Pulsed solid state laser generator and long range solid state laser rangefinder comprising it

Abstract

The present application relates to laser ranging technical field, especially a kind of pulse solid laser generator and including its long-range solid laser range finder. Just for pulse solid laser generator, total reflection mirror and output mirror are arranged along the same optical axis, and constitute optical resonant cavity;Gain medium component is composed of two pieces of Nd:YAG crystal arranged in series along the optical axis in optical resonant cavity;Pump source component includes two groups of laser diode pumping unit;Two groups of laser diode pumping unit and two pieces of Nd:YAG crystal one-to-one correspondence, respectively, around the corresponding crystal side arrangement;Electro-optic Q component is sequentially arranged by polaroid, RTP electro-optic Q crystal and 1 / 4 wave plate along the light path. In this way, on the one hand, total injected pump power and total gain can be improved, and heat load is dispersed to alleviate thermal lens and other thermal effects;On the other hand, narrow pulse width, high peak power laser pulse can be output, and output beam quality under high pump power is maintained.

Description

Technical Field

[0001] This invention relates to the field of laser ranging technology, and in particular to a pulsed solid-state laser generator and a long-range solid-state laser rangefinder including the same. Background Technology

[0002] Pulsed solid-state lasers, with their high peak power and narrow pulse width output characteristics, are core light sources for long-distance laser ranging, laser remote sensing, and other fields. Among them, side-pumped structures are widely used in medium- and high-power pulsed solid-state lasers due to their short heat dissipation path and strong power scalability.

[0003] Currently, mainstream side-pumped electro-optic Q-switched pulsed solid-state lasers generally employ a resonant cavity architecture consisting of a single Nd:YAG gain crystal and a set of surrounding laser diode pump units, achieving giant pulse laser output through an in-cavity electro-optic Q-switching component. In this architecture, the total injectable pump power is limited by the thermal capacity of the single Nd:YAG crystal, making it difficult to further increase the single-pulse output energy. Forcibly increasing the injection power of a single pump unit inevitably leads to a significant thermal gradient within the crystal, causing severe thermal lensing and thermally induced birefringence. This not only degrades the output beam quality and reduces optical-to-optical conversion efficiency but also increases the risk of crystal stress cracking, failing to meet the application requirements of high-energy, high-quality pulsed lasers for long-distance, high-precision detection scenarios.

[0004] Therefore, how to improve the single-pulse output energy of pulsed solid-state lasers while ensuring beam quality and device operational reliability is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a pulsed solid-state laser generator that addresses the problems of limited pump power, severe thermal effects caused by forcibly increasing power, degraded beam quality, and reduced device reliability in existing monolithic Nd:YAG crystal side-pumped architectures.

[0006] This invention relates to a pulsed solid-state laser generator, comprising a total reflection mirror, an output mirror, a pump source assembly, a gain medium assembly, and an electro-optic Q-switching assembly; the total reflection mirror and the output mirror are arranged opposite each other along the same optical axis to form an optical resonant cavity; The gain medium component consists of two Nd:YAG crystals arranged in series along the optical axis within the optical resonant cavity. The pump source assembly consists of two sets of laser diode pumping units; the two sets of laser diode pumping units are arranged one-to-one with two Nd:YAG crystals; each set of laser diode pumping units is arranged around the side of the corresponding Nd:YAG crystal to inject pump light into the corresponding Nd:YAG crystal in a side pumping manner. The electro-optic Q-switching component is positioned inside the optical resonant cavity along the optical axis. It consists of a polarizer, an RTP electro-optic Q-switching crystal, and a quarter-wave plate arranged sequentially along the optical path. The polarizer filters out linearly polarized light, maintaining a single polarization state oscillation within the optical resonant cavity. The RTP electro-optic Q-switching crystal changes the birefringence characteristics by applying and removing a high-voltage electric field, thus switching the Q value of the optical resonant cavity. The quarter-wave plate, in conjunction with the polarizer and the RTP electro-optic Q-switching crystal, completes the polarization state switching.

[0007] As a further improvement to the technical solution disclosed in this invention, a window, an optical wedge, and a photodiode are sequentially arranged along the optical path on the light-emitting side of the output mirror; the window is attached to the light-emitting end face of the output mirror, and both of its optical surfaces are coated with a 1064nm anti-reflection film; the optical wedge is inclinedly arranged on the light-emitting side of the window; the photosensitive surface of the photodiode is arranged facing the beam-splitting optical path of the optical wedge to collect the timing signal and power signal of the laser output.

[0008] As a further improvement to the technical solution disclosed in this invention, the pulsed solid-state laser generator also includes an integrated metal housing and multiple sets of sealing structures; the integrated metal housing encloses and forms a closed laser cavity, and the total reflection mirror, output mirror, pump source assembly, gain medium assembly, and electro-optic Q-switching assembly are all disposed inside the laser cavity; an inflation nozzle and an exhaust port are provided on the integrated metal housing; both the inflation nozzle and the exhaust port are connected to the laser cavity; the inflation nozzle is used to fill the laser cavity with protective gas; the exhaust port is used to discharge the original gas inside the laser cavity.

[0009] As a further improvement to the technical solution disclosed in this invention, a heat sink, a semiconductor cooler, a heat-conducting block, and heat dissipation fins are arranged inside the laser cavity; two Nd:YAG crystals and two sets of laser diode pump units are fixed to the upper surface of the heat sink in a one-to-one correspondence; the cold end of the semiconductor cooler is attached to the lower surface of the heat sink; the heat-conducting block connects the hot end of the semiconductor cooler and the heat dissipation fins; the heat dissipation fins are arranged inside the heat dissipation cavity of the integrated metal shell, and they are in thermal contact with the outer wall of the integrated metal shell, so that heat is conducted to the external environment through natural convection with the outside air.

[0010] As a further improvement to the technical solution disclosed in this invention, an annular heat insulation groove is provided on the circumferential edge of the heat sink; the annular heat insulation groove prevents the heat generated by the heat sink from spreading to the non-heat dissipation area of ​​the integrated metal shell.

[0011] As a further improvement to the technical solution disclosed in this invention, the pulsed solid-state laser generator also includes a temperature control circuit; the temperature control circuit consists of a thermistor temperature sensor, a microcontroller, and a field-effect transistor bridge circuit; the thermistor temperature sensor is attached to the surface of the heat sink and outputs a temperature sampling signal to the microcontroller; the microcontroller calculates the deviation between the received temperature sampling signal and the set temperature value, adjusts it through PID operation, and outputs a control signal to the field-effect transistor bridge circuit; the field-effect transistor bridge circuit is connected to a semiconductor cooler and regulates the current direction and amplitude of the semiconductor cooler to achieve heating or cooling functions.

[0012] Furthermore, the present invention also discloses a long-range solid-state laser rangefinder, including a transmitting lens, a receiving lens, a control system, a power supply, and the aforementioned pulsed solid-state laser generator; The output optical path of the pulsed solid-state laser generator corresponds to the incident end of the transmitting lens; the output optical path of the receiving lens corresponds to the photoelectric detection input end of the control system; the power supply provides power to both the pulsed solid-state laser generator and the control system. Inside the receiving lens, along the incident light path, are arranged the front lens group, field stop, cemented lens, filter, focusing plano-convex lens, and avalanche photodiode in sequence; the field stop is located at the focal plane of the front lens group, limiting the receiving field of view; the filter is a 1064nm narrowband filter; the photosensitive surface of the avalanche photodiode coincides with the exit focal point of the receiving lens, realizing photoelectric signal conversion.

[0013] As a further improvement to the technical solution disclosed in this invention, the transmitting lens is a Galilean beam expander structure, consisting of a biconcave lens, a first meniscus lens at the transmitting end, a second meniscus lens at the transmitting end, and a plano-convex lens at the transmitting end arranged sequentially along the optical path; the biconcave lens is used to diverge and expand the incident laser beam; the first meniscus lens at the transmitting end and the second meniscus lens at the transmitting end are used to correct spherical aberration; and the plano-convex lens at the transmitting end is used to output a collimated laser beam.

[0014] As a further improvement to the technical solution disclosed in this invention, the front lens group consists of a first plano-convex lens, a first meniscus lens, and a plano-concave lens arranged sequentially along the incident light path; the cemented lens is formed by cementing a second meniscus lens and a biconvex lens together.

[0015] As a further improvement to the technical solution disclosed in this invention, the receiving lens is provided with a receiving lens barrel; the barrel wall of the receiving lens barrel is provided with a field stop adjustment hole; the field stop is embedded in the inner cavity of the receiving lens barrel; the field stop can be moved along the optical axis and rotated around the optical axis through the field stop adjustment hole to adjust the position of the field stop, and after the adjustment is completed, the field stop and the receiving lens barrel are relatively fixed.

[0016] As a further improvement to the technical solution disclosed in this invention, the control system consists of a laser driver circuit board, an avalanche photodiode amplifier circuit board, and a main control circuit board. The laser driver circuit board is electrically connected to the pulsed solid-state laser generator, and outputs pump source drive signals and electro-optic Q-switching high-voltage control signals; The avalanche photodiode amplifier circuit board is electrically connected to the avalanche photodiode, and performs multi-stage amplification and threshold shaping on the converted electrical signal; The main control circuit board is electrically connected to the laser driver circuit board and the avalanche photodiode amplifier circuit board. It calculates the distance to the target based on the time difference between the laser main wave signal and the echo signal, outputs control parameters to the laser driver circuit board and the avalanche photodiode amplifier circuit board, and realizes data interaction with the host computer.

[0017] As a further improvement to the technical solution disclosed in this invention, the main control circuit board integrates a distance gating module, a repetition frequency configuration module, a current adjustment module, and a whole machine self-test module. The distance gating module is electrically connected to the avalanche photodiode amplifier circuit board to set the effective reception time window of the echo signal and filter out stray interference signals outside the time window. The repetition rate configuration module is electrically connected to the laser driver circuit board to configure the emission repetition frequency of the laser pulse; The current adjustment module is electrically connected to the laser driver circuit board to adjust the driving current amplitude of the laser diode pump unit; The self-test module is electrically connected to the laser driver circuit board, the avalanche photodiode amplifier circuit board, and the power supply. During the power-on phase or when a self-test command is received, it detects the working status of the laser driver circuit board, the avalanche photodiode amplifier circuit board, and the power supply, and provides feedback on the self-test results.

[0018] As a further improvement to the technical solution disclosed in this invention, the long-range solid-state laser rangefinder also includes a rangefinder housing; the transmitting lens, pulsed solid-state laser generator, receiving lens and control system are all fixedly installed inside the rangefinder housing; each assembly and mating surface of the rangefinder housing is fitted with a sealing structure to form a closed inner cavity isolated from the external environment.

[0019] Regarding pulsed solid-state laser generators, their practical applications can achieve at least the following beneficial technical effects, specifically: 1) The gain medium component consisting of two Nd:YAG crystals, combined with two sets of one-to-one laser diode pump units, can improve the total injection pump power and total gain of the optical resonant cavity, and increase the single-pulse output energy. Moreover, the heat load generated by pumping is distributed to the two Nd:YAG crystals, reducing the thermal gradient inside a single Nd:YAG crystal, thereby alleviating the thermal lensing effect and thermally induced birefringence effect, reducing the risk of cracking of a single Nd:YAG crystal due to thermal stress concentration, and improving the optical-to-optical conversion efficiency and device reliability. 2) The electro-optic Q-switching component, consisting of a polarizer, an RTP electro-optic Q-switching crystal, and a quarter-wave plate, can maintain a single polarization state oscillation within the optical resonant cavity. By applying and removing a high-voltage electric field to change the birefringence characteristics, it can switch the Q value and polarization state of the optical resonant cavity, outputting a narrow pulse width and high peak power laser pulse. Furthermore, the gain medium component composed of two Nd:YAG crystals can suppress the distortion effect of thermal effects on the beam, ensuring that the output beam quality does not deteriorate with the increase of pump power, thus facilitating the stable output of high-energy, high-quality pulsed lasers.

[0020] Regarding long-range solid-state laser rangefinders, their practical applications can achieve at least the following beneficial technical effects, specifically: 1) Using the above-mentioned pulsed solid-state laser generator as the emission source, the output pulsed laser is expanded and collimated by the emission lens before being emitted outward, which can reduce the divergence loss of the beam during long-distance transmission and expand the effective ranging range; and the control system synchronously manages the laser emission and echo detection process, calculates the target distance based on the time-of-flight principle, and ensures the accuracy of the ranging results. 2) The receiving lens adopts a structure in which the front lens group, field stop, cemented lens, 1064nm narrowband filter, focusing plano-convex lens and avalanche photodiode are arranged in sequence along the incident light path. The field stop is set at the focal plane of the front lens group, which can limit the receiving field of view and block off-axis stray light from entering the subsequent light path. The 1064nm narrowband filter filters the ambient background light that is not in the target band, and the focusing plano-convex lens accurately focuses the effective echo light onto the photosensitive surface of the avalanche photodiode, which helps to improve the signal-to-noise ratio and detection sensitivity of the echo signal, and ultimately ensures the reliable detection of weak echo signals at long distances. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1is a schematic perspective view of the long-distance solid-state laser range finder disclosed in the present invention; Figure 2 is Figure 1 a side view of

[0023] Figure 3 is Figure 2 a sectional view taken along line A-A of

[0024] Figure 4 is Figure 2 a sectional view taken along line B-B of

[0025] Figure 5 is Figure 4 a partial enlarged view of part I of

[0026] Figure 6 is a schematic diagram of the functional module composition and energy and signal flow directions of the laser diode driving circuit matched with the pulsed solid-state laser generator; Figure 7 is a functional link diagram for conversion and preprocessing of the echo optical signal at the receiving end; Figure 8 is a diagram of the overall architecture, module division and signal interaction logic of the whole machine control system; Figure 9 is an architecture diagram of the driving power supply circuit matched with the laser diode pumping unit, which adopts unified input of power modules, coordinated control of inverter energy storage and switching discharge.

[0027] 1-Transmitting lens; 11-Biconcave lens; 12-First meniscus lens at transmitting end; 13-Second meniscus lens at transmitting end; 14-Plano-convex lens at transmitting end; 2-Receiving lens; 21-Front lens group; 211-First plano-convex lens at receiving end; 212-First meniscus lens at receiving end; 213-Plano-concave lens at receiving end; 22-Field stop; 23-Cemented lens; 231-Second meniscus lens at receiving end; 232-Biconvex lens at receiving end; 24-Filter; 25-Focusing plano-convex lens; 26-Avalanche photodiode; 27-Receiving lens barrel; 3-Pulsed solid-state laser generator; 31-Full reflector; 32-Output mirror; 33-Pump source assembly; 331-Laser diode pumping unit; 34-Gain medium assembly; 341-Nd:YAG crystal; 35-Electro-optic Q-switch assembly; 351-Polarizer; 352-RTP electro-optic Q-switch crystal; 353-1 / 4 wave plate; 36-Window plate; 37-Optical wedge; 38-Integrated metal housing; 39-Heat sink; 310-Semiconductor refrigerator; 311-Thermal conduction block; 312-Radiating fin; 4-Protective housing. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The content of the present invention will be further described in detail below with reference to specific embodiments. Figures 1-3The diagram shows the structure of the long-range solid-state laser rangefinder disclosed in this invention. It can be seen that it is mainly composed of several parts, including a transmitting lens 1, a receiving lens 2, a pulsed solid-state laser generator 3, a control system (not shown in the figure), a power supply (not shown in the figure), and a protective housing 4. The transmitting lens 1, receiving lens 2, and pulsed solid-state laser generator 3 are all fixedly installed inside the protective housing 4, which can isolate external dust and moisture from corroding the internal optical and circuit components, improving the environmental adaptability and service life of the equipment. The pulsed solid-state laser generator 3 serves as the core emission light source, generating and outputting a pulsed laser beam with high peak power and narrow pulse width. The transmitting lens 1 is correspondingly set at the front end of the output optical path of the pulsed solid-state laser generator 3, expanding and collimating the output pulsed laser beam before emitting it outward, reducing the divergence loss of the beam during long-distance transmission, and expanding the effective ranging range of the equipment. The receiving lens 2 is set next to the transmitting lens 1, receiving the laser echo signal reflected back from the target being measured, and converging the echo signal before transmitting it to the photodetector. The control system establishes electrical connections with the pulsed solid-state laser generator 3 and the receiving lens 2 respectively, synchronously controlling the laser emission timing and echo detection process, and calculating the distance data of the target being measured based on the time-of-flight principle. The power supply provides a stable multi-channel power supply for the pulsed solid-state laser generator 3 and the control system.

[0029] like Figure 3 As shown, the pulsed solid-state laser generator 3 includes a total reflection mirror 31, an output mirror 32, a pump source assembly 33, a gain medium assembly 34, and an electro-optic Q-switching assembly 35. The total reflection mirror 31 and the output mirror 32 are arranged opposite each other along the same optical axis, forming an optical resonant cavity to provide optical feedback conditions for laser oscillation. The gain medium assembly 34 consists of two Nd:YAG crystals 341 arranged in series along the optical axis within the optical resonant cavity, providing population inversion gain for laser generation. The pump source assembly 33 consists of two sets of laser diode pump units 331, with each set corresponding to one of the two Nd:YAG crystals 341. Each set of laser diode pump units 331 is arranged around the side of the corresponding Nd:YAG crystal 341, injecting pump light into the corresponding Nd:YAG crystal 341 in a side-pumping manner to complete the energy excitation for population inversion.

[0030] In summary, the structural design consisting of two Nd:YAG crystals 341 paired with two sets of laser diode pump units 331 can improve the total injection pump power and total gain of the optical resonant cavity, thereby increasing the single-pulse output energy. The heat load generated during the pumping process is distributed between the two Nd:YAG crystals 341, reducing the thermal gradient within each individual Nd:YAG crystal 341, alleviating the thermal lensing effect and thermally induced birefringence, reducing the risk of cracking due to thermal stress concentration, and simultaneously improving the light-to-light conversion efficiency and device operational reliability. Similarly, Figure 3 , Figure 5 As shown, the electro-optic Q-switching component 35 is disposed inside the optical resonant cavity along the optical axis, and is composed of a polarizer 351, an RTP electro-optic Q-switching crystal 352, and a quarter-wave plate 353 arranged sequentially along the optical path. The polarizer 351 filters out linearly polarized light and maintains a single polarization state oscillation within the optical resonant cavity. The RTP electro-optic Q-switching crystal 352 changes its birefringence characteristics by applying and removing a high-voltage electric field, thereby achieving Q-value switching of the optical resonant cavity. The quarter-wave plate 353, together with the polarizer 351 and the RTP electro-optic Q-switching crystal 352, completes polarization state switching, jointly realizing giant pulse laser output. The electro-optic Q-switching component 35, composed of a polarizer 351, an RTP electro-optic Q-switching crystal 352, and a quarter-wave plate 353, can output laser pulses with narrow pulse width and high peak power. Combined with the gain medium component 34 composed of two Nd:YAG crystals 341, which suppresses thermally induced beam distortion, the output beam quality does not deteriorate with the increase of pump power, which is conducive to achieving stable output of high-energy, high-quality pulsed lasers.

[0031] A window 36, an optical wedge 37, and a photodiode are sequentially arranged along the optical path on the light-emitting side of the output mirror 32. The window 36 is fitted to the light-emitting end face of the output mirror 32, and both of its optical surfaces are coated with a 1064nm anti-reflection film to protect the end face of the output mirror 32 while reducing beam transmission loss. The optical wedge 37 is tilted on the light-emitting side of the window 36 and achieves micro-sampling of the laser beam through end face reflection. The photosensitive surface of the photodiode is set facing the beam-splitting optical path of the optical wedge 37 to collect the timing and power signals of the laser output in real time, providing feedback for the whole machine control system and maintaining the stability of the output parameters.

[0032] In addition, such as Figure 3 As shown, the pulsed solid-state laser generator 3 also includes an integrated metal housing 38 and multiple sets of sealing structures (not marked in the figure); the integrated metal housing 38 encloses a closed laser cavity, and the total reflection mirror 31, output mirror 32, pump source assembly 33, gain medium assembly 34, and electro-optic Q-switching assembly 35 are all disposed inside the laser cavity; the integrated metal housing 38 is provided with an inflation nozzle and an exhaust port, both of which are connected to the laser cavity; the inflation nozzle is used to fill the laser cavity with protective gas, and the exhaust port is used to discharge the original gas in the laser cavity. By replacing the gas, a clean and dry internal operating environment is created, avoiding moisture oxidation and dust accumulation of optical components, and improving the long-term stability and service life of the equipment.

[0033] A heat sink 39, a semiconductor cooler 310, a heat conduction block 311 and heat dissipation fins 312 are arranged inside the laser cavity; two Nd:YAG crystals 341 and two groups of laser diode pump units 331 are fixed on the upper surface of the heat sink 39 in one-to-one correspondence, to conduct the heat generated during operation to the heat sink 39; the cold end of the semiconductor cooler 310 is attached to the lower surface of the heat sink 39 to perform active temperature control and adjustment on the heat sink 39; the heat conduction block 311 connects the hot end of the semiconductor cooler 310 and the heat dissipation fins 312, to conduct the heat generated at the hot end to the heat dissipation fins 312; the heat dissipation fins 312 are arranged inside the heat dissipation cavity of the integrated metal housing 38, and are in thermal contact with the outer wall of the integrated metal housing 38, to conduct heat to the external environment through natural convection with the outside air. An annular heat insulation groove is provided on the circumferential edge of the heat sink 39, the annular heat insulation groove blocks the heat generated by the heat sink 39 from diffusing to the non-heat-dissipating area of the integrated metal housing 38, reduces the influence of thermal disturbance on the position and performance of optical elements, and maintains the stability of optical path accuracy.

[0034] The pulsed solid-state laser generator 3 is further provided with a supporting temperature control circuit; the temperature control circuit consists of a thermistor temperature sensor, a microcontroller and a field effect transistor bridge circuit; the thermistor temperature sensor is attached to the surface of the heat sink 39, and outputs a temperature sampling signal to the microcontroller in real time; the microcontroller calculates the deviation between the received temperature sampling signal and the set temperature value, and outputs a control signal to the field effect transistor bridge circuit after adjustment through PID operation; the field effect transistor bridge circuit is connected to the semiconductor cooler 310, regulates the current direction and amplitude of the semiconductor cooler 310 to realize heating or cooling functions, so that the heat sink 39 is maintained in a stable set temperature range, provides a constant operating temperature environment for the optical elements and the pump units, and improves the consistency of laser output parameters.

[0035] As shown in Figure 6 , the laser diode driving circuit supporting the pulsed solid-state laser generator 3 is composed of a charging circuit, an energy storage element, a discharge circuit, a sampling circuit, a control circuit and a protection circuit. After the power is connected, the energy storage element is charged through the charging circuit, and the control circuit triggers the discharge circuit according to the instruction to drive the laser diode pump unit 331 to output pulsed pump light; the sampling circuit collects operating parameters in real time and feeds them back to the control circuit, and cooperates with the protection circuit to realize safety protection under overcurrent and overvoltage conditions, maintain stable and reliable operation of the pump source, and provide circuit support for the consistency of laser output energy.

[0036] As described above, the pulsed laser output from the pulsed solid-state laser generator 3 needs to be expanded and collimated by the transmitting lens 1 before being emitted outward to meet the transmission requirements of long-distance ranging. The transmitting lens 1 is a Galilean beam expander structure, consisting of a biconcave lens 11, a first meniscus lens 12 at the transmitting end, a second meniscus lens 13 at the transmitting end, and a plano-convex lens 14 at the transmitting end, arranged sequentially along the optical path. The biconcave lens 11 is used to diverge and expand the incident laser beam, increasing the output aperture of the beam. The first meniscus lens 12 and the second meniscus lens 13 at the transmitting end are used to correct the spherical aberration generated during the beam expansion process and optimize the output beam quality. The plano-convex lens 14 at the transmitting end is used to output a laser beam with good collimation, reduce the divergence loss of the beam during long-distance transmission, and effectively extend the effective ranging range of the ranging device.

[0037] like Figure 4 , Figure 5 , Figure 7 As shown, inside the receiving lens 2, along the incident light path, a front lens group 21, a field stop 22, a cemented lens 23, a filter 24, a focusing plano-convex lens 25, and an avalanche photodiode 26 are arranged sequentially, forming the echo light signal conversion and preprocessing link. The front lens group 21 consists of a receiving end first plano-convex lens 211, a receiving end first meniscus lens 212, and a receiving end plano-concave lens 213 arranged sequentially along the incident light path, responsible for converging the incident echo light signal. The field stop 22 is located at the focal plane of the front lens group 21, limiting the receiving field of view. The receiver lens 23, composed of a second meniscus lens 231 and a biconvex lens 232, further converges and corrects aberrations in the beam. The filter 24, a 1064nm narrowband filter, filters ambient background light from non-target wavelengths, improving the signal-to-noise ratio of the echo signal. The focusing plano-convex lens 25 precisely focuses the effective echo light onto the photosensitive surface of the avalanche photodiode 26. The photosensitive surface of the avalanche photodiode 26 coincides with the exit focal point of the receiving lens 2, completing the conversion from optical to electrical signals. This complete receiver optical path design effectively improves the signal-to-noise ratio and detection sensitivity of the echo signal, ensuring reliable detection of weak echo signals at long distances.

[0038] just Figure 4 As shown, the receiving lens 2 is equipped with a receiving tube 27, which provides a mounting base for the internal optical components; the tube wall of the receiving tube 27 has a field stop adjustment hole. The field stop 22 is embedded in the inner cavity of the receiving tube 27; the field stop 22 can be moved along the optical axis and rotated around the optical axis through the field stop adjustment hole to adjust its position. After adjustment, the field stop 22 and the receiving tube 27 are relatively fixed, ensuring the field matching accuracy during the assembly and adjustment process and reducing the impact of assembly errors on the detection performance.

[0039] like Figure 8As shown, the overall control system adopts a modular architecture design, consisting of a laser driver circuit board, an avalanche photodiode amplifier circuit board, and a main control circuit board. The laser driver circuit board is electrically connected to the pulsed solid-state laser generator 3, outputting a pump source drive signal and an electro-optic Q-switching high-voltage control signal to ensure stable output of laser pulses according to set parameters. The avalanche photodiode amplifier circuit board is electrically connected to the avalanche photodiode 26, performing multi-stage amplification and threshold shaping on the converted echo signal to output a standard timing pulse signal. The main control circuit board is electrically connected to both the laser driver circuit board and the avalanche photodiode amplifier circuit board, calculating the distance to the target based on the time difference between the laser main wave signal and the echo signal, outputting control parameters to the laser driver circuit board and the avalanche photodiode amplifier circuit board, and realizing data interaction with the host computer.

[0040] The main control circuit board integrates a distance gating module, a repetition rate configuration module, a current adjustment module, and a self-test module. The distance gating module is electrically connected to the avalanche photodiode amplifier circuit board, setting the effective reception time window for the echo signal and filtering out stray interference signals outside the time window to improve the anti-interference capability of the ranging process. The repetition rate configuration module is electrically connected to the laser driver circuit board, configuring the emission repetition frequency of the laser pulse to adapt to different ranging application scenarios. The current adjustment module is electrically connected to the laser driver circuit board, adjusting the driving current amplitude of the laser diode pump unit 331 to achieve flexible control of the output energy. The self-test module is electrically connected to the laser driver circuit board, the avalanche photodiode amplifier circuit board, and the power supply respectively. During the power-on stage or when a self-test command is received, it detects the working status of the laser driver circuit board, the avalanche photodiode amplifier circuit board, and the power supply, and feeds back the self-test results, improving the reliability of equipment operation and facilitating daily maintenance and troubleshooting.

[0041] like Figure 9 As shown in the diagram, the drive power supply circuit for the laser diode pump unit 331 in this embodiment adopts an architecture of unified input of power module, coordinated control of inverter energy storage and switching discharge. The power module provides basic input power for the entire drive circuit, and its output is divided into two branches: one branch is connected to the voltage inverter module, and after voltage amplitude transformation and topology conversion, it is output to the filter energy storage module to complete the stable storage of power and ripple filtering, providing a stable energy source for the pulse discharge of the laser diode pump unit 331; the other branch is connected to the drive circuit to provide basic operating power for the control circuit.

[0042] The drive circuit outputs a timing control signal to the discharge switch. By controlling the on / off time and conduction duration of the discharge switch, the electrical energy stored in the filter energy storage module is loaded into the laser diode pump unit 331 in the form of narrow pulses, driving it to output pump light with corresponding power and pulse width. The working circuit of the laser diode pump unit 331 is connected in series to the feedback circuit. The feedback circuit collects the working current and working voltage signals of the laser diode pump unit 331 in real time and sends them back to the drive circuit, forming a closed-loop regulation circuit to ensure the consistency and stability of the pump output parameters. The protection circuit is connected to the drive circuit and the discharge switch signal respectively. When abnormal conditions such as overcurrent or overvoltage occur in the circuit, it can quickly send a protection trigger signal to the drive circuit. The drive circuit then turns off the discharge switch, cutting off the power supply circuit of the laser diode pump unit 331, avoiding damage to optical and electrical components due to overload, and improving the operational reliability of the entire drive power supply circuit.

[0043] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A pulsed solid-state laser generator, comprising a total reflection mirror, an output mirror, a pump source assembly, a gain medium assembly, and an electro-optic Q-switching assembly; wherein the total reflection mirror and the output mirror are arranged opposite each other along the same optical axis to form an optical resonant cavity, characterized in that: The gain medium component consists of two Nd:YAG crystals arranged in series along the optical axis within the optical resonant cavity. The pump source assembly consists of two sets of laser diode pumping units; the two sets of laser diode pumping units are arranged one-to-one with the two Nd:YAG crystals; each set of laser diode pumping units is arranged around the side of the corresponding Nd:YAG crystal to inject pump light into the corresponding Nd:YAG crystal in a side pumping manner. The electro-optic Q-switching component is disposed inside the optical resonant cavity along the optical axis, and is composed of a polarizer, an RTP electro-optic Q-switching crystal, and a quarter-wave plate arranged sequentially along the optical path. The polarizer filters out linearly polarized light and maintains a single polarization state oscillation within the optical resonant cavity. The RTP electro-optic Q-switching crystal changes the birefringence characteristics by applying and removing a high-voltage electric field, thereby switching the Q value of the optical resonant cavity. The quarter-wave plate, in conjunction with the polarizer and the RTP electro-optic Q-switching crystal, completes the polarization state switching.

2. The pulsed solid-state laser generator according to claim 1, characterized in that, The output mirror has a window, an optical wedge, and a photodiode arranged sequentially along the optical path on the light-emitting side. The window is fitted to the light-emitting end face of the output mirror, and both of its optical surfaces are coated with a 1064nm anti-reflection film. The optical wedge is arranged at an angle on the light-emitting side of the window. The photosensitive surface of the photodiode is arranged facing the beam-splitting path of the optical wedge to collect the timing and power signals of the laser output.

3. The pulsed solid-state laser generator according to any one of claims 1-2, characterized in that, It also includes an integrated metal housing and multiple sealing structures; the integrated metal housing encloses and forms a closed laser cavity, and the total reflection mirror, the output mirror, the pump source assembly, the gain medium assembly, and the electro-optic Q-switching assembly are all disposed inside the laser cavity; the integrated metal housing is provided with an inflation nozzle and an exhaust port; both the inflation nozzle and the exhaust port are connected to the laser cavity; the inflation nozzle is used to fill the laser cavity with protective gas; the exhaust port is used to discharge the original gas inside the laser cavity.

4. The pulsed solid-state laser generator according to claim 3, characterized in that, The laser cavity is equipped with a heat sink, a semiconductor cooler, a heat-conducting block, and heat dissipation fins. Two Nd:YAG crystals and two sets of laser diode pump units are fixed to the upper surface of the heat sink in a one-to-one correspondence. The cold end of the semiconductor cooler is attached to the lower surface of the heat sink. The heat-conducting block connects the hot end of the semiconductor cooler to the heat dissipation fins. The heat dissipation fins are arranged inside the heat dissipation cavity of the integrated metal shell and are in thermally conductive contact with the outer wall of the integrated metal shell, transferring heat to the external environment through natural convection with the outside air.

5. The pulsed solid-state laser generator according to claim 4, characterized in that, The heat sink is provided with an annular heat insulation groove along its circumferential edge; the annular heat insulation groove prevents the heat generated by the heat sink from spreading to the non-heat dissipation area of ​​the integrated metal shell.

6. The pulsed solid-state laser generator according to claim 4, characterized in that, It also includes a temperature control circuit; the temperature control circuit consists of a thermistor temperature sensor, a microcontroller, and a field-effect transistor bridge circuit; the thermistor temperature sensor is attached to the surface of the heat sink and outputs a temperature sampling signal to the microcontroller; the microcontroller calculates the deviation between the received temperature sampling signal and the set temperature value, adjusts it through PID operation, and outputs a control signal to the field-effect transistor bridge circuit; the field-effect transistor bridge circuit is connected to the semiconductor cooler and regulates the current direction and amplitude of the semiconductor cooler to achieve heating or cooling functions.

7. A long-range solid-state laser rangefinder, characterized in that, Includes a transmitting lens, a receiving lens, a control system, a power supply, and a pulsed solid-state laser generator as described in any one of claims 1-6; The output optical path of the pulsed solid-state laser generator corresponds to the incident end of the transmitting lens; the output optical path of the receiving lens corresponds to the photoelectric detection input end of the control system; the power supply provides power to the pulsed solid-state laser generator and the control system. The receiving lens contains, along the incident light path, a front lens group, a field stop, a cemented lens, a filter, a focusing plano-convex lens, and an avalanche photodiode. The field stop is located at the focal plane of the front lens group, limiting the receiving field of view. The filter is a 1064nm narrowband filter. The photosensitive surface of the avalanche photodiode coincides with the exit focal point of the receiving lens, realizing photoelectric signal conversion.

8. The long-range solid-state laser rangefinder according to claim 7, characterized in that, The transmitting lens is a Galilean beam expander structure, consisting of a biconcave lens, a first meniscus lens at the transmitting end, a second meniscus lens at the transmitting end, and a plano-convex lens at the transmitting end arranged sequentially along the optical path. The biconcave lens is used to diverge and expand the incident laser beam. The first meniscus lens at the transmitting end and the second meniscus lens at the transmitting end are used to correct spherical aberration. The plano-convex lens at the transmitting end is used to output a collimated laser beam.

9. The long-range solid-state laser rangefinder according to claim 7, characterized in that, The front lens group consists of a first plano-convex lens, a first meniscus lens, and a plano-concave lens arranged sequentially along the incident light path; the cemented lens is formed by cementing a second meniscus lens and a biconvex lens together.

10. The long-range solid-state laser rangefinder according to claim 7, characterized in that, The receiving lens is provided with a receiving lens barrel; the barrel wall of the receiving lens barrel is provided with a field stop adjustment hole; the field stop is embedded in the inner cavity of the receiving lens barrel; the position of the field stop can be adjusted by moving along the optical axis and rotating around the optical axis through the field stop adjustment hole, and after adjustment, the field stop is fixed relative to the receiving lens barrel.

11. The long-range solid-state laser rangefinder according to claim 7, characterized in that, The control system consists of a laser driver circuit board, an avalanche photodiode amplifier circuit board, and a main control circuit board. The laser driver circuit board is electrically connected to the pulsed solid-state laser generator and outputs a pump source drive signal and an electro-optic Q-switching high-voltage control signal. The avalanche photodiode amplifier circuit board is electrically connected to the avalanche photodiode, and performs multi-stage amplification and threshold shaping on the converted electrical signal. The main control circuit board is electrically connected to the laser driver circuit board and the avalanche photodiode amplifier circuit board, respectively. It calculates the distance to the target based on the time difference between the laser main wave signal and the echo signal, outputs control parameters to the laser driver circuit board and the avalanche photodiode amplifier circuit board, and realizes data interaction with the host computer.

12. The long-range solid-state laser rangefinder according to claim 11, characterized in that, The main control circuit board integrates a distance gating module, a repetition frequency configuration module, a current adjustment module, and a whole machine self-test module; The distance gating module is electrically connected to the avalanche photodiode amplifier circuit board, sets the effective reception time window for the echo signal, and filters out stray interference signals outside the time window; The repetition rate configuration module is electrically connected to the laser driver circuit board and configures the emission repetition frequency of the laser pulse; The current adjustment module is electrically connected to the laser driver circuit board and adjusts the driving current amplitude of the laser diode pump unit; The self-test module is electrically connected to the laser driver circuit board, the avalanche photodiode amplifier circuit board, and the power supply, respectively. During the power-on phase or when a self-test command is received, it detects the working status of the laser driver circuit board, the avalanche photodiode amplifier circuit board, and the power supply, and feeds back the self-test results.

13. The long-range solid-state laser rangefinder according to claim 7, characterized in that, It also includes the rangefinder housing; the transmitting lens, the pulsed solid-state laser generator, the receiving lens and the control system are all fixedly installed inside the rangefinder housing; each assembly and mating surface of the rangefinder housing is fitted with a sealing structure to form a closed inner cavity isolated from the external environment.

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