KR20200118565A - Laser generation device - Google Patents

Abstract

The present invention relates to a laser generating device and, more specifically, to a laser generating device for medical use. The purpose of the present invention is to provide the laser generating device capable of outputting both nanosecond and picosecond laser pulses in a single device using a Q-switch. A laser generating device according to a preferred embodiment of the present invention comprises: a laser gain medium (2); a polarizer (3), a first Q switch (4), a λ/4 wave plate (5) and a first resonator mirror (6) sequentially disposed on a first side of the laser gain medium (2); a second Q switch (7) and a second resonator mirror (8) sequentially arranged on a second side of the laser gain medium (2); and a controller (60) including a first control mode for performing a picosecond laser pulse generation operation and a second control mode for performing a nanosecond laser pulse generation operation. The present invention can control the pulse width and on/off timing of two Q-switches to output the nanosecond and picosecond laser pulses within the single device.

Description

Laser generation device {LASER GENERATION DEVICE}

The present invention relates to a laser generator, and more particularly, to a laser generator for medical use.

The method of oscillating the laser in the form of a short pulse is largely classified into two types. It is divided into a Q-switching method and a mode-locking method. Several methods have been developed to implement these methods. There are an active amplitude or frequency modulation method inside the resonator, a passive modulation method through a saturable absorbor, a synchronous gain modulation method, and the like. These methods are used in the Q-switching method, sometimes in the mode locking method, depending on the required purpose. In general, the Q-switching method is advantageous for obtaining high energy per pulse, and the mode locking method is advantageous for obtaining high peak power of a short pulse.

In the medical field, nanosecond pulsed lasers and picosecond pulsed lasers are mainly used. However, the conventional medical laser generating device cannot implement a nanosecond pulse laser and a picosecond pulse laser at the same time, so there is a problem that each must be provided separately.

[Prior technical literature]

[Patent Literature]

-Korean Patent Laid-Open Publication No. 10-2015-0115349 (published date: 2015.10.14., title of invention: picosecond laser generating device and method)

-Korean Patent Registration No. 10-0821563 (Announcement date: 2008.04.14, Title of invention: Q-switching driver of laser generator for high-density energy laser generation)

An object of the present invention is to provide a laser generating device capable of outputting both nanosecond and picosecond laser pulses within a single device using a Q-switch.

A laser generating device according to a preferred embodiment of the present invention comprises: a laser gain medium 2; A polarizer (3), a first Q switch (4), a λ/4 wave plate (5) and a first resonator mirror (6) sequentially disposed on the first side of the laser gain medium (2); A second Q switch (7) and a second resonator mirror (8) sequentially arranged on the second side of the laser gain medium (2); And a controller 60 including a first control mode 61 for performing a picosecond laser pulse generation operation and a second control mode 62 for performing a nanosecond laser pulse generation operation.

Here, the control unit 60 operates the second Q switch 7 twice with a time difference of Δt2 while the first Q switch 4 is operated in the first control mode 61. Picosecond laser pulses can be generated.

The second Q switch 7 is first operated to generate a seed mode, and the picosecond laser pulse may be generated by re-amplifying the seed mode more than a preset number of times.

Further, the second operation time of the second Q switch 7 may be a preset number of nanoseconds.

In addition, the seed mode may have a width less than a time when the second Q switch 7 is operated for the second time.

In addition, the controller 60 operates the second Q switch 7 twice with a time difference of Δt2 while the first Q switch 4 is operated in the second control mode 62. It can generate nanosecond laser pulses.

Here, the second Q switch 7 is first operated to generate the seed mode, and the nanosecond laser pulse may be generated by re-amplifying the seed mode more than a preset number of times.

In addition, the second operating time of the second Q switch 7 may be a preset number of nanoseconds.

In addition, the seed mode may have a width less than a time when the second Q switch 7 is operated for the second time.

In addition, the controller 60 may sequentially arrange and operate the first control mode 61 and the second control mode 62 according to a preset arrangement rule.

The present invention can control the pulse width and on/off timing of two Q-switches to output both nanosecond and picosecond laser pulses within a single device.

1 is a functional block diagram of a laser generating device according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a situation in which the laser generator of FIG. 1 outputs nanosecond and picosecond pulsed lasers.
3 shows various modified embodiments of the laser generating device of the present invention.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

Hereinafter, a laser generating apparatus according to an exemplary embodiment of the present invention will be described with reference to FIGS. 1 to 3. 1 is a functional block diagram of a laser generating device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a situation in which the laser generator of FIG. 1 outputs nanosecond and picosecond pulsed lasers. 3 shows various modified embodiments of the laser generating device of the present invention.

Referring to FIG. 1, the laser generating device may include various optical components arranged along the optical path 10.

First, a laser gain medium 2 may be installed on the optical path 10. As the laser gain medium 2, Nd:YAG, Ruby, Alexandrite, Erbium, Co2, or the like may be used. The invention does not limit the laser gain medium.

A polarizer 3, a first Q switch 4, a λ/4 wave plate 5, and a first resonator mirror 6 are sequentially arranged on the first side of the laser gain medium 2, each of which is an optical path It can be coupled to (10).

On the second side of the laser gain medium 2 a second Q switch 7 and a second resonator mirror 8 are sequentially arranged, each of which can be coupled to the optical path 10.

The λ/4 wave plate 5 may be a passive element, and the first and second Q switches 7 may be active elements.

In such a structure, the laser gain medium 2 can perform a pumping operation by the light irradiated by the lamp 1. At this time, as is well known, the laser gain medium 2 is reflected by a photon that is reflected between the first resonator mirror 6 and the second resonator mirror 8 and excites the laser gain medium 2, and the laser gain medium 2 Can be pumped. In addition, when the number of occupants is reversed by pumping, a laser may be generated. The first resonator mirror 6 and the second resonator mirror 8 may be total reflection mirrors.

The controller 60 may have a first control mode 61 and a second control mode 62. In the first control mode 61, the operation of the first Q switch 4 and the second Q switch 7 is controlled to generate a picosecond laser pulse. In the second control mode 62, the operation of the first Q switch 4 and the second Q switch 7 is controlled to generate a nanosecond laser pulse.

Hereinafter, matters in which nanosecond and picosecond laser pulses are generated will be described.

Referring to FIG. 2, the control unit 60 may output a lamp trigger signal. At this time, the lamp driver (not shown) may output a Lamp Electrical Pulse for turning on the lamp. Thereby, the laser gain medium 2 can start pumping. In addition, at the time point T1, the controller 60 may output a Q1 trigger pulse to the first Q driver 40. In addition, the controller 60 may output a Q2-1 trigger pulse to the second Q driver 70 at a time point T2 with a time difference between T1 and Δt1. In addition, the controller 60 may output a Q2-2 trigger pulse to the second Q driver 70 at a time point T3 with a time difference between T2 and Δt2.

Upon receiving the Q1 trigger pulse, the first Q driver 40 can output a Q1 electrical pulse for driving the first Q switch 4 from T4, which is a time delayed by Δt3 from T1, and the Q1 electric pulse The first Q switch 4 can be operated by.

In addition, while the first Q switch 4 is operated, a Q2 electrical pulse for operating the second Q switch 7 may be output through the second Q driver 40.

Q2 electric pulse (Q2 Eclectrical Pulse) can be output a total of two times. Hereinafter, the first output of the second Q2 electric pulse is referred to as a “first Q2 electric pulse”, and the second output is referred to as a “second Q2 electric pulse”. The first Q2 electric pulse and the second Q2 electric pulse may be output with a time difference of Δt2. Here, the first Q2 electric pulse may correspond to the Q2-1 trigger pulse, and the second Q2 electric pulse may correspond to the Q2-2 trigger pulse.

Referring to FIG. 2, a first Q2 electric pulse may be output at a time point T5, and a second Q2 electric pulse may be output at T6, which is a time point Δt2 elapses from T5. The first Q2 electric pulse and the second Q2 electric pulse may be output while the first Q switch 4 is operated, as described above. That is, while the first Q switch 4 is operated, the second Q switch 7 can be operated by the first Q2 electric pulse and the second Q2 electric pulse.

The pulse widths of the first Q2 electric pulse and the second Q2 electric pulse may be preset several nanoseconds. At this time, the pulse width of the first Q2 electric pulse and the second Q2 electric pulse is such that the width of the seed mode (SeedMode, SM) to be described later is less than the pulse width of the second Q2 electric pulse, and the width of the seed mode (SeedMode, SM) It is preferable to set the width to be a preset number of picoseconds (when a picosecond laser pulse is output in the first control mode) or a preset number of nanoseconds (when a nanosecond laser pulse is output in the second control mode).

While the first Q switch 4 is operating, the light emitted from the laser gain medium 2 moves to the first side, while the polarizer 3, the first Q switch 4, the λ/4 wave plate 5 The first resonator mirror 6 may be reached by passing through in sequence.

In addition, after the polarization by the polarizer 3, circular polarization through the λ/4 phase delay by the first Q switch 4, and the linear polarization by the λ/4 wave plate 5 are sequentially formed, the linear polarization is It can be reflected by the first resonator mirror 6. The reflected linearly polarized light may sequentially pass through the λ/4 wave plate 5 and the first Q switch 4.

At this time, circularly polarized light through λ/4 phase delay by the λ/4 wave plate 5 and linearly polarized light through λ/4 phase delay by the first Q switch 4 may be generated. After passing through the polarizer 3, this linear polarization can reach the second resonator mirror 8 while excitation of the laser gain medium 2.

Through this process, the laser gain medium 2 can be amplified by pumping the light.

In the present invention, a nano or pico seed mode (SeedMode, SM) may be generated by applying a predetermined number of nanoseconds (eg, 3 or 5.5 ns) to T5 with the first Q2 electric pulse. More specifically, by operating the second Q switch 7 for a preset number of nanoseconds, the phase of the light reciprocating the second side is delayed by λ/4, and the polarization state can be rotated by 90°.

Light during the time when the second Q switch 7 is operated by the first Q2 trigger pulse is dumped (optical mode extraction) through the polarizer 3, and the resonator round trip time 2L/c (c: speed of light, L Among the light corresponding to the optical path length (in other words, the resonator distance), light except for the light corresponding to the pulse width of the first Q2 electric pulse is generated in a seed mode (SM). Assuming that the 2L/cs is 6 nsec (resonator round trip time), for example, when 3ns and 5.5ns are applied to the first Q2 electric pulse, 3ns (nano seed mode) and 0.5.ns (500ps) (pico seed mode), respectively Mode) of the SeedMode can be created.

SeedMode (SM) is applied to the laser gain medium 2 for re-amplification.

At this time, the seed mode (SeedMode, SM) is a Gaussian curve (the gain of the laser gain medium 2) while the second Q switch 7 is not operated (from the point when the first Q2 trigger pulse is removed to T6). Can be re-amplified along the curve).

In addition, the seed mode (SedMode, SM) may have various modes that are discretely distributed along a Gaussian curve. In the various modes including the seed mode (SedMode, SM), an interval between modes may be 2L/c sec (c: speed of light, L optical path length (in other words, resonator distance)). The width of various modes other than the seed mode (SeedMode, SM) may be the same as that of the seed mode (SeedMode, SM).

In the process of re-amplifying the seed mode (SM), a laser of a specific seed mode may be dumped through the polarizer 3 by applying the second Q2 electric pulse to a predetermined number of nanoseconds.

As described above, the laser phase of a specific mode amplified by application of the second Q2 electric pulse for several nanoseconds is delayed by λ/4, and the polarization direction is rotated by 90°, and this specific re-amplified seed mode (SeedMode , SM) may be output through the polarizer 3.

At this time, by adjusting the timing T6 at which the second Q2 electric pulse is outputted, a picosecond pulse or a nanosecond pulse may be output when the seed mode (SM) is maximized. 2 illustrates that the laser gain medium 2 has a maximum gain when re-amplifying twice. At this time, the second Q2 electric pulse is the point at which 2 * 2L/c sec (c: speed of light, L optical path length (in other words, resonator distance)) elapses from the point when the application of the first Q2 electric pulse is terminated. By being output from, it is possible to output a high-power picosecond or nanosecond laser pulse with a maximum gain.

Depending on the designer, a high-output picosecond or nanosecond pulse can be output by appropriately adjusting the application timing and pulse width of L (resonator or optical path length), Q1, Q2-1, Q2-2 Trigger Pulse. In order to prevent the mode from being canceled by the operation of the second Q switch 7, the time the second Q switch 7 is operated is 2L/c sec (c: speed of light, L optical path length (in other words, , Resonator distance)), and the width of the seed mode is also the timing at which the second Q switch 7 is operated by Q2-2 Trigger Pulse, L (resonator or optical path length), and the laser gain medium. It is desirable to set appropriately in consideration of the gain characteristics. When generating a nanosecond pulsed laser, the width of the seed mode (nano seed mode) can be set to a preset number of nanoseconds, and when generating a picosecond pulsed laser, the width of the seed mode (pico seed mode) is set to a preset number of nanoseconds. Can be made. That is, a picosecond or nanosecond pulsed laser may be generated by controlling the width of the seed mode to the width of the first Q2 electric pulse. Each of the first control mode and the second control mode can be controlled so that the width of the seed mode is the same as above, and accordingly, the first control mode and the second control mode are respectively applied to Q2-1 and Q2-2 trigger pulse The timing, the application timing of the first and second Q2 electric pulses, and the pulse width can be controlled.

In Fig. 3, in the equipment in which the nanosecond pulse laser and the picosecond pulse laser are integrated, the picosecond pulse laser is continuously irradiated as shown in Fig. 6(a), and then the nanosecond pulse laser is continuously irradiated or Fig. 6 ( As in b), it can be used in combination in various modes such as irradiating while intersecting picosecond pulse laser and nanosecond pulse laser.

As described above, when generating a picosecond pulse laser, the controller 60 operates in the first control mode 61, and when generating a nanosecond pulse laser, the controller 60 operates in the second control mode 62 can do. As described above, it goes without saying that a function of converting the control mode to control the alternating or sequential generation of the nanosecond pulse laser and the picosecond pulse laser may be mounted on the controller.

As above, the present invention can generate nanosecond and picosecond laser pulses within a single resonator using two Q switches.

1: lamp
2: laser gain medium
3: polarizer
4: 1st Q switch
5: λ/4 wave plate
6: first resonator mirror
7: 2nd Q switch
8: second resonator mirror
10: optical path
40: first Q driver
60: control unit
61: first control mode
62: second control mode
70: 2nd Q driver

Claims (10)

Laser gain medium 2;
A polarizer (3), a first Q switch (4), a λ/4 wave plate (5) and a first resonator mirror (6) sequentially disposed on the first side of the laser gain medium (2);
A second Q switch (7) and a second resonator mirror (8) sequentially arranged on the second side of the laser gain medium (2); And
And a controller (60) including a first control mode (61) for performing a picosecond laser pulse generation operation and a second control mode (62) for performing a nanosecond laser pulse generation operation.
The method of claim 1,
The control unit 60 operates the second Q switch 7 twice while the first Q switch 4 is operated in the first control mode 61 with a time difference of Δt2. A laser generating device, characterized in that generating a laser pulse.
The method of claim 2,
The second Q switch 7 is first operated to create a seed mode,
And generating the picosecond laser pulse by re-amplifying the seed mode more than a preset number of times.
The method of claim 3,
The laser generating device, characterized in that the second operating time of the second Q switch (7) is a preset number of nanoseconds.
The method of claim 4,
Wherein the seed mode has a width less than a time when the second Q switch (7) is operated a second time.
The method of claim 1,
The control unit 60 operates the second Q switch 7 twice with a time difference of Δt2 while the first Q switch 4 is operated in the second control mode 62, thereby A laser generating device, characterized in that generating a pulse.
The method of claim 6,
The second Q switch 7 is first operated to create a seed mode,
The laser generating device, characterized in that generating the nanosecond laser pulse by re-amplifying the seed mode more than a preset number of times.
The method of claim 7,
The laser generating device, characterized in that the second operating time of the second Q switch (7) is a preset number of nanoseconds.
The method of claim 8,
Wherein the seed mode has a width less than a time when the second Q switch (7) is operated a second time.
The method of claim 1,
The controller (60) is a laser generating device, characterized in that the first control mode (61) and the second control mode (62) are sequentially arranged and operated according to a preset arrangement rule.

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