A high-energy laser damage equivalent loading system

Abstract

The application discloses a high-energy laser damage equivalent loading system and belongs to the technical field of laser damage and protection. The system comprises a high-energy laser source, a side imaging module and a front imaging and spectrum analysis module. The side imaging module and the front imaging and spectrum analysis module comprise an energy adjusting system I, an energy adjusting system II, a delay control system, a frequency multiplication wave selection system, a focusing system I, a focusing system II, a laser loading sample stage, a high-speed imaging system I, a high-speed imaging system II, a spectrum information acquisition system and an auxiliary illumination light source. The optical lenses involved include a beam splitter, a beam combiner, a reflector and a dichroic mirror. The high-energy laser damage equivalent loading system is used for simulating the laser damage process in a real environment, so as to deeply understand the action mechanism of materials under laser loading, and can realize in-situ characterization of ultrafast dynamics and obtain detailed image and spectrum information of the material damage process.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser damage and protection technology, in particular to a high-energy laser damage equivalent loading system. BACKGROUND

[0002] High-energy laser beams have the characteristics of high energy density, low launch cost, fast attack speed and high attack precision. When the material is impacted by high-energy laser, the irradiation area will face microscale plasma changes, temperature rise, material dissociation and thermal stress damage, which can easily cause structural failure or even disintegration. With the continuous development of laser damage and protection technology, it is urgent to restore the high-energy laser damage process in the experimental environment, thoroughly understand the mechanism of the material under laser loading, and promote the development of China's laser protection industry. The ultrafast and superstrong characteristics of femtosecond pulse laser, the energy density, action space and time scale of laser in the irradiation process are all extreme, so the physical effects and mechanisms involved in the femtosecond laser damage process contain nonlinearity and non-equilibrium, which can better explore the physical and chemical properties of the material under high-energy laser damage.

[0003] At present, the design and research and development mode of China's high-energy laser equivalent loading system still stays in the "trial and error method" and semi-empirical stage. The laser source with long action time is commonly used in the laser loading system, but the peak power density is limited and accompanied by thermal effects, which is not conducive to the mechanism of ultrafast time scale material. Secondly, when collecting information about the material damage process, most of the current methods are based on traditional optical imaging, and the time scale of in-situ collection is usually in nanoseconds, which cannot characterize the material damage process with picosecond or even femtosecond high time resolution.

[0004] Therefore, a high-energy laser damage equivalent loading system with high time resolution in-situ characterization capability is needed to solve the above problems. SUMMARY

[0005] The purpose of the present application is to provide a high-energy laser damage equivalent loading system, which can effectively solve the problem of ultrafast time dynamics that cannot be characterized during the laser loading process of the material while restoring the energy density of the real high-energy laser damage, and promote the transformation and application of material mechanism in the field of laser protection and laser weapons.

[0006] To achieve the above purpose, the present application provides a high-energy laser damage equivalent loading system, which comprises a high-energy laser source, a side imaging module and a front imaging and spectral analysis module.

[0007] The side imaging module comprises a high-speed imaging system I, and when the high-speed imaging system I acquires information: the high-energy laser source emits laser light, which is split into two beams by a first beam splitter, one of which is used as pump light and sequentially passes through an energy adjusting system I, a first reflector, a second reflector and a dichroic mirror to enter a focusing system I and is focused on a laser loading sample table, and the other of which is used as probe light and sequentially passes through an energy adjusting system II and a third reflector, then enters a time delay control system and a frequency doubling wave selection system, and then passes through a fourth reflector and a fifth reflector to enter a focusing system II, irradiates and passes through the laser loading sample table from the side, and is imaged on the high-speed imaging system I to acquire side image information, and the side imaging module is further provided with an auxiliary illumination light source.

[0008] The front imaging and spectral analysis module comprises a high-speed imaging system II, and when the high-speed imaging system II acquires information: the probe light is split by a second beam splitter after passing through the fifth reflector, is combined with the pump light at a beam combiner, is introduced into the focusing system I after passing through the dichroic mirror, and is irradiated onto a sample, the probe light beam carrying a signal is reflected out, and then passes through the dichroic mirror and a third beam splitter to enter the high-speed imaging system II and a spectral information acquisition system respectively to acquire front image information and spectral information.

[0009] Preferably, the high-energy laser source is an ultrafast second laser, which can output pulsed laser light with a wavelength of 1030 nm, and is internally provided with an optical parametric amplifier, which uses a nonlinear crystal to realize amplification and frequency conversion of a signal light beam, and by adjusting the crystal parameters, the wavelength of the pulsed laser light can be changed, so that the wavelength of the output pulsed laser light is adjustable between 480 nm and 1200 nm, thereby providing a wide range of wavelength selection to adapt to different application requirements.

[0010] Preferably, the energy adjusting system I and the energy adjusting system II are combined with a polarizer, a half-wave plate and a PBS crystal to cooperatively adjust the energy of the light beam to meet the laser energy requirements of different ablation threshold materials.

[0011] Preferably, the time delay control system comprises a driving device and a hollow corner mirror, the hollow corner mirror is precisely controlled to move by a stepping motor, the step length of the stepping motor can be as small as 100 nm, and the optical path of the probe light can be precisely controlled, so that the arrival time of the probe light is controlled.

[0012] Preferably, the frequency doubling wave selection system uses a lithium triborate LBO nonlinear optical crystal to double the frequency of the high-energy laser, and uses an absorption filter with a specific wavelength, and different wavelengths of light have different absorption abilities, so that the required wavelength light beam is selected.

[0013] Preferably, the focusing system I and the focusing system II are integrated with 5-fold, 10-fold, 15-fold and 20-fold objectives, and the objectives have a wide wavelength working range, and the objectives with different multiples can be selected according to the focusing conditions of different experimental requirements.

[0014] Preferably, the high-speed imaging system one and the high-speed imaging system two are equipped with both CCD and ICCD cameras, and appropriate cameras can be selected according to different high-energy laser damage observation requirements.

[0015] Preferably, the auxiliary illumination light source uses a continuous laser as an illumination system.

[0016] Preferably, the laser loading sample stage is composed of a high-precision electrically controlled displacement stage, and the position of the sample relative to the laser focal point can be precisely controlled by a computer.

[0017] Preferably, the spectral information acquisition system uses a spectrometer with high spectral resolution, and is equipped with a non-negative least squares algorithm calibration system to extract spectral data from the light carried by the sample after excitation.

[0018] Therefore, the high-energy laser damage equivalent loading system has the following beneficial effects:

[0019] (1) The laser damage process in the air can be simulated in the laboratory, and the laser experiment conditions are controllable, the time resolution is ultrafast, and the information acquisition capability is full-time scale, which significantly reduces the cost and risk compared with field testing;

[0020] (2) It is helpful to test and evaluate new materials and structures in response to high-energy lasers, and provides scientific basis for the development of laser protection technology, and promotes the development of high-energy laser weapon technology and high-energy laser protection technology.

[0021] The technical solutions of the present application will be further described in detail below with the aid of drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 FIG. 1 is a structural schematic diagram of the high-energy laser damage equivalent loading system of the present application;

[0023] Figure 2 FIG. 4 is a structural schematic diagram of the side imaging module of the high-energy laser damage equivalent loading system of the present application;

[0024] Figure 3 FIG. 5 is a structural schematic diagram of the front imaging and spectral analysis module of the high-energy laser damage equivalent loading system of the present application;

[0025] Figure 4 FIG. 6 is an impact wave evolution image of the high-energy laser damage equivalent loading system of the present application;

[0026] Figure 5 FIG. 7 is a plasma plume evolution image of the high-energy laser damage equivalent loading system of the present application;

[0027] Figure numerals: 1. high-energy laser source; 2. first beam splitter; 3. energy regulation system 1; 4. first reflector; 5. second reflector; 6. beam combiner; 7. dichroic mirror; 8. focusing system 1; 9. laser loading sample stage; 10. energy regulation system 2; 11. third reflector; 12. time delay control system; 13. frequency doubling and wave selection system; 14. fourth reflector; 15. fifth reflector; 16. second beam splitter; 17. focusing system 2; 18. high-speed imaging system 1; 19. third beam splitter; 20. high-speed imaging system 2; 21. spectrum information acquisition system; 22. auxiliary illumination light source. DETAILED DESCRIPTION

[0028] The following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort shall fall within the scope of protection of the present invention.

[0029] Example

[0030] like Figure 1 As shown, the present invention provides a high-energy laser damage equivalent loading system, including a high-energy laser source 1, a side imaging module and a front imaging and spectral analysis module, wherein the side imaging module and the front imaging and spectral analysis module include an energy regulation system 1 3, an energy regulation system 2 10, a delay control system 12, a frequency doubling and wave selection system 13, a focusing system 1 8, a focusing system 2 17, a laser loading sample stage 9, a high-speed imaging system 1 18, a high-speed imaging system 2 20, a spectral information acquisition system 21 and an auxiliary lighting source 22; the optical lenses involved include: a beam splitter, a beam combiner 6, a reflector and a dichroic mirror 7. In this embodiment, the high-energy laser damage material is taken as alumina ceramics as an example.

[0031] like Figure 2 As shown, the optical path of the side imaging module is as follows: the high-energy laser source 1 emits laser light of required parameters, which is split into two beams by the first beam splitter 2. One beam is used as pump light and passes through the energy regulation system 1 3, the first reflector 4, the second reflector 5 and the dichroic mirror 7 in sequence to enter the focusing system 1 8 and be focused on the laser loading sample stage 9. The other beam is used as detection light and passes through the energy regulation system 2 10 in sequence, and then is introduced into the delay control system 12 through the third reflector 11, and then enters the frequency doubling and wave selection system 13, and then passes through the fourth reflector 14 and the fifth reflector 15 to enter the focusing system 2 17, irradiates and passes through the laser loading sample stage 9 from the side, and is imaged by the high-speed imaging system 18 to obtain image information of the side of the sample after being loaded by the high-energy laser. At the same time, the auxiliary lighting light source 22 can be turned on according to experimental needs;

[0032] like Figure 3As shown, the light path of the front imaging and spectral analysis module is as follows: the pump light passes through the third mirror 11, the beam combiner 6 and the dichroic mirror 7 in sequence and is introduced into the focusing system 8, while the probe light is split by the second beam splitter 16 after passing through the fifth mirror 15, combined with the pump light at the beam combiner 6, introduced into the focusing system 8 through the dichroic mirror 7 and irradiated onto the sample, the probe light beam carrying the signal is reflected out, split into two beams by the dichroic mirror 7 and the third beam splitter 19, and then enters the high-speed imaging system 20 and the spectral information acquisition system 21, respectively, to obtain the image information of the ablation pit of the sample after being loaded by high-energy laser and the spectral information of the ablation process.

[0033] The high-energy laser source 1 is a femtosecond laser, which can output pulsed laser with a wavelength of 1030 nm, and is internally provided with an optical parametric amplifier. The signal beam is amplified and frequency converted by using a nonlinear crystal. By adjusting the crystal parameters, the wavelength of the output pulsed laser can be changed, and the wavelength of the output pulsed laser can be adjusted from 480 nm to 1200 nm, providing a wide range of wavelength selection to meet different application requirements. Based on the ultra-short action time, multi-photon effect and nonlinear phenomenon of femtosecond laser, various photon absorption, electron excitation, material phase transition, plasma shock wave, plume eruption and material removal and other ultrafast dynamic processes are contained, which helps to deeply understand the mechanism of the material after being loaded by high-energy laser.

[0034] Because different materials have different penetration and absorption rates for different wavelengths, the tunable ability of the wavelength means that the wavelength can be adjusted according to the damage requirements of the specific material, and the laser ablation properties of unknown materials under different wavelengths can also be explored. The flexibility and versatility of the system are improved. For the alumina ceramic material, a laser with a wavelength of 1030 nm and a pulse width of 500 fs is selected.

[0035] The energy adjustment system 3 and the energy adjustment system 10 combine the polarizer, the half-wave plate and the PBS crystal to cooperatively adjust the energy of the light beam. The polarizer is an optical element that selectively passes light vibrating in a certain specific direction, allowing light with the same polarization direction to pass through. The half-wave plate can change the polarization state of the light, continuously adjust the polarization direction of the light and thus adjust the energy of the light. The PBS crystal can further split and reflect the light, realizing accurate control and adjustment of the energy of the light beam. Through the cooperative action of the three components, the system can finely adjust the energy of the light beam to meet the laser energy requirements of different ablation threshold materials. In this embodiment, the pump light selects a single pulse laser energy of 400 μj, and the probe light selects a laser energy of 0.5 μj.

[0036] The time delay control system 12 comprises a driving device and a hollow corner mirror. The movement of the corner mirror is precisely controlled by a stepper motor, and the step length of the stepper motor can be as small as 100 nm, so that the optical path of the probe light can be precisely controlled, the arrival time of the probe light is controlled, and the time difference between the arrival time of the probe light and the pump light is ensured, so that the evolution information of the material at this moment under the loading of high-energy laser is obtained. When observing the shock wave, the time interval of each photo is set to 200 ps.

[0037] The frequency-doubling wave selection system 13 uses a lithium triborate (LBO) nonlinear optical crystal, has a wide transparent range, high optical quality, high nonlinear parameter, high laser damage threshold, and good thermal stability, doubles the frequency of the high-energy laser, and then cooperates with a specific wavelength absorption filter. Different wavelengths of light have different absorption abilities, and the required wavelength beam is selected. The wavelength of the probe light is selected as half of the wavelength of the pump light. According to the diffraction theory of light and the absorption characteristics of the material, the short wavelength helps to enhance the signal strength and has excellent imaging resolution. The probe light is frequency-doubled to output probe light of 515 nm.

[0038] The focusing system one 8 and the focusing system two 17 integrate 5-fold, 10-fold, 15-fold, and 20-fold objectives, and the objectives have a wide wavelength working range. The objectives with different focusing conditions can be selected according to different experimental requirements. The system has excellent laser focusing conditions, thereby ensuring extremely high laser energy density and realizing the equivalent loading of high-energy laser damage in a true sense. In this embodiment, the focusing system one 8 selects a 10-fold focusing objective, and the focusing system two 17 selects a 20-fold focusing objective.

[0039] The high-speed imaging system one 18 and the high-speed imaging system two 20 are internally provided with CCD and ICCD cameras. According to different high-energy laser damage observation requirements, appropriate cameras are selected. When the sample irradiated by the femtosecond and picosecond time scale high-energy laser is photographed, the CCD camera is directly selected, the time delay control system 12 controls the arrival time of the probe light, triggers image acquisition, and the generation of the material internal electron excitation and the shock wave can be directly observed. When the time scale is increased to nanoseconds, the ICCD camera is started, and the information acquisition rate is improved, so that the evolution of the plasma plume can be directly observed. When the sample is irradiated by the laser-induced plasma self-luminous and generates debris, the auxiliary illumination light source 22 can be started. The auxiliary illumination light source 22 uses a continuous laser as an illumination system. In this embodiment, the CCD is used to obtain the evolution process of the shock wave of the alumina ceramic when the alumina ceramic is damaged by the high-energy laser, as shown in FIG. 3. With the delay of time, the plasma absorbs laser energy, a large amount of plasma is ejected, and a plasma plume is generated on the surface of the sample. The ICCD is used to obtain the evolution process of the plasma plume, as shown in FIG. 4. Figure 4 Figure 5 In addition, the high-speed imaging system two 20 adopts a reflective pump imaging mode, and can obtain the full-time scale evolution information of the ablation pit surface.​

[0040] The laser loading sample stage 9 is composed of a high-precision electrically controlled displacement stage, which can precisely control the position of the sample relative to the laser focal point through a computer, wherein the observable sample can include transparent samples and opaque samples, specifically including fused quartz, silicon wafer, aluminum target, copper target, titanium target, carbon fiber, organic glass, metal film, dielectric film, zirconia ceramic, alumina ceramic, and other commonly used laser protection materials. In the embodiment, the sample surface is located at the position of the pump light focal point, and the spot area is selected as 6.04 μm.

[0041] The spectral information acquisition system 21 uses a spectrometer with high spectral resolution to extract spectral data from the light carried by the sample after excitation, has a wide spectral range, high data acquisition speed and multi-channel detection, and is internally provided with a non-negative least squares algorithm calibration system, and simultaneously with the high-speed imaging system 20, the surface of the material is characterized.

[0042] Therefore, the high-energy laser damage equivalent loading system can realize in-situ characterization of ultrafast dynamics, can obtain detailed image and spectral information of the material damage process by precisely controlling the beam energy and the arrival time of the probe light, can provide important scientific data for the field of laser protection and weapons, and can reduce the cost and risk compared with field testing, and is helpful to promote the development of high-energy laser weapon technology and protection technology.

[0043] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application but not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: it can still modify or equivalently replace the technical solutions of the present application, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A high-energy laser damage equivalent loading system, characterized in that: Includes a high-energy laser source, a side imaging module, and a front imaging and spectral analysis module; The side imaging module includes a high-speed imaging system 1. When the high-speed imaging system 1 acquires information: the high-energy laser source emits laser light, which is split into two beams by the first beam splitter. One beam, serving as pump light, sequentially passes through the energy regulation system 1, the first reflector, the second reflector, and the dichroic mirror to enter the focusing system 1 and be focused on the laser loading sample stage. The other beam, serving as detection light, sequentially passes through the energy regulation system 2 and the third reflector, and then sequentially enters the delay control system and the frequency doubling wave selection system. Thereafter, it passes through the fourth reflector and the fifth reflector to enter the focusing system 2, illuminates and passes through the laser loading sample stage from the side, and is imaged by the high-speed imaging system 1 to acquire side image information. The side imaging module is also provided with an auxiliary illumination light source. The front imaging and spectral analysis module includes a high-speed imaging system 2. When the high-speed imaging system 2 acquires information: the detection light passes through the fifth reflector and is separated by the second beam splitter, and is combined with the pump light into the same beam at the beam combining mirror. After passing through the dichroic mirror, it is introduced into the focusing system 1 and irradiated onto the sample. The detection light beam carrying the signal is reflected out, passes through the dichroic mirror and the third beam splitter, and enters the high-speed imaging system 2 and the spectral information acquisition system respectively to acquire front image information and spectral information.

2. A high-energy laser damage equivalent loading system according to claim 1, characterized in that: The high-energy laser source is an ultrafast split-second laser with an internal optical parametric amplifier.

3. The high-energy laser damage equivalent loading system according to claim 1, characterized in that: The energy regulation system 1 and the energy regulation system 2 are combined with a polarizer, a half-wave plate and a PBS crystal to coordinately regulate the energy of the light beam.

4. The high-energy laser damage equivalent loading system according to claim 1, characterized in that: The time delay control system includes a driving device and a hollow corner mirror, and the movement of the hollow corner mirror is precisely controlled by a stepping motor.

5. The high-energy laser damage equivalent loading system according to claim 1, characterized in that: The frequency doubling and wave selection system uses lithium triborate (LBO) nonlinear optical crystals to double the frequency of high-energy lasers and uses absorption filters of specific wavelengths to perform wave selection.

6. The high-energy laser damage equivalent loading system according to claim 1, characterized in that: The focusing system 1 and the focusing system 2 are integrated with 5x, 10x, 15x and 20x objective lenses.

7. The high-energy laser damage equivalent loading system according to claim 1, characterized in that: The first high-speed imaging system and the second high-speed imaging system are equipped with two cameras, CCD and ICCD.

8. The high-energy laser damage equivalent loading system according to claim 1, characterized in that: The auxiliary illumination light source uses a continuous laser as an illumination system.

9. The high-energy laser damage equivalent loading system according to claim 1, characterized in that: The laser loading sample stage is composed of a high-precision electric-controlled displacement stage.

10. The high-energy laser damage equivalent loading system according to claim 1, characterized in that: The spectral information acquisition system uses a spectrometer with high spectral resolution and is equipped with a non-negative least squares algorithm calibration system.

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