KR20230099963A - High energy pulsed laser transmission device in water - Google Patents

Abstract

The present invention relates to a laser fiber optic beam transmission device in an underwater environment. According to an embodiment of the present invention, an underwater high-power laser beam transmission device includes an optical fiber accommodating unit including an optical fiber for transmitting a pulsed laser generated from a laser generator; a light homogenization unit that converts the light emitted from the optical fiber into parallel light, converges the light converted into parallel light toward a target, and emits the light; and a nozzle part through which light from the light homogenization part is emitted, and water is filled in the optical fiber accommodating part.

Description

Underwater high power laser beam transmission device {HIGH ENERGY PULSED LASER TRANSMISSION DEVICE IN WATER}

The present invention relates to a high-power laser beam transmission device, and more particularly, to an underwater high-power laser beam transmission device capable of transmitting and monitoring a high-power laser beam in an underwater environment.

[0002] A conventional beam transmission system is known that transmits light generated from a high-energy pulse laser to an optical fiber. Industrially, high-power laser pulse beams can be widely used for generation of ultrasonic waves by ablation effect, processing of materials or surface treatment, and the like. However, high-power laser systems are usually large, require periodic maintenance, and are sensitive to external environments, limiting their industrial applications. That is, in the case of an object having a complicated structure or under a harsh environment, it is difficult to approach the high-power laser system as described above, and thus high-power laser pulse beam transmission is required.

Optical fiber-based laser beam processing systems use higher output energy than general laser systems. At this time, it is necessary to configure an optical transmission system such as a lens and a mirror in order to process using a laser at an accurate target position. In this optical system, it is possible to configure an accurate laser beam path by the refractive index between the lens and the medium. However, in a laser beam system that requires an underwater environment, the refractive index of fused silica, a common optical system material, is 1.46 (the refractive index of BK7 is 1.52 ), the refractive index of water is 1.33 compared to the refractive index of the air phase of 1.00, which is not significantly different. As a result, the existing general underwater system optical system has a configuration of "optical fiber - [air layer] - optical system [air layer] - final emission [water layer]". At this time, the light source transmitted through the optical fiber has a difference in transmission efficiency according to the state of the optical fiber exit surface. This is a common configuration.

However, in the case of high-power energy lasers, when energy beyond the limit (critical point) of general AR coatings that can be processed on the surface of an optical fiber must be transmitted, general AR coatings have problems with the cost of special coatings and limited companies that can implement them. .

The present invention is an invention made to solve the above problems, and there is a demand for an underwater high-power laser beam transmission device that can stably transmit a higher-power laser beam in an underwater environment by replacing the conventional technology using AR coating in an underwater environment. .

According to one aspect of the present invention to solve the above problems, there is provided an underwater high-power laser beam transmission device, the underwater high-power laser beam transmission device includes an optical fiber receiving portion including an optical fiber for transmitting a pulse laser generated from a laser generator; a light homogenization unit that converts the light emitted from the optical fiber into parallel light, converges the light converted into parallel light toward a target, and emits the light; and a nozzle part through which light from the light homogenization part is emitted, and water is filled in the optical fiber accommodating part.

In the above-described aspect, the optical fiber accommodating unit includes a water filter for purifying water and introducing it into the optical fiber accommodating unit; and a discharge port for discharging water inside the optical fiber accommodating unit.

In any one of the above aspects, the water discharged from the outlet is configured to be discharged outside the housing of the underwater high-power laser beam transmission device.

In any one of the above aspects, the water discharged from the outlet is configured to be discharged into the nozzle portion of the underwater high-power laser beam transmission device.

In any one of the above aspects, air or gas is sealed inside the light homogenizer.

In addition, in any one of the above aspects, the light homogenization unit further comprises a first lens, the first lens faces the water of the optical fiber receiving unit and the flat first surface on which the laser beam passing through the water is incident and the laser beam It includes a convex second surface facing the air layer to be emitted.

In addition, in any one of the above aspects, the light homogenization unit further comprises a second lens, the second lens is a convex first surface facing the air layer into which the laser beam is incident and the water on the target side from which the laser beam is emitted It includes a flat second surface that faces.

In addition, in any one of the above aspects, further comprising a monitoring means for monitoring the light incident from the nozzle side, the monitoring means, the single-sided coated optical member installed inside the light homogenization unit - the single-sided coated optical member is configured to pass the laser beam incident from the optical fiber side toward the nozzle side and reflect the light incident from the nozzle side; It includes; a camera means for photographing the light reflected from the optical member coated on one side.

Also in any one of the foregoing aspects, the camera means is configured to view the light coaxially with the laser beam.

According to the present invention, an underwater high-power laser beam transmission system that can stably transmit a higher-power laser beam in an underwater environment by replacing the technology using AR coating to reduce loss due to Fresnel reflection occurring on the surface of an optical fiber in a conventional underwater environment can provide

1 is a cross-sectional view of an underwater high power laser beam transmission device according to a first embodiment of the present invention;
2 is a cross-sectional view of an underwater high-power laser beam transmission device according to a second embodiment of the present invention;
3 is a diagram showing an example in which a laser beam monitoring means is additionally installed in the underwater high-power laser beam transmission device according to an embodiment of the present invention.

Advantages and features of the present invention, and methods for achieving them, will become clear with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms.

In this specification, this embodiment is provided to complete the disclosure of the present invention, and to completely inform those skilled in the art of the scope of the invention to which the present invention belongs. And the invention is only defined by the scope of the claims. Thus, in some embodiments, well-known components, well-known operations and well-known techniques have not been described in detail in order to avoid obscuring the interpretation of the present invention.

Like reference numbers designate like elements throughout the specification. And, the terms used (mentioned) in this specification are for describing the embodiments and are not intended to limit the present invention. In this specification, singular forms also include plural forms unless specifically stated otherwise in a phrase. Also, elements and operations referred to as 'include (or include)' do not exclude the presence or addition of one or more other elements and operations.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used in a meaning commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in commonly used dictionaries are not interpreted ideally or excessively unless they are defined.

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

1 is a diagram schematically showing an example of an underwater high-power laser beam transmission device 10 according to the present invention. As shown in FIG. 1, the underwater high-power laser beam transmission device 10 is typically connected to a laser generator (not shown) to homogenize the pulse laser generated from the laser generator and emit it through a nozzle unit.

The underwater high-power laser beam transmission device 10 includes an optical fiber accommodating part 100 including an optical fiber 120 transmitting a pulse laser generated from a laser generator as shown in FIG. 1; a light homogenization unit 200 that homogenizes the light emitted from the optical fiber 120; and a nozzle unit 300 for emitting light from the light homogenization unit 200 into water.

The optical fiber accommodating part 100 is connected to the rear end of the pulse laser generator and its inside is filled with water. Water used in the laser beam path may be polluted due to foreign substances generated when the high energy laser continuously penetrates. When such contaminants accumulate, the incident efficiency of the laser beam emitted from the optical fiber 120 and incident to the first lens 210 may be reduced or the incident surface of the first lens 21 may be damaged. In order to prevent this, it is preferable that purified water that has passed through the water filter 130 be used as the water filled in the optical fiber accommodating part 100 . To this end, it has a structure in which water passing through the filter is introduced into the optical fiber accommodating part 100 and drained by using an external force such as a pump. At this time, the drained water may have a drain hole 140 formed on one side of the optical fiber accommodating part 100 .

The light homogenization unit 200 includes at least two optical lenses 210 and 220 . The first lens 210 converts the laser beam emitted from the Guam fiber and incident through the water into parallel light in the light homogenizer 200, and the second lens 220 converts the laser beam incident as parallel light into a nozzle ( 300) to converge to the focus F.

In the case of the first lens, the surface direction of the lens is set in consideration of the refractive power (optical power) of water in contact with the first lens. In order to control the beam path of the laser, the convex surface (second surface) of the first lens 210 is configured to face the air (or gas) layer sealed inside the light homogenizer 200, and the water layer and the 1 The transmission path of the laser beam is formed by allowing the flat surface (first surface) of the lens, which has a low refractive index difference, to contact water.

At this time, the first surface in contact with the first lens 210 made of fused silica and the water has a reflectance of 0.2% at an incident angle of 0 degrees, which is the typical anti-reflection coated Results of less than 0.25% reflectivity can be achieved, and therefore the flat surface in contact with water does not require AR coating.

In addition, as shown in FIG. 1, a temperature difference with circulating water occurs on the first surface in contact with water in the light homogenization unit 200 filled with air (or gas), which may cause condensation inside the lens. This may result in reduced laser efficiency or damage to the lens surface. In order to prevent this, the inside of the light homogenization unit 200 is filled with dry air or nitrogen gas, and through this, internal moisture can be removed in advance.

Unlike the first lens 210, the second lens 220 is configured such that the convex surface (second surface) of the second lens contacts the air layer and the flat surface (first surface) of the second lens contacts the water at the nozzle side. A light path is formed.

As described above, according to an embodiment of the present invention, in order to reduce loss due to Fresnel reflection generated on the surface of the optical fiber, the boundary surface of the optical fiber surface is filled with water to suppress Fresnel reflection. In addition, when the fiber laser beam is transmitted using water, the wavefront distortion due to the surface processing of the optical fiber can be reduced, so that the beam can be transmitted only by cutting the optical fiber without polishing. In addition, if the beam can be transmitted only by cutting the optical fiber without polishing, it is helpful for maintenance and stable operation of the optical fiber beam transmission system.

2 is a diagram schematically showing another example of an underwater high-power laser beam transmission device 10 according to the present invention. As shown in FIG. 2, the underwater high-power laser beam transmission device 10 is typically connected to a laser generator (not shown) to homogenize the pulse laser generated from the laser generator and emit it through a nozzle unit.

The underwater high-power laser beam transmission device 10 includes an optical fiber accommodating part 100 including an optical fiber 120 transmitting a pulse laser generated from a laser generator as shown in FIG. 2; a light homogenization unit 200 that homogenizes the light emitted from the optical fiber 120; and a nozzle unit 300 for emitting light from the light homogenization unit 200 into water.

The optical fiber accommodating part 100 is connected to the rear end of the pulse laser generator and its inside is filled with water. Water used in the laser beam path may be polluted due to foreign substances generated when the high energy laser continuously penetrates. When such contaminants accumulate, the incident efficiency of the laser beam emitted from the optical fiber 120 and incident to the first lens 210 may be reduced or the incident surface of the first lens 21 may be damaged. In order to prevent this, it is preferable that purified water that has passed through the water filter 130 be used as the water filled in the optical fiber accommodating part 100 . To this end, it has a structure in which water passing through the filter is introduced into the optical fiber accommodating part 100 and drained by using an external force such as a pump. Unlike the first embodiment, in the embodiment shown in FIG. 2, a drain hole 140 is formed on one side of the optical fiber accommodating part 100 to drain water, and the drain hole passes through the bypass pipe 150 to the nozzle part 300. ) Is connected to one side of the nozzle and is configured to be discharged into the tip inner space (s) of the nozzle unit.

In this way, the water discharge path has a structure in which water is drained to the inner space (s) of the tip of the nozzle unit 300, which is the same as the laser beam path, so that foreign substances that may occur in laser processing penetrate into the nozzle and reduce the efficiency of the beam path. or prevent direct damage to the lens.

The light homogenization unit 200 includes at least two optical lenses 210 and 220 . The first lens 210 converts the laser beam emitted from the Guam fiber and incident through the water into parallel light in the light homogenizer 200, and the second lens 220 converts the laser beam incident as parallel light into a nozzle ( 300) to converge to the focus F.

In the case of the first lens, the surface direction of the lens is set in consideration of the refractive power (optical power) of water in contact with the first lens. In order to control the beam path of the laser, the convex surface (second surface) of the first lens 210 is configured to face the air (or gas) layer sealed inside the light homogenizer 200, and the water layer and the 1 The transmission path of the laser beam is formed by allowing the flat surface (first surface) of the lens, which has a low refractive index difference, to contact water.

At this time, the first surface in contact with the first lens 210 made of fused silica and the water has a reflectance of 0.2% at an incident angle of 0 degrees, which is the typical anti-reflection coated Results of less than 0.25% reflectivity can be achieved, and therefore the flat surface in contact with water does not require AR coating.

In addition, as shown in FIG. 1, a temperature difference with circulating water occurs on the first surface in contact with water in the light homogenization unit 200 filled with air (or gas), which may cause condensation inside the lens. This may result in reduced laser efficiency or damage to the lens surface. In order to prevent this, the inside of the light homogenization unit 200 is filled with dry air or nitrogen gas, and through this, internal moisture can be removed in advance.

Unlike the first lens 210, the second lens 220 is configured such that the convex surface (second surface) of the second lens contacts the air layer and the flat surface (first surface) of the second lens contacts the water at the nozzle side. A light path is formed.

3 is a diagram showing an example further including a monitoring 250 capable of monitoring the laser beam in the underwater high-power laser beam transmission device 10.

It is dangerous to directly observe the high-energy laser beam with eyes during laser processing. In the case of processing such as laser welding on the ground, it is possible to determine whether processing is being performed at the correct location by installing a monitoring device on the welding surface or a corresponding position, but in the case of an underwater environment, it is difficult to observe it.

In the present invention, since the light homogenizer 200 is filled with air (or gas), it is possible to monitor it through an additional optical system. In the present invention, as shown in FIG. 3, a coated single-sided coated lens 230 is additionally disposed on the laser beam path inside the light homogenization unit 200 to select and transmit a special wavelength range, and the light homogenization unit 200 ) By installing a transparent window 240 on some or all of the outer surfaces and observing the light reflected from the single-sided coating lens 230 using the monitoring camera 250, coaxial observation with the laser beam is possible. This is possible by transmitting the laser beam entering from the back side of the single-sided coating lens 230, that is, the light incident surface side, while reflecting the visible light coming from the nozzle part side, that is, the processing target, through the single-sided coating lens 230 toward the monitoring camera 250 side. will do

As described above, although the embodiments have been described with limited examples and drawings, those skilled in the art can make various modifications and variations from the above description. For example, the described techniques may be performed in an order different from the method described, and/or components of the described system, structure, device, circuit, etc. may be combined or combined in a different form than the method described, or other components may be used. Or even if it is replaced or substituted by equivalents, appropriate results can be achieved.

Therefore, other implementations, other embodiments, and equivalents of the claims should be construed as falling within the scope of the following claims.

10: high power laser beam transmission device 100: optical fiber receiving unit
110: housing 130: water filter
140: drain 200: light homogenization unit
300: nozzle unit 210: first lens
220: second lens 230: single-sided coating lens
240: transparent window 250: camera means

Claims (9)

In the underwater high-power laser beam transmission device,
An optical fiber accommodating unit including an optical fiber for transmitting the pulsed laser generated from the laser generator;
a light homogenization unit that converts the light emitted from the optical fiber into parallel light, converges the light converted into parallel light toward a target, and emits the light; and
A nozzle unit through which light from the light homogenization unit is emitted;
Characterized in that water is filled in the optical fiber receiving portion
Underwater high-power laser beam transmission device.
According to claim 1,
fiber optic receiver
a water filter for purifying water and introducing it into the optical fiber receiving unit; and
Characterized in that it further comprises; a discharge port for discharging the water inside the optical fiber receiving portion
Underwater high-power laser beam transmission device.
According to claim 2,
Characterized in that the water discharged from the outlet is configured to be discharged to the outside of the housing of the underwater high-power laser beam transmission device
Underwater high-power laser beam transmission device.
According to claim 2,
Characterized in that the water discharged from the outlet is configured to be discharged into the nozzle part of the underwater high-power laser beam transmission device
Underwater high-power laser beam transmission device.
According to claim 1,
Characterized in that air or gas is sealed inside the light homogenizer
Underwater high-power laser beam transmission device.
According to claim 1,
The light homogenization unit further comprises a first lens,
The first lens is characterized in that it comprises a flat first surface facing the water of the optical fiber accommodating part to which the laser beam passing through the water is incident and a convex second surface facing the air layer from which the laser beam is emitted.
Underwater high-power laser beam transmission device.
According to claim 6,
The light homogenization unit further comprises a second lens,
The second lens includes a convex first surface facing the air layer into which the laser beam is incident and a flat second surface facing the water on the target side from which the laser beam is emitted.
Underwater high-power laser beam transmission device.
According to claim 1,
Further comprising a monitoring means for monitoring the light incident from the nozzle side,
The monitoring means,
an optical member coated on one side installed inside the light homogenization unit, wherein the optical member coated on one side is configured to pass a laser beam incident from an optical fiber toward a nozzle side and reflect light incident from the nozzle side;
a camera means for photographing the light reflected from the optical member coated on one side;
characterized in that it includes
Underwater high-power laser beam transmission device.
According to claim 8,
The camera means is configured to observe the light coaxially with the laser beam.
Underwater high-power laser beam transmission device.

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