JPH09300089A - Laser irradiation device and lens barrel and nozzle used therefor - Google Patents

Abstract

(57) Abstract: A laser irradiation device capable of performing highly accurate processing with a small deviation of the focal position of a laser beam even when continuously processed at a high output for a long time, and a lens barrel and a nozzle used for the same. SOLUTION: The laser irradiation lens barrel and the nozzle of the laser emitting optical component are made of an optically transparent material. Since the radiant heat of the laser beam and the heat ray of the molten metal are transmitted through the parts made of the transparent material, these temperature rises are extremely small. The transparent material nozzle allows clear observation of laser reflected light and molten metal heat generation light. This transparent material may be used only in a portion necessary for observation when the temperature rise of the component is small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser irradiation apparatus, and more particularly to a high precision laser processing apparatus which does not deteriorate the processing accuracy even when used for a long time.

[0002]

2. Description of the Related Art In recent years, a method of irradiating a laser beam to heat and melt a work, welding a structure, or performing surface treatment has attracted attention. This can be modified into a metallurgically excellent material with high welding accuracy as compared with the conventional arc welding method. Also, it is relatively easy to transfer energy,
This is because there is such a characteristic. In a conventional laser welding or laser irradiation device that performs surface treatment, a lens barrel that holds a lens that collects a laser beam and a lens barrel portion that protects the lens barrel from spattering of molten metal called welding that occurs during welding are used. The constituent material of the nozzle is made of an optically opaque metallic material such as copper or aluminum alloy, and the nozzle is also made of ceramics or porcelain. Further, black coating may be applied to the inner surface of the lens barrel and the nozzle in order to prevent irregular reflection of the laser beam. This is to prevent the worker from being irradiated with the laser during processing.
As a result, when the laser beam is irradiated for a long time, the lens barrel and the nozzle are heated by the heat rays associated with the laser beam and the temperature rises. When the laser output is small or when the irradiation time is short, the air is naturally cooled by the convection of the surrounding air, so there is almost no problem due to overheating of the laser irradiation component. However, when the laser output increases or machining is performed for a long time, radiant heat more than that cooled by natural cooling is radiated to the irradiation component. In such a case, a copper water-cooling jig and water-cooling pipe may be provided on the irradiation component to prevent overheating.

[0003]

However, when irradiation is performed for a long time by using a laser beam having a higher output, even if such a measure is taken, the irradiation parts such as the lens barrel are deformed due to thermal strain. This may cause an error in the laser irradiation position. That is, when the lens barrel is made of an optically opaque metal material such as copper or aluminum alloy, the heat ray accompanying the laser beam is absorbed by the lens barrel material, so that the lens is forcibly cooled with water or air from the outside. Even so, heat is accumulated in the lens barrel and the temperature gradually rises. A laser optical system is a precision component generally composed of a plurality of lenses and a lens barrel holding them. The dimensions of these components change with changes in temperature. Since the focal position of the laser beam may change greatly even with a slight change in size, dimensions such as the penetration depth and width change in welding or the like due to the change in the focus position, resulting in an unstable weld quality. Further, in the laser cutting, the cutting width may change or the cut surface may have irregularities.

It is an object of the present invention to provide a laser irradiation apparatus in which a change in the focal position is unlikely to occur even when a laser is irradiated at a high output for a long time and a temperature of a laser irradiation component such as a lens barrel is small. It is in.

[0005]

To achieve the above object, according to the first aspect of the present invention, means for generating a laser beam, means for guiding the generated laser beam to a condenser lens, and condenser means are provided. A means for holding a lens and focusing the laser light at a fixed position, and a means for holding the condenser lens and focusing the laser light at a fixed position in at least a part. There is provided a laser irradiation device which is a laser irradiation lens barrel made of an optically transparent material. The optically transparent material is, for example, a material having a light transmittance of 50% or more, preferably 80% or more in a visible light region. However, since the purpose of the present invention is to suppress the temperature rise of the lens barrel by transmitting the heat rays associated with the laser beam, so long as the material can mainly transmit infrared rays occupying most of the heat rays, The light transmittance in the visible light region may be smaller than 50%.

At least a part of the material is made of an optically transparent material. For example, when the transparent material has a small mechanical strength, a structural material such as a reinforcing girder is used as an opaque metal material. In the case of addition, a case where a window is provided in a part of a conventional copper barrel and a transparent material is fitted therein is shown. Of course, materials with sufficient mechanical strength, such as quartz glass,
In the case of high-silica glass, the whole body may be a cylinder made of a transparent material. The lens barrel is arranged so that the condensing lens can be narrowed down so that the laser beam has an optimum beam diameter, that is, it suffices if a constant focal length can be maintained, so that the lens barrel in the direction perpendicular to the laser beam Any cross-sectional shape may be used. You can choose from circular, polygonal, elliptical, etc.

According to a second aspect of the present invention, in the first aspect of the present invention, a shield gas ejection nozzle can be provided on the workpiece side of the laser irradiation lens barrel. Furthermore, it is preferable that at least a part of the ejection nozzle is made of an optically transparent material. When the ejection nozzle is made of an opaque material, the temperature of this portion rises. Since the ejection nozzle is connected to the lens barrel, when the temperature of this portion rises, the temperature of the lens barrel portion and the lens rises due to heat conduction. As a result, the same focal position shift as described above occurs, so it is preferable that this portion also be made of an optically transparent material. Structurally, at least a part of it should be made of a transparent material. What kind of structure should be used depends on the type of laser used, output,
It is determined in consideration of the material of the transparent material used. Since the present invention is to prevent the shift of the focal position of the laser beam during construction as much as possible, either one of the lens barrel and the ejection nozzle, or both may be made of an optically transparent material. By constructing the jet nozzle with an optically transparent material, it is possible to judge the quality of the processing quality of the laser irradiation part during irradiation construction, so the reflected light of the laser inside the nozzle or the heat generation light of the molten metal It is possible to observe clearly on the spot, and it is possible to quickly respond to abnormalities during irradiation construction. Therefore, it is possible to obtain a highly reliable laser welded portion or laser processed portion of good quality. Furthermore, it is possible to accurately detect abnormalities in the glitter state due to reflected light on the surface to be illuminated or fluctuations in the laser output. The light amount of this glitter phenomenon is converted into an electrical signal for in-situ analysis and signal to the oscillator. It is also possible to adjust the laser output and cut off the laser instantly.

A third invention of the present invention comprises, as the optically transparent material in the first or second invention of the present invention, at least one selected from ceramics, glass, quartz, quartz and synthetic resins. It is characterized by The crystallized glass is milky white in appearance and has a low transmittance in the visible light region, but has a high transmittance for infrared light and can be used as a material for the lens barrel and nozzle of the present invention. Crystallized glass is suitable for the material of the present invention because it has excellent strength and heat resistance. As the glass material, there is used glass whose main component is silicon oxide and which is adjusted in trace elements such as sodium, calcium, lanthanum and zirconium to adjust the transmittance, strength and thermal expansion coefficient. Pyrex glass with boron added is also a suitable material. As the ceramic, translucent aluminum oxide, magnesium oxide, zirconium oxide, or the like can be used. Although these materials have higher strength than glass, they have the drawback of low visible light transmittance. Although quartz has excellent strength and light transmittance, it has a problem of high price. If fused quartz is used as the quartz, a lens barrel and a nozzle of any shape can be obtained.
These can be mixed and used. For example, a molten metal (sputtering) at the time of welding may adhere to the nozzle, and a material having a high melting point and an inexpensive material is desirable. Therefore, crystallized glass or the like is used, and further, it is not necessary to replace the lens barrel part once it is used, and a material having high rigidity is preferable, and therefore a translucent ceramic can be used. Further, even with the same nozzle, it is possible to select a material having excellent heat resistance particularly in a place where the temperature rises and a material having a not so large heat resistance in a place where the temperature does not rise so much. With this configuration, it is possible to provide a laser irradiation device having an excellent balance of cost and performance.

A fourth invention of the present invention is characterized in that the surface of the optically transparent material in the first, second or third invention of the present invention is subjected to a non-reflective coating treatment. The heat ray accompanying the laser beam preferably passes through the transparent material and escapes to the outside of the lens barrel or the ejection nozzle, but when the light is reflected on the surface of the transparent material, particularly on the inner surface side where the laser beam is irradiated. , Not enough heat can escape, resulting in an increase in temperature. Therefore, by forming a film that reduces the reflectance of light on the surface of a transparent material, it becomes possible to suppress the temperature rise. As a non-reflective coating, use a multi-layered inorganic thin film such as titanium oxide or silicon oxide that is normally used, and adjust the film thickness and composition to minimize reflection in the wavelength range of the laser light to be irradiated. To do. With this configuration, it is possible to further reduce the temperature rise of the lens barrel and the nozzle portion. The fifth invention of the present invention is
In the first aspect of the present invention, since the temperature rise of the lens barrel portion closest to the laser beam is the largest, only the portion is made of a transparent material, and the outer cylinder for cooling the lens barrel portion on the outer peripheral side of the lens barrel. The structure is such that the portion is made of a transparent material or an opaque material. In this case, the cooling effect can be enhanced by flowing an inert gas for cooling between the lens barrel and the outer cylinder.

The lens barrel or nozzle used in the laser irradiation apparatus as described above does not change in the focal position even when the laser irradiation apparatus is used for a long time, and therefore continuous processing can be performed while maintaining the processing accuracy.

The laser irradiating device is a YAG laser, C
It can be applied to laser irradiation devices such as O ₂ laser and excimer laser. If the device has a laser irradiation unit,
By applying to laser welding equipment, laser cutting equipment, laser surface treatment equipment, etc., high precision welding, high precision processing, etc. become possible. Further, since the focal position does not change much even when it is continuously used and high-precision laser irradiation is possible, it can be applied to a laser irradiation device for lithography.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In a welding torch for TIG (tungsten inert gas arc) welding, a technique of manufacturing a shield gas nozzle with quartz glass, high silica glass, or low expansion crystallized glass for visual observation of the welded portion is practical. It is disclosed in Kaisha 62-96965. According to this configuration,
It is described that the state of the molten pool due to the arc is observed and the welding current can be fed back to it to fine-tune the welding current and the electrode position to perform welding work, with the effect of significantly reducing the occurrence of welding defects. There is. In TIG welding,
A voltage is applied between the electrode and the work piece, and the arc that is generated melts the work piece to perform welding.Therefore, there is a problem whether the nozzle of the welding torch is made of transparent or opaque material. There wasn't. On the other hand, in the laser irradiation device, since the workpiece is heated by using the laser light, when the lens barrel or the nozzle is made of the transparent material, the workpiece is irradiated with diffuse reflection and radiant heat of the laser light. There were concerns about a decrease in the heat input of laser light, a decrease in processing accuracy, and an obstacle to laser light irradiation on the human body. Therefore, conventionally, a lens barrel portion that holds the condenser lens of the laser irradiation device,
The nozzle portion was made of an optically opaque material such as copper or aluminum. Copper and aluminum are selected because they have higher heat resistance and better thermal conductivity than organic materials. However, these materials have a high thermal conductivity but are optically opaque materials, so that they absorb heat, and when used for a long time, there is a problem that the temperature rises as a result. Since the laser irradiation device narrows the laser beam to a very narrow beam diameter for use, a slight deviation of the focal position may increase the beam diameter, making accurate welding difficult. Even a slight deformation due to thermal expansion of irradiation parts such as lenses and lens barrels poses a serious problem.

The present inventors have accomplished the present invention by researching a laser irradiation apparatus in which the shift of the focal position is small even if a high-power laser beam is continuously used for a long time. That is, when an optically transparent material was used for the lens barrel and the nozzle member, which was thought to be unusable due to heating by the radiation heat from the laser optical axis, the temperature rise due to the radiation heat of the laser light was hardly seen. On the contrary, it was found that the temperature rise of the irradiation parts such as the lens barrel, the nozzle and the lens part is very small even if it is used for a long time because the light is transmitted through the lens barrel without absorbing it. It was

The operation of the present invention will be described with reference to the drawings, taking a YAG laser device as an example. A laser excited by a laser oscillator is transmitted by an optical fiber, passes through an image forming lens in a lens barrel of a laser irradiation component, is emitted from an opening of a nozzle for shield gas, and is focused at a fixed position. The laser generates heat on the surface of the irradiated material according to the output, heats, melts, and evaporates to process various materials. In order to ensure the safety of the operator, the laser irradiation parts are installed on the carriage, etc. in the chamber.
Irradiate the material to be irradiated with laser. The irradiation status is monitored by a TV camera or the like, and the quality of processing is judged by observing the generation status of laser light and heat generation light.

The radiant heat of the laser light hits the lens barrel and the nozzle to generate heat. When the laser output is small, there is no problem with natural cooling, but at high output, the temperature rises with time. Since the lens barrel and the nozzle are made of a transparent material, the radiant heat of the laser beam and the heat ray of the molten metal pass through these parts, so that the temperature rise is extremely small.

Comparing the temperature rise between the lens barrel made of an opaque material and the nozzle, the nozzle is larger. Therefore, it is preferable to use a transparent material for the nozzle, and the lens barrel may be an opaque material. Further, in high-power laser processing, it is necessary to perform a non-reflective coating treatment on a transparent material and provide a cooling mechanism. The cooling mechanism is provided with a heat sink,
It is common to attach a water cooling jig, but overheating can be prevented by making these materials transparent. The water cooling jig may be made of an opaque material on the outer wall portion of the water cooling structure, but the inner wall thereof is made of a transparent material like the lens barrel. The radiant heat of the laser light passes through the inner wall of the lens barrel and the water cooling jig to be water cooled.

By using an optically transparent material for both the lens barrel and the nozzle, or at least for the nozzle, it is possible to judge whether the processing quality of the laser irradiation portion during the irradiation is good or not by the reflected light of the laser or the molten metal. The effect of being able to observe the exothermic light and the like in real time is also produced. The laser light shines in response to the shield gas, and the exothermic light of the molten metal also occurs inside the nozzle as a similar light emitting phenomenon. By making the working environment dark, this light emission phenomenon can be more clearly confirmed through the transparent nozzle. This light emission phenomenon maintains a constant bright state in a stable welding condition, but the bright state changes due to changes in the material of the irradiated surface, changes in the reflected light due to the geometrical shape of the surface, and fluctuations in laser output. Anomalies can be detected. Although this light emission phenomenon can be directly visually observed through a light-shielding glass or the like, it is desirable to indirectly monitor it with a television camera or the like for safety. Further, it is also possible to convert the amount of light of this light emission phenomenon into an electric signal, perform in-situ analysis, and send the signal to the laser oscillator to adjust or cut off the laser output.

Examples of the present invention will be shown below.

Example 1 FIG. 1 is a schematic view of a YAG laser irradiation device. Y excited by the YAG laser oscillator 1
An AG laser (hereinafter abbreviated as a laser) is transmitted by an optical fiber 2, passes through an imaging lens 5 in a lens barrel 4, is emitted as a laser beam 3 from an opening at a tip of a nozzle 7 for shield gas, and is irradiated. Focus at a fixed position near the surface of the material 8. The lens barrel 4 and the nozzle 7 are a chamber 9 for processing.
It is connected to the traveling carriage 10 in which the irradiation work is performed. The nozzle 7 supplies a shielding gas such as He and Ar from the gas generation source 6 and a processing gas according to the purpose. The irradiation status is observed by the monitor TV 12 by the TV camera 11. At the same time, the light obtained by the observation is converted into an electric signal and fed back to the laser oscillator 1.

FIG. 2 is an enlarged view of a side surface of an example of a laser irradiation component and its cross section. The optical fiber 2 is fixed to an optical fiber support 4H integrated with the lens barrel 4. The optical fiber support 4H is made of an opaque aluminum alloy, but it may be made of a transparent material. In this embodiment, the lens barrel 4 is made of transparent glass, and the nozzle 7 is made of a transparent material such as acrylic resin which has good workability. For comparison, a lens barrel 4 made of an aluminum alloy and a nozzle 7 made of an opaque material of a copper alloy were prepared. The lens barrel has a diameter of 150 mm. Using these laser irradiation components, multi-mode, continuous wave, output 90
0W, moving speed 10mm / sec for 60 seconds stainless steel SUS3
04 The irradiated material was irradiated. As the shield gas, Ar gas is passed through the shield gas pipe 14 from the nozzle 7 at 20 l / min.
Non-reflective transparent glass 22 that protects the imaging lens 5 at a flow rate of
I made it squirt. This shield gas prevents oxidation of the molten metal at the focal position of the laser light 3.

FIG. 3 is a graph showing the relationship between the irradiation time and the temperatures of the lens barrel and the nozzle portion. The temperature of the lens barrel 4 made of the opaque material aluminum alloy increased at the same time as the irradiation started and reached 68 ° C. 60 seconds later, but the temperature at the same position of the lens barrel made of transparent material glass was 20 ° C. before irradiation. Almost no change was observed with ℃. When the temperature at the center of the nozzle 7 is a copper alloy, which is an opaque material, the irradiation start 60
138 ° C after a second, 25 for transparent acrylic resin
° C. It has been found that the use of transparent materials is extremely effective in preventing overheating of laser-irradiated parts.

FIG. 4 shows the amount of change in the laser focus position in the laser irradiation direction depending on the temperature of the lens barrel. The lens barrel temperature is 68 ° C
Then, the focus position changed about 0.8mm. Even such a slight change in the focus position appears as a large change in beam diameter at the laser beam irradiation position on the surface of the irradiated material. Further, it is difficult to manufacture the lens barrel with the same coefficient of thermal expansion in all directions, and in general, the coefficient of thermal expansion is not uniform. In contrast, it changes vertically. Due to such movement of the focal position, the welding beads become uneven in the case of welding, and the cutting accuracy is lowered in the case of cutting.

Further, the laser light shines in response to the shield gas, and the exothermic light of the molten metal also occurs inside the nozzle as a similar light emission phenomenon. This light emission phenomenon is transparent in the chamber 9 in the dark state. Through the nozzle, it could be clearly confirmed by the monitor TV 12 through the TV camera 11. In the laser-irradiated component made of an opaque material, only the exothermic light of the molten metal is partially observed at the tip of the nozzle.

(Embodiment 2) In the laser irradiation component having the same shape as that of Embodiment 1, the lens barrel 4 is made of an opaque aluminum alloy, and only the nozzle 7 is made of a transparent material of acrylic resin.
Multi-mode, output 600W, continuous wave, moving speed 10mm
Irradiation of the stainless steel SUS304 irradiated material in the dark chamber for 60 seconds / sec.
Although the temperature of the part slightly increased to 25 ° C., the temperature at the central position of the nozzle 7 was almost unchanged from 15 ° C. before irradiation. It has been found that if the output is small, even if only the shielding gas jet nozzle is made of a transparent material, it is extremely effective in preventing overheating. In addition, the light emission phenomenon at the time of laser irradiation that occurred inside the nozzle was clearly confirmed as in Example 1. Further, if the temperature of the nozzle portion does not rise, only the portion suitable for observing the laser brilliance phenomenon may be made of the transparent material.

(Example 3) As in Example 2, the lens barrel 4 was made of an opaque aluminum alloy, and only the nozzle 7 was made of a transparent material such as glass and quartz glass. The nozzle made of glass has a non-reflective coating on the inner surface of the cylinder. Laser is multimode, output 900W, continuous wave moving speed 1
Irradiation was performed on the stainless steel SUS304 irradiated material at 0 mm / second for 60 seconds.

(Embodiment 4) FIG. 5 is a YAG laser irradiation apparatus in which a transparent glass lens barrel 4 is provided with a cooling jig 15 for preventing overheating, and the cooling jig inner wall 16 has a transparent acrylic resin. Is. Cooling water is supplied to the lens barrel 4 through a cooling water pipe 17. The outer wall is an opaque material of aluminum alloy. This is to block excessive laser radiation scattered light. The nozzle 7 is transparent glass. The laser was irradiated in a multi-mode, output of 1200 W, continuous wave at a moving speed of 10 mm / sec for 120 seconds on the stainless steel SUS304 irradiated material.
In this laser irradiation component, the radiant heat of laser light causes
Since the transparent material of the cooling jig inner wall 16 penetrates and is water-cooled, the temperature rise is very small. Further, the temperature of the nozzle portion did not rise, and the brilliance phenomenon of the laser beam was clearly observable on the monitor TV through the transparent nozzle. That is, it was proved from this example that the use of an opaque material for the inner wall of the cooling jig enhances the cooling effect in laser emission at high output for a long time. (Embodiment 5) In FIG. 6, the lens barrel portion is formed by cylindrical aluminum frames 18 and 19 and three quartz glasses 20. The laser light is guided to the lens barrel through the optical fiber passing through the conduit tube 22. The aluminum frames 18 and 19 are joined by a fastening screw 21. Since the lens barrel having such a structure has a simple structure, the manufacturing cost can be reduced. Further, even when glass having low strength is used, the aluminum frame serves as a reinforcing material, so that the laser irradiation apparatus having high mechanical strength can be obtained.

[0027]

According to the first aspect of the present invention, since the temperature rise of the component due to the radiant heat accompanying the emission of the laser beam is small, the deformation of the lens barrel and the lens is also small. As a result, since the focal position of the laser beam does not change, a sound quality laser welded portion or laser processed portion with stable dimensions such as welding penetration depth and width can be obtained.

According to the second aspect of the present invention, it is possible to judge whether the processing quality of the laser irradiation portion is good or bad during the irradiation process. Therefore, the reflected light of the laser inside the nozzle or the generated heat of the molten metal, etc. Can be clearly observed on the spot,
It is possible to quickly respond to abnormalities during irradiation construction. Therefore, it is possible to obtain a highly reliable laser welded portion or laser processed portion of good quality. Furthermore, it is possible to accurately detect abnormalities in the glitter state due to reflected light on the surface to be illuminated or fluctuations in the laser output. The light amount of this glitter phenomenon is converted into an electrical signal for in-situ analysis and signal to the oscillator. It is also possible to adjust the laser output and cut off the laser instantly.

According to the third aspect of the present invention, it is possible to provide a laser irradiation apparatus having an excellent balance of cost, performance and the like.

According to the fourth aspect of the present invention, the temperature rise of the lens barrel and the nozzle portion can be further reduced.

According to the fifth aspect of the present invention, the lens barrel or nozzle used in the laser irradiation device does not change the focus position even when the laser irradiation device is used for a long time, and therefore maintains the processing accuracy. Can be continuously processed.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a processing laser irradiation device used in a first embodiment.

FIG. 2 is a cross-sectional view of a side surface of a lens barrel and a nozzle portion of a laser irradiation component example of the first embodiment.

FIG. 3 is a graph of the results showing the relationship between the irradiation time and the temperatures of the lens barrel and the nozzle portion.

FIG. 4 is a diagram showing a change in focal position depending on a lens barrel temperature.

FIG. 5 is a side view of a laser irradiation component with a water cooling function and a perspective sectional view thereof.

FIG. 6 is a diagram showing an embodiment of a laser irradiation apparatus of the present invention.

[Explanation of symbols]

1 ... Laser oscillator, 2 ... Optical fiber, 3 ... Laser light,
4 ... Lens barrel, 4H ... Optical fiber support, 5 ... Imaging lens, 6 ... Gas generating source, 7 ... Nozzle, 8 ... Irradiated material, 9 ...
Chamber, 10 ... Traveling vehicle, 11 ... TV camera, 1
2 ... Monitor TV, 13 ... Optical analysis control device, 14 ... Shield gas piping, 15 ... Cooling jig, 16 ... Cooling jig inner wall, 17 ... Cooling water piping, 18, 19 ... Aluminum frame, 20 ... Quartz glass, 21 ... Fastening screws, 22 ... Non-reflective transparent glass.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Onuma 7-1-1 Omika-cho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Research Laboratory, Ltd. No. 1 Hitachi Ltd., Hitachi Research Laboratory (72) Inventor Yasukata Tamai 3-1-1, Saiwaicho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Works Hitachi Factory (72) Inventor Hiroo Koide Hitachi, Ibaraki Prefecture 3-1, 1-1, Saiwaicho, Ichi, Hitachi, Ltd. Hitachi factory

Claims (8)

[Claims] 1. Laser irradiation comprising: means for generating laser light; means for guiding the generated laser light to a condenser lens; and means for holding the condenser lens and focusing the laser light at a fixed position. In the apparatus, the means for holding the condenser lens and focusing the laser light at a fixed position is a laser irradiation lens barrel at least a part of which is made of an optically transparent material. Irradiation device. 2. A shield gas jet nozzle is provided on the workpiece side of the laser irradiation lens barrel, and at least a part of the jet nozzle is made of an optically transparent material. A laser irradiation device characterized by the above. 3. A laser irradiation apparatus, wherein the optically transparent material according to claim 1 or 2 is one or more selected from glass, quartz, quartz and synthetic resin. 4. A laser irradiation apparatus characterized in that the surface of the optically transparent material according to any one of claims 1 to 3 is subjected to a non-reflective coating treatment. 5. The laser irradiation apparatus according to claim 1, further comprising an outer cylinder for guiding a cooling gas to the outside of the laser irradiation lens barrel. 6. A laser welding apparatus using the laser irradiation apparatus according to claim 1. 7. A lens barrel for a laser irradiation device, at least a part of which is made of an optically transparent material. 8. A nozzle for a laser irradiation device, characterized in that at least a part thereof is made of an optically transparent material.