A laser device for cleaning the surface of cultural relics

Abstract

The present invention discloses a laser device for cleaning the surface of cultural relics, relating to the field of cultural relic restoration technology. The device primarily comprises a femtosecond laser module, a three-dimensional galvanometer module, and a display module. The femtosecond laser module is configured to emit a high-frequency GHz laser light, which is used to clean the surface of the cultural relic. The three-dimensional galvanometer module is capable of receiving the high-frequency GHz laser light emitted by the femtosecond laser module and controlling the position of the laser light acting on the surface of the cultural relic by controlling the optical path of the high-frequency GHz laser light. The display module is configured to display a planar image of the high-frequency GHz laser light irradiated on the surface of the cultural relic. The present invention utilizes a high-frequency GHz laser light to clean cultural relics, stimulating an "ablation cooling" mechanism on the surface of the cultural relic. This mechanism ablates impurities on the surface of the cultural relic without damaging the base of the cultural relic. Furthermore, the display module visualizes the laser light, enabling the effect of cleaning the cultural relic while observing it.

Description

Technical Field

[0001] The present invention relates to the technical field of cultural relic restoration, in particular to a laser device for cleaning the surface of cultural relics. Background Art

[0002] Cultural relics are often preserved in open or semi-open areas. Due to natural weathering, human activity, biological erosion, and environmental pollution, their surfaces suffer varying degrees of surface damage, including contaminant accumulation, discoloration, hard scaling, smoke buildup, accumulation of harmful salts, and microbial attack. These surface coverings not only visually pollute the artifacts, but their harmful components also pose a serious threat to their preservation, causing damage and hindering the implementation and effectiveness of further conservation measures. Therefore, the removal of harmful contaminants from artifact surfaces is a fundamental technology for cultural relic conservation and a crucial element in its success.

[0003] Currently, common cleaning methods for cultural relics include chemical cleaning, steam jet cleaning, particle jet cleaning, and laser cleaning. Among these cleaning techniques, chemical cleaning suffers from the difficulty of determining the long-term impact of residues on the artifacts and is prone to environmental pollution. A problem with steam jet cleaning is that, when used on artifacts with degraded surfaces, the high temperature of the steam can cause uneven thermal expansion inside and outside the artifacts, leading to stress fractures. Particle jet cleaning can severely abrade the surface, particularly at sharp corners. Laser cleaning, on the other hand, utilizes a high-power-density laser beam to irradiate the surface of the object being cleaned, causing surface contaminants to instantly fragment, evaporate, or peel off, freeing them from the surface. Laser cleaning is characterized by its excellent cleaning effectiveness, non-contact operation, environmental friendliness, residue-free operation, safety, reliability, water conservation, precise controllability, wide applicability, and low operating costs. However, existing laser cleaning techniques for cultural relics require lasers of varying intensities depending on the type of artifact. Using an inappropriate laser can damage the artifact's substrate, potentially damaging it. Therefore, a laser device for cleaning the surface of cultural relics is needed that is less susceptible to damage. Summary of the Invention

[0004] The purpose of the present invention is to provide a laser device for cleaning the surface of cultural relics, so as to solve the problems existing in the above-mentioned prior art and prevent the substrate of the cultural relics from being damaged.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a laser device for cleaning the surface of cultural relics, comprising

[0007] A femtosecond laser module, which is used to emit GHz high-repetition-rate laser light, and the GHz high-repetition-rate laser light is used to clean the surface of cultural relics;

[0008] A three-dimensional galvanometer module, which is capable of receiving the GHz high repetition rate laser emitted by the femtosecond laser module and controlling the position of the GHz high repetition rate laser on the surface of the cultural relic;

[0009] A display module is used to display a planar image of the surface of the cultural relic irradiated by the GHz high repetition rate laser.

[0010] Preferably, the femtosecond laser module includes a laser oscillator, which includes a semiconductor saturable absorber mirror, a first gain fiber, a dispersive dielectric film, a first single-mode semiconductor pump laser, a first wavelength division multiplexer, and a first optical fiber isolator connected in sequence through optical fibers, and is used to generate GHz high repetition rate laser;

[0011] The length of the optical resonant cavity of the laser oscillator is less than 10 cm, and the generation of the GHz high repetition rate laser is ensured according to the mode locking principle.

[0012] Preferably, the femtosecond laser module further includes an amplifier component, which is connected to the laser oscillator and is used to amplify the GHz high repetition rate laser emitted by the laser oscillator.

[0013] Preferably, the amplifier assembly includes a first-stage amplifier, a second-stage amplifier, and a third-stage amplifier, the first-stage amplifier is connected to the laser oscillator via an optical fiber, and the first-stage amplifier, the second-stage amplifier, and the third-stage amplifier are sequentially connected via optical fibers;

[0014] The first-stage amplifier comprises a second single-mode semiconductor pump laser, a second wavelength division multiplexer, a second gain fiber, a second fiber isolator and a single-mode fiber connected in sequence through optical fibers, and the first-stage amplifier is used for primary amplification of the GHz high repetition rate laser;

[0015] The second-stage amplifier comprises a third single-mode semiconductor pump laser, a third wavelength division multiplexer, a third gain fiber and a third fiber isolator connected in sequence through optical fibers, and the second-stage amplifier is used for second-stage amplification of the GHz high repetition rate laser;

[0016] The third-stage amplifier includes a multimode semiconductor pump laser, a fourth wavelength division multiplexer, a double-clad gain fiber and a fourth fiber isolator connected in sequence through optical fibers. The third-stage amplifier is used for third-stage amplification of the GHz high repetition rate laser.

[0017] Preferably, a processing module is further included, which is connected to the end of the amplifier component and is used to perform pulse shaping and direction change processing on the GHz high repetition rate laser.

[0018] Preferably, the processing module includes a collimator, a first reflector, a first grating, a second reflector and a second grating, which are arranged in sequence. The collimator is connected to the amplifier component, and can convert the GHz high repetition rate laser into collimated light, and make the GHz high repetition rate laser pass through the collimator, the first grating, and the second grating in sequence to be incident on the second reflector, and then pass through the second grating and the first grating to be incident on the first reflector after being reflected by the second reflector, and then be reflected by the first reflector to be transmitted into the three-dimensional galvanometer module.

[0019] Preferably, the three-dimensional galvanometer module includes a zoom module, a scanning module and a focusing module arranged in sequence, the zoom module is used to change the focal length of the GHz high repetition rate laser, the scanning module is used to change the incident direction and scanning range of the GHz high repetition rate laser, and the focusing module is used to focus the GHz high repetition rate laser. The GHz high repetition rate laser can be focused on the surface of the cultural relic after passing through the zoom module, the scanning module and the focusing module in sequence;

[0020] Wherein, the focusing module includes a convex lens, the zoom module includes a zoom lens group, and the scanning module includes a scanning galvanometer.

[0021] Preferably, the three-dimensional galvanometer module further includes a third reflector and a dichroic mirror, the dichroic mirror is located in front of the zoom lens group, and the third reflector is located between the zoom lens group and the scanning galvanometer; wherein the dichroic mirror can reflect the GHz high repetition rate laser, so that the GHz high repetition rate laser passes through the zoom lens group, the third reflector, the scanning galvanometer and the convex lens in sequence and then acts on the surface of the cultural relic; the dichroic mirror can also allow light returned from the surface of the cultural relic to pass through and transmit it to the display module for imaging.

[0022] Preferably, the display module includes an attenuation plate, an aperture, an objective lens and a CCD arranged in sequence along the transmission direction of the light returned from the surface of the cultural relic. The CCD electrical signal is connected to a display. The light returned from the surface of the cultural relic can pass through the attenuation plate, the aperture and the objective lens in sequence and be incident on the CCD, and the image is displayed on the display.

[0023] Preferably, it further comprises an intelligent platform module, wherein the intelligent platform module is used to place the cultural relics and can adjust the position of the cultural relics;

[0024] The intelligent platform module includes an X-axis adjustment frame, a Y-axis adjustment frame, a Z-axis adjustment frame, and a fixed platform. The X-axis adjustment frame, the Y-axis adjustment frame, and the Z-axis adjustment frame form a three-dimensional coordinate system, which are perpendicular to each other. In addition, the intelligent platform module is electrically connected to the display. The display can control the movement of the X-axis adjustment frame, the Y-axis adjustment frame, and the Z-axis adjustment frame. The fixed platform is used to fix the cultural relic. The X-axis adjustment frame and the Y-axis adjustment frame are used to adjust the planar position of the cultural relic to ensure that different positions of the cultural relic can be cleaned. The Z-axis adjustment frame can tune the distance of the cultural relic relative to the three-dimensional galvanometer module according to the imaging picture of the display, thereby adjusting the imaging spot size of the cultural relic.

[0025] Compared with the prior art, the present invention has achieved the following technical effects:

[0026] The femtosecond laser module of the present invention is used to emit GHz high repetition rate laser, which is used to clean the surface of cultural relics. The three-dimensional galvanometer module can receive the GHz high repetition rate laser emitted by the femtosecond laser module and control the position of the GHz high repetition rate laser acting on the surface of the cultural relics. The display module is used to display a planar image of the surface of the cultural relics irradiated by the GHz high repetition rate laser. Using the GHz high repetition rate laser to clean cultural relics can stimulate the "ablation cooling" mechanism on the surface of the cultural relics, that is, after ablating impurities on the surface of the cultural relics, no damage is caused to the substrate of the cultural relics. In addition, using the display module to visualize the laser can achieve the effect of cleaning the cultural relics while observing.

[0027] Using GHz high-repetition-rate lasers to clean cultural relics can stimulate the "ablation cooling" mechanism on the surface of the cultural relics. That is, after ablating impurities on the surface of the cultural relics, it will not cause damage to the base of the cultural relics. The specific principle is:

[0028]

[0029]

[0030] E diff =α(T c -T0)N

[0031] Among them, E diff is the heat diffused by the laser pulse, T c is the ablation temperature, T0 is the initial temperature of the object, τ0 is the thermal relaxation time, τ R is the pulse interval, α is the thermal diffusion coefficient, and N is the number of pulses. The first formula is the energy of heat diffusion from a single pulse to the surrounding material, the second formula is the energy of heat diffusion from the Nth pulse to the surrounding material under high repetition rate conditions, and the third formula is the energy of heat diffusion from the Nth pulse to the surrounding material under low repetition rate conditions. From the above model, we can see that for high repetition rate conditions, that is, τR It is much smaller than τ0, and the heat diffusion to the surrounding materials is much smaller than the result under low repetition frequency conditions, that is, it will not cause damage to the cultural relic base. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 Schematic diagram of the structure of a laser device for cleaning the surface of cultural relics in an embodiment of the present invention;

[0034] Figure 2 Schematic diagram of the structure of a femtosecond laser module in an embodiment of the present invention.

[0035] In the figure: 100 - femtosecond laser module; 101 - processing module; 102 - 3D galvanometer module; 103 - display module; 104 - intelligent platform module; 1 - semiconductor saturable absorber mirror; 2 - first gain fiber; 3 - dispersive dielectric film; 4 - first single-mode semiconductor pump laser; 5 - first wavelength division multiplexer; 6 - first fiber isolator; 7 - second single-mode semiconductor pump laser; 8 - second wavelength division multiplexer; 9 - second gain fiber; 10 - second fiber isolator; 11 - single-mode fiber; 12 - third wavelength division multiplexer; 13 - third single-mode semi-conductor pump laser Conductor-pumped laser; 14-third gain fiber; 15-third fiber isolator; 16-fourth wavelength division multiplexer; 17-multimode semiconductor-pumped laser; 18-double-clad gain fiber; 19-fourth fiber isolator; 21-first reflector; 22-first grating; 23-second grating; 24-second reflector; 25-collimator; 26-CCD; 27-objective lens; 28-aperture; 29-attenuator; 30-third reflector; 31-display; 32-dichroic mirror; 33-zoom lens group; 34-scanning galvanometer; 35-convex lens. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] The purpose of the present invention is to provide a laser device for cleaning the surface of cultural relics, so as to solve the problems existing in the prior art and prevent the substrate of the cultural relics from being damaged.

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Example 1

[0040] like Figure 1-Figure 2 As shown, the present invention provides a laser device for cleaning the surface of cultural relics, including a femtosecond laser module 100, a three-dimensional galvanometer module 102 and a display module 103. The femtosecond laser module 100 is used to emit GHz high repetition rate laser, which is used to clean the surface of cultural relics; the three-dimensional galvanometer module 102 can receive the GHz high repetition rate laser emitted by the femtosecond laser module 100 and control the position where the GHz high repetition rate laser acts on the surface of the cultural relics; the display module 103 is used to display a planar image of the GHz high repetition rate laser irradiating the surface of the cultural relics. Using the GHz high repetition rate laser to clean the cultural relics can stimulate the "ablation cooling" mechanism on the surface of the cultural relics, that is, after ablating impurities on the surface of the cultural relics, it will not cause damage to the substrate of the cultural relics. Moreover, using the display module 103 to visualize the laser can achieve the effect of cleaning the cultural relics while changing the observation edge. Moreover, when using the GHz high repetition rate laser to ablate the same volume, the required single pulse energy is greatly reduced compared with ordinary lasers, reduced to the inverse of the repetition frequency.

[0041] Specifically, using GHz high-repetition-rate lasers to clean cultural relics can stimulate the "ablation cooling" mechanism on the surface of the cultural relics. That is, after ablating impurities on the surface of the cultural relics, it will not cause damage to the base of the cultural relics. The principle is as follows:

[0042]

[0043]

[0044] E diff =α(T c -T0)N

[0045] Among them, E diff is the heat diffused by the laser pulse, T c is the ablation temperature, T0 is the initial temperature of the object, τ0 is the thermal relaxation time, τ R is the pulse interval, α is the thermal diffusion coefficient, and N is the number of pulses. The first formula is the energy of heat diffusion from a single pulse to the surrounding material, the second formula is the energy of heat diffusion from the Nth pulse to the surrounding material under high repetition rate conditions, and the third formula is the energy of heat diffusion from the Nth pulse to the surrounding material under low repetition rate conditions. From the above model, we can see that for high repetition rate conditions, that is, τ R It is much smaller than τ0, and the heat diffusion to the surrounding materials is much smaller than the result under low repetition frequency conditions, that is, it will not cause damage to the cultural relic base.

[0046] In this embodiment, a femtosecond laser module 100 includes a laser oscillator comprising a semiconductor saturable absorber mirror 1, a first gain fiber 2, a dispersive dielectric film 3, a first single-mode semiconductor pump laser 4, a first wavelength division multiplexer 5, and a first fiber isolator 6, connected in sequence via optical fibers, for generating high-repetition-rate GHz laser light. The optical resonator of the laser oscillator is less than 10 cm long. Based on the principle of mode locking, the generation of high-repetition-rate GHz laser light is ensured. The optical resonator of the laser is an optical cavity in which the frequency of the laser wave is limited by the resonance conditions. The length of the optical resonator affects the frequency of the laser wave. The spectral spacing can be calculated using the following formula: Spectral spacing = c / (2*I), where c represents the speed of light and L represents the length of the optical resonator. This shows that a short laser resonator length is required to generate high-frequency laser light. This embodiment utilizes a laser oscillator with an optical resonator less than 10 cm. Compared to existing laser oscillators with longer optical resonators, this embodiment can generate high-repetition-rate laser light exceeding 1 GHz, thereby ensuring the occurrence of the ablation cooling mechanism.

[0047] The semiconductor saturable absorber mirror 1 includes a semiconductor saturable absorber and a reflecting mirror. Ultrashort pulses of the order of femtoseconds can be generated through the saturable absorption characteristics of the semiconductor saturable absorber mirror 1.

[0048] The gain fiber is used to amplify the optical signal in the laser. When the laser signal passes through the gain fiber, the excited particles of the dopant interact with the photons, achieving optical signal amplification. The first single-mode semiconductor pump laser 4 is used to excite and amplify the femtosecond laser light generated by the semiconductor saturable absorber mirror 1. The first wavelength division multiplexer 5 combines optical signals of different wavelengths into a single beam and transmits it through a single optical fiber. The optical signals of different wavelengths are then separated at the receiving end. This fully utilizes the vast bandwidth resources provided by the low-loss region of the single-mode optical fiber 11. The low-loss window of the optical fiber can be divided into several channels based on the frequency (or wavelength) of each channel's light wave. In this way, multiple optical signals can be multiplexed and transmitted within a single optical fiber, thereby increasing the system's transmission capacity. The optical fiber isolator uses an optical polarization element to maintain a different polarization direction between the input and output optical signals, thereby achieving optical signal isolation. Any reflected or echo signals generated at the output end cannot be transmitted back to the input end, thus achieving unidirectional transmission and isolation of the optical signal.

[0049] In this embodiment, the femtosecond laser module 100 further includes an amplifier component, which is connected to the laser oscillator and is used to amplify the GHz high repetition rate laser emitted by the laser oscillator. The amplifier component includes a first-stage amplifier, a second-stage amplifier, and a third-stage amplifier. The first-stage amplifier is connected to the laser oscillator via an optical fiber, and the first-stage amplifier, the second-stage amplifier, and the third-stage amplifier are connected in sequence via optical fibers.

[0050] The first-stage amplifier includes a second single-mode semiconductor pump laser 7, a second wavelength division multiplexer 8, a second gain fiber 9, a second optical fiber isolator 10 and a single-mode optical fiber 11, which are connected in sequence through optical fibers. The first-stage amplifier is used for primary amplification of GHz high repetition rate laser;

[0051] The second-stage amplifier includes a third single-mode semiconductor pump laser 13, a third wavelength division multiplexer 12, a third gain fiber 14 and a third fiber isolator 15, which are connected in sequence through optical fibers. The second-stage amplifier is used for the second-stage amplification of GHz high repetition rate laser light;

[0052] The third-stage amplifier includes a multimode semiconductor pump laser 17, a fourth wavelength division multiplexer 16, a double-clad gain fiber 18, and a fourth fiber isolator 19, which are connected in sequence through optical fibers. The third-stage amplifier is used for the third-stage amplification of GHz high-repetition-rate lasers. The doping ions of the gain fibers are all ytterbium ions. After processing by the amplifier components, a laser with a central wavelength of 1030nm, an average power of 10W, a pulse width of 300fs, and a repetition frequency of 3GHz is finally generated.

[0053] It should be noted that the power of the fourth optical fiber isolator 19 is greater than the power of the first optical fiber isolator 6 , the second optical fiber isolator 10 and the third optical fiber isolator 15 .

[0054] In this embodiment, a processing module 101 is also included. The processing module 101 is connected to the end of the amplifier and is used to perform pulse shaping and redirection processing on the GHz high repetition rate laser. The processing module 101 includes a collimator 25, a first reflector 21, a first grating 22, a second grating 23 and a second reflector 24, which are arranged in sequence. The collimator 25 is connected to the third-stage amplifier and can convert the GHz high repetition rate laser into collimated light. The GHz high repetition rate laser passes through the collimator 25, the first grating 22 and the second grating 23 in sequence, and is reflected by the second reflector 24 and then passes through the second grating 23 and the first grating 22 before being emitted through the first reflector 21. It can be transmitted to the three-dimensional galvanometer module 102, and the GHz high repetition rate laser is dispersed by the grating to ensure that the required wavelength can enter the three-dimensional galvanometer module 102.

[0055] In this embodiment, the three-dimensional galvanometer module 102 includes a focusing module, a zoom module and a scanning module. The GHz high repetition rate laser can be focused on the surface of the cultural relic after passing through the zoom module, the scanning module and the focusing module in sequence. The scanning module is used to change the incident direction and scanning range of the GHz high repetition rate laser, the zoom module is used to change the focal length of the GHz high repetition rate laser, and the focusing module is used to focus the GHz high repetition rate laser; wherein, the focusing module includes a convex lens 35, the zoom module includes a zoom lens group 33, and the scanning module includes a scanning galvanometer 34. The scanning galvanometer 34 controls the optical path, thereby realizing the deflection and focusing of the laser beam. The three-dimensional galvanometer module 102 can control the position of the laser focus on the surface of the cultural relic through the convex lens 35, and can realize the adjustment of the focus height.

[0056] In this embodiment, the three-dimensional galvanometer module 102 also includes a third reflector 30 and a dichroic mirror 32. The dichroic mirror 32 is used to separate the GHz high repetition rate laser according to the wavelength. The GHz high repetition rate laser transmitted by the processing module is reflected by the dichroic mirror 32 and passes through the zoom lens group 33, the third reflector 30, the scanning galvanometer 34 and the convex lens 35 in sequence before acting on the surface of the cultural relic. The GHz high repetition rate laser returned from the surface of the cultural relic can pass through the dichroic mirror 32 and then be transmitted to the display module 103 for imaging. The dichroic mirror 32 can transmit or reflect light according to the wavelength to realize spectral splitting.

[0057] The three-dimensional galvanometer module 102 is used to control the position of the laser focus on the surface of the cultural relic. The focal length of the convex lens 35 is 250mm, the scanning galvanometer 34 has a scanning angle of ±0.35rad, the wavelength of the transmitted light of the dichroic mirror is 400-700nm, and the wavelength of the reflected light of the dichroic mirror is 700nm-1200nm. In addition to controlling the laser focus in the two-dimensional plane scanning, it can also realize the adjustment of the focus height with a tuning range of ±70mm, which is used for position correction due to the uneven surface of the cultural relic during the cultural relic cleaning process.

[0058] In this embodiment, the display module 103 includes an aperture 28, an attenuation plate 29, an objective lens 27, a CCD 26, and a display 31. The display module 103 is connected to the three-dimensional galvanometer module 102. The GHz high repetition rate laser returning from the surface of the cultural relic can enter the display module 103 after passing through the three-dimensional galvanometer module 102 and can be used for imaging. The aperture 28 is an aperture 28 with adjustable spot size. The aperture 28 and the objective lens 27 are used to adjust the size of the spot of the GHz high repetition rate laser incident on the CCD 26. The attenuation plate 29 is used to attenuate the G laser incident on the CCD 26. Hz high repetition rate laser intensity, the display 31 is electrically connected to the CCD26, and the display 31 is used to display the imaging of the display module 103. The attenuator can weaken the amount of light entering the CCD26, and will not weaken a certain color light more than other colors of light, so as to ensure the overall balance of the light. Since the optical path of the GHz high repetition rate laser and the optical path returning from the surface of the cultural relic both pass through the three-dimensional galvanometer module 102 and then enter the display module 103, the display module 103 can display the image of the laser focal plane, so that cleaning and observation can be achieved at the same time.

[0059] In this embodiment, an intelligent platform module 104 is also included. The intelligent platform module 104 is used to place cultural relics and can adjust the position of cultural relics. The intelligent platform module 104 includes an X-axis adjustment frame, a Y-axis adjustment frame, a Z-axis adjustment frame and a fixed platform. In addition, the intelligent platform module 104 is connected to the display 31 by electrical signals. The display 31 can control the movement of the X-axis adjustment frame, the Y-axis adjustment frame and the Z-axis adjustment frame. The fixed platform is used to fix the cultural relics. The X-axis adjustment frame and the Y-axis adjustment frame are used to adjust the plane position of the cultural relics to ensure that different positions of the cultural relics can be cleaned. The Z-axis adjustment frame can tune the distance between the cultural relics and the three-dimensional galvanometer module 102 according to the imaging picture of the display 31, thereby being able to Adjust the imaging spot size of the cultural relic. The adjustable stroke of the X-axis adjustment frame and the Y-axis adjustment frame is 150 mm, and the adjustable stroke of the Z-axis adjustment frame is 100 mm. The platform load capacity of the fixed cultural relic is 20 kg. The adjustment is made through the driver connected to the display 31. The adjustment resolution of the X-axis adjustment frame, the Y-axis adjustment frame, and the Z-axis adjustment frame is 0.1 mm, and the maximum electronic displacement speed is 15 mm / s. The intelligent platform module 104 can be connected to the display 31 and adjusted through the driver. The imaging picture of the display 31 is used as a reference for tuning. If the surface of the cultural relic is rough, the Z-axis adjustment frame can be tuned and the focus can be adjusted until the image is clear, thus completing the position correction due to the uneven surface of the cultural relic.

[0060] It should be noted that the intelligent platform module 104 may not be provided. When encountering larger cultural relics, the three-dimensional galvanometer module 102 may be provided to move to clean the cultural relics.

[0061] Example 2

[0062] In this embodiment, for different cultural relic matrices and impurity types, GHz femtosecond lasers of different wavelengths can be selected according to the absorption characteristics to generate femtosecond lasers to implement cultural relic cleaning. In addition to the ablation cooling mechanism that can protect the matrix material, at certain wavelengths, when the absorption coefficient of the pollutant particles is higher than that of the substrate material, the pollutants are separated from the substrate surface under the action of the laser and most of the heat is taken away. The remaining very little heat is absorbed by the substrate and surrounding materials through heat conduction. After the pollutants are removed, the substrate surface will still be irradiated by the laser. Since the substrate material has an extremely low absorption rate for lasers in this wavelength band, most of it is reflected, and the substrate will not have a significant temperature increase. At the same laser energy, the thermal damage is also smaller. Taking a femtosecond laser with a wavelength of 1550nm as an example, the laser oscillator is composed of a semiconductor saturable absorber mirror 1, a first gain fiber 2, a dispersive dielectric film 3, a first wavelength division multiplexer 5 and a first optical fiber isolator 6 in sequence. The first-stage amplifier includes a second single-mode semiconductor pump laser 7, a second wavelength division multiplexer 8, a second gain fiber 9, a second optical fiber isolator 10 and a single-mode optical fiber 11, which are connected in sequence through optical fibers. The first-stage amplifier is used for primary amplification of GHz high repetition rate lasers; the second-stage amplifier includes a third single-mode semiconductor pump laser 13, a third wavelength division multiplexer 12, a third single-mode semiconductor pump laser 14, a third single-mode semiconductor pump laser 15, a third single-mode semiconductor pump laser 16, a third single-mode semiconductor pump laser 17, a third single-mode semiconductor pump laser 18, a third single-mode semiconductor pump laser 19, a third single-mode semiconductor pump laser 20, a third single-mode semiconductor pump laser 21, a third single-mode semiconductor pump laser 22, a third single-mode semiconductor pump laser 23, a third single-mode semiconductor pump laser 24, a third single-mode semiconductor pump laser 25, a third single-mode semiconductor pump laser 26, a third single-mode semiconductor pump laser 27, a third single-mode semiconductor pump laser 28, a third single-mode semiconductor pump laser 29, a third single-mode semiconductor pump laser 30, a third single-mode semiconductor pump laser 31, a third single-mode semiconductor pump laser 32, a third single-mode semiconductor pump laser 33, a third single-mode semiconductor pump laser 34, a third single-mode semiconductor pump laser 35, a third single-mode semiconductor pump laser 36, a third single-mode semiconductor pump laser 37, a third single-mode semiconductor pump laser 38, a third single-mode semiconductor pump laser 39, a third The three gain fibers 14 and the third fiber isolator 15 are connected in sequence through optical fibers. The second-stage amplifier is used for the second-stage amplification of GHz high repetition rate lasers. The third-stage amplifier includes a multimode semiconductor pump laser 17, a fourth wavelength division multiplexer 16, a double-clad gain fiber 18, and a fourth fiber isolator 19, which are connected in sequence through optical fibers. The third-stage amplifier is used for the third-stage amplification of GHz high repetition rate lasers. The doping ions of the gain fibers are all erbium ions, generating a laser with a central wavelength of 1550nm, an average power of 20W, a pulse width of 200fs, and a repetition frequency of 1-10GHz.

[0063] Example 3

[0064] This embodiment targets different types of cultural relic substrates, such as stone cultural relics or paper cultural relics, and the required galvanometer scanning range needs to be modified accordingly. For example, the three-dimensional galvanometer module 102 includes a focusing module, a zoom module, and a scanning module, and is composed of a dichroic mirror 32, a zoom lens group 33, a third reflector 30, a scanning galvanometer 34, and a convex lens 35 arranged in sequence. The three-dimensional galvanometer module 102 is used to control the position of the laser focus on the surface of the cultural relic, wherein the focal length of the convex lens 35 is 250mm, and the scanning galvanometer 34 has a scanning angle of ±0.35rad. In addition to controlling the laser focus in a two-dimensional plane scan, it can also achieve adjustment of the focus height, with a tuning range of ±70mm, which is used to correct the position of the uneven surface of the cultural relic during the cultural relic cleaning process.

[0065] Example 4

[0066] The display module 103 can be used to compare changes in brightness, saturation, and hue before and after cleaning an area, adjusting cleaning parameters in real time. When the surface contaminant removal rate reaches 90%, cleaning of that area is stopped. This embodiment requires adjustments to the display module 103 and intelligent operating platform components to meet the required display image size or displacement requirements. For example, the aperture 28, which controls the size of the incident CCD spot, and the attenuator 29, which controls the intensity of the incident CCD spot, can be used. If a larger spot size is required, the Z-axis adjustment frame, which is perpendicular to the artifact surface, is adjusted. The frame has a tuning range of 100 mm.

[0067] Display module 103 consists of an aperture 28 for adjusting the size of the light spot, an attenuation plate 29 for controlling the intensity of the light spot, an objective lens 27, a CCD 26, and a display 31. The combination of aperture 28, attenuation plate 29, and objective lens 27 adjusts the intensity and size of the light spot incident on CCD 26. Because both the femtosecond laser's action light path and the return light path from the artifact's surface pass through 3D galvanometer module 102, display module 103 can display an image of the laser's focal plane, enabling simultaneous cleaning and observation.

[0068] The intelligent platform module 104 includes X- and Y-axis adjustment frames in plane with the surface of the artifact. These frames drive the X- and Y-axis adjustment frames, each with an adjustable travel of 150 mm. A Z-axis adjustment frame, perpendicular to the artifact surface, has an adjustable travel of 100 mm. The platform can hold artifacts on a 20 kg platform. Connected to a computer and controlled via a driver, the X, Y, and Z-axis adjustment frames have an adjustment resolution of 0.1 mm and a maximum electronically controlled displacement speed of 15 mm / s. If the artifact surface is rough, the Z-axis adjustment frame can be adjusted to achieve a clear image, effectively correcting the artifact's uneven surface.

[0069] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A laser device for cleaning the surface of cultural relics, characterized in that: include A femtosecond laser module, configured to emit GHz high-repetition-rate laser light, which is used to clean the surface of cultural relics. The femtosecond laser module comprises a laser oscillator and an amplifier assembly. The laser oscillator comprises a semiconductor saturable absorber mirror, a first gain fiber, a dispersive dielectric film, a first single-mode semiconductor pump laser, a first wavelength division multiplexer, and a first optical fiber isolator, which are sequentially connected via optical fibers and are configured to generate GHz high-repetition-rate laser light. The optical resonant cavity of the laser oscillator has a length of less than 10 cm and is configured to ensure the generation of the GHz high-repetition-rate laser light based on the mode-locking principle. The amplifier assembly is connected to the laser oscillator and is configured to amplify the GHz high-repetition-rate laser light emitted by the laser oscillator. The amplifier assembly includes a first-stage amplifier, a second-stage amplifier, and a third-stage amplifier, the first-stage amplifier is connected to the laser oscillator via an optical fiber, and the first-stage amplifier, the second-stage amplifier, and the third-stage amplifier are sequentially connected via optical fibers; The first-stage amplifier comprises a second single-mode semiconductor pump laser, a second wavelength division multiplexer, a second gain fiber, a second fiber isolator and a single-mode fiber connected in sequence through optical fibers, and the first-stage amplifier is used for primary amplification of the GHz high repetition rate laser; The second-stage amplifier comprises a third single-mode semiconductor pump laser, a third wavelength division multiplexer, a third gain fiber and a third fiber isolator connected in sequence through optical fibers, and the second-stage amplifier is used for second-stage amplification of the GHz high repetition rate laser; The third-stage amplifier comprises a multimode semiconductor pump laser, a fourth wavelength division multiplexer, a double-clad gain fiber and a fourth optical fiber isolator connected in sequence through optical fibers, and is used for amplifying the GHz high repetition rate laser in the third stage; A three-dimensional galvanometer module, which is capable of receiving the GHz high repetition rate laser emitted by the femtosecond laser module and controlling the position of the GHz high repetition rate laser on the surface of the cultural relic; A display module is used to display a planar image of the surface of the cultural relic irradiated by the GHz high repetition rate laser.

2. The laser device for cleaning the surface of cultural relics according to claim 1, characterized in that: It also includes a processing module, which is connected to the end of the amplifier component and is used to perform pulse shaping and direction change processing on the GHz high repetition rate laser.

3. The laser device for cleaning the surface of cultural relics according to claim 2, characterized in that: The processing module includes a collimator, a first reflector, a first grating, a second reflector and a second grating, which are arranged in sequence. The collimator is connected to the amplifier component and can convert the GHz high repetition rate laser into collimated light, and make the GHz high repetition rate laser pass through the collimator, the first grating, and the second grating in sequence to be incident on the second reflector, and then pass through the second grating and the first grating to be incident on the first reflector after being reflected by the second reflector, and then be reflected by the first reflector to enter the three-dimensional galvanometer module.

4. The laser device for cleaning the surface of cultural relics according to claim 1, characterized in that: The three-dimensional galvanometer module includes a zoom module, a scanning module, and a focusing module arranged in sequence. The zoom module is used to change the focal length of the GHz high repetition rate laser. The scanning module is used to change the incident direction and scanning range of the GHz high repetition rate laser. The focusing module is used to focus the GHz high repetition rate laser. The GHz high repetition rate laser can be focused on the surface of the cultural relic after passing through the zoom module, the scanning module, and the focusing module in sequence. Wherein, the focusing module includes a convex lens, the zoom module includes a zoom lens group, and the scanning module includes a scanning galvanometer.

5. The laser device for cleaning the surface of cultural relics according to claim 4, characterized in that: The three-dimensional galvanometer module also includes a third reflector and a dichroic mirror. The dichroic mirror is located in front of the zoom lens group, and the third reflector is located between the zoom lens group and the scanning galvanometer. The dichroic mirror can reflect the GHz high repetition rate laser so that the GHz high repetition rate laser passes through the zoom lens group, the third reflector, the scanning galvanometer and the convex lens in sequence and then acts on the surface of the cultural relic. The dichroic mirror can also allow light returning from the surface of the cultural relic to pass through and transmit it to the display module for imaging.

6. The laser device for cleaning the surface of cultural relics according to claim 1, characterized in that: The display module includes an attenuation plate, an aperture, an objective lens, and a CCD, which are sequentially arranged along the transmission direction of the light returning from the surface of the cultural relic. The CCD electrical signal is connected to a display. The light returning from the surface of the cultural relic can pass through the attenuation plate, the aperture, and the objective lens in sequence and be incident on the CCD, and the image is displayed on the display.

7. The laser device for cleaning the surface of cultural relics according to claim 6, characterized in that: It also includes an intelligent platform module, which is used to place the cultural relics and can adjust the position of the cultural relics; The intelligent platform module includes an X-axis adjustment frame, a Y-axis adjustment frame, a Z-axis adjustment frame, and a fixed platform. The X-axis adjustment frame, the Y-axis adjustment frame, and the Z-axis adjustment frame form a three-dimensional coordinate system, which are perpendicular to each other. In addition, the intelligent platform module is electrically connected to the display. The display can control the movement of the X-axis adjustment frame, the Y-axis adjustment frame, and the Z-axis adjustment frame. The fixed platform is used to fix the cultural relic. The X-axis adjustment frame and the Y-axis adjustment frame are used to adjust the planar position of the cultural relic to ensure that different positions of the cultural relic can be cleaned. The Z-axis adjustment frame can tune the distance of the cultural relic relative to the three-dimensional galvanometer module according to the imaging picture of the display, thereby adjusting the imaging spot size of the cultural relic.

Images