A laser ranging device and method based on a double-expansion lens

Abstract

The application discloses a kind of laser ranging device and method based on double beam expander, it is related to laser ranging technical field, in device control processing component controls laser generation component to generate original laser beam;Beam management unit outputs two light beams of fixed energy proportion;Double beam expander component simultaneously integrates two beam expanders, one beam expander is in preset short distance range with preset small energy large beam divergence angle as main light beam, another beam expander is in preset long distance range with preset large energy small beam divergence angle as main light beam;Double beam expander component sends two light beams into corresponding beam expander respectively, emits to target after synchronous execution beam expansion and collimation;Receiving sensing component detects target laser echo signal and carries out photoelectric conversion, amplification shaping;Control processing component processes to be used digital signal to calculate target distance value.The application can realize the dynamic balance of short distance large coverage range and long distance high energy density, ensure the ranging performance in whole distance range.

Description

Technical Field

[0001] This application relates to the field of laser ranging technology, and in particular to a laser ranging device and method based on a dual-beam expander lens. Background Technology

[0002] In the field of laser ranging, beam expanders are key components for controlling the laser beam divergence angle. Existing technologies mainly suffer from the following problems: (1) Conflict between coverage and range: The beam divergence angle and energy of a single beam expander lens are fixed, which cannot simultaneously meet the requirements of large coverage at close range and high energy density at long range. Specifically, at close range, although a large beam divergence angle can cover a larger area, the energy density is insufficient, which affects the ranging capability; at long range, although a small beam divergence angle can ensure energy density, the coverage is limited and it is difficult to meet the requirements of large-area ranging.

[0003] (2) Poor dynamic adaptability: Traditional systems cannot dynamically adjust the beam divergence angle and energy distribution according to the target distance, resulting in ranging performance being limited by fixed parameters, making it difficult to cope with complex and ever-changing real-world application scenarios.

[0004] (3) High system complexity: If different beam expanders are switched through mechanical structure, the system size and cost will increase, and the response speed will be slow, which will not meet the real-time requirements. Summary of the Invention

[0005] The purpose of this application is to provide a laser ranging device and method based on dual beam expanders, which can achieve a dynamic balance between large coverage at close range and high energy density at long range, ensuring ranging performance across the entire range.

[0006] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a laser ranging device based on a dual beam expander lens, including a control and processing unit, a laser generation component, a beam management unit, a dual beam expander lens component, and a receiving and sensing component; The control and processing unit is used to control the laser generation component to generate the original laser beam, and to output two beams with a fixed energy ratio through the beam management unit. The dual beam expander assembly integrates two beam expanders, which correspond to two independent optical path structures. One beam expander uses a preset low-energy, large-beam divergence angle as the main beam in a preset short-range area, while the other beam expander uses a preset high-energy, small-beam divergence angle as the main beam in a preset long-range area. The dual beam expander assembly is used to send the two beams into the corresponding beam expanders, and simultaneously perform beam expansion and collimation before emitting them to the target. The receiving sensing component is used to detect the laser echo signal of the target object, and to perform photoelectric conversion, amplification and shaping on the laser echo signal of the target object to obtain a digital signal to be used and transmit it to the control processing component; the control processing component is also used to process the digital signal to be used to calculate the distance value of the target object.

[0007] Secondly, this application provides a laser ranging method based on a dual-beam expander lens, applied to the aforementioned laser ranging device based on a dual-beam expander lens, comprising: The control processing unit controls the laser generation component to generate the original laser beam, and the beam management unit outputs two beams with a fixed energy ratio. Two beams are fed into their respective beam expanders via a dual beam expander assembly, which simultaneously expands and collimates the beams before emitting them to the target. The dual beam expander assembly integrates two beam expanders, which correspond to two independent optical path structures. One beam expander uses a preset low-energy, large-beam divergence angle as the main beam within a preset short-range, while the other beam expander uses a preset high-energy, small-beam divergence angle as the main beam within a preset long-range. The laser echo signal of the target object is detected by receiving the sensing component, and the laser echo signal of the target object is photoelectrically converted, amplified and shaped to obtain the digital signal to be used. The control processing unit processes the digital signal to be used to calculate the distance value of the target object.

[0008] According to the specific embodiments provided in this application, the following technical effects are disclosed: The dual-beam expander lens assembly of this application integrates two beam expanders, each corresponding to a separate optical path structure. This independent optical path design ensures the purity and stability of the dual beams. One beam expander uses a preset low-energy, high-beam divergence angle as the main beam within a preset close-range range, while the other beam expander uses a preset high-energy, low-beam divergence angle as the main beam within a preset long-range range. Through the coordinated operation of the dual beam expanders, the adaptability and performance of the ranging system are significantly improved. Furthermore, at close range, one beam expander ensures coverage, while at long range, the other ensures energy density, ensuring ranging performance across the entire range. This achieves high-performance ranging. The integrated dual-beam expander lens design avoids complex mechanical switching mechanisms, reducing system size and cost. The device in this application has no mechanical switching structure; it achieves millisecond-level dynamic adjustment through electronic control, meeting the real-time requirements of ranging. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of a laser rangefinder based on a dual-beam expander lens in one embodiment of this application.

[0011] Figure 2 This is a structural layout diagram of the beam management unit.

[0012] Figure 3 This is a layout diagram of the dual-beam expander lens assembly. Detailed Implementation

[0013] The technical solutions of 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. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0014] This application achieves a dynamic balance between a wide coverage area at close range and a high energy density at long range by simultaneously emitting two laser beams with different divergence angles and energies, significantly improving the adaptability and performance of the ranging system.

[0015] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] In one exemplary embodiment, such as Figure 1 As shown, a laser ranging device based on a dual-beam expander lens is provided, including a control and processing unit, a laser generation component, a beam management unit, a dual-beam expander lens assembly, and a receiving and sensing component. The control and processing unit controls the laser generation component to generate a raw laser beam and outputs two beams with a fixed energy ratio through the beam management unit.

[0017] In one specific application, the laser generating component includes a driving and execution unit and a laser unit arranged sequentially.

[0018] The control processing unit is used to generate control signals and send them to the drive and execution unit according to preset instructions (which can be internally preset strategies or externally input instructions).

[0019] The drive and execution unit is used to drive the laser unit to emit a raw laser beam with a specific power and repetition frequency according to the control signal, and the raw laser beam enters the beam management unit.

[0020] Specifically, the laser unit provides a highly stable laser source that supports pulsed output; that is, as the system's light source, it provides highly stable, high-beam-quality laser output. In one application, the laser unit employs a diode-pumped solid-state laser, with an operating mode supporting nanosecond-level pulsed output to accommodate time-of-flight (ToF) ranging. Its internal structure includes a laser drive power supply and a temperature control (TEC) module to ensure long-term stability of the output wavelength and power.

[0021] The drive and execution unit outputs drive current to the laser unit according to the control signal and performs precise temperature control; that is, it receives instructions from the control processing unit, converts them into high-precision analog voltage signals, and drives the actuator. In a specific application, the functions of the drive and execution unit include the following settings: a drive circuit drives the discharge switch according to the control signal, and the drive voltage is adjusted by the current feedback signal of the diode-pumped solid-state laser to achieve stable drive current output; a temperature control circuit is used, utilizing the TEC as a device for heating and cooling, and by sampling the TEC temperature and performing PID calculations, a control pulse is issued. The direction and conduction time of the current are controlled by the control pulse, thereby achieving precise temperature control of the device.

[0022] The beam management unit is used to precisely split the received raw laser beam into two beams with a fixed energy ratio. The two processed beams enter the corresponding beam expanders (3 mrad and 1 mrad), are expanded and collimated, and then emitted toward the target.

[0023] Specifically, the beam management unit splits the laser beam into two paths, achieving synchronous emission of two beams; that is, its core function is to efficiently and accurately allocate laser energy and manage the paths of the two beams. In a specific application, the beam management unit includes a beam splitter, which, through a simple and reliable fixed beam splitter, splits the laser emitted from the laser unit into two laser beams with a fixed energy ratio. The structural layout is as follows: Figure 2 As shown.

[0024] A fixed beam splitter is used as the core beam-splitting element to achieve a fixed ratio of laser energy distribution between the dual beam expanders with minimal complexity, maximum reliability, and cost-effectiveness. Specifically, polarization beam splitting technology is employed to ensure the independence and purity of the two laser beams. The splitting ratio (transmittance and reflectivity of S-beams versus P-beams) is sensitive to the angle of incidence and requires precise installation and fixation. The advantage of using a beam splitter is its natural match with the polarized laser, resulting in high efficiency. The selection of the splitting ratio can be based on the properties of the target being measured, such as the size of the target, its range of motion, and the distance range requiring wide coverage. In this application, the splitting ratio of the beam splitter can be set to 50:1.

[0025] In one specific application, the beam management unit also includes a follow-up mirror; the follow-up mirror is positioned behind the beam splitter; before operation, the pitch and azimuth angles of the beam splitter and the follow-up mirror are precisely adjusted to ensure that the two output beams are coaxial with the optical axes of the two beam expanders, respectively.

[0026] The dual beam expander assembly integrates two beam expanders, which correspond to two independent optical path structures. One beam expander uses a preset low-energy, large-beam divergence angle as the main beam in a preset short-range area, while the other beam expander uses a preset high-energy, small-beam divergence angle as the main beam in a preset long-range area. The dual beam expander assembly is used to send the two beams into the corresponding beam expanders, and then simultaneously perform beam expansion and collimation before emitting them to the target.

[0027] Specifically, the dual beam expander assembly expands and collimates the incident laser beam to form an outgoing beam with a specific divergence angle, which is crucial for determining ranging performance. In a specific application, one beam expander has a 3 mrad beam divergence angle and 1 mJ energy, while the other has a 1 mrad beam divergence angle and ≥50 mJ energy. This application simplifies the switching mechanism by simultaneously covering the target with two beams. At close range (within 2 km), a low-energy, high-beam divergence beam is used as the main beam, significantly expanding the close-range coverage. At long range (beyond 2 km), a high-energy, low-beam divergence beam is used as the main beam, significantly improving the long-range energy density. No mechanical adjustment is required, resulting in a fast response speed. Furthermore, an independent optical path structure is used to avoid mutual interference between the two beams, ensuring signal purity.

[0028] Among them, the lens with a 3mrad beam divergence angle and 1mJ energy (wide-angle channel) adopts a Galilean beam expander structure and uses aspherical lenses to replace multiple spherical lens groups. While ensuring the 1mJ energy threshold, it strictly controls wavefront distortion to ensure beam quality (M 2 (Factor), and achieved miniaturization.

[0029] A lens with a 1 mrad beam divergence angle and ≥50 mJ energy (narrow-angle high-energy channel): The optical structure includes a sequentially arranged aspherical negative lens and a doublet objective lens group. This application employs a beam-expanding structure with more stringent aberration correction, utilizing the powerful spherical aberration correction capability of the aspherical negative lens, and combining it with a doublet objective lens for final collimation and correction of residual aberrations, effectively shortening the lens length. The structure is as follows: Figure 3 As shown. All lenses are coated with an antireflective coating with a preset high damage threshold to prevent laser damage.

[0030] The receiving sensing component is used to detect the laser echo signal of the target object, and to perform photoelectric conversion, amplification and shaping on the laser echo signal of the target object to obtain a digital signal to be used and transmit it to the control processing component; the control processing component is also used to process the digital signal to be used to calculate the distance value of the target object.

[0031] Specifically, the receiving sensing component detects laser pulse signals in real time, providing signals to the control processing unit. That is, it receives the diffusely reflected laser pulse signal from the target object, converts it into an electrical signal, and amplifies and shapes it for output. In a specific application, the receiving sensing component includes a receiving lens, a photodetector, and a receiving amplifier arranged sequentially. The receiving lens focuses the diffusely reflected laser signal from the target object as a target object laser echo signal onto the photosensitive surface of the photodetector. The photodetector converts the received target object laser echo signal into an electrical pulse signal. The receiving amplifier amplifies the electrical pulse signal and shapes it for output after reaching a preset detection threshold. The output signal is a narrow-pulse TTL signal and is marked as a ready-to-use digital signal.

[0032] To elaborate further, the photodetector is an avalanche photodiode, which consists of a signal amplification circuit, a TPG control circuit, a threshold detection circuit, a bias power supply, and a noise feedback control circuit. It is responsible for converting the laser signal returned by the target into an electrical signal, which is then amplified, shaped, and output to the control and processing unit.

[0033] The control processing unit is responsible for running the core algorithm, coordinating the work of each module, and outputting the distance value. Specifically, it adopts an ARM+FPGA architecture to achieve precise control of each module, and uses algorithms to effectively filter out noise signals, extract the real target echo signal, and then perform subsequent calculations; that is, based on the real-time control logic of FPGA and ARM, it achieves precise timing control of each module. At the software level, the control processing unit is used to: use FPGA-based, parallel time-domain signal processing technology to perform target matching on the digital signal to be used, and detect the real target echo signal; based on the real target echo signal, it uses the count value to analyze and obtain the target distance value.

[0034] In a specific application, the device is at least suitable for UAV-borne ranging platforms and vehicle-mounted ranging platforms. Taking a vehicle-mounted ranging platform as an example, if the device of this application is integrated into a vehicle, after a user triggers a ranging request, the following processing steps are performed: (1) Power on the device and initialize and self-test each module. After the device is powered on, the TEC starts and preheats the laser to a stable working state.

[0035] (2) Upon startup, the device first performs incident collimation: ensuring that the laser emitted from the laser unit is a collimated Gaussian beam and incident at a specific incident angle calibrated by the beam splitter to guarantee that the splitting ratio meets the nominal value. Then, dual-path output occurs: the beam splitter divides the laser into two paths, transmission (T) and reflection (R), which are guided to the incident ends of two beam expanders, respectively. Next, beam emission occurs: the dual beam expander assembly synchronously emits laser beams to achieve close-range large coverage or long-range high energy density ranging.

[0036] (3) The receiving lens focuses the laser echo signal diffusely reflected from the target onto the photosensitive surface of the photodetector. The photodetector converts the received laser pulse signal into an electrical pulse signal. The receiving amplifier amplifies the weak signal output by the photoelectric conversion. After reaching the detection threshold, the signal is shaped and output as a narrow pulse TTL signal.

[0037] (4) The shaped output signal is transmitted to the control processing unit. The time-domain correlation parallel signal processing technology based on FPGA is used to perform target matching by utilizing the time-domain correlation of multiple frames of data, detect the real target echo signal, and use the count value to parse the real distance value of the target to be measured.

[0038] In other practical applications, the device can be further optimized as follows: 1) Optical path optimization: Use high-transmittance optical materials to reduce energy loss. 2) Heat dissipation design: Configure a wind-cooled heat dissipation module for the high-energy laser to ensure long-term operational stability. 3) Signal processing: Integrate parallel signal processing algorithms into the control and processing components to improve the system's processing speed and enhance the detection sensitivity of the ranging system.

[0039] Based on the same inventive concept, this application also provides a method. The solution provided by this method is similar to the solution described in the above-described apparatus. Therefore, the specific limitations of one or more method embodiments provided below can be found in the limitations of the apparatus described above, and will not be repeated here.

[0040] In one exemplary embodiment, a laser ranging method based on a dual-beam expander lens is provided, applied to the aforementioned laser ranging device based on a dual-beam expander lens, the method comprising: S1 controls the laser generation component to generate the original laser beam by controlling the processing unit.

[0041] S2 outputs two beams with a fixed energy ratio through the beam management unit.

[0042] S3, the two beams are sent into the corresponding beam expanders through the dual beam expander assembly, and beam expansion and collimation are performed simultaneously before being emitted to the target. The dual beam expander assembly integrates two beam expanders, which correspond to two independent optical path structures. One beam expander uses a preset low energy and large beam divergence angle as the main beam in a preset short distance range, while the other beam expander uses a preset high energy and small beam divergence angle as the main beam in a preset long distance range.

[0043] S4, the laser echo signal of the target object is detected by the receiving sensor component, and the laser echo signal of the target object is photoelectrically converted, amplified and shaped to obtain the digital signal to be used.

[0044] S5, the control processing unit processes the digital signal to be used to calculate the distance value of the target object.

[0045] Compared with the prior art, this application has the following advantages: (1) Dynamic adaptability: Through the coordinated operation of dual beam expanders, a dynamic balance between large coverage at close range and high energy density at long range is achieved, significantly improving the adaptability and performance of the ranging system.

[0046] (2) High-performance ranging: At close range, a 3 mrad lens ensures coverage, and at long range, a 1 mrad lens ensures energy density, ensuring ranging performance across the entire range. Specifically, a design with dual beam expanders working in tandem is adopted. By optimizing the beam divergence angle and energy distribution, the ranging device achieves high performance at both close and long ranges.

[0047] (3) Fast response: There is no mechanical switching structure. The system achieves millisecond-level dynamic adjustment through electronic control, meeting real-time requirements. Specifically, the control process is simplified, and a dynamic balance between close-range large coverage and long-range high energy density can be achieved without lens switching logic.

[0048] (4) Simplified structure: The integrated design of dual beam expanders avoids complex mechanical switching mechanisms, reducing system size and cost.

[0049] (5) Strong anti-interference capability: Independent optical path and anti-interference design ensure the purity and stability of the dual beams. Specifically, the optical paths of the dual beam expanders are designed independently and separated as much as possible in physical space to avoid crosstalk. Digital circuits and analog circuits use independent power and ground planes and are connected by optical couplers; shielding and filtering circuits are used for sensitive analog signals to reduce electromagnetic interference.

[0050] (6) Based on the heterogeneous architecture of ARM+FPGA, a high-performance and highly flexible dual-beam expander lens collaborative ranging system is realized through hardware logic optimization and dynamic software configuration.

[0051] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A laser ranging device based on dual beam expanders, characterized in that, The device includes a control and processing component, a laser generation component, a beam management unit, a dual beam expander lens component, and a receiving and sensing component. The control and processing unit is used to control the laser generation component to generate the original laser beam and output two beams with a fixed energy ratio through the beam management unit; the beam management unit includes a beam splitter and a follow-up mirror; the beam splitter has a splitting ratio of 50:1; the follow-up mirror is located behind the beam splitter; before operation, the pitch and azimuth angles of the beam splitter and the follow-up mirror are adjusted to ensure that the two output beams are coaxial with the optical axes of the two beam expanders respectively; The dual beam expander assembly integrates two beam expanders, which correspond to two independent optical path structures. One beam expander uses a preset low-energy, large-beam divergence angle as the main beam in a preset short-range area, while the other beam expander uses a preset high-energy, small-beam divergence angle as the main beam in a preset long-range area. The dual beam expander assembly is used to send the two beams into the corresponding beam expanders, and simultaneously perform beam expansion and collimation before emitting them to the target. The receiving sensing component is used to detect the laser echo signal of the target object, and to perform photoelectric conversion, amplification and shaping on the laser echo signal of the target object to obtain a digital signal to be used and transmit it to the control processing component; the control processing component is also used to process the digital signal to be used to calculate the distance value of the target object.

2. The laser ranging device based on a dual-beam expander lens according to claim 1, characterized in that, The laser generation component includes a driving and execution unit and a laser unit arranged sequentially. The control processing unit is used to generate control signals according to preset instructions and send them to the drive and execution unit; The drive and execution unit is used to drive the laser unit to emit a raw laser beam according to the control signal, and send the raw laser beam to the beam management unit.

3. The laser ranging device based on a dual-beam expander lens according to claim 1, characterized in that, Of the two beam-expanding lenses, one has a beam divergence angle of 3 mrad and an energy of 1 mJ, and the other has a beam divergence angle of 1 mrad and an energy of ≥50 mJ. Among them, the lens with a beam divergence angle of 3mrad and an energy of 1mJ adopts an optical structure of Galilean beam expansion and uses aspherical lenses to replace multiple spherical lens groups. Lens with 1 mrad beam divergence and ≥50 mJ energy: The optical structure includes an aspherical negative lens and a doublet lens group arranged in sequence, and all lenses are coated with an anti-reflective coating with a preset high damage threshold.

4. The laser ranging device based on a dual-beam expander lens according to claim 1, characterized in that, The receiving sensing component includes a receiving lens, a photodetector, and a receiving amplifier arranged sequentially. The receiving lens is used to focus the laser signal diffusely reflected back by the target object as the target object laser echo signal onto the photosensitive surface of the photodetector; The photodetector is used to convert the received laser echo signal from the target object into an electrical pulse signal. The receiving amplifier is used to amplify the electrical pulse signal and, after reaching a preset detection threshold, to shape and output it; wherein, the output signal is a narrow pulse TTL signal and is marked as a digital signal to be used.

5. The laser ranging device based on a dual-beam expander lens according to claim 1, characterized in that, The control processing unit adopts an ARM+FPGA architecture, and the control processing unit is used for: Using FPGA-based parallel time-domain signal processing technology, target matching is performed on the digital signal to be used to detect the real target echo signal; based on the real target echo signal, the target distance value is obtained by parsing the count value.

6. The laser ranging device based on a dual-beam expander lens according to claim 2, characterized in that, The laser unit employs a diode-pumped solid-state laser; The driving and execution unit includes a driving circuit to drive the discharge switch according to the control signal and adjust the driving voltage by the current feedback signal of the diode-pumped solid-state laser to achieve a stable driving current output.

7. The laser ranging device based on a dual-beam expander lens according to claim 1, characterized in that, The device is applicable to at least UAV-borne ranging platforms and vehicle-mounted ranging platforms.

8. A laser ranging method based on a dual-beam expander lens, applied to the laser ranging device based on a dual-beam expander lens as described in any one of claims 1-7, characterized in that, The method includes: The control processing unit controls the laser generation component to generate the original laser beam, and the beam management unit outputs two beams with a fixed energy ratio. Two beams are fed into their respective beam expanders via a dual beam expander assembly, which simultaneously expands and collimates the beams before emitting them to the target. The dual beam expander assembly integrates two beam expanders, which correspond to two independent optical path structures. One beam expander uses a preset low-energy, large-beam divergence angle as the main beam within a preset short-range, while the other beam expander uses a preset high-energy, small-beam divergence angle as the main beam within a preset long-range. The laser echo signal of the target object is detected by receiving the sensing component, and the laser echo signal of the target object is photoelectrically converted, amplified and shaped to obtain the digital signal to be used. The control processing unit processes the digital signal to be used to calculate the distance value of the target object.

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