing lens, the hole portion of the reflector with a hole and the first receiving lens are located on the same optical axis; wherein the laser is used to emit laser light; the focusing lens is used to focus the laser light so as to focus the laser light through the hole portion of the reflector with a hole to the first receiving lens; the first receiving lens is used to collimate the laser light and direct the collimated laser light to the target, and receive the echo laser light reflected by the target, and then direct the echo laser light to the area of ​​the reflector with a hole except the hole portion; the reflector with a hole is used to transmit the received echo laser light to the detector; the detector is used to realize ranging according to the received echo laser light, so as to realize a low-cost and high-precision coaxial laser ranging device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 It is a structural schematic diagram of a coaxial laser ranging device provided in an embodiment of the present application;

[0014] Figure 2 is another structural schematic diagram of a coaxial laser ranging device provided in an embodiment of the present application;

[0015] Figure 3 It is a structural schematic diagram of another coaxial laser ranging device provided in an embodiment of the present application;

[0016] Figure 4 This is another structural schematic diagram of a coaxial laser ranging device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0017] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but in a possible example also includes steps or units that are not listed, or in a possible example also includes other steps or units inherent to these processes, methods, products or devices.

[0018] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0019] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] In the related technologies, in the fields of large-scale building deformation measurement and autonomous driving environment perception, such as deformation and settlement of tunnels, bridges and buildings, and autonomous driving safe path planning, the measurement accuracy requirements of ranging devices are getting higher and higher. Tunnel deformation refers to the horizontal and vertical displacement of its structure. In the process of tunnel operation, deformation is often one of the main reasons for tunnel cracking and structural failure. When the deformation exceeds the normal range, it directly affects the structural characteristics of the tunnel, and even the damage of the tunnel, seriously threatening the safety of train operation. When the deformation of large-scale objects such as bridges and aircraft exceeds the normal range, it will also cause catastrophic consequences. When detecting, identifying and tracking targets, autonomous driving environment perception equipment needs to build digital models for the number, position and state of moving and stationary targets, and make accurate judgments on the behavior of moving targets to plan safe routes. At present, the research and application hotspot of ranging devices is laser ranging. Laser ranging systems are divided into coaxial ranging systems and non-coaxial ranging systems. The laser emission and receiving optical paths of the coaxial ranging system are coaxial, and the laser emission optical paths of the non-coaxial ranging system are not coaxial. Theoretically, the coaxial ranging system has better ranging performance than the non-coaxial system because there is no step to unify multiple local coordinates into global coordinates. However, in practical applications, except for a few expensive total stations, the coaxial design has serious energy loss problems and is rarely used in long-distance measurements. It is difficult to improve the ranging accuracy of non-coaxial system ranging solutions. Developing a coaxial ranging system with high energy utilization is very meaningful to break the current bottleneck of ranging accuracy.

[0021] Therefore, the present application provides a coaxial laser ranging device, which comprises: a laser, a focusing lens, a reflector with a hole, a first receiving lens and a detector, wherein the laser, the focusing lens, the hole portion of the reflector with a hole and the first receiving lens are located on the same optical axis; wherein,

[0022] The laser is used to emit laser light;

[0023] The focusing lens is used to focus the laser so as to focus the laser onto the first receiving lens through the hole of the perforated reflector;

[0024] The first receiving lens is used to collimate the laser, direct the collimated laser toward a target, receive the echo laser reflected by the target, and direct the echo laser toward an area of ​​the perforated reflector other than the hole;

[0025] The perforated reflector is used to transmit the received echo laser to the detector;

[0026] The detector is used to measure the distance according to the received echo laser.

[0027] The coaxial laser ranging device in the embodiment of the present application does not require a complex structure, expensive components, or software system, and therefore can reduce the cost of the coaxial laser ranging device. In addition, due to its low loss, it can achieve a high energy utilization rate of the coaxial laser ranging device, which helps to ensure a higher ranging accuracy.

[0028] See also Figure 1 , Figure 1 is a schematic diagram of the structure of a coaxial laser ranging device provided in an embodiment of the present application, such as Figure 1 As shown, the coaxial laser ranging device may include: a laser, a focusing lens, a reflector with a hole, a first receiving lens and a detector, wherein the laser, the focusing lens, the hole portion of the reflector with a hole and the first receiving lens are located on the same optical axis; wherein,

[0029] The laser is used to emit laser light;

[0030] The focusing lens is used to focus the laser so as to focus the laser onto the first receiving lens through the hole of the perforated reflector;

[0031] The first receiving lens is used to collimate the laser and direct the collimated laser toward a target, receive the echo laser reflected by the target, and direct the echo laser toward an area of ​​the perforated reflector other than the hole;

[0032] The perforated reflector is used to transmit the received echo laser to the detector;

[0033] The detector is used to measure the distance according to the received echo laser.

[0034] In a specific implementation, the detector can receive the echo laser from the reflector with a hole through the aperture. The aperture refers to an entity that limits the light beam in the optical system.

[0035] In the embodiment of the present application, the focusing lens may also include an equivalent focusing lens or a non-equivalent focusing lens.

[0036] The first receiving lens may include a collimating lens or an equivalent collimating lens.

[0037] The size of the aperture of the reflector with holes is determined by the spot size of the focusing hole. The smaller the aperture, the smaller the light leakage loss, that is, the higher the total energy of the received light. For example, when measuring the aperture size, when the spot energy is 100%, the aperture size is: 0.32mm (H) × 0.31mm (V); when the spot energy is 95%, the aperture size is 81μm (H) × 77μm (V), etc., which is not limited here. Among them, H represents horizontal and V represents vertical.

[0038] The reflector with a hole may include one reflector or two reflectors. For example, the emission angle of the reflector with a hole may be 45°.

[0039] Among them, the coaxial laser ranging device forms a laser emission optical system through the optical path coordination between various components. In this laser emission optical system, the laser emitted by the laser is collimated by a focusing lens (or an equivalent focusing lens) and a first receiving lens. The focusing lens converges the light beam from the laser at the center of the hole of the perforated reflector (or a nearby position along the optical axis), and this position is also the object focus of the first receiving lens. The converged light spot continues to propagate and is highly collimated by the first receiving lens before being emitted. This design solves the constraints of the divergence angle and the diameter of the emitted light spot on the hole size in the coaxial design. Because the laser emission surface after collimation is on the last lens surface, the diameter of the emitted light spot has no effect on the inside of the system, and the pinhole size only needs to meet the passing of the focusing light spot, so as to maximize the collimation effect. In the laser receiving optical system, the first receiving lens and the collimating lens of the laser emission system are the same lens, but the parts used are different, that is, the first receiving lens has the functions of collimation and receiving lasers.

[0040] In an embodiment of the present application, a coaxial laser rangefinder may include: a laser, a focusing lens, a reflector with a hole, a collimating lens, a receiving lens and a detector. These components are fixedly installed to form a measurement system, and the collimating lens and the receiving lens can both be the first receiving lens. The laser can be a pulsed laser, which can be used as a light source for laser ranging. The laser, the focusing lens, the reflector with a hole and the collimating lens together constitute a laser emission system for high-energy and highly collimated outgoing lasers. The receiving lens, the reflector with a hole, the receiving lens and the detector constitute a laser receiving system for obtaining high-energy received signals; all components are fixedly installed according to the coaxial optical path, and are calibrated and calibrated before installation, and the relative installation relationship does not change during operation.

[0041] Optionally, the first receiving lens includes an outer ring area and an inner ring area;

[0042] The inner ring area is used for laser collimation, and the outer ring area is used for receiving echo laser.

[0043] Among them, in the embodiment of the present application, the inner ring area is used for laser collimation, that is, the laser is directly directed to the target, and the outer ring area is used for receiving the echo laser, that is, transmitting the echo laser to the receiving reflector.

[0044] Optionally, the focal length of the outer ring area is different from that of the inner ring area.

[0045] Among them, the focal lengths of the outer ring area and the inner ring area are different to achieve different functions of the two areas.

[0046] Optionally, the first receiving lens is a spliced ​​lens; the spliced ​​lens is formed by splicing a lens where the outer ring area is located and a lens where the inner ring area is located.

[0047] In the specific implementation, Figure 2 As shown, the first receiving lens can be a spliced ​​lens (or a mosaic structure), which can be divided into an inner ring area (U area) and an outer ring area (E area). The inner ring area is used for laser collimation, and the outer ring area is used for laser reception. The focal lengths of the inner ring area and the outer ring area are different. Most of the echo light beams pass through the outer ring and are incident on the reflecting surface of the perforated reflector. After reflection, they enter the detector, and the energy loss problem caused by light leakage from the small holes is solved. In addition, a small part of the echo light beam passes through the inner ring and is incident on the reflecting surface of the perforated reflector. At this time, it is a thin light beam. After reflection, it enters the detector, reducing light leakage loss.

[0048] In a specific implementation, the light is highly collimated along the emission optical path and finally passes through the first receiving lens. Figure 2 The echo laser reflected by the target can be divided into two parts for reception. Most of it is received by the first receiving lens in the E area and its subsequent optical path, and a small amount is received by the first receiving lens as shown in the figure. Figure 2 The U area shown in and its subsequent optical path reception.

[0049] Optionally, the first receiving lens includes a single lens or a lens combination consisting of at least two lenses.

[0050] In a specific implementation, the first receiving lens includes a single lens or a lens combination consisting of at least two lenses, and the first receiving lens is used to realize the laser collimation and laser receiving functions.

[0051] Optionally, a difference between a first size of a hole portion of the reflector with a hole and a size of a focusing spot of the focusing lens is within a preset range.

[0052] The preset range can be preset, or the system defaults that the lower limit of the preset range is greater than 0. For example, the preset range can be 0 to 0.2 mm. The first size of the hole portion of the reflector with a hole can be slightly larger than the size of the focused light spot, that is, the hole portion of the reflector with a hole can just accommodate the focused light spot of the focusing lens, and no diffraction phenomenon will occur. Because the outgoing light path adopts the design of focusing through-hole, the hole size can be larger than the focused light spot, and the small hole size further reduces the loss of echo energy.

[0053] Optionally, in the aspect of achieving distance measurement according to the received echo laser, the detector is specifically used for:

[0054] Distance measurement is achieved based on the received echo laser using a pulse method or a phase method.

[0055] In a specific implementation, ranging can be achieved through echo laser, or proximity detection. Specifically, ranging can be achieved based on the received echo laser using a pulse method or a phase method. Of course, ranging can also be achieved based on the received echo laser using other methods, which are not limited here.

[0056] Optionally, the laser includes a frequency modulated laser or a continuous laser.

[0057] In a specific implementation, the laser may be any device having a laser emission function, for example, the laser includes a frequency modulated laser or a continuous laser.

[0058] Optionally, the coaxial laser ranging device further includes a second receiving lens;

[0059] The second receiving lens is used to receive the echo laser reflected by the perforated reflector and converge the echo laser to the detector.

[0060] In the specific implementation, Figure 3 As shown, the second receiving lens can be used to receive the echo laser reflected by the perforated reflector and collimate the echo laser to the detector.

[0061] Of course, the echo laser reflected by the perforated reflector may first pass through the aperture and then reach the second receiving lens, where the echo laser is received by the second receiving lens and then collimated to the detector.

[0062] Optionally, the second receiving lens includes a single lens or a lens combination consisting of at least two lenses.

[0063] The second receiving lens includes a single lens or a lens combination consisting of at least two lenses, and the collimation function can be achieved through the second receiving lens.

[0064] In a specific implementation, the embodiment of the present application provides a coaxial laser ranging device with high energy utilization. The laser emission energy is close to the laser light emission energy; the emitted laser is highly collimated, and the energy density of the light wave propagating in the air decreases slowly; the loss of received light due to the small hole light leakage problem is negligible (less than 2%). The energy utilization of the laser emission system and the receiving system can be greatly improved, the coaxial ranging system can be put into practical use, and the accuracy bottleneck of the non-coaxial ranging structure can be broken, and the ranging performance of the ranging system can be improved.

[0065] In the embodiment of the present application, the focusing lens may be a focusing lens group, the first receiving lens may be a collimating lens group, and the second receiving lens may also be a collimating lens group, wherein the focusing lens group or the collimating lens group may be a zoom lens group, that is, fine adjustment is made along the optical axis direction to adjust the divergence and convergence of the light beam. For example, the light spot can be focused on the target surface (target), and the energy density of the outgoing light beam can be adjusted.

[0066] In the specific implementation, in the embodiment of the present application, Figure 4 As shown, the coaxial laser ranging device in the embodiment of the present application may include a laser emission system, which may include: a laser (which may contain a collimation system itself), a focusing lens group (at least one focusing lens), a perforated reflector, and a collimating lens group (at least one collimating lens). The laser is focused on the small hole (or near the small hole) of the perforated reflector and then incident on the collimating lens group, and then emitted after collimation.

[0067] In the embodiment of the present application, the optical axes of the laser emitting system and the laser receiving system are coaxial, which can achieve the unification of the coordinate system. The coordinate relationship between the two only needs to be calculated along a single coordinate axis, thereby simplifying the subsequent ranging operation and improving the ranging efficiency.

[0068] Furthermore, in the embodiment of the present application, the coaxial laser ranging device in the embodiment of the present application may include a laser receiving system, which may include: a first receiving mirror group (at least one receiving lens), a reflector with a hole, a second receiving lens and a detector. The first receiving mirror group can be divided into two parts, an internal part and an external part. The internal structure is a collimating mirror group of the laser emission system; the external structure focuses most of the received light on the receiving surface of the detector, and the internal structure injects a small amount of energy of the received light beam onto the detector surface.

[0069] In a specific implementation, the laser emission optical path and the laser receiving optical path in the coaxial laser ranging device are coaxial.

[0070] The coaxial laser ranging device in the embodiment of the present application adopts a coaxial split-field-of-view transceiver scheme. In the laser emitting optical system, the laser emitted by the laser is collimated by a focusing lens (or an equivalent focusing lens) and a collimating lens (or an equivalent collimating lens). The focusing lens converges the light beam from the laser at the center of the hole of the perforated reflector (or a nearby position along the optical axis), and this position is also the object focus of the collimating lens. The converged light spot continues to propagate and is emitted after being highly collimated by the collimating lens. This design solves the constraints of the divergence angle and the diameter of the emitted light spot on the hole size in the coaxial design. Because the laser emission surface after collimation is on the last lens surface, the diameter of the emitted light spot has no effect on the internal system, and the pinhole size only needs to meet the passing of the focusing light spot, and the collimation effect is pursued to the maximum extent. In the laser receiving optical system, the first receiving lens and the collimating lens of the laser emitting system are the same lens, and the parts used are different. The lens is a spliced ​​lens (or mosaic structure), which is divided into an inner ring and an outer ring. The inner ring is used for laser collimation, and the outer ring is used for receiving. The two have different focal lengths. Most of the echo light beams pass through the outer ring and are incident on the reflective surface of the reflector with holes. After reflection, they enter the detector, and the energy loss problem caused by light leakage from the small holes is solved. In addition, a small part of the echo light beam passes through the inner ring and is incident on the reflective surface of the reflector with holes. At this time, it is a thin beam. After reflection, it enters the detector, reducing light leakage loss. Because the output light path adopts the design of focusing through holes, the small hole size can be larger than the focusing spot, which can avoid diffraction. The small hole size further reduces the loss of echo energy.

[0071] Furthermore, since there is no need for complex structures, expensive components, or software systems, the cost of the coaxial laser ranging device can be reduced. In addition, since the loss is small, an axis laser ranging device with high energy utilization can be realized, which helps to ensure higher ranging accuracy.

[0072] The above is an implementation method of the embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the embodiment of the present application. These improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A coaxial laser ranging device, characterized in that: The coaxial laser distance measuring device comprises: a laser, a focusing lens, a reflector with a hole, a first receiving lens and a detector, wherein the laser, the focusing lens, the hole of the reflector with a hole and the first receiving lens are located on the same optical axis; wherein, The laser is used to emit laser light; The focusing lens is used to focus the laser so as to focus the laser onto the first receiving lens through the hole of the perforated reflector; The first receiving lens is used to collimate the laser and direct the collimated laser toward a target, receive the echo laser reflected by the target, and direct the echo laser toward an area of ​​the perforated reflector other than the hole; The perforated reflector is used to transmit the received echo laser to the detector; The detector is used to measure the distance according to the received echo laser; Wherein, the coaxial laser ranging device further comprises a second receiving lens; The second receiving lens is used to receive the echo laser reflected by the perforated reflector and converge the echo laser to the detector; Wherein, the first receiving lens includes an outer ring area and an inner ring area; The inner ring area is used for laser collimation, and the outer ring area is used for receiving echo laser; Wherein, the focal length of the outer ring area is different from that of the inner ring area; Wherein, the first receiving lens is a spliced ​​lens; the spliced ​​lens is formed by splicing the lens where the outer ring area is located and the lens where the inner ring area is located; Wherein, the first receiving lens includes a single lens or a lens combination consisting of at least two lenses.

2. The coaxial laser ranging device according to claim 1, characterized in that: The second receiving lens includes a single lens or a lens combination consisting of at least two lenses.

3. The coaxial laser ranging device according to claim 1 or 2, characterized in that: The difference between the first size of the hole portion of the hole reflector and the size of the focusing spot of the focusing lens is within a preset range.

4. The coaxial laser ranging device according to claim 1 or 2, characterized in that: In the aspect of achieving distance measurement according to the received echo laser, the detector is specifically used for: Distance measurement is achieved based on the received echo laser using a pulse method or a phase method.

5. The coaxial laser ranging device according to claim 1 or 2, characterized in that: The laser includes a frequency modulated laser or a continuous laser.

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