KR20210104309A - Thermal lensing effect controling system for medical laser - Google Patents

Abstract

The present invention relates to a medical laser thermal lens effect control system capable of stably and uniformly controlling a thermal lensing effect using a mechanical switch despite a change in the frequency of a laser output. The medical laser thermal lens effect control system of the present invention comprises: a laser driving unit comprising a power supply unit and a microprocessor unit; a seed laser unit oscillating and emitting a low-power laser light by generating a seed light having a narrow line width having a constant overlapping frequency according to a driving signal of the laser driving unit; a first optical path unit for primarily amplifying the laser light input from the seed laser unit; and a second optical path unit for secondarily amplifying and outputting the laser light amplified by the first optical path unit. The first optical path unit includes a mechanical switch for selectively blocking or allowing the laser light to be incident.

Description

Thermal lensing effect control system for medical laser

The present invention relates to a medical laser thermal lensing effect control system, which uses a mechanical switch to stably and uniformly control a thermal lensing effect despite a change in the frequency of a laser output. It's about the system.

Recently, medical lasers have been used for various purposes such as surgical operation and acne treatment, treatment of pigmented lesions of the skin, wrinkle removal, and maintenance of skin elasticity.

The application of lasers in this medical field is that the pulse duration and pulse intensity of the laser can have an effect, for example, during which the laser energy diffuses into the surrounding tissue during the pulse or causes undesirable localized vaporization. An appropriate heating effect was realized by maintaining the pulse duration below the thermal relaxation time of the tissue or structures to be treated.

In this regard, the sub-nanosecond pulse laser energy is transformed using a lens, and thus a non-uniform energy cross-section characterized by a plurality of regions having a relatively high energy per unit area dispersed within a background region of a relatively low energy per unit area. to generate a therapeutic beam with

As a result, although there is no change in the output energy, a difference in diffusion of the laser beam occurs, and a thermal lensing effect is generated due to the difference in diffusion depth and beam diameter of the laser, acting as an unstable factor.

As a prior art for improving this, the 'pulse laser driving system' of Korean Patent Publication No. 10-1191707 is shown in FIG. 1 .

This conventional technique includes a light source 11 that emits light by a light source input voltage, an active medium 12 pumped by the light of the light source 11, and a plurality of reflectors with the active medium 12 interposed therebetween. An optical device unit (10) including a laser resonator (13-1, 13-2) and a Q switch (14) disposed on an optical path in the laser resonator and selectively opened and closed according to an applied Q switch input voltage (10) and a PFN 21 that receives a voltage from the power supply 22 and applies a light source input voltage having a predetermined magnitude to the light source 11, and receives a voltage from the power supply 22 and amplifies it to a predetermined magnitude Q The Q switch driver 23 for applying the Q switch input voltage to the switch 14, and the light source input voltage according to the set laser oscillation intensity, and the Q switch driving delay time according to the pumping time of the active medium 12 The laser driving unit 20 including the control block 24 for controlling the Q switch 14 to be driven after elapsed, and the laser oscillation for the magnitude of the light source input voltage and the Q switch driving delay time divided according to the laser oscillation intensity Control signal data is stored, and it is composed of a control console unit 30 that outputs a laser oscillation control signal to the laser driving unit 200 through a wired/wireless communication network.

Through this, since it is possible to oscillate with the maximum amount of laser output with the minimum amount of electrical energy, it is possible to save electrical energy and accurately control the oscillation intensity of the desired laser.

In addition, since the light source input voltage of an appropriate size required for the set laser oscillation intensity is applied, the lifetime of the pulse laser driving system including the light source and the optical device can be used to the maximum, and the voltage generator according to the input Q switch input voltage control signal By controlling the amplitude of the input voltage of the Q switch amplified to be corrected according to the preset voltage, the laser oscillation intensity required by the user can be precisely and accurately output.

However, in this conventional technique, the thermal lensing phenomenon can be neglected because this phenomenon is slight in the nanosecond laser among medical lasers, but the picosecond laser has a pulse width 10 times or more compared to the nanosecond laser. It is narrow, and the thermal lens phenomenon is very prominent, so there is a limit for medical application, and there is a problem in that the manufacturing cost is very high when an optical element (eg, Q switch) is used.

The present invention, which was devised to solve the problems of the prior art as described above, has an object to enable stable and uniform control of the thermal lens effect despite the frequency change of the laser output even when the picosecond laser is applied for medical purposes. have.

In addition, another object of the present invention is to implement a system that is not only easy to manufacture and control but also inexpensive in terms of cost by using a mechanical switch to control the thermal lens effect.

The above object of the present invention is a medical laser thermal lens effect control system, comprising: a laser driving unit including a power supply unit and a microprocessor unit; a seed laser unit oscillating and emitting a low-power laser light by generating a seed light having a narrow line width having a constant overlapping frequency according to a driving signal of the laser driver; a first optical path unit for primary amplification of the laser light input from the seed laser unit; and a second optical path unit for secondarily amplifying and outputting the laser light amplified in the first light path unit, wherein the first optical path unit is provided with a mechanical switch that selectively blocks or allows the laser light to be incident characterized by a medical laser thermal lensing effect control system.

Therefore, the medical laser thermal lensing effect control system of the present invention has the effect of stably and uniformly controlling the thermal lensing effect despite the frequency change of the laser output.

In addition, the present invention has the effect of realizing a system that is not only easy to manufacture and control, but also inexpensive in terms of cost by using a mechanical switch to control the thermal lens effect.

1 is a configuration diagram of a pulse laser driving system according to the prior art;
2 is a block diagram of a medical laser thermal lens effect control system according to the present invention;
3 is a schematic diagram of a mechanical switch according to the invention;
4 is a diagram illustrating waveforms according to the operation of the thermal lens effect control system according to the present invention.

The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that there is.

Accordingly, the configuration shown in the embodiments and drawings described in the present specification is only the most preferred embodiment of the present invention and does not represent all the technical spirit of the present invention, so at the time of the present application, various It should be understood that there may be equivalents and variations.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of a medical laser thermal lens effect control system according to the present invention. As shown in FIG. 2 , a laser driving unit including a power supply 110 and a microprocessor unit 120 is provided.

Here, the flash lamp 140 for injecting excitation energy into the laser medium 340 and 430 and the reflector 130 for resonating the laser light primarily generated in the laser medium are limited to the description required in the present invention. A detailed description will be omitted.

A seed laser unit 200 generates seed light with a narrow line width having a constant overlapping frequency by a laser diode according to a driving signal of the laser driver, and oscillates and emits low-power laser light.

However, in order to use the laser light input from the seed laser unit 200 for medical purposes, the energy is low and a process for amplifying it is required. By having the second optical path units 410 to 430 for secondary amplifying and outputting the laser light amplified by the first light path unit 310 to 360, the low energy laser light has an energy suitable for medical use. do.

Here, the first optical path forming the primary optical path emits the low-power laser light oscillated by the seed laser unit 200 to the flash lamp ( By the discharge of 140), the laser light is incident on the first laser medium 340 amplifying.

Thereafter, the linearly polarized light output from the first laser medium 340 is totally reflected in the total reflection mirror 360 through the 1/4 wave plate 350 that converts the circularly polarized light into circularly polarized light, and the total reflected laser light is converted into linearly polarized light. It is incident on the polarizer 330, which is an optical filter using the characteristic of showing a large difference in the transmission characteristics of light depending on the polarization direction through the 1/4 wave plate 350.

In addition, the second light path unit receives the laser light input from two or more reflector mirrors 410 and 420 and the reflection mirrors 410 and 420 that reflect the laser light incident from the polarizer 500 to receive the flash lamp. It is incident on the second laser medium 430 amplifying the laser light by the discharge of 140 .

Here, the combination of two or more reflective mirrors of the second light path unit suffices as long as a combination capable of injecting laser light into the second laser medium 430 without having to have a specific angle is sufficient.

In addition, it is more preferable that the first laser medium 340 and the second laser medium 430 amplifying laser light by discharging the flash lamp 140 are Nd:YAG rods.

In order to control the thermal lensing effect generated by the medical laser, a mechanical switch 500 for selectively blocking or allowing the incident of laser light is provided in the first optical path unit to control the thermal lensing effect. .

Here, the mechanical switch 500 is illustrated as being installed in two for convenience in FIG. 2 , but one or two is installed before the first laser medium 340 or between the quarter wave plate 350 and the total reflection mirror 360 . It is possible to install all of them, and it is generally determined by the correlation between the discharge frequency of the flash lamp 140 and the frequency of the picosecond laser pulse to be used for actual medical purposes.

3 is a schematic diagram of a mechanical switch according to the present invention;

The reason for adopting the mechanical switch in the present invention is as follows.

In general, in medical lasers, the operating frequency of the flash lamp is 1 to 10 Hz, and the laser beam size is varied from 2 to 10 mm. Among them, when the operating frequency of the flash lamp is 1 Hz, the thermal lensing effect is negligible. However, when the operating frequency of the flash lamp is increased to 8 ~ 10Hz, the laser beam divergence angle becomes smaller, so the size of the laser beam becomes smaller and the output changes occur, making it difficult to adjust the laser power and laser output beam size due to the thermal lens effect used to solve

As shown in FIG. 3, the mechanical switch 500 alternately generates magnetic poles and magnetic fields of the electromagnet to induce rotational motion in the permanent magnet, and according to the rotational motion of the permanent magnet, the shutter portion directly connected to the permanent magnet is opened and closed. A solenoid shutter 510 and a laser blocking bar 520 through which the laser light passes by the operation of the solenoid shutter 510 while blocking the laser light is provided.

In addition, a shock absorber for absorbing the impact caused by the rotation of the optical sensor (photo sensor; 530) and the laser blocking bar (520) for detecting rotation depending on whether the light is blocked by the protrusion formed on the mechanical switch (500) ( A shock absorber; 540) is additionally provided.

Here, the laser blocking bar 520 is preferably formed of any one material of plastic having a diffuser function, acetal, or PTFE (Polytetrafluoroethylene) known as Teflon.

4 is a diagram illustrating waveforms according to the operation of the thermal lens effect control system according to the present invention. In general, for medical purposes, the flash lamp 140 operates between 1 and 10 Hz, and when the flash lamp 140 operates at a frequency of 8 to 10 Hz, the difference in the thermal lens effect depending on the frequency is small, so the laser output frequency and The operations for controlling the laser beam size are classified as follows.

- When the output pico laser frequency is 1, 2, 4, 8Hz, the flash lamp operates at 8Hz

- When the output pico laser frequency is 3 or 9 Hz, the flash lamp operates at 9 Hz.

- When the output pico laser frequency is 5 or 10 Hz, the flash lamp operates at 10 Hz.

In order to explain the operation related to the generation of the picosecond laser for controlling the laser thermal lens effect for medical use, in FIG. 4, when the flash lamp 140 operates at a frequency of 8 Hz, the output pico laser frequency is 1 Hz (FIG. 4a) , the case of 4 Hz (FIG. 4b) and the case of 8 Hz (FIG. 4C) are exemplified.

Here, it should be noted that the numerical description of the pulse width and the delay time described on the waveform example diagram is merely an example since various modifications exist.

First, a case where the flash lamp 140 of FIG. 4A is 8 Hz - 1 Hz pico laser will be briefly described as follows.

When one seed laser pulse is generated by the seed laser unit 200 , the flash lamp trigger signal is generated at 8 Hz, which is the operating frequency of the flash lamp 140 , and accordingly, the pulse of the flash lamp (lamp pulse) is also lit at the same frequency, 8Hz.

Thereafter, when the output pico laser frequency is 1 Hz, the solenoid shutter 510 of the microprocessor unit 120 is operated while maintaining the state in which the laser light is blocked by the laser blocking bar 520 of the mechanical switch 500 . The first amplified laser light is incident on the polarizing plate 330 by passing the laser light at a frequency of 1 Hz according to the signal, so that the firstly amplified laser light is transmitted to the second optical path unit, and the second amplified amplified seed laser pulse In contrast, a pico laser pulse is output with a frequency of 1 Hz, which is a huge pulse.

Here, the delay time required for generating the waveform of the pico laser pulse corresponds to the delay time after the laser diode is driven to generate the seed laser pulse.

Hereinafter, descriptions overlapping those of FIG. 4A will be briefly described.

When the flash lamp 140 of FIG. 4b is 8Hz - pico laser 4Hz, four seed laser pulses are generated, and accordingly, the laser light is emitted at a frequency of 4Hz by the operation signal of the solenoid shutter 510 of the microprocessor unit 120. The first amplified laser light passing through is incident on the polarizing plate 330 so that the firstly amplified laser light is transmitted to the second optical path part, and the second amplified pico laser pulse with a frequency of 4Hz, which is a huge pulse compared to the seed laser pulse. to be output.

In addition, when the flash lamp 140 of FIG. 4c is 8 Hz - pico laser 8 Hz, 8 seed laser pulses are generated, and accordingly, a frequency of 8 Hz (open state), the primary amplified laser light is incident on the polarizing plate 330, so that the primary amplified laser light is transmitted to the second optical path part, and the amplified secondary is a giant pulse compared to the seed laser pulse. Let the pico laser pulse be output with a frequency of 8Hz.

Although the present invention has been illustrated and described with reference to preferred embodiments as described above, it is not limited to the above-described embodiments, and those of ordinary skill in the art to which the present invention pertains within the scope not departing from the spirit of the present invention Various changes and modifications will be possible.

110: power supply 120: microprocessor unit
130: reflector 140: flash lamp
200: seed laser unit
310, 320, 350 : 45° reflection mirror
330: polarizer 340: first laser medium
360: total reflection mirror
410, 420: reflection mirror
430: second laser medium
500: mechanical switch 510: solenoid shutter
520: laser blocking bar 530: optical sensor

Claims (6)

A medical laser thermal lens effect control system comprising:
a laser driving unit including a power supply unit and a microprocessor unit;
a seed laser unit oscillating and emitting a low-power laser light by generating a seed light having a narrow line width having a constant overlapping frequency according to a driving signal of the laser driver;
a first optical path unit for primary amplification of the laser light input from the seed laser unit;
and a second optical path unit for secondary amplifying and outputting the laser light amplified by the first optical path unit,
Medical laser thermal lens effect control system, characterized in that the first optical path portion is provided with a mechanical switch that selectively blocks or allows the incident of the laser light.
According to claim 1,
The first optical path unit includes two 45° reflective mirrors reflecting the low-power laser light oscillated from the seed laser unit, a polarizer, a first laser medium amplifying the laser light by discharging the flash lamp, a quarter wave plate, and Consisting of a total reflection mirror, the second light path unit receives two or more reflection mirrors that reflect laser light incident from the polarizer, and a second that receives laser light input from the reflection mirror and amplifies the laser light by discharging the flash lamp. A medical laser thermal lensing effect control system, characterized in that it consists of a laser medium.
3. The method of claim 2,
wherein the mechanical switch is installed on at least one path before the first laser medium or between the quarter wave plate and the total reflection mirror.
3. The method of claim 2,
The medical laser thermal lensing effect control system, characterized in that the first laser medium and the second laser medium are Nd:YAG rods.
According to claim 1,
The mechanical switch is a medical laser thermal lens effect control, characterized in that it is composed of a solenoid shutter, a laser blocking bar, a photosensor for detecting the rotation of the mechanical switch, and a shock absorber for absorbing the impact caused by the rotation of the laser blocking bar system.
6. The method of claim 5,
The laser blocking bar is a medical laser thermal lens effect control system, characterized in that it is formed of any one material of plastic, acetal, or Teflon having a diffuser function.

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