MULTIPLE LASER PULSE OSCILLATION METHOD AND APPARATUS USING MULTIPLE-Q SWITCHING

Abstract

Provided is a multiple laser pulse oscillation method using multiple Q-switching capable of reducing peak power of laser and increasing energy efficiency. A multiple laser pulse oscillation method using multiple Q-switching includes: forming one period of light energy; exciting electrons of a gain medium by the light energy; performing first Q-switching during one period of the light energy; oscillating a first laser pulse by the first Q-switching; performing second Q-switching during one period of the light energy; and oscillating a second laser pulse by the second Q-switching.

Claims

1. A multiple laser pulse oscillation method using multiple Q-switching, the method comprising: forming one period of light energy; exciting electrons of a gain medium by the light energy; performing first Q-switching during one period of the light energy; oscillating a first laser pulse from the excited electrons of the gain medium by the first Q-switching; performing second Q-switching during the one period of the light energy; and oscillating a second laser pulse from the excited electrons of the gain medium by the second Q-switching.

2. The method of claim 1, wherein the first Q-switching has a delay time ranging from 80 μs to 150 μs directly after the light energy is formed.

3. The method of claim 1, wherein the second Q-switching has a delay time ranging from 10 μs to 30 μs from the first Q-switching.

4. The method of claim 1, further comprising: performing third Q-switching when a delay time ranging from 10 μs to 30 μs passes after the second Q-switching is performed, during the one period of the light energy; and oscillating a third laser pulse by the third Q-switching.

5. The method of claim 4, further comprising: performing fourth Q-switching when a delay time ranging from 10 μs to 30 μs passes after the third Q-switching is performed, during the one period of the light energy; and oscillating a fourth laser pulse by the fourth Q-switching.

6. The method of claim 5, further comprising: performing fifth Q-switching when a delay time ranging from 10 μs to 30 μs passes after the fourth Q-switching is performed, during the one period of the light energy; and oscillating a fifth laser pulse by the fifth Q-switching.

7. The method of claim 6, further comprising: performing sixth Q-switching when a delay time ranging from 10 μs to 30 μs passes after the fifth Q-switching is performed, during the one period of the light energy; and oscillating a sixth laser pulse by the sixth Q-switching.

8. The method of claim 7, further comprising: performing seventh Q-switching when a delay time ranging from 10 μs to 30 μs passes after the sixth Q-switching is performed, during the one period of the light energy; and oscillating a seventh laser pulse by the seventh Q-switching.

9. The method of claim 1, wherein the one period of the light energy ranges from 200 μs to 350 μs.

10. A multiple laser pulse oscillation apparatus comprising a mirror, a wavelength portion, a Q-switching portion, a polarization portion, a gain medium portion, an output coupler portion, a first control portion, and a second control portion, the apparatus performing: forming one period of light energy in the gain medium portion as the first control portion applies an electrical control signal; exciting electrons of the gain medium of the gain medium portion by the light energy; performing first Q-switching in the Q-switching portion as the second control portion applies an electrical control signal during one period of the light energy; oscillating a first laser pulse by the first Q-switching; performing second Q-switching in the Q-switching portion during the one period of the light energy; and oscillating a second laser pulse by the second Q-switching.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0021] FIG. 1 is a schematic view of a multiple laser pulse oscillation apparatus using multiple Q-switching that implements a multiple laser pulse oscillation method using multiple Q-switching, according to the present disclosure.

[0022] FIG. 2 is a flowchart of a multiple laser pulse oscillation method using multiple Q-switching according to the present disclosure.

[0023] FIG. 3 is a graph showing results of performing a multiple laser pulse oscillation method using multiple Q-switching according to an embodiment of the present disclosure.

MODE OF DISCLOSURE

[0024] The disclosure will now be described more fully with reference to the accompanying drawings, in which embodiments of the disclosure are shown. The disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the disclosure to those skilled in the art. Like reference numerals in the drawings denote like elements Furthermore, various components and regions in the drawings are schematically illustrated. Accordingly, the present invention is not limited by the relative size or distance drawn in the accompanying drawings.

[0025] According to the present disclosure, in order to reduce high laser oscillation peak power and maintain high output energy, a Q-switching laser generates three or more laser pulses in one period by operating, for example, two or more or three or more Q-switches in one pulse period, for example, 230 μs to 330 μs. The pulse period may mean one light emission period of a flash lamp in a pulse power circuit to discharge a flash lamp. As the laser injects multiple Q-switching pulses in one pumping period by operating multiple Q-switches at a certain interval, the laser pulse may include a plurality of laser pulses, for example, three or more laser pulses. As a result, peak power of the laser pulse may be reduced. Furthermore, by controlling a Q-switching signal delay time, excited electrons may be efficiently used for laser oscillation, and thus overall laser oscillation output energy may be increased. A high single pulse peak power problem according to the related art may be solved, and as the total laser oscillation output energy is increased, a possibility of clinical application may be expended.

[0026] FIG. 1 is a schematic view of a multiple laser pulse oscillation apparatus 100 using multiple Q-switching that implements a multiple laser pulse oscillation method using multiple Q-switching according to the present disclosure.

[0027] Referring to FIG. 1, the multiple laser pulse oscillation apparatus 100 may include a mirror 110, a wavelength portion 120, a Q-switching portion 130, a polarization portion 140, a gain medium portion 150, an output coupler portion 160, a first control portion 170, and a second control portion 180. The mirror 110, the wavelength portion 120, the Q-switching portion 130, the polarization portion 140, the gain medium portion 150, and the output coupler portion 160 may be arranged in the above-described order.

[0028] The first control portion 170 may be connected to the gain medium portion 150 to apply an electrical signal thereto. The second control portion 180 may be connected to the Q-switching portion 130 to apply an electrical signal thereto and may further include a driving driver for the Q-switching portion, a transformer for high voltage, and the like. The gain medium portion 150 may include a gain medium such as ND-YAG rad, YVO4 Alexandria, difference sapphire rad, and the like, and a flash lamp. The output coupler portion 160 may include a mirror. The wavelength portion 120 and the polarization portion 140 may each have a flat plate shape.

[0029] A laser pulse that is oscillated by the multiple laser pulse oscillation apparatus 100 may be generated in the following method.

[0030] FIG. 2 is a flowchart of a multiple laser pulse oscillation method S 100 using multiple Q-switching according to the present disclosure.

[0031] Referring to FIG. 2, a multiple laser pulse oscillation method S100 using multiple Q-switching may include: forming one period of light energy (S110), exciting electrons of a gain medium by the light energy (S120); performing first Q-switching during one period of the light energy (S130); oscillating a first laser pulse from the excited electrons of the gain medium by the first Q-switching (S140); performing second Q-switching during one period of the light energy (S150); and oscillating a second laser pulse from the excited electrons of the gain medium by the second Q-switching (S160).

[0032] In detail, with reference to FIG. 1, when the first control portion 170 applies an electrical control signal to the gain medium portion 150, one period of light energy is formed as a voltage and a current increase and then decrease in the flash lamp included in the gain medium portion 150. The electrons of the gain medium included in the gain medium portion 150 are excited by the light energy.

[0033] Next, when first Q-switching is performed as the second control portion 180 applies an electrical control signal to the Q-switching portion 130 during one period of the light energy, a laser pulse oscillates to the outside from the excited electrons in the gain medium. The laser pulse may be reflected by the mirror 110 in the opposite direction, and may pass through the wavelength portion 120, the polarization portion 140, and the output coupler portion 160, thereby oscillating to the outside. When necessary, the laser pulse may be reflected by the output coupler portion 160 in the opposite direction. Furthermore, when necessary, the laser pulse may be polarized by the polarization portion 140, thereby oscillating by changing the direction.

[0034] Next, when second Q-switching is performed as the second control portion 180 applies an electrical control signal to the Q-switching portion 130 during one period of the light energy, a laser pulse oscillates again to the outside from the excited electrons in the gain medium. In the present disclosure, the first Q-switching and the second Q-switching are performed during one period of the light energy.

[0035] Next, third Q-switching to seventh Q-switching are performed in the same method during one period of the light energy, thereby oscillating a third laser pulse to a seventh laser pulse, respectively. The seventh Q-switching is exemplary, and the present disclosure includes performing certain n-time Q-switching.

[0036] The first Q-switching may have a delay time ranging from 80 μs to 150 μs directly after the light energy is formed.

[0037] The second Q-switching may have a delay time ranging from 10 μs to 30 μs from the first Q-switching.

[0038] During one period of the light energy, performing third Q-switching when a delay time ranging from 10 μs to 30 μs passes after the second Q-switching is performed, and oscillating a third laser pulse by the third Q-switching, may be further included.

[0039] During one period of the light energy, performing fourth Q-switching when a delay time ranging from 10 μs to 30 μs passes after the third Q-switching is performed, and oscillating a fourth laser pulse by the fourth Q-switching, may be further included

[0040] During one period of the light energy, performing fifth Q-switching when a delay time ranging from 10 μs to 30 μs passes after the fourth Q-switching is performed, and oscillating a fifth laser pulse by the fifth Q-switching, may be further included.

[0041] During one period of the light energy, performing sixth Q-switching when a delay time ranging from 10 μs to 30 μs passes after the fifth Q-switching is performed, and oscillating a sixth laser pulse by the sixth Q-switching, may be further included.

[0042] During one period of the light energy, performing seventh Q-switching when a delay time ranging from 10 μs to 30 μs passes after the sixth Q-switching is performed, and oscillating a seventh laser pulse by the seventh Q-switching, may be further included.

[0043] The delay time is exemplary and may have various time ranges.

[0044] Furthermore, the light energy may be formed by repeating the above-described method in next one period, and also the Q-switching may be repeatedly performed in the same method,

[0045] FIG. 3 is a graph showing results of performing a multiple laser pulse oscillation method using multiple Q-switching according to an embodiment of the present disclosure.

[0046] Referring to FIG. 3, the voltage and the current of a flash lamp are shown, and it may be seen that the one period of light energy is provided. One period of the light energy may range from about 200 μs to about 350 μs. Eight Q-switching pulse peaks indicating eight-time Q-switching and eight laser pulse output peaks that are oscillated accordingly during one period of the light energy are shown.

[0047] A delay time from when a voltage of the flash lamp is applied to a first Q-switch pulse may range from about 80 μs to about 150 μs. A delay time to a second Q-switch pulse with respect to the first Q-switch pulse may range from about 15 μs to about 35 μs. A delay time to a third Q-switch pulse with respect to the first Q-switch pulse may range from about 40 μs to about 60 μs. A delay time to a fourth Q-switch pulse with respect to the first Q-switch pulse may range from about 65 μs to about 85 μs. A delay time to a fifth Q-switch pulse with respect to the first Q-switch pulse may range from about 90 μs to about 110 μs. A delay time to a sixth Q-switch pulse with respect to the first Q-switch pulse may range from about 115 μs to about 135 μs. A delay time to a seventh Q-switch pulse with respect to the first Q-switch pulse may range from about 140 μs to about 160 μs.

[0048] In a Q-switching laser according to the related art, electrons are accumulated in the excited state in the gain medium until a Q-switch is turned on, and when the Q-switch is turned on, the electrons in the excited state accumulated so far are simulated to resonate, thereby oscillating laser. When one-time Q-switching is performed, the electrons continuously receive light energy even after a Q-switch delay time so as to be continuously changed to the excited state. However, Q-switching is performed no longer during one period of light energy, and thus laser is oscillated no longer during one period of light energy.

[0049] However, in the multiple laser pulse oscillation method using multiple Q-switching according to the present disclosure, as Q-switching is continuously performed during one period of light energy, there is efficiency of further using the excited electrons, and as laser is continuously oscillated, the pumping energy of laser may be effectively used as a whole.

[0050] While the disclosure has been particularly shown and described with reference to preferred embodiments using specific terminologies, the embodiments and terminologies should be considered in descriptive sense only and not for purposes of limitation. Therefore, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the following claims.

INDUSTRIAL APPLICABILITY

[0051] The present disclosure may be used for a laser generation method.