High-energy laser damage equivalent loading system

Abstract

The invention discloses a high-energy laser damage equivalent loading system, which belongs to the technical field of laser damage and protection, and comprises a high-energy laser source, a side imaging module and a front imaging and spectrum analysis module, wherein the side surface imaging module and the front surface 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 table, a high-speed imaging system I, a high-speed imaging system II, a spectrum information acquisition system and an auxiliary illumination light source; wherein the related optical lenses comprise a beam splitter, a beam combiner, a reflector and a dichroscope; the high-energy laser damage equivalent loading system aims at simulating the laser damage process in a real environment so as to deeply understand the action mechanism of a material under laser loading, in-situ characterization of ultrafast dynamics can be achieved, and detailed images and spectral information of the material damage process can be obtained.

Description

Technical Field

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

[0002] High-energy laser beams are often used as a high-precision, fast-killing photobomb in military and other fields. They have the characteristics of high energy density, low launch cost, fast strike speed and high strike accuracy. When a material is impacted by a high-energy laser, the irradiated area will face microscopic plasma changes, temperature rise, material dissociation and thermal stress damage, which can easily cause structural failure or even disintegration. With the continuous development of military strategies and tactics, there is an urgent need for scientific research systems to restore the high-energy laser damage process in an experimental environment, thoroughly understand the mechanism of action of materials when loaded by lasers, and promote the development of my country's laser protection industry. The ultrafast and ultra-strong characteristics of femtosecond pulse lasers make the energy density, action space and time scale of the lasers tend to extremes during the irradiation process. Therefore, the physical effects and action mechanisms involved in the femtosecond laser damage process include nonlinearity and non-equilibrium, which can more clearly explore the physical and chemical properties of the stimulated materials during the high-energy laser damage process.

[0003] At present, the design and development mode of high-energy laser equivalent loading system in my country is still at the stage of "trial and error" and semi-empirical. Laser light sources with long action time are often used in laser loading systems, but the peak power density is limited and accompanied by thermal effects, which is not conducive to the mechanism of stimulating ultrafast time scale materials. Secondly, when collecting information on the material damage process, most of the current methods are based on traditional optical imaging, and the time scale of in-situ collection is often at the nanosecond level, which cannot characterize the material damage process with high time resolution of picoseconds or even femtoseconds.

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

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

[0006] To achieve the above-mentioned object, the present invention provides a high-energy laser damage equivalent loading system, comprising a high-energy laser source, a side imaging module and a front imaging and spectral analysis module;

[0007] 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 divided into two beams by the first beam splitter. One beam is used as pump light and passes through the energy regulation system 1, the first reflector, the second reflector and the dichroic mirror in sequence to enter the focusing system 1 and be focused on the laser loading sample stage. The other beam is used as detection light and passes through the energy regulation system 2 and the third reflector in sequence, and then enters the delay control system and the frequency doubling wave selection system in sequence, and then passes through the fourth reflector and the fifth reflector to enter the focusing system 2, irradiate and pass through the laser loading sample stage from the side, and is imaged on the high-speed imaging system 1 to acquire side image information. The side imaging module is also provided with an auxiliary lighting source.

[0008] 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 respectively enters the high-speed imaging system 2 and the spectral information acquisition system to acquire the front image information and spectral information.

[0009] Preferably, the high-energy laser source is an ultrafast split-second laser that can output pulsed laser with a wavelength of 1030nm, and has a built-in optical parametric amplifier that uses nonlinear crystals to achieve amplification and frequency conversion of signal beams. By adjusting the crystal parameters, the laser wavelength can be changed, making the output pulsed laser wavelength adjustable from 480 to 1200nm, providing a wide range of wavelength options to meet different application requirements.

[0010] Preferably, 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 beam energy to meet the laser energy requirements of materials with different ablation thresholds.

[0011] Preferably, the 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 stepper motor. The step size of the stepper motor can be as small as 100nm, and the optical path of the detection light can be precisely controlled, thereby controlling the arrival time of the detection light.

[0012] Preferably, the frequency doubling and wave selection system uses lithium triborate LBO nonlinear optical crystal to double the frequency of high-energy lasers, and uses absorption filters of specific wavelengths to select the required wavelength beam according to the different absorption capacities of light of different wavelengths.

[0013] Preferably, the focusing system 1 and the focusing system 2 integrate 5x, 10x, 15x, and 20x objective lenses, which have a wide wavelength working range, and objective lenses of corresponding magnifications can be selected according to the focusing conditions required by different experiments.

[0014] Preferably, the high-speed imaging system 1 and the high-speed imaging system 2 are equipped with two types of cameras, namely, CCD and ICCD, and suitable 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 electric-controlled translation stage, and the position of the sample relative to the laser focus 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 carrying the sample after being stimulated.

[0018] Therefore, the present invention adopts the above-mentioned high-energy laser damage equivalent loading system, which has the following beneficial effects:

[0019] (1) It can simulate the laser damage process in the air in the laboratory, with controllable laser experimental conditions, ultra-fast time resolution and full-time scale information collection capabilities, significantly reducing costs and risks compared to field testing;

[0020] (2) It helps to test and evaluate the response of new materials and structures to high-energy lasers, provides a 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 solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0023] Figure 2 This is a schematic diagram of the structure of a side imaging module of a high-energy laser damage equivalent loading system of the present invention;

[0024] Figure 3 This is a schematic diagram of the structure of a front imaging and spectral analysis module of a high-energy laser damage equivalent loading system of the present invention;

[0025] Figure 4 This is a shock wave evolution image of a high-energy laser damage equivalent loading system of the present invention;

[0026] Figure 5 This is a plasma plume evolution image of a high-energy laser damage equivalent loading system of the present invention;

[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. 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. spectral 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 invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are 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, and the high-energy laser damage material in this embodiment takes alumina ceramic 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 divided 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 is 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 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 in the high-speed imaging system 18 to obtain image information of the side of the sample after being loaded with high-energy laser. At the same time, the auxiliary lighting source 22 can be turned on according to experimental needs;

[0032] like Figure 3As shown, the optical path of the front imaging and spectral analysis module is as follows: the pump light passes through the third reflector 11, the beam combining mirror 6 and the dichroic mirror 7 in sequence and is introduced into the focusing system 8, while the detection light passes through the fifth reflector 15 and is separated by the second beam splitter 16, and is combined into the same beam with the pump light at the beam combining mirror 6, and is introduced into the focusing system 8 after passing through the dichroic mirror 7 and the third beam splitter 19, and then irradiates the sample. The detection light beam carrying the signal is reflected out, and is divided 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 after the sample is loaded with high-energy laser and the spectral information of the ablation process.

[0033] High-energy laser source 1 is an ultrafast femtosecond laser that can output pulsed lasers with a wavelength of 1030nm. It has an optical parametric amplifier built in, and uses nonlinear crystals to achieve amplification and frequency conversion of signal beams. By adjusting the crystal parameters, the laser wavelength can be changed, making the output pulsed laser wavelength 480-1200nm adjustable, providing a wide range of wavelength options to meet different application requirements. Based on the ultra-short action time, multi-photon effect and nonlinear phenomena of femtosecond lasers, including ultrafast dynamic processes such as various photon absorption, electron excitation, material phase change, plasma shock waves, plume eruption and material removal, these advantages help to deeply understand the mechanism of materials after being loaded with high-energy lasers.

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

[0035] Energy regulation system 1 3 and energy regulation system 2 10 combine polarizer, half-wave plate and PBS crystal to coordinately regulate the energy of the light beam. The polarizer can selectively pass through an optical element that vibrates light in a specific direction to allow light with the same polarization direction to pass through; while the half-wave plate can change the polarization state of the light, continuously adjust the polarization direction of the light, and thus regulate the energy of the light. The PBS crystal can further split and reflect the light to achieve precise control and regulation of the beam energy. Through the synergistic effect of these three components, the system can finely adjust the beam energy to meet the laser energy requirements of materials with different ablation thresholds. In this embodiment, the pump light uses a single-pulse laser energy of 400 μj, and the detection light uses a laser energy of 0.5 μj.

[0036] The time delay control system 12 includes a driving device and a hollow corner mirror. The stepper motor accurately controls the movement of the corner mirror. The step length of the stepper motor can be as small as 100nm, and the optical path of the detection light can be accurately controlled, thereby controlling the arrival time of the detection light, ensuring the time difference between the arrival time of the detection light and the pump light, thereby obtaining the evolution information of the material loaded by the high-energy laser at this moment. When observing the shock wave, the time interval of each photo is set to 200ps.

[0037] The frequency doubling and wave selection system 13 uses lithium triborate LBO nonlinear optical crystals, which have a wide transparent range, high optical quality, high nonlinear parameters, high laser damage threshold and good thermal stability. It doubles the frequency of high-energy lasers, and then uses a specific wavelength absorption filter to select the required wavelength beam according to the different absorption capabilities of different wavelengths of light. The wavelength of the detection light is selected to be half of the pump light. According to the diffraction theory of light and the absorption characteristics of materials, a short wavelength helps to enhance the signal strength and has excellent imaging resolution. The detection light is frequency-doubled to output a 515nm detection light.

[0038] Focusing system 1 8 and focusing system 2 17 integrate 5x, 10x, 15x, and 20x objective lenses, and the objective lenses have a wide wavelength working range, and the corresponding magnification objective lenses can be selected according to the focusing conditions required by different experiments. The system has excellent laser focusing conditions, thereby ensuring extremely high laser energy density and achieving equivalent loading of high-energy laser damage in the true sense. In this embodiment, focusing system 1 8 uses a 10x focusing objective lens, and focusing system 2 17 uses a 20x focusing objective lens.

[0039] High-speed imaging system 1 18 and high-speed imaging system 2 20 are equipped with two types of cameras, CCD and ICCD. The appropriate camera can be selected according to different high-energy laser damage observation requirements. When photographing the phenomenon of samples irradiated by high-energy lasers on a femtosecond or picosecond time scale, the CCD camera is directly selected. The delay control system 12 controls the arrival time of the detection light and triggers image acquisition, so that the electron excitation inside the material and the generation of shock waves can be directly observed. When the shooting time scale is increased to nanoseconds, the ICCD camera is turned on to increase the information acquisition rate, so that the evolution of the plasma plume can be directly observed. When the spontaneous emission of the plasma generated by the sample ends and debris is generated, the auxiliary lighting source 22 can be turned on. The auxiliary lighting source 22 uses a continuous laser as the lighting system. This embodiment uses CCD to obtain the evolution process of the shock wave when the alumina ceramic is damaged by a high-energy laser, such as Figure 4 As time goes by, the plasma absorbs the laser energy and erupts in large quantities, generating a plasma plume on the sample surface. The evolution of the plasma plume was obtained using ICCD, as shown in Figure 2. Figure 5 In addition, the high-speed imaging system 20 adopts reflection pump imaging to obtain the full time scale evolution information of the ablation crater surface.

[0040] The laser loading sample stage 9 is composed of a high-precision electric-controlled displacement stage, and the position of the sample relative to the laser focus can be precisely controlled by a computer, wherein the observable samples may include transparent samples and opaque samples, specifically including fused quartz, silicon wafers, aluminum targets, copper targets, titanium targets, carbon fibers, organic glass, metal films, dielectric films, zirconium oxide ceramics, aluminum oxide ceramics, and other commonly used laser protection materials. In this embodiment, the sample surface is located at the focus of the pump light, and the spot area is selected to be 6.04 μm.

[0041] The spectral information acquisition system 21 uses a spectrometer with high spectral resolution to extract spectral data from the light after the sample is excited. It has a wide spectral range, high data acquisition speed and multi-channel detection, and a built-in non-negative least squares algorithm calibration system. It can characterize the material surface simultaneously with the high-speed imaging system 20.

[0042] Therefore, the present invention adopts the above-mentioned high-energy laser damage equivalent loading system to realize in-situ characterization of ultrafast dynamics; by precisely controlling the beam energy and the arrival time of the detection light, detailed images and spectral information of the material damage process can be obtained; the time resolution capability can reach the femtosecond level, which can provide important scientific data for the field of laser protection and weapons; in addition, compared with field testing, it reduces costs and risks, and helps 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 solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A high energy laser damage equivalent loading system, characterized in that: It 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 divided into two beams by the first beam splitter. One beam is used as pump light and passes through the energy regulation system 1, the first reflector, the second reflector and the dichroic mirror in sequence to enter the focusing system 1 and be focused on the laser loading sample stage. The other beam is used as detection light and passes through the energy regulation system 2 and the third reflector in sequence, and then enters the delay control system and the frequency doubling wave selection system in sequence, and then passes through the fourth reflector and the fifth reflector to enter the focusing system 2, irradiate and pass through the laser loading sample stage from the side, and is imaged on the high-speed imaging system 1 to acquire side image information. The side imaging module is also provided with an auxiliary lighting 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 respectively enters the high-speed imaging system 2 and the spectral information acquisition system to acquire the 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 and is equipped with an optical parametric amplifier.

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

5. A 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 crystal to double the frequency of high-energy laser and uses absorption filters of specific wavelengths for wave selection.

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

7. A high energy laser damage equivalent loading system according to claim 1, characterized in that: The high-speed imaging system 1 and the high-speed imaging system 2 are equipped with two types of cameras, namely, CCD and ICCD.

8. A 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. A 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. A 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.

Images