JP2016101596A - Laser irradiation device and surface treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser irradiation device with an improved treatment capacity for executing surface treatment by irradiating an irradiation object in liquid with a laser.SOLUTION: A laser irradiation device having an irradiation optical system for converging a laser beam to irradiate an irradiation object in liquid is configured such that the irradiation optical system irradiates the object with the laser beam in a state where a surface part at an irradiation object side in a most objective side optical element 323 arranged adjacent to the irradiation object is arranged in the liquid, and a surface part of the most objective side optical element opposite to the irradiation object side, and other optical elements are contained in a housing that is substantially prevented from infiltration of the liquid. The laser irradiation device comprises; liquid discharge means 440 that is provided in the vicinity of an outer peripheral edge of the most objective side optical element, and discharges a liquid flow substantially along the surface part at the irradiation object side; and liquid suction means 450 that is provided in the vicinity of the outer peripheral edge of the most objective side optical element on a side of the objective side optical element opposite to the liquid discharge means with a central part sandwiched therebetween, and sucks the liquid flow flowing substantially along the surface part of the objective side optical element at the irradiation object side.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a laser irradiation apparatus and a surface treatment method, and more particularly to an apparatus for improving a processing capability when performing surface treatment by irradiating an irradiation object in a liquid with a laser.

For example, in a nuclear power plant, it is known that foreign matters such as fuel debris that is solidified by cooling a reactor fuel melted in cooling water adheres to the wall surface of a pressure vessel.
It has been proposed to decontaminate the plant by crushing and collecting the fuel debris adhering to the surface of the object in water by focusing and irradiating it with high-power laser.

Further, as a conventional technique for irradiating a laser irradiation target with water, for example, Patent Document 1 discloses an underwater laser that directly processes a workpiece in water and removes and collects foreign matters such as metal fume and processing waste. A processing device is described.
The technique described in the cited document 1 collects foreign matter by introducing water from the inside into a cylindrical nozzle through which a laser beam passes and sucking water in a suction cover that covers the periphery of the processing location. Is to do.

JP-A-6-269975

However, in the technique described in Patent Document 1, the cylindrical member through which the laser beam passes is filled with water, and the laser beam propagates in water over a relatively long distance, resulting in energy loss. It gets bigger.
In addition, when a foreign object flows out into the water and drifts in the water between the condenser lens and the irradiation target, the foreign object floating in the water also prevents the laser beam from reaching the irradiation target, resulting in an energy arrival rate. (Proportion of reaching the irradiation object in the emitted energy) decreases.
In view of the above-described problems, an object of the present invention is to provide a laser irradiation apparatus and a surface treatment method with improved processing capability when performing surface treatment by irradiating an irradiation target in a liquid with a laser. .

The present invention solves the above-described problems by the following means.
The invention according to claim 1 is a laser irradiation apparatus including an irradiation optical system for converging a laser beam emitted from a laser oscillator and irradiating an irradiation target disposed in a liquid, wherein the irradiation optical system includes: In the state where the surface portion on the irradiation object side in the most objective optical element arranged adjacent to the irradiation object is arranged in the liquid, the laser light is irradiated, and the most objective optical element The surface portion opposite to the irradiation object side and the other optical elements are housed in a housing in which the liquid is substantially prevented from entering, and are provided in the vicinity of the outer peripheral edge of the most objective optical element. A liquid ejecting means for ejecting a liquid flow substantially along the surface portion on the object side, and an opposite side of the outer peripheral edge of the most objective optical element with the central portion of the most objective optical element sandwiched between the liquid ejecting means Provided on the side A laser irradiation apparatus comprising: a liquid suction means for sucking the liquid stream flowing substantially along the surface of the irradiated object side of the objective side optical element.
According to this, by preventing the liquid from entering the housing, the laser light does not pass through the liquid until it passes through the most objective optical element, so that the propagation distance of the laser light in the liquid is minimized. As a limit, energy loss can be suppressed, the energy arrival rate can be increased, and high energy can be given to the irradiation object, and the processing capability can be improved.
In addition, by forming a liquid flow on the surface of the most object side optical element on the irradiation object side (the side in contact with the liquid), foreign substances that are separated from the object and float in the liquid Prevents adhesion to the surface and suppresses degradation of optical performance, and further improves processing capability by removing foreign matter between the most objective side optical element and the irradiation object to improve energy arrival rate be able to.
Furthermore, by sucking and collecting this liquid flow, foreign matter can be prevented from diffusing into the liquid, and the foreign matter can be appropriately collected.

According to a second aspect of the present invention, the irradiation optical system includes: a deflection optical system that deflects an emission side optical axis by a predetermined angle with respect to an incident side optical axis of the laser beam; The laser irradiation apparatus according to claim 1, further comprising: a rotation driving unit that rotates around an axis.
According to this, even when a continuous wave (CW) type laser oscillator is used, it is possible to prevent high energy from being continuously irradiated to one point of the irradiation target and appropriately scan the irradiation target. can do.

The invention according to claim 3 is characterized in that the liquid suction means sucks suspended matter formed when the irradiation target is irradiated with the laser light together with the liquid flow. 2. The laser irradiation apparatus according to 2.
According to this, it is possible to reliably collect suspended matters and prevent toxic substances from diffusing into the liquid.

The invention according to claim 4 is characterized in that the suction amount of the liquid suction means is equal to or larger than the discharge amount of the liquid discharge means. It is a laser irradiation apparatus as described in above.
According to this, the collection | recovery capability of a floating substance can be improved more.

The invention according to claim 5 is the laser irradiation apparatus according to any one of claims 1 to 4, wherein the most objective optical element is detachable from a main body of the housing. is there.
According to this, when the foreign object adheres to the most objective optical element or deterioration such as burnout occurs, the performance can be restored at low cost by replacing only the most objective optical element.

The invention according to claim 6 is the laser irradiation apparatus according to any one of claims 1 to 5, wherein the most objective-side optical element is formed in a substantially flat plate shape.
According to this, the running cost can be reduced by configuring the most objective side optical element having a high replacement frequency with respect to other optical elements at a low cost.

The invention according to claim 7 is characterized in that the most objective side optical element constitutes a part of a condensing optical system for condensing the laser beam at a predetermined focal point. A laser irradiation apparatus according to claim 1.
According to this, since the light beam has not yet converged when passing through the most objective side optical element, the energy of the laser beam is concentrated on a part of the most object side optical element and the most object side optical element is burned out. Can be prevented.

According to an eighth aspect of the present invention, the irradiation optical system is moved relative to the irradiation object so that an interval between the most objective optical element and the irradiation object is within a predetermined range, and the laser The laser irradiation apparatus according to any one of claims 1 to 7, further comprising irradiation optical system driving means for scanning the surface of the irradiation object with light.
According to this, the processing can be automated to save the labor of the worker.
As such an irradiation optical system driving means, for example, a single-axis stage such as an XY stage or a multi-axis stage such as a robot arm can be used.

The invention according to claim 9 is characterized in that the irradiation optical system driving means sets the irradiation optical system to the irradiation object so that a distance between the most objective optical element and the irradiation object is 10 mm or less. The laser irradiation apparatus according to claim 8, wherein the laser irradiation apparatus is relatively moved.
According to this, the distance which a laser beam propagates in the liquid can be made small, and the loss of energy can be suppressed.

The invention according to claim 10 is a surface treatment method for converging a laser beam emitted from a laser oscillator to irradiate an irradiation object disposed in a liquid, and for irradiating the irradiation object with the laser beam. The optical system irradiates laser light in a state where the surface portion on the irradiation object side in the most objective optical element disposed adjacent to the irradiation object is disposed in the liquid, and the most object side The surface portion of the optical element opposite to the irradiation object side and the other optical element are accommodated in a housing substantially prevented from entering the liquid, and are provided in the vicinity of the outer peripheral edge portion of the most objective optical element. The liquid discharge means discharges a liquid flow substantially along the surface on the irradiation object side, and near the outer peripheral edge of the most objective side optical element, the liquid discharge means has a position of the most objective side optical element. In the center From the liquid suction means provided on the opposite side to the laser light to the irradiation object in a state of sucking the liquid flow flowing substantially along the surface portion of the most object side optical element on the irradiation object side The surface treatment method is characterized in that the irradiation is performed.
According to this, substantially the same effect as that of the laser irradiation apparatus described above can be obtained.

  As described above, according to the present invention, it is possible to provide a laser irradiation apparatus and a surface treatment method that have improved processing capability when performing surface treatment by irradiating an irradiation object in a liquid with laser. .

It is an external view of the head in the Example of the laser irradiation apparatus to which this invention is applied. It is sectional drawing of the head in the laser irradiation apparatus of an Example. It is a figure which shows typically the structure of the laser irradiation unit in the laser irradiation apparatus of an Example. It is a schematic diagram which shows the behavior of the beam in the laser irradiation apparatus of an Example. It is a fragmentary sectional perspective view of the head of the laser irradiation apparatus of an Example. It is a fragmentary sectional perspective view in the edge part vicinity of the irradiation target object side of the head of the laser irradiation apparatus of an Example. It is a four-plane figure of the cylindrical housing in the head of the laser irradiation apparatus of an Example. It is a four-view figure of the cap in the head of the laser irradiation apparatus of an Example. It is a see-through | perspective perspective view of the cap in the head of the laser irradiation apparatus of an Example. It is a figure which shows typically the behavior of the liquid flow at the time of use in the laser irradiation apparatus of an Example.

  In the present invention, the problem of providing a laser irradiation apparatus and a surface treatment method with improved processing capability when performing surface treatment by irradiating a laser on an irradiation object in a liquid is arranged on the irradiation object side most. The optical elements other than the most objective side optical element are accommodated in an airtight housing and a liquid flow is generated along the surface of the irradiation side of the most objective side optical element to prevent adhesion of debris and the like. Resolved by collecting.

Embodiments of a laser irradiation apparatus and a surface treatment method to which the present invention is applied will be described below.
Although the laser irradiation apparatus and the surface treatment method of the present embodiment are suitable for decontamination processing that crushes and collects fuel debris and the like attached to the inner wall surface of a nuclear power plant, for example, the application is not limited thereto. .

FIG. 1 is an external view of a head in the laser irradiation apparatus of the embodiment.
The laser irradiation apparatus includes a laser oscillator (not shown), a fiber F, and a head 10.
The laser oscillator is a light source that includes an excitation source, a laser medium, an optical resonator, and the like.
The laser oscillator may be either a continuous wave (CW) type or a pulsed type. For example, an arc lamp, a flash lamp, or the like can be used.
Moreover, you may provide the drive means for adding an excitation current etc. and driving according to the light source to be used.
The laser medium is preferably a solid laser (ruby laser, YAG laser, etc.) or a semiconductor laser (laser diode).
In particular, it is preferable to use a fiber laser as the solid-state laser.
The laser medium is not particularly limited, and a gas laser (CO2 laser, excimer laser, etc.), a liquid laser (dye laser), or the like may be used.

The fiber F transmits the laser beam generated by the laser oscillator to the laser irradiation unit 100 of the head 10.
The fiber F is configured by forming a reinforcing coating and a protective coating around an optical fiber in which a core is coated with a clad.
The fiber F has flexibility so as not to prevent the head 10 from scanning the irradiation object.

The head 10 is disposed adjacent to the irradiation target, and irradiates the irradiation target with the laser light generated by the laser oscillator and transmitted by the fiber F.
The head 10 includes a laser irradiation unit 100 (see FIG. 2), an irradiation unit housing 200, a cylindrical housing 300, a cap 400, and the like.

FIG. 3 is a diagram schematically showing the configuration of the laser irradiation unit 100.
As shown in FIG. 3, the laser irradiation unit 100 includes a fiber connection part 110, a condensing optical system 120, a deflection optical system 130, and the like.
The fiber connector 110 is connected to the end of the fiber F on the head 10 side, and guides the transmitted laser beam to the condensing optical system 120.

  The condensing optical system 120 condenses the laser light incident from the fiber F so as to converge at a predetermined focal point FP.

The deflection optical system 130 bends the laser light emitted from the condensing optical system 120 by a predetermined deflection angle.
For example, the deflection optical system 130 includes a wedge prism.
The deflection optical system 130 is rotationally driven at a predetermined rotational speed around a rotational axis disposed substantially parallel to the optical axis of the condensing optical system 120 by a driving power source 131 such as an electric motor or an air motor. The

FIG. 4 is a schematic diagram illustrating the behavior of the beam in the laser irradiation apparatus of the example.
With the above-described configuration, the beam B emitted from the laser irradiation unit 100 has the central portion of the deflection optical system 130 through which the optical axis of the condensing optical system 120 passes, and the deflection angle of the deflection optical system 130 is a half apex angle. The behavior of turning in the circumferential direction along the side surface of the cone is shown.
At this time, the focal point FP of the beam B is centered on the optical axis of the condensing optical system 120 and turns on a circumference along a plane orthogonal to the optical axis.
When the head 10 is held so that the optical axis of the condensing optical system 120 is orthogonal to the processing symmetry plane and the focal point FP is on the processing target surface with respect to the processing target surface, the focal point FP of the beam B is on the circumference. The processing target surface is scanned while turning.
By adopting such a configuration, even when a CW laser is used, it is possible to prevent the laser beam from being continuously irradiated to the same portion.

The irradiation unit housing 200 is a housing that houses the laser irradiation unit 100.
The irradiation unit housing 200 is formed in a substantially cylindrical shape, and the laser irradiation unit 100 is accommodated on the inner diameter side thereof.
The irradiation unit housing 200 is formed by, for example, injection molding of a resin material, and has a two-part configuration with a plane including the central axis as an example.
A bracket 210 used for fixing and supporting the irradiation unit housing 200 is formed on the outer diameter side of the irradiation unit housing 200.

The cylindrical housing 300 is a member that is formed so as to protrude from the emission-side end of the laser irradiation unit 100 in the irradiation unit housing 200 toward the irradiation object side, and through which the beam B passes.
The cylindrical housing 300 is formed in a cylindrical shape substantially concentric with the irradiation unit housing 200 by, for example, injection molding of a resin material.
The cap 400 is a member that is provided at the end of the cylindrical housing 300 on the irradiation object side and holds the protective glass 323 and the like.
The irradiation unit housing 200 and the cylindrical housing 300 are formed to be substantially watertight, and are sealed so that the liquid does not enter the inside even when processing is performed in the liquid.

Hereinafter, the configuration of the cylindrical housing 300, the cap 400, and the like will be described in more detail.
FIG. 5 is a partial cross-sectional perspective view of the head 10.
FIG. 6 is a partial cross-sectional perspective view in the vicinity of the end of the head 10 on the irradiation object side.
FIG. 7 is a four-side view of the cylindrical housing.
Fig.7 (a) is the external view which looked at the cylindrical housing 300 along the central axis from the irradiation object side.
FIG.7 (b) is a bb part arrow directional view of Fig.7 (a).
FIG.7 (c) is a cc part arrow directional view of FIG.7 (d).
FIG. 7D is a sectional view taken along the line dd in FIG. 7C.

The cylindrical housing 300 has a main body part 310 and a tip part 320.
The distal end portion 320 is formed in a part near the end on the irradiation object side, and the main body portion 310 is formed closer to the irradiation unit housing 200 than the distal end portion 320 (substantially all other than the distal end portion 320).

  The main body 310 includes a discharge flow channel 311, a suction flow channel 312, a discharge side pump connection portion 313, a suction side pump connection portion 314, a housing connection portion 315, a bracket 316, and the like.

The discharge channel 311 introduces liquid supplied from a discharge port of a pump (not shown) into a discharge channel 440 of the cap 400 described later.
The suction channel 312 introduces liquid introduced from a suction channel 450 of the cap 400 described later to a suction port of a pump (not shown).
The discharge flow channel 311 and the suction flow channel 312 are arranged to face each other with the central axis of the cylindrical housing 300 interposed therebetween.

As shown in FIG. 7A, the discharge channel 311 and the suction channel 312 form a region between the outer peripheral surface and the inner peripheral surface of the main body 310 over a predetermined width in the circumferential direction of the main body 310. The hollow portion is formed integrally with the main body portion 310.
The discharge channel 311 and the suction channel 312 have a cross-sectional shape that extends substantially in an arc shape when viewed from the central axis direction of the cylindrical housing 300.
The flow passage cross-sectional area of the suction flow passage 312 is set larger than that of the discharge flow passage 311.
Specifically, the suction channel 312 has a range (center angle) around the central axis of the cylindrical housing 300 that is set wider (larger) than the discharge channel 311.

The discharge-side pump connection portion 313 is a conduit that is connected to a discharge port of a pump (not shown) via a flexible hose and the like and supplies liquid discharged from the pump to the discharge flow path 311.
The discharge-side pump connection portion 313 is formed so as to protrude from the outer peripheral surface in the vicinity of the end portion of the main body portion 310 on the irradiation unit housing 200 side.

The suction-side pump connection portion 314 is a conduit that is connected to a suction port of a pump (not shown) via a flexible hose and the like and supplies the liquid introduced from the suction flow path 312 to the pump.
The suction-side pump connection portion 314 is formed to protrude from the outer peripheral surface in the vicinity of the end portion of the main body portion 310 on the irradiation unit housing 200 side.
The suction side pump connection part 314 is arranged and formed so as to be substantially axially aligned with the discharge side pump connection part 313 with respect to the central axis of the cylindrical housing 300.

The housing connection part 315 is formed at the end of the main body part 310 on the irradiation unit housing 200 side, and the outer diameter of the main body part 310 is reduced in a step shape.
The housing connection portion 315 is fitted into the end opening on the irradiation object O side of the irradiation unit housing 200.
The bracket 316 is a portion used for supporting, fixing, and the like of the cylindrical housing 300 and is formed so as to protrude from the outer peripheral surface of the main body 310.

The tip portion 320 is a portion on which the cap 400 is put, and has an outer diameter smaller than that of the main body portion 310.
A circular opening 321 concentric with the central axis of the cylindrical housing 300 is formed at the protruding end portion of the distal end portion 320.
Around the opening 321 is formed a recess 322 formed by denting the end surface of the tip 320 in a stepped manner.
A protective glass 323 is detachably inserted into the recess 322.

The protective glass 323 is a disk-shaped member formed of a transparent flat glass, and transmits the incident beam B without substantially deflecting it.
The protective glass 323 is removable from the cylindrical housing 300 by removing the cap 400 from the cylindrical housing 300.
The protective glass 323 is replaced when the use of the apparatus causes deterioration such as adhesion of foreign matter or burning.

On the outer peripheral edge of the recess 322, a groove 324 is formed which is formed by denting the surface facing the object to be irradiated, and extends circumferentially.
An O-ring 325 formed of a rubber-based elastic material is fitted in the groove portion 324.
The O-ring 325 seals the outer peripheral edge of the protective glass 323 and prevents liquid or the like from entering the inside of the cylindrical housing 300.

The cap 400 is a member that covers the distal end portion 320 of the cylindrical housing 300.
FIG. 8 is a four-sided view of the cap.
FIG. 8A is a perspective view of the cap 400 viewed from the radial direction.
FIG.8 (b) is a bb part arrow directional view of Fig.8 (a).
FIG.8 (c) is the cc part arrow directional view (figure seen from the irradiation target object side) of FIG.8 (b).
FIG.8 (d) is the dd part arrow line view (figure seen from the irradiation unit side) of FIG.8 (b).
FIG. 9 is a perspective view of the cap.
The cap 400 presses the surface of the protective glass 323 on the irradiation object side, holds the protective glass 323, and applies pressure to the O-ring 325 through the protective glass 323.

The cap 400 includes an outer peripheral surface portion 410, an end surface portion 420, a curved surface portion 430, and the like.
The outer peripheral surface portion 410 is a substantially cylindrical portion that is fitted on the outer diameter side of the distal end portion 320 of the cylindrical housing 300.
The outer diameter of the outer peripheral surface portion 410 is substantially the same as the outer diameter of the main body portion 310 of the cylindrical housing 300.
The inner diameter of the outer peripheral surface portion 410 is substantially the same as the outer diameter of the distal end portion 320 of the cylindrical housing 300.
The outer peripheral surface portion 410 is fixed to the distal end portion 320 of the cylindrical housing 300 by fastening means such as screws.

The end surface portion 420 is a flat plate-like portion provided at the end of the cap 400 on the irradiation object side.
The end surface portion 420 is formed in a disk shape, and is formed along a plane that is substantially orthogonal to the central axis of the cylindrical housing 300.
An opening 421 is formed at the center of the end surface portion 420.
The opening 421 is formed in a circular shape substantially concentric with the central axis of the cylindrical housing 300.
The opening 421 has a function of sucking a foreign substance that is separated from the irradiation target by irradiation and floats in the liquid while the beam B emitted from the protective glass 323 passes when the irradiation target is irradiated with the beam.

The curved surface portion 430 is a portion that connects between the end portion on the end surface portion 420 side of the outer peripheral surface portion 410 and the outer peripheral edge portion of the single surface portion 420.
The curved surface portion 430 is formed so that the cross-sectional shape when the cap 400 is cut in the radial direction is an arc shape in which the outer side of the cap 400 is convex.

The cap 400 is further formed with a discharge channel 440 and a suction channel 450.
The discharge flow path 440 deflects the liquid flow that flows from the discharge flow path 311 of the cylindrical housing 300 along the longitudinal direction of the cylindrical housing 300 by about 90 degrees along the inner surface of the curved surface portion 430, thereby protecting the protective glass 323. The liquid is discharged as a substantially laminar liquid flow along the surface.
The discharge channel 440 is formed by recessing the inner surface of the cap 400 of the outer peripheral surface 410, the curved surface 430, and the end surface 420 into a groove shape.

The suction flow channel 450 takes in the liquid flow that flows from the discharge flow channel 440 in the vicinity of the surface portion of the protective glass 323 along the diameter direction of the protective glass 323, and deflects the liquid flow by about 90 degrees along the inner surface of the curved surface portion 430. The liquid flow along the longitudinal direction of the cylindrical housing 300 is introduced into the suction flow path 312 of the cylindrical housing 300.
The suction channel 450 is formed by recessing the inner surface portion of the outer peripheral surface portion 410, the curved surface portion 430, and the end surface portion 420 into a groove shape.
The suction channel 450 has a channel cross-sectional area larger than that of the discharge channel 450 by making the width of the groove portion wider than that of the discharge channel 440.

Hereinafter, a surface treatment method for removing foreign matters attached to the surface of an irradiation object disposed in a liquid such as water will be described using the laser irradiation apparatus described above.
In this embodiment, the irradiation object is, for example, a structural member of a nuclear power plant disposed in cooling water, and the foreign object to be removed is so-called fuel debris in which the molten fuel is cooled and solidified and adhered. The application object of the invention is not limited to this.

In the head 10 of the laser irradiation apparatus, at least the distal end portion of the cylindrical housing 300 and the cap 400 are disposed in water.
At this time, the region closer to the laser irradiation unit 100 than the protective glass 323 inside the cylindrical housing 300 is prevented from entering water and is filled with air.
At the time of irradiation, the head 10 is held so that the distance between the surface of the protective glass 323 on the irradiation object side and the irradiation symmetry surface is, for example, 10 mm or less.
Such a holding of the head 10 can be performed using, for example, a robot that can scan the irradiation target by moving the head 10 along a preset trajectory.

Next, using a pump (not shown), a water flow is supplied to the discharge side pump connection portion 313 and a water flow is sucked from the suction side pump connection portion 314.
At this time, it is preferable that the flow rate of the water flow sucked from the suction side pump connection portion 314 is equal to or larger than the flow rate of the water flow supplied to the discharge side pump connection portion 313.

Then, the laser irradiation unit 100 irradiates the irradiation object with the laser beam B.
The focal point FP of the beam B is adjusted so as to substantially coincide with the surface of the irradiation object.
As a result, the fuel debris adhering to the surface of the irradiation object is crushed and separated from the irradiation object, and floats in water.
Fuel debris floating in the water is sucked into the inside of the cap 400 from the opening 421 of the cap 400, and further accompanying the water flow flowing along the surface of the protective glass 323 from the discharge channel 440 toward the suction channel 450, The air is sucked from the suction flow channel 450 and collected through the suction flow channel 312 of the cylindrical housing 300, the suction side pump connection portion 314, and the like.
In this case, it is preferable to provide a foreign substance collecting means such as a filter in a part of the flow path from the suction side pump connection part 314 to the pump.

  As described above, according to the present embodiment, it is possible to provide a laser irradiation apparatus and a surface treatment method with improved processing capability when performing surface treatment by irradiating an irradiation object in a liquid with laser. it can.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
For example, the structure, material, shape, quantity, arrangement, and the like of each member constituting the laser irradiation apparatus are not limited to the above-described embodiments, and can be changed as appropriate.
For example, in the embodiment, the protective glass 323 that is the most objective side optical element is formed in a flat plate shape, but the most objective side optical element constitutes a part of a condensing optical system that condenses the laser beam at a predetermined focal point. You may make it serve as a lens to do. According to this, since the light beam is not yet condensed at the stage where the laser beam passes through the lens, it is possible to prevent the high energy from being concentrated on one point of the lens and causing burning.
In the embodiment, the distance between the most objective optical element and the irradiation object is set to, for example, 10 mm or less, but this distance is not particularly limited. For example, when a green laser having a wavelength that is difficult to attenuate even in a liquid is used, a decrease in performance can be suppressed even when the distance between the most objective optical element and the irradiation object is set larger than this.
Further, the object to be treated is not limited to fuel debris of a nuclear power plant, and the liquid is not limited to cooling water.
For example, the present invention can be used for surface cleaning (for example, moss removal) in a water and sewage facility.

O irradiation object (processing object) 10 head F fiber 100 laser irradiation unit 110 fiber connection part 120 condensing optical system 130 deflection optical system 131 driving power source B beam FP focus 200 irradiation unit housing 210 bracket 300 cylindrical housing 310 Main body 311 Discharge flow path 312 Suction flow path 313 Discharge side pump connection section 314 Suction side pump connection section 315 Housing connection section 316 Bracket 320 Front end section 321 Opening 322 Recessed section 323 Protective glass 324 Groove section 325 O-ring 400 Cap 410 Outer peripheral surface section 420 End face Part 430 curved surface part 440 discharge channel 450 suction channel

Claims (10)

A laser irradiation apparatus including an irradiation optical system for converging a laser beam emitted from a laser oscillator and irradiating an irradiation target disposed in a liquid,
The irradiation optical system irradiates a laser beam in a state where a surface portion on the irradiation object side in the most objective optical element disposed adjacent to the irradiation object is disposed in the liquid, and The surface portion opposite to the irradiation object side of the most objective side optical element and the other optical element are accommodated in a housing in which the liquid is substantially prevented from entering,
Liquid ejecting means for ejecting a liquid flow substantially along the surface portion on the irradiation object side provided near the outer peripheral edge of the most objective optical element;
Near the outer peripheral edge of the most objective optical element, on the opposite side of the liquid ejection means with the center of the most objective optical element sandwiched, the surface of the most objective optical element on the irradiation object side And a liquid suction means for sucking a liquid flow flowing substantially along the line. The irradiation optical system includes a deflection optical system that deflects the emission-side optical axis at a predetermined angle with respect to the incident-side optical axis of the laser light, and a rotational drive that rotationally drives the deflection optical system around the incident-side optical axis. The laser irradiation apparatus according to claim 1, further comprising: means. 3. The laser irradiation apparatus according to claim 1, wherein the liquid suction unit sucks floating matter formed when the irradiation target is irradiated with the laser light together with the liquid flow. 4. The laser irradiation apparatus according to claim 1, wherein the suction amount of the liquid suction unit is equal to or greater than the discharge amount of the liquid discharge unit. 5. The laser irradiation apparatus according to any one of claims 1 to 4, wherein the most objective optical element is detachable from a main body of the housing. The laser irradiation apparatus according to any one of claims 1 to 5, wherein the most objective optical element is substantially formed in a flat plate shape. 6. The laser irradiation according to claim 1, wherein the most objective-side optical element constitutes a part of a condensing optical system that condenses laser light at a predetermined focal point. apparatus. The irradiation optical system is moved relative to the irradiation target so that the distance between the most objective optical element and the irradiation target falls within a predetermined range, and the surface of the irradiation target is irradiated with the laser light. The laser irradiation apparatus according to claim 1, further comprising an irradiation optical system driving unit that scans the beam. The irradiation optical system driving means moves the irradiation optical system relative to the irradiation object so that a distance between the most objective optical element and the irradiation object is 10 mm or less. The laser irradiation apparatus according to claim 8. A surface treatment method for converging a laser beam emitted from a laser oscillator and irradiating an irradiation object arranged in a liquid,
The irradiation optical system for irradiating the irradiation object with the laser light is a state in which the surface portion on the irradiation object side in the most objective optical element arranged adjacent to the irradiation object is arranged in the liquid The surface portion opposite to the irradiation object side of the most objective side optical element and the other optical element are accommodated in a housing in which the liquid intrusion is substantially prevented,
A liquid flow is ejected from a liquid ejection means provided in the vicinity of the outer peripheral edge of the most objective side optical element substantially along the surface part on the irradiation object side, and in the vicinity of the outer peripheral edge of the most objective optical element. A liquid flow that flows substantially along a surface portion of the most objective side optical element on the irradiation object side from a liquid suction means provided on the opposite side of the central portion of the most objective side optical element with respect to the liquid ejection means. Irradiating the laser beam to the irradiation object in a state of inhalation.

Images