Multiple laser pulse oscillation method and multiple laser pulse oscillation device using multiple Q switches

Abstract

To provide a method for oscillating a multiple laser pulse using a multiple Q switch which can improve the energy efficiency and can reduce the peak power of lasers.SOLUTION: The method for oscillating a multiple laser pulse using a multiple Q switch includes the steps of: forming one cycle of light energy; exciting electrons of a gain medium by the light energy; executing a first Q switch during one cycle of the light energy; oscillating a first laser pulse by the first Q switch; executing a second Q switch during one cycle of the light energy; and oscillating the second laser pulse by the second Q switch.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The technical idea of the present invention relates to a laser generation method, and more particularly, to a method for generating multiple laser pulses and a device for generating multiple laser pulses using a multiple Q-switch.

Background Art

[0002] Since the first laser, the ruby laser, was developed in 1960 and appeared in the medical field, Nd:YAG lasers, helium-neon lasers, and dye lasers have been developed and have shown excellent effects in the treatment of skin diseases. The basic principle of such lasers is that there are natural frequencies for targets such as water, melanin, and oxyhemoglobin, and when irradiated with lasers of similar frequencies, a reaction occurs in a specific target. This is the greatest feature of lasers, which can selectively perform surgery on the target, and is related to the absorption degree of each target. The biggest difference is that, compared with general light rays having many wavelengths, a laser always has a fixed single wavelength. Due to these differences in wavelengths, various laser substances have their own specific wavelengths, and the types of lasers are classified into various types such as excimer, diode, CO2, Nd:YAG, etc. according to the medium.

[0003] Depending on the application, lasers are used in various ways: in general hospitals, they are used on soft tissue surgical sites for incision, ulcer treatment, tattoo removal, and disinfection; in dentistry, they are used on both hard and soft tissues for cavity removal, implant surgery, and nerve hypersensitivity; and there are many different types of lasers depending on their respective applications. Historically, in 1963, ruby ​​and argon lasers were first used to treat flame nevi, and from the mid-1970s, argon and carbon dioxide lasers began to be used extensively for the treatment of vascular lesions, pigmentary diseases, and tumors. More recently, even more diverse lasers have been developed and are being used to treat various skin diseases that were previously impossible or difficult to treat. Currently, lasers used in dermatology can be broadly categorized into those used to treat various skin tumors and scars, those used to treat vascular diseases, and those used for tattoo removal. Recently, with the growing interest in skin aging and skin regeneration, the functions of existing laser devices, which have generally been used for vascular lesions, pigmentation lesions, and hair removal, are expanding to include skin lifting, elasticity, and regeneration functions, and the demand for these functions is increasing.

[0004] Q-switching lasers are a representative technology for generating the most widely used short-pulse lasers. Q-switching lasers have short pulse widths of 5 to 15 nanoseconds and possess high pulse power. For example, a laser with a 10-nanosecond pulse width and an output energy of 1 joule has a high laser pulse power of 100 MW. Due to this high power, there may be limitations to its clinical use, such as in skin treatments.

[0005] To oscillate the above-mentioned Q-switched laser, a flash lamp is discharged, and the light energy generated from the flash lamp is injected into the laser medium, exciting electrons in the laser medium and causing a density inversion, which in turn generates laser resonance. The width of the light energy generated from the flash lamp is approximately 250 microseconds (μs), and the light energy generated during the duration of the pulse continuously excites electrons from the laser medium.

[0006] The Nd:YAG laser has an excited state duration of approximately 230 μs. The Q-switch signal is injected with a delay of approximately 150 μs after the start of initial pumping, resulting in the oscillation of a laser with a short pulse width and high peak power. Here, even after the laser has started oscillating, light energy is continuously injected from the flash lamp, so electrons are continuously excited in the Nd:YAG laser medium, but they can no longer contribute to the laser oscillation. In other words, after the Q-switch signal is applied, the light energy is no longer used, resulting in the wasteful consumption of both light and electrical energy. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Korean Registered Patent No. 10-1229111 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The technical problem that the present invention aims to solve is to provide a multiple laser pulse oscillation method using multiple Q switches that can reduce the peak power of the laser and improve energy efficiency.

[0009] However, these challenges are illustrative, and the technical concept of the present invention is not limited to them. [Means for solving the problem]

[0010] A method for oscillating multiple laser pulses using multiple Q switches according to the technical concept of the present invention for achieving the aforementioned technical problems includes the steps of: forming one cycle of light energy; exciting electrons in a gain medium with the light energy; executing a first Q switch during one cycle of the light energy; oscillating a first laser pulse from the electrons excited in the gain medium by the first Q switch; executing a second Q switch during one cycle of the light energy; and oscillating a second laser pulse from the electrons excited in the gain medium by the second Q switch.

[0011] In one embodiment of the present invention, the first Q-switch may have a delay time in the range of 80 μs to 150 μs immediately after the formation of the light energy.

[0012] In one embodiment of the present invention, the second Q switch can have a delay time in the range of 10 μs to 30 μs in the first Q switch.

[0013] In one embodiment of the present invention, during one cycle of the light energy, the steps of executing the second Q switch, followed by a delay time in the range of 10 μs to 30 μs, and then executing the third Q switch, and oscillating a third laser pulse by the third Q switch may be further included.

[0014] In one embodiment of the present invention, during one cycle of the optical energy, the steps of executing the third Q switch, followed by a delay time in the range of 10 μs to 30 μs, and then executing the fourth Q switch, and oscillating a fourth laser pulse by the fourth Q switch may be further included.

[0015] In one embodiment of the present invention, during one cycle of the light energy, the steps of executing the fourth Q switch, followed by a delay time in the range of 10 μs to 30 μs, and then executing the fifth Q switch, and oscillating a fifth laser pulse by the fifth Q switch may be further included.

[0016] In one embodiment of the present invention, during one cycle of the optical energy, the steps of executing the 5th Q switch, followed by a delay time in the range of 10 μs to 30 μs, and then executing the 6th Q switch, and oscillating a 6th laser pulse by the 6th Q switch may be further included.

[0017] In one embodiment of the present invention, during one cycle of the optical energy, the steps of executing the 6th Q switch, followed by a delay time in the range of 10 μs to 30 μs, and then executing the 7th Q switch, and oscillating a 7th laser pulse by the 7th Q switch may be further included.

[0018] In one embodiment of the present invention, one cycle of the light energy can be in the range of 200 μs to 350 μs.

[0019] The multiple laser pulse oscillator utilizing multiple Q switches according to the technical concept of the present invention is a multiple laser pulse oscillator including a mirror, a wavelength section, a Q switch section, a polarization section, a gain medium section, an output coupler section, a first control section, and a second control section, wherein the first control section applies an electrical control signal to form one cycle of light energy in the gain medium section, the electrons of the gain medium in the gain medium section are excited by the light energy, the second control section applies an electrical control signal during one cycle of the light energy to execute a first Q switch in the Q switch section, the first Q switch oscillates a first laser pulse, the Q switch section oscillates a second Q switch during one cycle of the light energy, and the second Q switch oscillates a second laser pulse. [Effects of the Invention]

[0020] In the multi - laser pulse oscillation method using a multi - Q switch according to the technical idea of the present invention, during one cycle of the formed light energy, the multi - Q switch can be executed to oscillate multi - laser pulses. Therefore, it is possible to provide an effect of reducing the output of the laser pulse to a desired level. Also, since the laser pulse can be oscillated by using the energy of excited electrons that are not used when executing the Q switch once, an efficient laser oscillation effect can be provided.

[0021] The effects of the present invention described above are described exemplarily, and the scope of the present invention is not limited by these effects. [Brief Description of the Drawings]

[0022] [Figure 1] It is a schematic diagram showing a multi - laser pulse oscillation device using a multi - Q switch for implementing a multi - laser pulse oscillation method using a multi - Q switch according to the technical idea of the present invention. [Figure 2] It is a flowchart showing a multi - laser pulse oscillation method using a multi - Q switch according to the technical idea of the present invention. [Figure 3] It is a graph showing the result of executing a multi - laser pulse oscillation method using a multi - Q switch according to an embodiment of the present invention. [[ID=​​​​Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention are provided to more fully explain the technical idea of the present invention to those with ordinary knowledge in the relevant technical field. The following embodiments can be modified into various other forms, and the scope of the technical idea of the present invention is not limited to the following embodiments. Rather, these embodiments are provided to make the present disclosure more substantial and complete and to fully convey the technical idea of the present invention to those skilled in the art. The same reference numerals in this specification always mean the same elements. Further, various elements and regions in the drawings are schematically drawn. Therefore, the technical idea of the present invention is not limited by the relative sizes and intervals depicted in the attached drawings.

[0024] The technical idea of the present invention is to operate the Q-switch two or more times, for example three or more times, in one pulse period (for example, 230 μs to 330 μs) in order to reduce the high laser oscillation peak power and maintain the high output energy. In a Q-switch laser, three or more laser pulses are generated in one cycle. Here, the pulse period means the light emission period of one flash lamp in the pulse power circuit for discharging the flash lamp. By operating multiple Q-switches at regular intervals during one pumping period of the above laser, multiple Q-switch pulses can be injected, so that the above laser pulses can be made plural, for example three or more. As a result of these, the peak power of the above laser pulses can be lowered. Also, by adjusting the Q-switch signal delay time, excited electrons can be efficiently used for laser oscillation, and the overall laser oscillation output energy can be increased. Thereby, the problems caused by the conventional high single-pulse peak power can be solved, and the possibility of clinical application can be expanded because the total laser oscillation output energy is increased.

[0025] Figure 1 is a schematic diagram showing a multiple laser pulse oscillator 100 utilizing a multiple Q switch, which implements a multiple laser pulse oscillation method using a multiple Q switch according to the technical concept of the present invention.

[0026] Referring to Figure 1, the multiplex laser pulse oscillator 100 includes a mirror 110, a wavelength section 120, a Q-switch section 130, a polarization section 140, a gain medium section 150, an output coupler section 160, a first control section 170, and a second control section 180. The mirror 110, wavelength section 120, Q-switch section 130, polarization section 140, gain medium section 150, and output coupler section 160 can be arranged in the order described above.

[0027] The first control unit 170 is connected to the gain medium unit 150 and can receive an electrical signal. The second control unit 180 is connected to the Q-switch unit 130 and can receive an electrical signal, and may further include a drive driver for the Q-switch unit and a high-voltage transformer. The gain medium unit 150 may include a gain medium such as an Nd:YAG rod, YVO4, alexandrite, or titanium-sapphire rod, and a flash lamp. The output coupler unit 160 may include a mirror. The wavelength unit 120 and the polarization unit 140 may each have a flat plate shape.

[0028] The laser pulses generated by the multiple laser pulse oscillator 100 can be generated in the following manner.

[0029] Figure 2 is a flowchart illustrating the S100 multiple laser pulse oscillation method using multiple Q switches according to the technical concept of the present invention.

[0030] Referring to Figure 2, the multiple laser pulse oscillation method S100 using multiple Q switches includes the steps of: forming one cycle of light energy S110; exciting electrons in a gain medium by the light energy S120; executing a first Q switch S130 during one cycle of the light energy; oscillating a first laser pulse from the excited electrons in the gain medium by the first Q switch S140; executing a second Q switch S150 during one cycle of the light energy; and oscillating a second laser pulse from the excited electrons in the gain medium by the second Q switch S160.

[0031] Specifically, relating to Figure 1, when the first control unit 170 applies an electrical control signal to the gain medium unit 150, the voltage and current in the flash lamp contained in the gain medium unit 150 increase and then decrease, forming one cycle of light energy. This light energy excites the electrons in the gain medium contained in the gain medium unit 150.

[0032] Next, during one cycle of the above-mentioned light energy, the second control unit 180 applies an electrical control signal to the Q-switch unit 130 to execute the first Q-switch, causing a laser pulse to oscillate externally from the electrons excited in the gain medium. The laser pulse is reflected in the opposite direction by the mirror 110 and can oscillate externally by passing through the wavelength unit 120, the polarization unit 140, and the output coupler unit 160. If necessary, the laser pulse can be reflected in the opposite direction by the output coupler unit 160. Also, if necessary, the laser pulse can be polarized by the polarization unit 140 and oscillate in a different direction.

[0033] Next, during one cycle of the light energy, the second control unit 180 applies an electrical control signal to the Q-switch unit 130 to execute the second Q-switch, causing the electrons excited in the gain medium to oscillate to the outside again. Herein, the technical idea of ​​the present invention is that the first Q-switch and the second Q-switch are executed during one cycle of the light energy.

[0034] Subsequently, the third to seventh Q switches can be executed in the same manner during one cycle of the above-mentioned light energy to generate the third to seventh laser pulses, respectively. Here, the seventh Q switch is illustrative, and executing any n Q switches is included in the technical concept of the present invention.

[0035] The above-mentioned first Q-switch can have a delay time in the range of 80 μs to 150 μs immediately after the formation of the above-mentioned light energy.

[0036] The second Q switch described above can have a delay time in the range of 10 μs to 30 μs in the first Q switch described above.

[0037] During one cycle of the above-mentioned light energy, the method may further include the steps of executing the second Q-switch, followed by a delay time in the range of 10 μs to 30 μs, and then executing the third Q-switch, and oscillating a third laser pulse by the third Q-switch.

[0038] During one cycle of the above-mentioned light energy, the method may further include the steps of executing the third Q-switch, followed by a delay time in the range of 10 μs to 30 μs, and then executing the fourth Q-switch, and oscillating a fourth laser pulse by the fourth Q-switch.

[0039] During one cycle of the above-mentioned light energy, the following steps may be further included: executing the fourth Q-switch, followed by a delay time in the range of 10 μs to 30 μs, and then executing the fifth Q-switch; and oscillating a fifth laser pulse by the fifth Q-switch.

[0040] During one cycle of the above-mentioned light energy, the method may further include the steps of executing the fifth Q switch, followed by a delay time in the range of 10 μs to 30 μs, and then executing the sixth Q switch, and oscillating a sixth laser pulse by the sixth Q switch.

[0041] During one cycle of the above-mentioned light energy, the method may further include the steps of executing the sixth Q-switch, followed by a delay time in the range of 10 μs to 30 μs, and then executing the seventh Q-switch, and oscillating a seventh laser pulse by the seventh Q-switch.

[0042] Here, the above delay time is illustrative and can have various time ranges.

[0043] Furthermore, the above-described method allows the light energy to be repeatedly generated as the next cycle, and the Q-switch can also be repeatedly executed in the same manner.

[0044] Figure 3 is a graph showing the results of performing a multiplex laser pulse oscillation method using a multiplex Q switch according to one embodiment of the present invention.

[0045] Referring to Figure 3, the voltage and current of the flash lamp are shown, indicating that it provides one cycle of light energy. One cycle of this light energy is in the range of approximately 200 μs to 350 μs. During one cycle of this light energy, eight Q-switch pulse peaks are shown, indicating eight Q-switches, and eight laser pulse output peaks are shown, which were generated as a result.

[0046] The delay time from when the voltage is applied to the flash lamp to the first Q-switch pulse may be in the range of approximately 80 μs to 150 μs. Based on the first Q-switch pulse, the delay time to the second Q-switch pulse may be in the range of approximately 15 μs to 35 μs. Based on the first Q-switch pulse, the delay time to the third Q-switch pulse may be in the range of approximately 40 μs to 60 μs. Based on the first Q-switch pulse, the delay time to the fourth Q-switch pulse may be in the range of approximately 65 μs to 85 μs. Based on the first Q-switch pulse, the delay time to the fifth Q-switch pulse may be in the range of approximately 90 μs to 110 μs. Based on the first Q-switch pulse, the delay time to the sixth Q-switch pulse may be in the range of approximately 115 μs to 135 μs. Based on the first Q-switch pulse, the delay time to the seventh Q-switch pulse may be in the range of approximately 140 μs to 160 μs.

[0047] In conventional Q-switched lasers, electrons accumulate in an excited state in the gain medium until the Q-switch is turned on. When the Q-switch is turned on, the previously accumulated excited electrons are stimulated, causing the laser to oscillate while resonating. When a single Q-switch is performed, the electrons continue to receive light energy and change to an excited state even after the Q-switch delay time. However, since the Q-switch is not performed any further within one cycle of light energy, the laser does not oscillate any further within that cycle of light energy.

[0048] However, according to the multiple laser pulse oscillation method utilizing multiple Q-switches based on the technical concept of the present invention, since the Q-switching is performed continuously with the light energy of one cycle, it is possible to have an efficiency that allows for the use of more excited electrons, the laser oscillates continuously, and the overall pumping energy of the laser can be used effectively.

[0049] It will be apparent to any person with ordinary skill in the art to which the technical concept of the present invention pertains, that the technical concept of the present invention described above is not limited to the embodiments and accompanying drawings, and that various substitutions, modifications, and alterations are possible without departing from the technical concept of the present invention. [Industrial applicability]

[0050] The technical concept of this invention can be applied to laser generation methods.

Claims

1. A multiple laser pulse oscillator comprising a Q-switch section, a gain medium section equipped with alexandrite and a flash lamp, and a high-voltage transformer for the Q-switch section. A method for generating multiple laser pulses, The steps include forming one cycle of light energy using the gain medium, The steps include: the electrons of the alexandrite being excited by the light energy; The light energy is in the range of 200 μs to 350 μs for one cycle, and during one cycle, Immediately after the formation of the light energy, the Q-switching unit executes a first Q-switch having a delay time in the range of 80 μs or more and less than 150 μs. The first step of generating a first laser pulse from the excited electrons of the alexandrite using the first Q switch, The steps include executing a second Q switch with a delay time in the range of 10 μs to 30 μs from the first Q switch using the Q switch unit, The second Q switch generates a second laser pulse from the excited electrons of the alexandrite, A method for oscillating multiple laser pulses, including the method described above.

2. The steps include: executing the second Q switch, then, after a delay time in the range of 10 μs to 30 μs, the third Q switch is executed by the Q switch unit; The steps include: generating a third laser pulse from the electrons excited by the alexandrite using the third Q switch; The multiple laser pulse oscillation method according to claim 1, further comprising:

3. The steps include: executing the third Q switch, then, after a delay time in the range of 10 μs to 30 μs, the fourth Q switch is executed by the Q switch unit; The steps include: oscillating a fourth laser pulse using the fourth Q switch, The multiple laser pulse oscillation method according to claim 2, further comprising:

4. The steps include: executing the fourth Q switch, then, after a delay time in the range of 10 μs to 30 μs, the fifth Q switch is executed by the Q switch unit; The steps include: oscillating a fifth laser pulse using the fifth Q switch; The multiple laser pulse oscillation method according to claim 3, further comprising:

5. The steps include: executing the fifth Q switch, then, after a delay time in the range of 10 μs to 30 μs, the sixth Q switch is executed by the Q switch unit; The steps include: oscillating a sixth laser pulse using the sixth Q switch, The multiple laser pulse oscillation method according to claim 4, further comprising:

6. The steps include: executing the sixth Q switch, then, after a delay time in the range of 10 μs to 30 μs, the seventh Q switch is executed by the Q switch unit; The steps include: oscillating a seventh laser pulse using the seventh Q switch, The multiple laser pulse oscillation method according to claim 5, further comprising:

7. The multiple laser pulse oscillation method according to claim 1, wherein one cycle of the light energy is in the range of 200 μs to 350 μs.

8. A multiplex laser pulse oscillator comprising a mirror, a wavelength section, a Q-switch section, a polarization section, a gain medium section equipped with alexandrite and a flash lamp, an output coupler section, a first control section and a second control section, The first control unit applies an electrical control signal to form a cycle of light energy in the gain medium section in the range of 200 μs to 350 μs. The electrons of the alexandrite are excited by the aforementioned light energy, During one cycle of the light energy, the second control unit applies an electrical control signal to the Q-switch unit, thereby executing the first Q-switch. After the execution of the first Q-switch, a first laser pulse is generated from the excited electrons of the alexandrite with a delay time in the range of 80 μs to less than 150 μs. Furthermore, after a delay of 10 μs to 30 μs following the execution of the first Q switch, the second control unit again applies an electrical control signal to the Q switch unit to execute the second Q switch. The second Q-switch is configured to generate a second laser pulse from the excited electrons of the alexandrite, The second control unit includes a high-voltage transformer for the Q-switch section. Multiple laser pulse oscillator.

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