Apparatus and method for measuring damage limit level of laser gain medium

Abstract

The present invention relates to a device for measuring the damage limit of a laser amplification medium and a method for measuring the damage limit. A device for measuring the damage limit of a laser amplification medium according to one embodiment of the present invention may include: an ultrashort pulse generator that generates laser light having an ultrashort pulse; an amplification unit that irradiates the laser light onto a laser amplification medium to amplify the output of the laser light; and a beam measurement unit that generates a beam profile of the laser light output from the amplification unit and measures a damage threshold of the laser amplification medium by utilizing a change in the beam profile according to a Kerr lens phenomenon.

Description

Technology Field

[0001] The present invention relates to a device and method for measuring the damage limit of a laser amplification medium, and more specifically, to a device and method for measuring the damage limit of a laser amplification medium capable of measuring the damage limit of a laser amplification medium due to the Kerr lens effect. Background Technology

[0003] Ultrashort pulses are pulses with a very short duration ranging from picoseconds to femtoseconds. Laser light with ultrashort pulses (hereinafter referred to as ultrashort lasers) enables non-thermal processing with minimal thermal degradation of materials and allows for high-quality ultra-precision processing compared to conventional laser processing. In particular, since biological tissues and organic materials are susceptible to heat, using ultrashort pulse laser light with minimal thermal degradation can be utilized for various types of precision processing, such as micro-incision of organic materials, electrical and electronic materials, and biological tissues. In other words, industrial demand for high-power ultrashort lasers for ultra-precision laser processing is increasing, and there is a demand for higher power output for ultrashort lasers to improve processing efficiency and productivity.

[0004] Generally, to achieve high output power for microwave lasers, a method of amplifying pulse energy by incidenting a microwave seed pulse onto a laser amplification medium can be utilized. Conventionally, bulk-type laser amplification media have been used, but this presents limitations in output enhancement due to thermal issues. Therefore, to overcome these limitations, various forms of laser amplification media capable of effectively dissipating heat, such as thin disks, slabs, and optical fibers, are being proposed. However, thin disks and slabs have complex structures, while optical fibers face limitations in increasing peak power due to nonlinear effects occurring in high-energy pulses.

[0005] As a solution to this problem, a Thin Rod Amplifier (TRA) has been proposed. The TRA is a long, thin, cylindrical laser amplification medium in which the ultrashort laser proceeds without internal guiding, and the pumping laser is guided internally. Through this, it is possible to stably increase laser output while maintaining a simple structure.

[0006] However, even when using a TRA, high-peak output pulses within the TRA can be focused by the Kerr lens effect during the amplification process of the ultrashort laser, and in this case, damage to the medium due to self-focusing may occur. That is, considering the thermal and nonlinear characteristics of the laser amplification medium, it is necessary to stably amplify the output in a safe region where the laser amplification medium is not damaged. In particular, in the case of a TRA, which enables efficient thermal emission and pulse amplification with a simple configuration, surface damage due to self-focusing may occur more easily because the length of the laser amplification medium is longer than that of conventional bulk amplification media. Prior art literature

[0008] Korean Registered Patent Publication No. 10-0757101 The problem to be solved

[0009] The present invention aims to provide a device for measuring the damage limit of a laser amplification medium and a method for measuring the damage limit of a laser amplification medium, which can provide a damage threshold for the laser amplification media.

[0010] The present invention aims to provide a device for measuring the damage limit of a laser amplification medium and a method for measuring the damage limit of a laser amplification medium, which can accurately measure the damage limit of the laser amplification medium by utilizing the characteristic that the beam size changes due to the Kerr lens effect when the peak output intensity of the ultrashort pulse increases. means of solving the problem

[0012] A device for measuring the damage limit of a laser amplification medium according to one embodiment of the present invention may include: an ultrashort pulse generator that generates laser light having an ultrashort pulse; an amplification unit that irradiates the laser light onto a laser amplification medium to amplify the output of the laser light; and a beam measurement unit that generates a beam profile of the laser light output from the amplification unit and measures the damage threshold of the laser amplification medium by utilizing a change in the beam profile according to a Kerr lens phenomenon.

[0013] Here, the ultrashort pulse generator may include a main oscillator that generates an initial laser light having an ultrashort pulse; an output controller that controls the output intensity of the initial laser light; and a pulse picker that controls the number of pulses of the initial laser light to set the repetition rate of the laser light.

[0014] Here, the beam measuring unit can generate a first beam profile measured while increasing the output intensity of a first laser light having a low repetition rate, and a second beam profile measured while increasing the output intensity of a second laser light having a high repetition rate.

[0015] Here, the beam measuring unit compares the size of the first beam profile and the size of the second beam profile to extract an output intensity at which the size of the first beam profile becomes larger than the size of the second beam profile by more than a set value, and can obtain a damage threshold for the laser amplification medium using the output intensity.

[0016] Here, the output controller can control the output intensity of the initial laser light using a half-wave plate and a polarizer.

[0017] Here, the pulse speaker can control the number of pulses of the initial laser light by using a Pockels cell, a polarizer, and a high reflective mirror.

[0018] Here, the laser amplification medium may be a TRA (Thin Rod Amplifier).

[0019] Here, the beam measuring unit can generate a beam profile corresponding to a cross-sectional image of the laser light using an image sensor.

[0020] A method for measuring the damage limit of a laser amplification medium according to one embodiment of the present invention may include: a step of generating laser light having an ultrashort pulse; a step of irradiating the laser light onto a laser amplification medium to amplify the output of the laser light; and a step of generating a beam profile of the amplified laser light and measuring the damage threshold of the laser amplification medium using a change in the beam profile due to a Kerr lens phenomenon.

[0021] In addition, the means for solving the above-mentioned problem do not enumerate all the features of the present invention. Various features of the present invention and the advantages and effects derived therefrom can be understood in more detail by referring to the specific embodiments below. Effects of the invention

[0023] According to the device and method for measuring the damage limit of a laser amplification medium according to one embodiment of the present invention, a damage threshold can be provided for each laser amplification medium. Accordingly, by considering the damage limits of the laser amplification media, it is possible to configure a laser amplification system under conditions where the laser amplification medium is not damaged.

[0024] According to the device and method for measuring the damage limit of a laser amplification medium according to one embodiment of the present invention, it is possible to measure an accurate damage threshold that takes into account both the Curcents effect caused by the nonlinearity of the laser amplification medium and the Thermal Lens effect caused by the pump heat of the pump laser.

[0025] According to the device and method for measuring the damage limit of a laser amplification medium according to one embodiment of the present invention, since the damage threshold of the laser amplification medium can be accurately predicted, an ultrashort optical pulse amplifier can be efficiently configured, thereby significantly increasing laser amplification efficiency. In addition, since the output can be stably amplified within a range where the laser amplification medium is not damaged, laser development costs can be significantly reduced. Brief explanation of the drawing

[0027] FIG. 1 is a block diagram showing a damage limit measuring device for a laser amplification medium according to one embodiment of the present invention. FIG. 2 is a schematic diagram showing a damage limit measuring device for a laser amplification medium according to one embodiment of the present invention. Figure 3 is an example of damage to the laser amplification medium that occurred during the process of amplifying an ultrashort laser using a Yb:YAG laser medium of the TRA structure. FIG. 4 is an exemplary diagram showing a beam profile according to one embodiment of the present invention. FIG. 5 is a graph showing the damage limit measurement according to one embodiment of the present invention. FIG. 6 is a flowchart illustrating a method for measuring the damage limit of a laser amplification medium according to one embodiment of the present invention. Specific details for implementing the invention

[0028] Hereinafter, preferred embodiments are described in detail with reference to the attached drawings so that those skilled in the art can easily practice the present invention. However, in describing the preferred embodiments of the present invention in detail, if it is determined that a detailed description of related known functions or configurations may unnecessarily obscure the essence of the present invention, such detailed description is omitted. Additionally, the same reference numerals are used throughout the drawings for parts having similar functions and operations.

[0029] Additionally, throughout the specification, when a part is described as being 'connected' to another part, this includes not only cases where they are 'directly connected,' but also cases where they are 'indirectly connected' with other elements in between. Furthermore, the term 'includes' a component means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Also, terms such as "part" or "module" described in the specification refer to a unit that processes at least one function or operation, which may be implemented in hardware or software, or as a combination of hardware and software.

[0030] Additionally, terms such as first, second, etc., may be used to describe various components, but said components are not limited by said terms, and said terms are used only for the purpose of distinguishing one component from another.

[0032] FIG. 1 is a block diagram showing a damage limit measuring device for a laser amplification medium according to one embodiment of the present invention.

[0033] Referring to FIG. 1, a damage limit measuring device (100) according to one embodiment of the present invention may include an ultrashort pulse generating unit (110), an amplification unit (120), and a beam measuring unit (130).

[0034] Hereinafter, a device for measuring the damage limit of a laser amplification medium according to one embodiment of the present invention will be described with reference to FIG. 1.

[0036] The ultrashort pulse generator (110) can generate laser light having ultrashort pulses. That is, after generating laser light in the ultrashort pulse generator (110), the generated laser light can be transmitted to the amplification unit (120) to amplify the laser light.

[0037] Specifically, the ultra-short pulse generator (110) may include a master oscillator (111), a power controller (112), and a pulse picker (113).

[0038] The main oscillator (111) generates initial laser light having ultrashort pulses and may include laser media such as Yb:YAG, Nd:YAG, Yb:Y2O3, Yb:CALGO, Yb:KGW, Yb:KYW, Yb:KLuW, Yb:glass, Yb:YVO4, Er:YAG, Tm:YAG, Ho:YAG, Cr:YAG, etc. However, it is not limited thereto, and the main oscillator (111) may also generate initial laser light having ultrashort pulses using various types of laser media such as optical fibers and solids.

[0039] The output controller (112) can receive an initial laser light from the main oscillator (111) and can control the output intensity of the received initial laser light. Referring to FIG. 2, the output controller (112) may include a half-wave plate and a thin film polarizer (TFP), and can control the output intensity of the initial laser light using these. The initial laser light output from the main oscillator (111) can be aligned by a collimation lens and input to the output controller (112), and the initial laser light output from the output controller (112) can be input to the pulse speaker (113) through a light splitter (F-iso: Faraday isolator). The light splitter (F-iso) can block the laser light from the pulse speaker (113) from entering the output controller (112), while allowing the laser light to travel from the output controller (112) toward the pulse speaker (113).

[0040] The pulse speaker (113) can set the repetition rate of the initial laser light by adjusting the number of pulses of the initial laser light. As shown in FIG. 2, the pulse speaker (113) may include a Pockels cell, a polarizer, and a High Reflective Mirror (HR), and the pulse speaker (113) can adjust the number of pulses of the laser light using an Electro-Optic Modulator (EOM) or Acousto-Optic Modulator (AOM) method. According to an embodiment, the pulse speaker (113) can adjust the repetition rate of the initial laser light to have a low repetition rate of 100 to 1000 kHz or a high repetition rate of 10 to 80 MHz.

[0041] The amplification unit (120) can receive laser light from the ultrashort pulse generator (110) and irradiate the received laser light onto a laser amplification medium (A) to amplify the output of the laser light. Here, a laser amplification medium (A) for measuring a damage threshold may be installed in the amplification unit (120).

[0042] Referring to FIG. 2, the amplification unit (120) can use a Long Wave Pass Filter (LWPF) to inject the pump light of a pump laser diode (Pump LD) along with the laser light into a laser amplification medium (A), and the remaining pump light can be transmitted to a dumper through the LWPF. At this time, the pump light output from the pump laser diode can pass through a Collimation Lens (CL) and a Focusing Lens (FL) and be incident on the LWPF.

[0043] Here, a TRA may be installed as a laser amplification medium (A), in which case the TRA may be implemented with a laser medium such as Yb:YAG, Nd:YAG, Yb:Y2O3, Yb:CALGO, Yb:KGW, Yb:KYW, Yb:KLuW, Yb:glass, Yb:YVO4, Er:YAG, Tm:YAG, Ho:YAG, or Cr:YAG. Below, the case in which a TRA is installed as a laser amplification medium (A) is described as an example. However, the content of the present invention is not limited thereto, and various types of laser amplification media (A) other than TRA that are intended to measure a damage threshold may be installed in the amplification unit (120) to measure the damage threshold.

[0044] Meanwhile, most of the materials constituting the TRA are nonlinear materials, and a Kerr lens effect may occur in which the refractive index changes in proportion to the square of the electric field strength when a pulse with high peak output intensity passes through. Since the Kerr lens effect is generally largest at the center of the beam with the highest pulse intensity and smaller at the edges of the beam, the change in refractive index over time acts similarly to the action of a lens, resulting in a focusing effect of the pulse beam, which is called self-focusing. When amplifying an ultrashort laser, self-focusing due to this Kerr lens phenomenon may occur, leading to damage to the laser amplification medium (A) in many cases. Specifically, FIG. 3 is an example of damage to the laser amplification medium that occurred during the process of amplifying an ultrashort laser using a Yb:YAG laser medium with a TRA structure. As shown in FIG. 3(a), the Yb:YAG surface can be damaged by magnetic focusing on the surface of the TRA, and as shown in FIG. 3(b), it can be confirmed that damage can occur within the laser amplification medium in addition to the surface of the TRA due to the progression of filamentation caused by magnetic focusing. Here, the peak output intensity when damage to the laser amplification medium occurs corresponds to 5 MW in the case of FIG. 3(a) and 5.2 MW in the case of FIG. 3(b).

[0045] Here, the damage threshold for the laser amplification medium (A) can be measured by gradually increasing the peak output intensity of the ultrashort laser to induce a Kernz effect, and then measuring the peak output intensity at the point when the laser amplification medium (A) installed in the amplification unit (120) is damaged.

[0046] The beam measuring unit (130) can generate a beam profile of the laser light output from the amplification unit (120) and can measure the damage threshold of the laser amplification medium by utilizing the change in the beam profile due to the Kerr lens phenomenon. As shown in FIG. 2, the beam measuring unit (130) may include an image sensor and can generate a beam profile corresponding to a cross-sectional image of the laser light using the image sensor. Here, the image sensor can be implemented as a CCD (Charge-Coupled Device) or CMOS (Complementary Metal-Oxide Semiconductor), and any other device capable of generating a beam profile of the laser light can be utilized. Additionally, the beam measuring unit (130) may further include an output intensity measuring unit (Power Meter, 131) to measure the output intensity of the amplified laser light output from the amplification unit (120).

[0047] Specifically, the beam measuring unit (130) can generate a first beam profile while increasing the output intensity of a first laser light having a low repetition rate, and generate a second beam profile while increasing the output intensity of a second laser light having a high repetition rate.

[0048] Here, the case of a high repetition rate corresponds to a case where the peak output intensity is low and non-linear phenomena occur less frequently, and the output intensity of the pulse can be gradually amplified by increasing the output intensity of the pumping laser diode of the amplifier (120) to generate a first beam profile according to the amplified output intensity. For example, a first beam profile generated by increasing the output intensity at a high repetition rate of 80 MHz can be generated as shown at the top of FIG. 4.

[0049] On the other hand, in the case of a low repetition rate, the peak output intensity is high, which corresponds to a case where a high non-linear phenomenon may occur. By increasing the output intensity of the pumping laser diode of the amplifier (120) and gradually amplifying the output intensity of the pulse, a second beam profile according to the amplified output intensity can be generated. For example, a second beam profile generated by increasing the output intensity at a low repetition rate of 1 MHz can be generated as shown at the bottom of FIG. 4.

[0050] Subsequently, the beam measuring unit (130) can compare the size of the first beam profile with the size of the second beam profile to extract an output intensity at which the size of the first beam profile becomes larger than the size of the second beam profile by more than a set value. For example, when comparing the first beam profile and the second beam profile of FIG. 4, in the case of the first beam profile, the beam size (beam diameter) does not change significantly even when the output intensity measured by the output intensity measuring unit (131) increases to 1.5W, 3.4W, 6.9W, and 8W, but in the case of the second beam profile, it can be confirmed that the beam size increases rapidly starting from at least 6.9W. Therefore, it can be determined that damage has occurred within the laser amplification medium (A) before the output intensity reaches 6.9W.

[0051] Specifically, referring to FIG. 5, when the output intensity measured by the output intensity measuring unit (131) is lower than 2.5W, the sizes of the first beam profile and the second beam profile are almost identical; however, when the amplification is greater than 2.5W, it can be seen that the size of the beam increases relatively rapidly at a repetition rate of 1 MHz. Therefore, it can be determined that damage has occurred within the laser amplification medium (A) at an output intensity of 2.5W. By utilizing this, the beam measuring unit (130) can compare the size (diameter) of the first beam profile and the size (diameter) of the second beam profile, recognize when the size of the first beam profile increases beyond a set value, and extract the output intensity at that time.

[0052] Here, the pulse energy corresponding to an output intensity of 2.5W is 2.5μJ, and when the pulse width of the laser light is 500fs, the peak output intensity corresponds to 5MW. This indicates that when laser light with a peak output intensity higher than 5MW is incident on the laser amplification medium (A), a magnetic focusing phenomenon may occur rapidly due to the Kern lens effect. Therefore, the beam measuring unit (130) can set the peak output intensity at which magnetic focusing occurs in the laser amplification medium (A) as the damage limit of the corresponding laser amplification medium (A). Here, the measured damage limit of 5MW shows a result that matches well when compared with 5, 2MW, and 5MW, where actual damage to the laser amplification medium occurred in FIG. 3.

[0053] Additionally, the damage threshold of the laser amplification medium (A) can be set by further considering the beam size of the laser light incident into the laser amplification medium (A). That is, since the time at which damage occurs to the laser amplification medium (A) may differ when the beam sizes of each laser light incident into the laser amplification medium (A) are different, the damage threshold can be set based on the peak power density (W / cm²). 2 It can be represented more accurately using ). For example, if the beam size of the laser light incident on the amplifier (120) is 400 μm and the damage limit peak output intensity is 5 MW, the peak output density is approximately 4 GW / cm² 2 ...corresponds to this. Therefore, in the case of the corresponding laser amplification medium (A), the peak power density is 4 GW / cm². 2 A laser amplification system can be designed so as not to exceed [value].

[0055] FIG. 6 is a flowchart illustrating a method for measuring the damage limit of a laser amplification medium according to an embodiment of the present invention. Here, each step can be performed by a damage limit measuring device according to an embodiment of the present invention.

[0056] Referring to FIG. 6, the damage limit measuring device can generate laser light having ultrashort pulses (S10). The damage limit measuring device may include a main oscillator, an output controller, a pulse speaker, etc. After generating initial laser light having ultrashort pulses in the main oscillator, the output controller controls the output intensity of the initial laser light received, and the pulse speaker controls the number of pulses of the initial laser light to set the repetition rate of the initial laser light.

[0057] Subsequently, the damage limit measuring device can amplify the output of the laser light by irradiating the laser light onto the laser amplification medium (S20). Specifically, the damage limit measuring device can use an LWPF to incident the pump light of the pump laser diode along with the laser light onto the laser amplification medium, and the remaining pump light can be transmitted to the damper through the LWPF. Here, a TRA may be installed as a laser amplification medium within the damage limit measuring device, and the TRA may be implemented with a laser medium such as Yb:YAG, Nd:YAG, Yb:Y2O3, Yb:CALGO, Yb:KGW, Yb:KYW, Yb:KLuW, Yb:glass, Yb:YVO4, Er:YAG, Tm:YAG, Ho:YAG, Cr:YAG, etc. In addition, various types of laser amplification media to measure the damage threshold, other than the TRA, may be installed within the damage limit measuring device.

[0058] Subsequently, the damage limit measuring device can generate a beam profile of the amplified laser light and measure the damage threshold of the laser amplification medium by utilizing the change in the beam profile due to the Kerr lens phenomenon (S30). The damage limit measuring device may include an image sensor and can generate a beam profile corresponding to a cross-sectional image of the laser light using the image sensor. Here, the image sensor can be implemented as a CCD or CMOS, and any other device capable of generating a beam profile of the laser light can be utilized.

[0059] Here, the damage limit measuring device can generate a first beam profile while increasing the output intensity of a first laser light having a low repetition rate, and generate a second beam profile while increasing the output intensity of a second laser light having a high repetition rate. Subsequently, the damage limit measuring device can compare the size of the first beam profile with the size of the second beam profile to extract an output intensity at which the size of the first beam profile becomes larger than the size of the second beam profile by more than a set value.

[0060] That is, at a high repetition rate, the peak output intensity is low so no damage occurs to the laser amplification medium, but at a low repetition rate, damage to the laser amplification medium may occur due to the high peak output intensity. Therefore, it is possible to determine whether damage has occurred within the laser amplification medium by comparing the first beam profile and the second beam profile. According to an embodiment, after comparing the size (diameter) of the first beam profile and the size (diameter) of the second beam profile, if the size of the first beam profile increases beyond a set value, it is determined that damage has occurred within the laser amplification medium, and the output intensity at that time can be extracted. Accordingly, the damage limit measuring device can calculate the peak output intensity using the extracted output intensity and set it as the damage limit value of the laser amplification medium. Here, the output intensity corresponds to the output intensity of the laser light amplified by the laser amplification medium.

[0061] Meanwhile, according to an embodiment, the damage limit of the laser amplification medium is the peak power density (W / cm²). 2 It is also possible to express it as ). For example, if the beam size of the laser light incident on the laser amplification medium is 400 μm and the damage limit peak power intensity is 5 MW, then the peak power density is 4 GW / cm² 2 can be set as the damage threshold. In this case, the peak power density for the corresponding laser amplification medium is 4 GW / cm² 2 A laser amplification system can be designed so as not to exceed [value].

[0063] The present invention is not limited by the aforementioned embodiments and attached drawings. It will be obvious to those skilled in the art that the components according to the present invention can be substituted, modified, and changed within the scope of the technical concept of the present invention without departing from the spirit of the invention. Explanation of the symbols

[0065] 100: Damage limit measuring device 110: Ultrashort pulse generator 111: Main oscillator 112: Output controller 113: Pulse Speaker 120: Amplifier 130: Beam measuring unit

Claims

Claim 1 A laser amplification medium damage limit measuring device comprising: a laser pulse generator that generates laser light having a laser pulse; an amplifier that irradiates the laser light onto a laser amplification medium to amplify the output of the laser light; and a beam measuring unit that generates a beam profile of the laser light output from the amplifier and measures a damage threshold of the laser amplification medium using a change in the beam profile according to a Kerr lens phenomenon, wherein the beam measuring unit generates a first beam profile measured while increasing the output intensity of a first laser light having a low repetition rate and a second beam profile measured while increasing the output intensity of a second laser light having a high repetition rate. Claim 2 A device for measuring the damage limit of a laser amplification medium, characterized in that, in claim 1, the ultrashort pulse generator comprises: a main oscillator that generates an initial laser light having ultrashort pulses; an output controller that controls the output intensity of the initial laser light; and a pulse picker that controls the number of pulses of the initial laser light to set the repetition rate of the laser light. Claim 3 delete Claim 4 A device for measuring the damage limit of a laser amplification medium, characterized in that, in claim 1, the beam measuring unit compares the size of the first beam profile with the size of the second beam profile, extracts an output intensity at which the size of the first beam profile becomes larger than the size of the second beam profile by more than a set value, and uses the output intensity to obtain a damage threshold for the laser amplification medium. Claim 5 A device for measuring the damage limit of a laser amplification medium, comprising: a laser pulse generator for generating laser light having a laser pulse; an amplifier for irradiating the laser light onto a laser amplification medium to amplify the output of the laser light; and a beam measuring unit for generating a beam profile of the laser light output from the amplifier and measuring a damage threshold of the laser amplification medium using a change in the beam profile according to a Kerr lens phenomenon, wherein the laser pulse generator comprises: a main oscillator for generating an initial laser light having a laser pulse; an output controller for controlling the output intensity of the initial laser light; and a pulse picker for controlling the number of pulses of the initial laser light to set the repetition rate of the laser light, and wherein the output controller controls the output intensity of the initial laser light using a half-wave plate and a polarizer. Claim 6 A device for measuring the damage limit of a laser amplification medium, comprising: a laser pulse generator for generating laser light having a laser pulse; an amplifier for irradiating the laser light onto a laser amplification medium to amplify the output of the laser light; and a beam measuring unit for generating a beam profile of the laser light output from the amplifier and measuring a damage threshold of the laser amplification medium using a change in the beam profile according to a Kerr lens phenomenon, wherein the laser pulse generator comprises: a main oscillator for generating an initial laser light having a laser pulse; an output controller for adjusting the output intensity of the initial laser light; and a pulse picker for adjusting the number of pulses of the initial laser light to set the repetition rate of the laser light, wherein the pulse picker adjusts the number of pulses of the initial laser light using a Pockels cell, a polarizer, and a high reflective mirror. Claim 7 A device for measuring the damage limit of a laser amplification medium, characterized in that, in claim 1, the laser amplification medium is a TRA (Thin Rod Amplifier). Claim 8 A device for measuring the damage limit of a laser amplification medium, characterized in that, in claim 1, the beam measuring unit uses an image sensor to generate a beam profile corresponding to a cross-sectional image of the laser light. Claim 9 A method for measuring the damage limit of a laser amplification medium, comprising: a step of generating laser light having ultrashort pulses; a step of irradiating the laser light onto a laser amplification medium to amplify the output of the laser light; and a step of generating a beam profile of the amplified laser light and measuring a damage threshold of the laser amplification medium using a change in the beam profile according to a Kerr lens phenomenon, wherein the measuring step involves generating a first beam profile measured while increasing the output intensity of a first laser light having a low repetition rate and a second beam profile measured while increasing the output intensity of a second laser light having a high repetition rate.

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