High-stability variable optical gain laser ranging device

Abstract

The application provides a high-stability variable optical gain laser ranging device, comprising a laser emitting assembly, a laser receiving assembly, a driving circuit and a processing module, the laser emitting assembly and the laser receiving assembly are connected with the driving circuit, the driving circuit is connected with the processing module, the laser emitting assembly comprises a laser emitting module, a collimating module is arranged at the front end of the laser emitting module, the laser receiving assembly comprises a light detection module, a light collecting conical tube is arranged in front of the light detection module, a base medium is filled in the light collecting conical tube, a gain medium is doped in the base medium, a pump laser is arranged on the side wall of the light collecting conical tube, and the pump laser is connected with the driving circuit. The application can realize gain amplification of weak reflected light by arranging the gain medium in the light collecting conical tube and arranging the pump laser on the side wall of the light collecting conical tube, and the detection capability of the ranging device is improved. Preferably, the stability and anti-interference capability of the system can be improved by arranging a background light balancing assembly.

Description

Technical Field

[0001] This invention relates to laser ranging technology, and more particularly to a highly stable variable optical gain laser ranging device. Background Technology

[0002] A laser rangefinder is an instrument that uses laser light to accurately measure the distance to a target (also known as laser ranging). When working, a laser rangefinder emits a laser beam towards the target, a photodetector receives the reflected laser beam, and a timer measures the time it takes for the laser beam to travel from emission to reception, thus calculating the distance from the observer to the target. However, because the laser beam reflected from the target is usually quite weak, this significantly limits the detection capability of the rangefinder. Summary of the Invention

[0003] The purpose of this invention is to provide a highly stable variable optical gain laser ranging device with stronger detection capabilities.

[0004] By incorporating a gain medium within the light-receiving conical tube and placing a pump laser on its sidewall, the weak reflected light can be amplified, thereby enhancing the detection capability of the ranging device. Preferably, by adding a background light equalization component, the system's stability and anti-interference capability can be improved.

[0005] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0006] According to one aspect of the present invention, a high-stability variable optical gain laser ranging device is provided, comprising a laser emitting component, a laser receiving component, a driving circuit, and a processing module. Both the laser emitting component and the laser receiving component are connected to the driving circuit, which is connected to the processing module. The laser emitting component includes a laser emitting module with a collimation module at its front end. The laser receiving component includes a light detection module with a light-collecting conical tube in front of it. The light-collecting conical tube is filled with a substrate medium doped with a gain medium. A pump laser is disposed on the sidewall of the light-collecting conical tube and connected to the driving circuit.

[0007] In one embodiment, the device further includes a background light equalization component, the background light equalization component comprising:

[0008] The sensor is used to monitor information inside the light-receiving conical tube;

[0009] An information acquisition module is connected to the processing module via a signal, and the sensor is connected to the information acquisition module via a signal.

[0010] A circulation pump is connected to the light-receiving conical tube via a pipeline. The circulation pump is also signal-connected to the processing module. An adjustment component is installed inside the circulation pump.

[0011] In one embodiment, the sensor includes a temperature sensor disposed on the side wall of the light-collecting conical tube for monitoring the temperature inside the light-collecting conical tube; the adjustment component includes a temperature adjustment component.

[0012] In one embodiment, the sensor includes a liquid pressure sensor disposed on the side wall of the light-collecting conical tube for monitoring the pressure inside the light-collecting conical tube; the regulating component includes a flow rate control component.

[0013] In one embodiment, the sensor includes a background light intensity sensor, and the substrate medium also contains dissolved background light absorbing particles; the background light intensity sensor is disposed on the side wall of the light-collecting conical tube and is used to detect the background light intensity inside the light-collecting conical tube; the adjustment component includes a color particle concentration control component.

[0014] In one embodiment, the substrate medium is water, and the gain medium is rare earth ions.

[0015] In one embodiment, the pump laser is a semiconductor laser with a wavelength of 915nm to 976nm.

[0016] In one embodiment, the pump laser is a 940nm wavelength semiconductor laser, and the gain medium is Er ions or Yb ions.

[0017] In one embodiment, a waterproof connector is provided at the pipeline interface between the light-collecting cone and the circulating pump, and the waterproof connector is made of stainless steel.

[0018] In one embodiment, a laser protection module is further provided at the front end of the collimation module.

[0019] The beneficial effects of this invention are: by setting a gain medium in the light-collecting conical tube and setting a pump laser on the side wall of the light-collecting conical tube, the weak reflected light can be amplified, thereby improving the detection capability of the ranging device. Preferably, by setting a background light equalization component, the stability and anti-interference capability of the system can be improved. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] The above-described features and advantages of the present invention will be better understood after reading the following detailed description of embodiments of the present disclosure in conjunction with the accompanying drawings. In the drawings, components are not necessarily drawn to scale, and components having similar related characteristics or features may have the same or similar reference numerals.

[0022] Figure 1 This is a schematic diagram of the system structure according to an embodiment of this application;

[0023] Figure 2 This is a schematic diagram of the components of the background light equalization component;

[0024] The components are as follows: 1-Collimation module; 2-Laser emission module; 3-Pump laser; 4-First waterproof interface; 5-Second waterproof interface; 6-Temperature sensor; 7-Background light intensity sensor; 8-Liquid pressure sensor; 9-Light detection module; 10-Light receiving conical tube; 11-Laser protection module; 12-Gain medium; 13-Circulation pump; 14-Information acquisition module; 15-Processing module. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0026] like Figure 1 As shown, this application provides a high-stability variable optical gain laser ranging device, including a laser emitting component, a laser receiving component, a driving circuit 16, and a processing module 15. The laser emitting component and the laser receiving component are both connected to the driving circuit 16, and the driving circuit 16 is connected to the processing module 15.

[0027] The laser emitting component includes a laser emitting module 2. The core component of the laser emitting module 2 is a laser, which operates in pulse mode. When ranging begins, it emits a pulsed laser beam with a width on the order of nanoseconds. Since the laser pulse travels at a constant speed in space, after a certain time, the pulse will encounter the object being measured and undergo diffuse reflection. The light within a certain solid angle will return to the receiving system of the ranging system. The time difference between these two events multiplied by the speed of light is twice the distance to the object being measured.

[0028] The laser can be a semiconductor laser, a fiber laser, a solid-state laser, etc. In this embodiment, a fiber laser is used. Fiber lasers have good beam quality, stable center wavelength, require no maintenance, have low power consumption, generate little heat, and the output is in flexible fiber, making their placement relatively easy. The center wavelength of the laser can be 1030nm, 1064nm, 1080nm, 1535nm, 1545nm, 1550nm, etc. In this embodiment, a wavelength of 1550nm is selected.

[0029] A collimation module 1 is installed at the front end of the laser emitting module 2. The light emitted by the laser emitting module 2 is divergent light with a large divergence angle. During long-distance transmission, its power attenuates very quickly due to the scattering effect of aerosols and the atmosphere. The function of the collimation module 1 is to compress the divergence angle of the laser, allowing the laser to propagate further and thus the measurement distance to be greater. The collimation module consists of an optical lens and a lens barrel. The optical lens can be a single spherical or aspherical convex lens, concave lens, meniscus lens, or a combination of several of these. In this embodiment, an aspherical plano-convex lens is selected, which simplifies the structure while eliminating the aberrations caused by spherical lenses and reducing energy loss during the collimation process.

[0030] The laser receiving component includes a photodetector module 9. The main function of the photodetector module 9 is to receive optical signals, convert them into electrical signals, and amplify them again to obtain a high signal-to-noise ratio echo signal. This signal is first transmitted to the information acquisition module 14, which converts the electrical signal into data. Then, the data is sent to the processing module 15. After processing by the processing module 15, the laser time of flight (TOF) is obtained. Multiplying this time by the speed of light yields a distance, which is twice the distance to the target being measured.

[0031] The detector of the light detection module 9 can be a PD, APD, PIN diode, SPAD, photomultiplier tube, etc. In this embodiment, an APD is selected as the detector because its main characteristics are fast response speed, high bandwidth, and low noise. Since the end area of ​​the conical tube is relatively large, a multi-APD series connection is used to collect the weak signal light as completely as possible.

[0032] A light-collecting conical tube 10 is positioned in front of the light detection module 9. The main function of the light-collecting conical tube 10 is to collect light signals reflected back from the target within a certain solid angle. A specific reflective film is coated on the sidewall of the light-collecting conical tube 10. This film has extremely high reflectivity for laser wavelengths within a certain range, but extremely high transmittance for wavelengths outside this range, thus preventing other wavelengths from being received by the detector and increasing noise, which would affect the detection effect. The field of view of the light-collecting conical tube 10 can be flexibly controlled by adjusting the taper of the tube. The material of the light-collecting conical tube 10 can be gold, silver, aluminum, iron, copper, glass, etc. In this embodiment, glass is chosen because it has high light transmittance and is an ideal substrate for optical thin films.

[0033] The returned optical power is mostly in the order of nW, pW, or even smaller, which limits the detection capability of the detection equipment. Therefore, this device also includes a weak light amplification function. According to the principle of stimulated emission of light, weak light amplification requires three key elements: a pump source, a gain medium, and a laser source. In this device, the gain medium (taking erbium ions as an example) is doped in the substrate medium (e.g., water) and fills the light-receiving conical tube 10. The pump source is a pump laser 3 disposed on the side wall of the light-receiving conical tube 10, and the pump laser 3 is connected to the driving circuit 16.

[0034] The laser emitted by laser emitting module 2 is reflected by a distant reflective object, and a weak reflected laser beam enters the conical receiving tube 10, thus becoming the laser source. When its photons pass through the gain medium, they excite erbium ions at a high energy level, emitting two photons in the same state as the original laser source. These excited photons can also excite other erbium ions at high energy levels. As long as the pump source continuously provides energy to the erbium ions, this process will continue indefinitely. In this way, the received laser source is continuously amplified, and the amplified laser beam is received by the detector to obtain a high-quality signal. Applying this method can improve the detection capability of the detection equipment by several orders of magnitude.

[0035] The substrate medium can be a gas or a liquid. For example, liquid water can be selected as the substrate medium and rare earth ions can be used as the gain medium.

[0036] The pump laser 3 can be a semiconductor laser with wavelengths of 915nm, 940nm, or 976nm. In this embodiment, a semiconductor laser with a wavelength of 940nm is selected, and the gain medium is selected as erbium (Er) or ytterbium (Yb) ions, as 940nm is exactly at the absorption peak of these two ions.

[0037] Based on this, to improve the system's anti-interference capability and stability, and to enhance the ranging device's detection capability under complex conditions, this device also includes a background light equalization component. The background light equalization component comprises a sensor, an information acquisition module 14, and a circulation pump 13. The sensor monitors environmental information (such as temperature and pressure) within the light-receiving conical tube 10 and sends the monitored information to the information acquisition module 14, which is signal-connected to the processing module 15. The circulation pump 13 is connected to the light-receiving conical tube 10 via a pipeline and is signal-connected to the processing module 15. The circulation pump 13 contains an adjustment component, which the processing module 15 controls to adjust the environment within the light-receiving conical tube.

[0038] Furthermore, considering the thermal effect in the gain medium, a portion of the pump light power is converted into heat. The resulting temperature gradient and subsequent mechanical stress cause a prism effect, distorting the amplified beam. Therefore, the sensor in the background light equalization component includes a temperature sensor 6, which is mounted on the side wall of the receiving conical tube 10. The main function of the temperature sensor 6 is to monitor the temperature of the gain medium in the receiving conical tube 10. This temperature value is acquired by the information acquisition module 14 and transmitted to the processing module 15. The processing module 15 determines whether this temperature value matches the set value. If a deviation occurs, the processing module 15 issues a command to the circulation pump to adjust the temperature of the circulation medium to the set temperature. The temperature sensor 6 can be digital or analog; in this embodiment, a digital temperature sensor is used.

[0039] Accordingly, the regulating component in the circulating pump 13 includes a temperature regulating component, which has both heating and cooling functions. When the processing module 15 detects that the temperature in the conical tube is too high, it sends a specific command to the circulating pump 13. As the gain medium flows through the circulating pump 13, the temperature regulating component inside the circulating pump 13 cools the gain medium to the initially set temperature. Conversely, when the processing module 15 detects that the temperature in the conical tube is too high, it sends a command to the circulating pump 13. As the gain medium flows through the circulating pump 13, the temperature regulating component inside the circulating pump 13 heats the gain medium to the initially set temperature. The constant temperature of the gain medium also keeps the detector temperature in the photodetector module stable. This has a significant advantage: the detector operates under the most suitable bias voltage, and the detection effect will not deteriorate due to changes in the external temperature.

[0040] In another embodiment, the sensor includes a liquid pressure sensor 8, which is disposed on the side wall of the light-collecting conical tube 10. Its main purpose is to measure the pressure parameters of the medium in the light-collecting conical tube 10. The pressure value transmitted by this pressure sensor is collected by the information acquisition module 14 and then transmitted to the processing module 15. The processing module 15 will determine whether the pressure value meets the set value. If it does not meet the set value, the processing module 15 will send a command to the circulation pump 13 to adjust the flow rate of the circulation pump 13 to adjust the pressure value of the circulating medium in the light-collecting conical tube 10 to the set value, so as to prevent the pressure value from being too high and causing damage to the system, or the pressure value from being too low and causing air bubbles to form, thus affecting the detection effect.

[0041] The liquid pressure sensor 8 can be a piezoresistive pressure sensor, a ceramic pressure sensor, a diffused silicon pressure sensor, a sapphire pressure sensor, a piezoelectric pressure sensor, etc. In this embodiment, a sapphire pressure sensor is selected.

[0042] Accordingly, the regulating components of the circulating pump 13 include a flow rate control component. When the processing module 15 learns that the pressure of the gain medium in the conical tube is too high, it will issue a specific command to the circulating pump 13. At this time, the circulating pump 13 will appropriately reduce parameters such as the flow rate of the gain medium to control its pressure to remain constant. Conversely, when it learns that the pressure is too low, it will also appropriately increase the pressure of the gain medium by controlling the circulating pump parameters.

[0043] In another possible embodiment, background light absorbing particles are also dissolved in the substrate medium to absorb interfering light. The sensor includes a background light intensity sensor 7, which can be a PD, APD, PIN diode, SPAD, photomultiplier tube, etc. In this embodiment, an APD is used, which is more sensitive to background light. The background light intensity sensor 7 is disposed on the side wall of the light-collecting conical tube 10, and its main function is to sense the intensity of background light in the liquid. This intensity value is first passed through the information acquisition module 14 and then uploaded to the processing module 15. After receiving the intensity value, the processing module 15 will determine whether the value is consistent with the set intensity. If there is a deviation, the processing module will issue a command to the circulation pump 13.

[0044] Accordingly, the regulating component of the circulation pump 13 includes a color particle concentration control component. When the processing module 15 learns that the background light intensity of the gain medium in the conical tube is greater than the initial default value, it will issue a specific instruction to the circulation pump 13. As the gain medium flows through the circulation pump 13, the circulation pump 13 will increase the color particle concentration in the gain medium to absorb excess background light photons, thereby achieving the purpose of background light equalization and maximizing the rangefinder's ranging capability under strong background light.

[0045] It is easy to understand that the backlight equalization component can also simultaneously include the aforementioned temperature control, pressure control, and backlight intensity control functions, as shown in the functional module diagram below. Figure 2 As shown.

[0046] Preferably, a first waterproof connector 4 and a second waterproof connector 5 are provided at the pipe interface between the receiving conical tube 10 and the circulating pump 13. The function of the waterproof connector is mainly to prevent water leakage at the connection between the hose and the receiving conical tube 10. The waterproof connector can be made of gold, silver, iron, copper, aluminum, stainless steel, etc. In this embodiment, stainless steel is used to enhance the overall structural strength.

[0047] In addition, a laser protection module 11 can be installed at the front end of the collimation module 1. The main function of the laser protection module 11 is to prevent sunlight from being focused onto the laser through the emitting aspherical mirror, which could cause the laser to overheat and burn out due to prolonged exposure. Its surface is coated with a special film system and special doping to absorb light of specific wavelengths, providing double protection against overheating and damage to the laser. The spectrum of this module can be long-wavelength cutoff, short-wavelength cutoff, bandpass, etc. In this embodiment, a laser protection module 11 with bandpass spectral characteristics is selected.

[0048] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0049] The prior description of this disclosure is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not intended to be limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0050] The above description is merely a preferred example of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application shall be included within the scope of protection of this application.

Claims

1. A highly stable variable optical gain laser ranging device, characterized in that, The system includes a laser emitting component, a laser receiving component, a driving circuit, and a processing module. Both the laser emitting component and the laser receiving component are connected to the driving circuit, which is connected to the processing module. The laser emitting component includes a laser emitting module with a collimation module at its front end. The laser receiving component includes a light detection module with a light-collecting conical tube in front of it. The light-collecting conical tube is filled with a substrate medium doped with a gain medium. A pump laser is disposed on the sidewall of the light-collecting conical tube and connected to the driving circuit. The substrate medium is water. It also includes a background light equalization component, which includes: The sensor is used to monitor the state inside the light-collecting conical tube; An information acquisition module, wherein the information acquisition module is signal-connected to the processing module, and the sensor is signal-connected to the information acquisition module; and A circulation pump is connected to the light-receiving conical tube via a pipeline. The circulation pump is also signal-connected to the processing module. An adjustment component is installed inside the circulation pump. The sensor includes a liquid pressure sensor, which is disposed on the side wall of the light-collecting conical tube and is used to monitor the pressure inside the light-collecting conical tube; the regulating component includes a flow rate control component; The substrate medium also contains dissolved background light absorbing particles; the sensor includes a background light intensity sensor, which is disposed on the side wall of the light-collecting conical tube and is used to detect the background light intensity inside the light-collecting conical tube; the adjustment component includes a color particle concentration control component.

2. The high-stability variable optical gain laser ranging device according to claim 1, characterized in that, The sensor includes a temperature sensor disposed on the side wall of the light-collecting conical tube for monitoring the temperature inside the light-collecting conical tube; the adjustment component includes a temperature adjustment component.

3. The high-stability variable optical gain laser ranging device according to claim 1, characterized in that: The substrate medium is water, and the gain medium is rare earth ions.

4. The high-stability variable optical gain laser ranging device according to claim 1, characterized in that: The pump laser is a semiconductor laser with a wavelength of 915nm~976nm.

5. The high-stability variable optical gain laser ranging device according to claim 4, characterized in that: The pump laser is a 940nm wavelength semiconductor laser, and the gain medium is Er ions or Yb ions.

6. The high-stability variable optical gain laser ranging device according to claim 1, characterized in that: A waterproof connector is provided at the pipeline interface between the light-collecting conical tube and the circulating pump, and the waterproof connector is made of stainless steel.

7. The high-stability variable optical gain laser ranging device according to claim 1, characterized in that: The collimation module is also equipped with a laser protection module at its front end.

Images