A laser beam wide-range pointing angle calibration device

Abstract

This invention discloses a wide-field pointing angle calibration device for laser beams, including an optical measurement component and a multi-dimensional motion adjustment mechanism. The multi-dimensional motion adjustment mechanism includes a drive mechanism and a mounting platform. The drive mechanism drives the mounting platform to move towards the desired orientation. The optical measurement component is fixed on the mounting platform, and the drive mechanism drives the optical measurement component to move through the mounting platform, thereby adjusting the azimuth pointing of the optical measurement component so that it can receive laser beams of different pointing angles. The outputs of the drive mechanism and the optical measurement component are connected to a host computer. This invention can provide synchronous calibration of wide-field pointing angles for multi-beam laser wind measuring radar, improving calibration efficiency.

Description

Technical Field

[0001] This utility model relates to laser beam pointing angle calibration, specifically to a laser beam wide-range pointing angle calibration device, belonging to the field of laser wind radar technology. Background Technology

[0002] Atmospheric wind field measurement is a crucial technological foundation in meteorology and aerodynamics. Multibeam laser wind radar, through a multi-angle collaborative detection mechanism, can achieve precise reconstruction of three-dimensional vector wind fields: it employs a spatially discrete laser beam array (such as...) Figure 1 As shown, radial wind speed components are obtained (typically with an inclination angle ≥20°), and three-dimensional wind field parameters are calculated using a vector synthesis algorithm based on a preset geometric configuration. This technology has significant engineering value in fields such as wind farm optimization, meteorological disaster early warning, and aviation safety monitoring.

[0003] The core limiting factor for the performance of multi-beam laser wind radar systems lies in the calibration accuracy of the laser beam pointing angle, which is exponentially positively correlated with the wind field reconstruction error. The pointing angle includes both azimuth and elevation angles. The elevation angle is the angle between the beam and the Z-axis; the azimuth angle is the angle between the beam's projection line in the XOY plane and the X-axis. Theoretical research indicates that achieving centimeter-level wind measurement accuracy requires establishing a sub-milliradian calibration system with a pointing angle error ≤0.5 mrad, posing a significant challenge to existing calibration techniques.

[0004] Traditional manual target marking methods have significant technical limitations: reliance on visual positioning leads to substantial systematic errors (>10 mrad), and the operation process is complex and has poor repeatability. Furthermore, this method is primarily applicable to visible light beams; infrared measurements require secondary positioning using a laser observation card, introducing additional positioning errors.

[0005] While precision measurement technology based on CCD imaging can improve calibration accuracy to the level of ±0.1mrad (by calculating the incident angle through the sub-pixel offset between the laser beam imaging spot and the CCD reference), it is limited by an effective field of view of ±2°, making it difficult to meet the engineering requirements for synchronous calibration of the pointing angle of multi-beam systems with a wide distribution of ≥20°. Utility Model Content

[0006] To address the limitation of field of view in existing CCD imaging measurement technology, the purpose of this invention is to provide a laser beam wide-range pointing angle calibration device. This invention can provide synchronous calibration of a wide-range pointing angle for multi-beam laser wind radar, while improving calibration efficiency.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0008] A wide-range laser beam pointing angle calibration device includes an optical measurement component for calculating the incident angle of the laser beam entering it, i.e., the relative pointing angle. The device also includes a multi-dimensional motion adjustment mechanism and a host computer. The multi-dimensional motion adjustment mechanism includes a drive mechanism and a mounting platform. The drive mechanism is connected to the mounting platform to drive the mounting platform to move towards the desired pose. The optical measurement component is fixed on the mounting platform, and the drive mechanism drives the optical measurement component to move through the mounting platform, thereby adjusting the orientation of the optical measurement component so that it can receive laser beams of different pointing angles. The outputs of the drive mechanism and the optical measurement component are connected to the host computer.

[0009] Furthermore, the optical measurement assembly includes a laser, a beam splitter, a collimating objective lens, an image acquisition module, and an image processing module.

[0010] The laser is used to emit marking laser light;

[0011] The beam splitter is used to reflect the marking laser and guide it to the collimating lens, which then transmits the laser beam received by the collimating lens to the image acquisition module.

[0012] Collimating objective lenses are used to collimate the marking laser into a parallel beam and emit it, while simultaneously receiving the laser beam to be tested or the reflected marking laser and focusing it into an imaging spot;

[0013] Image acquisition module: used to capture the imaging spot and convert it into a digital image signal;

[0014] Image processing module: used to receive the digital image signal to analyze the imaging spot image, locate the center position of the imaging spot, and calculate the incident angle of the laser beam based on the offset between the center position of the imaging spot and the center of the photosensitive surface of the image acquisition module.

[0015] Furthermore, a reticle is provided between the laser and the beam splitter prism, which is used to provide reference marks for identifying the laser.

[0016] Furthermore, the reticle has a cross-shaped cutout structure, so that the marking laser emitted by the laser becomes a cross-shaped beam after passing through the reticle and is directed towards the beam splitter.

[0017] Furthermore, the multi-dimensional motion adjustment mechanism includes an X-axis slide base, a Y-axis slide base, an azimuth turntable base, and a pitch turntable base;

[0018] An X-axis slide and an X-axis drive motor are mounted on the X-axis slide base. The X-axis drive motor is connected to the X-axis slide and is used to drive the X-axis slide to move along the X-axis guide rail on the X-axis slide base.

[0019] The Y-axis slide base is fixedly installed on the X-axis slide. A Y-axis slide and a Y-axis drive motor are installed on the Y-axis slide base. The Y-axis drive motor is connected to the Y-axis slide and is used to drive the Y-axis slide to translate along the Y-axis guide rail on the Y-axis slide base.

[0020] The azimuth turntable base is fixedly installed on the Y-axis slide. An azimuth turntable and an azimuth drive motor are installed on the azimuth turntable base via an azimuth axis. The azimuth drive motor is connected to the azimuth turntable and is used to drive the azimuth turntable to rotate around the azimuth axis. The azimuth axis is parallel to the Z-axis direction.

[0021] The pitch turntable base is fixedly installed on the azimuth turntable. The pitch turntable and the pitch drive motor are installed on the pitch turntable base via the pitch axis. The pitch drive motor is connected to the pitch turntable and is used to drive the pitch turntable to rotate around the pitch axis. The pitch axis is parallel to the XOY plane.

[0022] The optical measurement component is fixed on the pitch turntable; the pitch turntable is the mounting platform for the optical measurement component; the pitch drive motor, azimuth drive motor, Y-axis drive motor and X-axis drive motor together constitute the drive mechanism.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. This invention adjusts the orientation of the optical measurement component through a multi-dimensional motion adjustment mechanism to receive the laser beam under test, thereby expanding the field of view of the optical measurement component. The optical measurement component then measures the incident angle of the laser beam under test, i.e., the relative pointing angle. Finally, the host computer performs a secondary calculation on the relative pointing angle based on the parameters of the drive mechanism (if the drive mechanism is a drive motor, this parameter is the motor code feedback value) to obtain the actual pointing angle of the laser beam under test. This invention proposes a composite calibration approach of multi-dimensional turntable-assisted optical measurement, breaking through the field-of-view limitations of traditional methods and achieving wide-range pointing angle calibration. This invention achieves omnidirectional coverage of the beam pointing angle (±60°×360°) through opto-mechanical-electronic collaborative calibration technology.

[0025] 2. This utility model adopts a closed-loop feedback mechanism for the centroid of the marking laser spot to achieve online calibration of the reference axis, improve calibration efficiency, and increase the system installation alignment efficiency by more than 80%.

[0026] 3. This utility model is the first to create a common baseline (i.e., in the same reference axis coordinate system) multi-channel calibration architecture, which has the function of synchronous calibration of multi-beam (≥3 channels) pointing angle of lidar, and the overall calibration efficiency is more than 5 times higher than that of traditional methods.

[0027] This invention is applicable to the rapid calibration of the pointing angle of multi-beam systems, provides large field-of-view synchronous calibration for multi-beam laser wind radar, and also provides a standardized calibration solution for the mass production of equipment such as lidar and optical seekers. Attached Figure Description

[0028] Figure 1 - Schematic diagram of the spatial distribution of the laser beam array.

[0029] Figure 2 - Block diagram of the laser beam pointing angle calibration device system of this utility model.

[0030] Figure 3 - A schematic diagram of the mechanical structure of the laser beam pointing angle calibration device of this utility model.

[0031] ①-Optical measurement components; ②-Pitch turntable; ③-Azimuth turntable; ④-Y-axis slide; ⑤-X-axis slide; ⑥-Pitch drive motor; ⑦-Azimuth drive motor; ⑧-Y-axis drive motor; ⑨-X-axis drive motor; ⑩-Azimuth axis; ⑪-Pitch axis. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] The inventive concept of this utility model is as follows: the orientation of the optical measurement component is adjusted by a multi-dimensional motion adjustment mechanism so that it can receive the laser beam to be measured, thereby expanding the field of view of the optical measurement component. Then, the optical measurement component measures the incident angle of the laser beam to be measured at this time, that is, the relative pointing angle. Finally, the host computer performs a second calculation on the relative pointing angle to obtain the actual pointing angle of the laser beam to be measured.

[0034] For a detailed implementation scheme of this utility model, please refer to [link / reference]. Figure 2 The system includes an optical measurement component for calculating the incident angle of a light beam entering it; it also includes a multi-dimensional motion adjustment mechanism and a host computer; the multi-dimensional motion adjustment mechanism includes a drive mechanism and a mounting platform, the drive mechanism being connected to the mounting platform to drive the mounting platform to move toward the required pose; the optical measurement component is fixed on the mounting platform, and the drive mechanism drives the optical measurement component to move through the mounting platform so that the optical measurement component can receive laser beams to be measured at different pointing angles; the outputs of the drive mechanism and the optical measurement component are connected to the host computer, which is used to perform a secondary calculation on the relative pointing angle calculated by the optical measurement component based on the output data of the drive mechanism, so as to achieve the final calibration of the pointing angle.

[0035] The optical measurement component in this device is equivalent to the precision measurement technology based on CCD imaging mentioned in the background art. Although it can achieve high-precision pointing angle calibration, it is limited by an effective field of view of ±2°, making it difficult to meet the engineering requirements for synchronous pointing angle calibration of multi-beam systems with a wide distribution of ≥20°. Therefore, this device uses the optical measurement component as the core sensing unit, with a multi-dimensional motion adjustment mechanism working in conjunction with the optical measurement component. The multi-dimensional motion adjustment mechanism adjusts the pose of the optical measurement component to align with the laser beams to be measured, ensuring that all laser beams can enter the field of view of the optical measurement component, thereby expanding the field of view of the optical measurement component. Based on the driving amount of the driving mechanism, a secondary calculation is performed on the relative pointing angle obtained by the optical measurement component after pose adjustment to obtain the actual pointing angle of the laser beams to be measured, thus achieving wide-field-of-view multi-beam laser pointing angle calibration.

[0036] See also Figure 2 The optical measurement assembly includes a laser, a beam splitter, a collimating objective lens, an image acquisition module, and an image processing module. The functions of each component of the optical measurement assembly are as follows:

[0037] The laser is used to emit marking laser light;

[0038] Beam splitter: 1. Used to reflect the marking laser and guide it to the collimating objective; 2. Transmits the laser beam to be measured or the reflected marking laser beam received by the collimating objective to the image acquisition module;

[0039] Collimating objective lens: 1. Used to collimate the marking laser into a parallel beam and emit it; 2. Receive the laser beam to be measured or the reflected marking laser and converge it into an imaging spot;

[0040] Image acquisition module: includes an image sensor based on CCD / CMOS / PSD, used to capture the imaging spot and convert it into a digital image signal;

[0041] Image processing module: used to receive the digital image signal to analyze the imaging spot image, locate the center position of the imaging spot, and calculate the incident angle of the laser beam based on the offset between the center position of the imaging spot and the center of the photosensitive surface of the image acquisition module.

[0042] Furthermore, this device also includes a reticle between the laser and the beam splitter prism, which serves to provide reference marks for identifying the laser beam. In this embodiment, the reticle is a cross-shaped reticle with a cross-shaped perforation structure, so that the identifying laser beam emitted by the laser becomes a cross-shaped beam after passing through the reticle and is directed towards the beam splitter prism.

[0043] In this embodiment, the multi-dimensional motion adjustment mechanism includes an X-axis slide base, a Y-axis slide base, an azimuth turntable base, and a pitch turntable base; for details, please refer to... Figure 3 . Figure 3 This also constitutes a schematic diagram of the mechanical structure of the laser beam pointing angle calibration device of this utility model, which can be applied to the laser beam pointing angle calibration of multi-beam laser wind measuring radar.

[0044] An X-axis slide ⑤ and an X-axis drive motor ⑨ are mounted on the X-axis slide base. The X-axis drive motor ⑨ is connected to the X-axis slide ⑤ and is used to drive the X-axis slide ⑤ to move along the X-axis direction guide rail on the X-axis slide base.

[0045] The Y-axis slide base is fixedly installed on the X-axis slide ⑤. The Y-axis slide ④ and the Y-axis drive motor ⑧ are installed on the Y-axis slide base. The Y-axis drive motor ⑧ is connected to the Y-axis slide ④ and is used to drive the Y-axis slide ④ to translate along the Y-axis direction guide rail on the Y-axis slide base.

[0046] The azimuth turntable base is fixedly installed on the Y-axis slide table ④. An azimuth turntable ③ and an azimuth drive motor ⑦ are installed on the azimuth turntable base via an azimuth axis ⑩. The azimuth drive motor ⑦ is connected to the azimuth turntable ③ and is used to drive the azimuth turntable ③ to rotate around the azimuth axis ⑩. The azimuth axis ⑩ is parallel to the Z-axis direction.

[0047] The pitch turntable base is fixedly installed on the azimuth turntable ③. The pitch turntable ② and the pitch drive motor ⑥ are installed on the pitch turntable base via the pitch axis ⑪. The pitch drive motor ⑥ is connected to the pitch turntable ② and is used to drive the pitch turntable ② to rotate around the pitch axis ⑪. The pitch axis ⑪ is parallel to the XOY plane.

[0048] The optical measurement component ① is fixed on the pitch turntable ②; the pitch turntable ② is the mounting platform for the optical measurement component; the pitch drive motor ⑥, azimuth drive motor ⑦, Y-axis drive motor ⑧ and X-axis drive motor ⑨ together constitute the drive mechanism.

[0049] This device consists of a pitch turntable, an azimuth turntable, and an X / Y axis slide, forming a four-degree-of-freedom motion adjustment mechanism. Through precision bearings and drive motors, it achieves multi-dimensional high-precision coordinated adjustment of the optical measurement components in pitch rotation, azimuth rotation, vertical lifting, and planar displacement. This enables fine adjustment of the large-angle pose of the optical measurement components, ensuring that all laser beams to be measured can be acquired by the image acquisition module.

[0050] All motors in this device are stepper motors or servo motors, used to drive the corresponding turntable and slide table movement, and can provide real-time feedback of the motor code value of the current working status.

[0051] Figure 2 Connectors 1 / 2 / 3 / 4 are used to connect different motors to the pitch turntable, azimuth turntable, Y-axis slide, and X-axis slide, so as to adjust the optical measurement components in the corresponding dimensions through the motors.

[0052] The calibration device of this utility model is used as follows:

[0053] 1) Orient the optical measurement components toward the optical emission window of the laser beam to be measured;

[0054] 2) Turn on the laser in the optical measurement assembly to emit a marker laser. The marker laser is projected onto the optical emission window of the laser beam under test and reflected back at a specific angle by a mirror. When the reflection angle is sufficiently small, the marker laser is reflected back into the optical measurement assembly. The image processing module can then determine whether the marker laser is perpendicularly illuminating the optical emission window. When perpendicularly illuminating, the reflected marker laser image spot is located at the center of the photosensitive surface of the image acquisition module. If not perpendicular, keep the optical emission window of the laser beam under test stationary and adjust the position of the optical measurement assembly using a multi-dimensional motion adjustment mechanism so that the marker laser, after exiting the collimating objective lens, perpendicularly illuminates the optical emission window of the laser beam under test. The host computer records the parameters corresponding to the drive mechanism in the perpendicular state and uses them as the initial parameters for the drive mechanism, then turns off the laser.

[0055] Step 2) Emits a marking laser and, with the assistance of a multi-dimensional motion adjustment mechanism, calibrates the reference axis (Z-axis) so that it coincides with the main optical path axis of the optical measurement component of this invention. After the reference axis (Z-axis) is calibrated, subsequent steps can be performed to calibrate the actual laser beam to be measured.

[0056] 3) Turn on the laser to be tested. If one or more laser beams are acquired by the image acquisition module, the relative pointing angle of the laser beams can be directly obtained by the image processing module. In this case, no secondary calculation is required, and the obtained relative pointing angle is the actual pointing angle.

[0057] 4) For the remaining laser beams not acquired by the image acquisition module, the pose of the optical measurement component is adjusted by a multi-dimensional motion adjustment mechanism, so that each of the remaining laser beams is acquired by the image acquisition module. The image processing module calculates the relative pointing angle of each remaining laser beam in this state and sends it to the host computer. Since the relative pointing angle obtained at this time is obtained under the change of the pose of the optical measurement component, it is not the actual pointing angle of the laser beam under test, and it needs to be calculated a second time. The host computer needs to record the parameters of the drive mechanism corresponding to each remaining laser beam when it is acquired by the image acquisition module and use them as parameters for the second calculation. When the drive mechanism is a drive motor, the parameters corresponding to the drive mechanism refer to the absolute position data corresponding to the coded feedback value of each drive motor when the remaining laser beam is acquired by the image acquisition module.

[0058] 5) The host computer performs secondary calculations on the corresponding relative pointing angles obtained by the image processing module based on the secondary calculation parameters corresponding to each remaining laser beam to be measured obtained in step 4), thus obtaining the actual pointing angle of each remaining laser beam to be measured. The secondary calculation process is the process of compensating for the influence of the pose change of the optical measurement component on the pointing angle. It mainly involves mathematical and geometric calculations, which are not within the scope of this utility model and will not be elaborated here.

[0059] 6) The actual pointing angle obtained from the secondary calculation in step 5) and the pointing angle obtained directly in step 3) are the calibration results of the spatial pointing angle of the laser beam under test in the reference axis coordinate system.

[0060] This invention uses an optical measurement component as the core sensing unit, and a multi-dimensional motion adjustment mechanism works in conjunction with the optical measurement component to achieve wide-field-of-view multi-beam laser pointing angle calibration through the following aspects.

[0061] 1. Multi-dimensional linkage precision adjustment mechanism: The four-degree-of-freedom motion adjustment mechanism is composed of a pitch turntable, an azimuth turntable and an X / Y axis slide table. Through precision bearings and drive motors, the optical measurement components can achieve multi-dimensional high-precision coordinated adjustment in pitch rotation, azimuth rotation, vertical lifting and lowering and planar displacement, so as to realize large-angle pose adjustment of the optical measurement components.

[0062] 2. Dynamic reference axis self-calibration: Utilizing the reflection characteristics of the marking laser mirror, the position of the reflected spot is monitored in real time by the optical measurement component, driving the multi-dimensional turntable to adjust in a closed loop until the spot returns to the center of the photosensitive surface of the image acquisition module of the optical measurement component, locking the normal reference axis of the emission window, eliminating the influence of installation errors, and improving the reliability of the calibration reference.

[0063] 3. Construction of multi-beam spatial relationship: The three-dimensional spatial pointing angles of the acquired multiple laser beams are unified to the normal reference axis coordinate system through coordinate system transformation, a three-dimensional spatial distribution model is constructed and the angle parameters between beams are generated. The angle between each laser beam and the reference axis and the relative angle between each laser beam are quantitatively displayed, thereby supporting the common baseline calibration of multi-beam lidar.

[0064] The above embodiments of this utility model are merely illustrative examples and are not intended to limit the implementation of this utility model. Those skilled in the art can make other variations and modifications based on the above description. It is impossible to exhaustively list all possible implementations here. All obvious variations or modifications derived from the technical solutions of this utility model are still within the protection scope of this utility model.

Claims

1. A laser beam wide-range pointing angle calibration device, comprising an optical measurement component, wherein the optical measurement component is used to calculate the incident angle of the laser beam entering it, i.e., the relative pointing angle, characterized in that: It also includes a multi-dimensional motion adjustment mechanism and a host computer; the multi-dimensional motion adjustment mechanism includes a drive mechanism and a mounting platform, the drive mechanism is connected to the mounting platform to drive the mounting platform to move in the required pose; the optical measurement component is fixed on the mounting platform, and the drive mechanism drives the optical measurement component to move through the mounting platform, thereby adjusting the orientation of the optical measurement component so that the optical measurement component can receive the laser beam to be measured at different pointing angles; the outputs of the drive mechanism and the optical measurement component are connected to the host computer.

2. The laser beam wide-range pointing angle calibration device according to claim 1, characterized in that: The optical measurement assembly includes a laser, a beam splitter, a collimating objective lens, an image acquisition module, and an image processing module. The laser is used to emit marking laser light; The beam splitter is used to reflect the marking laser and guide it to the collimating lens, which then transmits the laser beam received by the collimating lens to the image acquisition module. Collimating objective lenses are used to collimate the marking laser into a parallel beam and emit it, while simultaneously receiving the laser beam to be tested or the reflected marking laser and focusing it into an imaging spot; Image acquisition module: used to capture the imaging spot and convert it into a digital image signal; Image processing module: used to receive the digital image signal to analyze the imaging spot image, locate the center position of the imaging spot, and calculate the incident angle of the laser beam based on the offset between the center position of the imaging spot and the center of the photosensitive surface of the image acquisition module.

3. The laser beam wide-range pointing angle calibration device according to claim 2, characterized in that: A reticle is placed between the laser and the beam splitter; the reticle is used to provide reference marks for identifying the laser.

4. The laser beam wide-range pointing angle calibration device according to claim 3, characterized in that: The reticle has a cross-shaped cutout structure, so that the marking laser emitted by the laser becomes a cross-shaped beam after passing through the reticle and is directed towards the beam splitter.

5. A laser beam wide-range pointing angle calibration device according to claim 1, characterized in that: The multi-dimensional motion adjustment mechanism includes an X-axis slide base, a Y-axis slide base, an azimuth turntable base, and a pitch turntable base. An X-axis slide and an X-axis drive motor are mounted on the X-axis slide base. The X-axis drive motor is connected to the X-axis slide and is used to drive the X-axis slide to move along the X-axis guide rail on the X-axis slide base. The Y-axis slide base is fixedly installed on the X-axis slide. A Y-axis slide and a Y-axis drive motor are installed on the Y-axis slide base. The Y-axis drive motor is connected to the Y-axis slide and is used to drive the Y-axis slide to translate along the Y-axis guide rail on the Y-axis slide base. The azimuth turntable base is fixedly installed on the Y-axis slide. An azimuth turntable and an azimuth drive motor are installed on the azimuth turntable base via an azimuth axis. The azimuth drive motor is connected to the azimuth turntable and is used to drive the azimuth turntable to rotate around the azimuth axis. The azimuth axis is parallel to the Z-axis direction. The pitch turntable base is fixedly installed on the azimuth turntable. The pitch turntable and the pitch drive motor are installed on the pitch turntable base via the pitch axis. The pitch drive motor is connected to the pitch turntable and is used to drive the pitch turntable to rotate around the pitch axis. The pitch axis is parallel to the XOY plane. The optical measurement component is fixed on the pitch turntable; the pitch turntable is the mounting platform for the optical measurement component; the pitch drive motor, azimuth drive motor, Y-axis drive motor and X-axis drive motor together constitute the drive mechanism.

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