Laser irradiation device

Abstract

To provide a deposit removal method and a deposit removal device capable of efficiently removing a deposit on a surface of a structure and recovering the removed matter using suction.SOLUTION: A laser head (3) is configured from an optical system (4) for irradiation with laser beam (30), suctioning means (33) for suctioning removed matter (60) produced at the point where the laser beam (30) is directed, and an attachment (5) configured to be capable of abutting a surface (20) of a structure, the optical system (4) being operated to scan the irradiation point of the laser beam so as to draw a trajectory of a first circle having a radius r1 around the optical axis of the laser beam (30) on a surface substantially perpendicular to the optical axis.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technology for removing coatings from the surface of a structure by irradiating it with a laser and then suctioning and recovering the removed material. In particular, the present invention relates to a laser irradiation device and laser irradiation system that uses a portable laser head to irradiate laser light onto fixed or large structures such as bridges, buildings, ships, and pipes to remove coatings or deposits, and a coating or deposit removal method that uses such a device and system. [Background technology]

[0002] To ensure the long-term safety of immovable structures such as bridges, highways, elevated railway tracks, buildings, tanks, and machinery and equipment, it is necessary to periodically strip and remove the paint coating from the surface of the base material (steel) to prevent corrosion and repaint it. Conventional paint removal methods include sandblasting, which uses sand to remove the coating, paint stripping agents, and mechanical tools. The blasting method generates a large amount of secondary waste. This secondary waste is a mixture of paint dust containing hazardous substances such as lead, hexavalent chromium, and PCBs, and abrasives such as silica sand and garnet. It places a heavy burden on the environment and is expensive to process. Furthermore, the abrasives are sprayed using compressed air, which can potentially damage the base material underneath the coating. Another problem is the loud noise generated when the abrasives collide. Both the methods using paint strippers and mechanical tools have the problem of being inefficient due to the low area treated per unit time. In addition, each method also has the problem of generating chemical waste and being noisy.

[0003] Patent Document 1 discloses a method for removing paint from the exterior panels of aircraft and other aircraft bodies using a laser processing device to improve work efficiency and avoid danger, in contrast to the conventional method of spraying highly toxic chemicals onto the painted surface and manually scraping off the paint film. The laser processing device described in Patent Document 1 includes a lens that irradiates the surface of the object to be treated with laser light, a lens support mechanism that supports the lens and can adjust the height of the lens from the surface of the object to be treated, and a gas ejection means that sprays gas onto the laser-irradiated area. The document also describes a gas suction port located within a box-shaped container that exhausts gas from the box-shaped container and discharges any removed material that has scattered from the laser-irradiated area. The document also describes a sweeping process of sweeping the irradiation position of the laser beam in a first direction while shifting it in a second direction intersecting with the first direction, using a first deflector that is arranged in the optical path of the laser beam incident on the lens and that changes the traveling direction of the laser beam to move the irradiation position of the laser beam in a first direction within the surface of the object to be processed, and a second deflector that is arranged in the optical path of the laser beam incident on the lens and that changes the traveling direction of the laser beam to move the irradiation position of the laser beam in a second direction intersecting with the first direction within the surface of the object to be processed. In this laser processing device, the document also describes a laser irradiation head attached to the tip of a manipulator arm, and the manipulator arm is controlled by a manipulator body to move and support the laser irradiation head to a desired position on the surface of the object to be processed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-309899 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the technology described in Patent Document 1, it is possible to remove the coating film on the surface of the object to be treated by laser ablation without using chemicals, and also to collect and discharge the removed material that has scattered from the surface of the object to be treated using a gas suction means.

[0006] However, the laser irradiation head described in Patent Document 1 is supported by a manipulator arm and moved to a desired position, making it difficult to use in environments where sufficient working space is not available or for structures with complex shapes. It is also difficult for workers to carry and handle the device. The laser processing device described in Patent Document 1 is a laser processing device intended for use in removing paint films from aircraft and other objects stored in a factory, and does not take into consideration the mobility of the laser processing device itself. In other words, the coating removal method described in Patent Document 1 cannot be applied to removing paint films from structures that are difficult to move (e.g., bridges, highways, elevated railway tracks, buildings, etc.).

[0007] In addition, Patent Document 1 discloses a scanning optical system that uses a first deflector, such as a galvanometer mirror or a polygon mirror, to linearly scan the laser beam irradiation position (hereinafter referred to as linear scanning). This method of repeating linear scanning makes it difficult to efficiently process a wide area in a short time, and thus is unable to process the wide surface area of ​​structures such as bridges at low cost. Furthermore, when the laser beam is linearly scanned, the optical path length changes, which changes the relative distance between the focal point of the laser beam and the actual irradiation point, making it difficult to uniformly remove the coating. Controlling the focus of the laser beam in accordance with the change in optical path length caused by linear scanning of the laser beam requires a complex mechanism. Furthermore, if the reflected light from the laser beam irradiated on the coating surface enters the laser mechanism, it may damage the fiber or other components. Typically, a complex mechanism is required to prevent damage from the reflected light, but it is difficult to install such a mechanism in a small, portable laser head. Furthermore, in Patent Document 1, the removed material scattered from the surface of the object to be treated is collected by a suction means, but there is a risk that some of the removed material produced from the laser irradiation point will adhere to the scanning optical system.In this case, not only will the energy of the laser light be attenuated, but the laser light may cause the adhesion point to become hot, which may damage the optical system.

[0008] An object of the present invention is to provide a laser irradiation device and a laser irradiation system including a small and lightweight laser head that can solve at least some of the above-mentioned problems. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the laser irradiation device of the present invention is a laser irradiation device including a laser oscillator, a fiber that transmits laser light output from the laser oscillator, and a portable laser head that focuses the laser light transmitted through the fiber and irradiates the surface of a structure, wherein the laser head includes an optical system that irradiates the laser light, and a shielding member that protects the optical system from material removed from the irradiation point of the laser light, and the optical system scans the irradiation point of the laser light on a surface that is approximately perpendicular to the optical axis of the laser light, so as to trace a circular locus of radius r centered on the optical axis.

[0010] In the laser irradiation device, the optical system preferably includes a first wedge prism that deflects the laser light in a direction outward from the optical axis, a second wedge prism that deflects the laser light deflected by the first wedge prism toward the optical axis, and a driving means that rotates the first wedge prism and the second wedge prism together around the optical axis, and the shielding member is attached to the tip of the laser head and has an outlet on the optical axis through which the laser light passes. The device may also include a suction source and suction means that sucks up material removed from the irradiation point of the laser light. The laser head may include an attachment configured to be able to contact the surface of the structure.

[0011] The laser irradiation device of the present invention is a laser irradiation device including a laser oscillator, a fiber that transmits laser light output from the laser oscillator, a suction source, and a portable laser head that focuses the laser light transmitted through the fiber and irradiates it onto the surface of a structure, wherein the laser head comprises an optical system that irradiates the laser light, a suction means that suctions the removed material that results from the irradiation point of the laser light, and an attachment that is configured to be able to abut against the surface of the structure, and the optical system is configured to scan the irradiation point of the laser light so as to trace a locus of a first circle with a radius r1 centered on the optical axis on a surface that is approximately perpendicular to the optical axis of the laser light.

[0012] In the above laser irradiation device, it is preferable that the attachment is configured so that when it contacts the surface of the structure, the surface of the structure is positioned at or closer to the focal length of the laser light. Furthermore, it is preferable that the optical system has a variable focus mechanism, and the laser head has a distance sensor that measures the surface-to-surface distance from the principal point of the optical system to the surface of the structure, and that a control unit is provided that changes the focal length of the laser light using the variable focus mechanism of the optical system so that the focal length is equal to or longer than the surface-to-surface distance measured by the distance sensor. Furthermore, it is preferable that the surface of the structure is positioned within a range of -5 to -25 mm on the laser head side of the focal point of the laser light.

[0013] In the above laser irradiation device, it is preferable that the laser head has a sensor that detects that the attachment is in contact with or close to the surface, and a control unit that limits the irradiation of laser light when the sensor does not detect that the attachment is in contact with or close to the surface. Also, it is preferable that the laser head has a vibration sensor that detects vibrations and vibration means, and a control unit that vibrates the laser head using the vibration means when the vibration detected by the vibration sensor is smaller than a predetermined threshold.

[0014] In the above laser irradiation device, the optical system preferably includes a first wedge prism that deflects the laser beam relative to the optical axis, and a driving means that rotates the first wedge prism and a shielding member disposed between the first wedge prism and the surface of the structure about the optical axis. The optical system also preferably includes a deflection means that further deflects the laser beam deflected by the first wedge prism relative to its optical path, and scans the irradiation point of the laser beam on a surface substantially perpendicular to the optical axis so as to trace a locus of a second circle with a radius r2 centered on a moving point on the circumference of the first circle. The deflection angle of the deflection means is preferably smaller than the deflection angle of the first wedge prism.

[0015] It is preferable that the deflection means is a second wedge prism, the first wedge prism rotates at a first rotation speed, and the second wedge prism rotates at a second rotation speed faster than the first rotation speed. Also, it is preferable that the attachment has a mirror that reflects the irradiated laser light onto a side surface of a protrusion formed on the surface of the structure.

[0016] The laser head preferably further includes a distance sensor that measures the surface-to-surface distance from the principal point of the optical system to the surface of the structure, and a control unit that changes the focal length of the laser light using a variable focus mechanism of the optical system so that the focal length is the same as or longer than the surface-to-surface distance measured by the distance sensor. The attachment preferably has an extension mechanism that can change the surface-to-surface distance from the principal point of the optical system to the surface of the structure. The laser head preferably has a sensor that detects whether the attachment is in contact with or close to the surface, and a control unit that limits the irradiation of the laser light when the sensor does not detect that the attachment is in contact with or close to the surface.

[0017] In the above-described laser irradiation device, the laser head may have a moving means for traveling inside the pipe, and the optical system may be configured to scan the irradiation point of the laser light so as to trace a circular locus with a radius r corresponding to half the inner diameter of the pipe. The optical system may have a reflecting mirror that reflects the laser light at a predetermined angle and a driving means that rotates the reflecting mirror about an optical axis, and the irradiation point of the laser light may be scanned behind the tip of the laser head. The optical system may have an interchangeable optical unit including an optical member that focuses or deflects the laser light, and a main body part including a driving means that rotates the interchangeable optical unit, and the interchangeable optical unit is preferably configured to be detachable from the main body part. The laser head preferably has at least two irradiation means that irradiate red laser light, and each irradiation means is preferably arranged so that the red laser light is irradiated obliquely with respect to the optical axis of the optical system, and the red laser light irradiated from the at least two irradiation means intersects at a predetermined position.

[0018] In any of the above laser irradiation devices, the laser head preferably has a gas spraying means for spraying gas supplied from a gas supply source near the irradiation point of the laser beam. The gas spraying means preferably fills the inside of the housing with a gas flow. The laser head preferably has an auxiliary irradiation means for applying energy near the irradiation point of the laser beam. The laser head preferably has a cooling means for cooling at least a part of the optical system. In the optical system, the fiber connection part connected to the tip of the fiber preferably has a lens for focusing the laser beam. The energy density per unit time at the focus of the laser beam is preferably 1.25×10 -4 ~5×10 -4 J / μm 2Preferably, the laser head has a laser beam intensity within a range of 100 to 200 μm, and the spot diameter of the irradiation point is within a range of 20 to 200 μm. It is preferable that the laser head further comprises a control unit that stops the laser beam irradiation from the laser head when a group of sensors provided in the laser head determines that the laser beam is deviating from the desired position. It is preferable that the laser head has a surface condition detection sensor that detects the surface condition or a camera that observes the surface condition, and a display device that displays information about the surface condition acquired by at least one of the surface condition detection sensor or the camera. It is preferable that the laser head further comprises a control unit that sets laser irradiation conditions based on the information about the surface condition.

[0019] The laser oscillator preferably includes a communication function connectable to a network, and a control unit that transmits information to a server via the network using the communication function, acquires laser irradiation conditions selected by the server, and sets the laser irradiation conditions. The laser oscillator is preferably a continuous wave type. The laser oscillator preferably generates laser light with an output of 200 to 500 W and a wavelength in the range of 1060 to 1100 nm.

[0020] Any of the above laser irradiation devices is preferably mounted on a vehicle configured to be movable.

[0021] The laser irradiation system of the present invention comprises a laser irradiation device including a laser head equipped with a surface condition detection sensor that detects the surface condition of a structure, and a communication function that can be connected to a network, and a server that can be connected to the network, wherein the server acquires information regarding the surface condition detected by the surface condition detection sensor from the laser irradiation device via the network using the communication function, and selects laser irradiation conditions based on the information regarding the surface condition of the structure, and the laser irradiation device acquires the selected laser irradiation conditions and is capable of irradiating a laser based on the selected laser irradiation conditions.

[0022] In the above laser irradiation system, the laser irradiation device is preferably mounted on a mobile vehicle. The laser irradiation device preferably has a control unit that restricts irradiation of laser light until it receives an irradiation permission signal from the server. When a group of sensors provided in the laser head determines that the laser light is deviating from the desired position, the server preferably stops emitting laser light from the laser head. The server preferably acquires information about the surface condition of the structure after laser irradiation, detected by the surface condition detection sensor, from the laser irradiation device via the network using the communication function, and associates the information with the selected laser irradiation conditions to create a database. Furthermore, the server preferably acquires information about the maintenance and management of the laser irradiation device, including the usage status of the laser irradiation device, and maintains and manages the laser irradiation device.

[0023] One aspect of the present invention includes a vehicle equipped with any one of the above laser irradiation devices.

[0024] The server of the present invention is characterized in that it selects laser irradiation conditions from a laser irradiation device that includes a laser head equipped with a surface condition detection sensor that detects the surface condition of a structure and a communication function that can be connected to a network, based on information regarding the surface condition obtained by the surface condition detection sensor via the network, and transmits the selected laser irradiation conditions to the laser irradiation device.

[0025] The server preferably transmits an irradiation permission signal to the laser irradiation device to permit the laser irradiation device to irradiate the laser light.

[0026] The paint film removal method of the present invention is a paint film removal method for removing paint film on the surface of a structure by laser irradiation, and is characterized in that a laser irradiation device including a laser oscillator, a fiber for transmitting laser light output from the laser oscillator, a suction source, and a portable laser head for focusing the laser light transmitted through the fiber and irradiating it onto the surface of the structure is moved to an installation location of the structure, and the laser head irradiates the laser light transmitted through the fiber onto the surface approximately perpendicular to the optical axis of the laser light, so as to trace a locus of a first circle with a radius r1 centered on the optical axis, while sucking up the removed material that is produced from the irradiation point of the laser light.

[0027] The paint film removal method of the present invention is a paint film removal method for removing paint film on the surface of a structure by laser irradiation, and is characterized in that a laser irradiation device including a laser oscillator, a fiber for transmitting laser light output from the laser oscillator, a suction source, and a portable laser head for focusing the laser light transmitted through the fiber and irradiating it onto the surface of the structure is moved to an installation location of the structure, and the laser head irradiates the surface with the laser light transmitted through the fiber so that the surface-to-surface distance from the principal point of the optical system to the surface of the structure is the same as or shorter than the focal length of the laser light, while sucking up the removed material that is produced from the irradiation point of the laser light.

[0028] In the coating removal method, it is preferable that the surface of the structure is in the range of −5 to −25 mm on the laser head side from the focal point of the laser light.

[0029] The method for removing deposits from the inside of a pipe by laser irradiation comprises: moving a laser irradiation device to an installation location of the pipe, the laser irradiation device including a laser oscillator, a fiber for transmitting laser light output from the laser oscillator, a suction source, and a laser head mounted on a moving means capable of traveling inside the pipe and irradiating the laser light transmitted through the fiber, and while traveling the laser head inside the pipe, scanning an irradiation point of the laser light so as to describe a circular locus with a radius r corresponding to half the inner diameter of the pipe, and suctioning off the removed material from the irradiation point of the laser light. In any of the above methods, the irradiation conditions of the laser light may be changed by removing an interchangeable optical unit including an optical element for focusing or deflecting the laser light from a main body of the laser head and attaching another interchangeable optical unit to the main body. [Effects of the Invention]

[0030] According to the present invention, a portable and mobile laser irradiation device including a small and lightweight laser head can be used to remove coatings and other materials from surfaces at the site of structures that are difficult to move, and the removed material can also be sucked and collected. Furthermore, a laser head equipped with an optical system capable of circular scanning can efficiently treat a wide range of surfaces, reducing the cost of coating removal. Other effects will be described in the detailed description of the invention. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a schematic diagram of a laser irradiation device according to a first embodiment; [Figure 2A] An explanatory diagram showing the positional relationship between the focus and the irradiation point [Figure 2B] A diagram that explains the positional relationship between the focal point and the irradiation point when the laser light is deflected. [Figure 3] Schematic diagram of a laser head according to a second embodiment [Figure 4] FIG. 10 is an explanatory diagram showing an example of a trajectory of a laser irradiation point in the second embodiment; [Figure 5] Schematic diagram of a laser head according to a third embodiment. [Figure 6] FIG. 11 is an explanatory diagram showing an example of a trajectory of a laser irradiation point in the third embodiment; [Figure 7] FIG. 10 is an explanatory diagram showing another example of the trajectory of the laser irradiation point in the third embodiment; [Figure 8] FIG. 10 is an explanatory diagram showing an example of an attachment for a laser head according to a fourth embodiment; [Figure 9] FIG. 10 is an explanatory diagram showing another example of an attachment for the laser head according to the fourth embodiment; [Figure 10] FIG. 10 is an explanatory diagram showing yet another example of an attachment for the laser head according to the fourth embodiment; [Figure 11] 10 is a schematic diagram of a laser head according to a fifth embodiment. [Figure 12] Example of distance measurement means of laser head of fifth embodiment [Figure 13] Example of focal point indication by distance measurement means of laser head of fifth embodiment [Figure 14] 10 is a schematic diagram of a laser irradiation system according to a sixth embodiment. [Figure 15] FIG. 13 is a schematic configuration diagram illustrating an example of a laser head according to a seventh embodiment. [Figure 16] FIG. 13 is a schematic configuration diagram showing another example of the laser head according to the seventh embodiment. [Figure 17] FIG. 13 is a schematic configuration diagram illustrating an example of a laser head according to an eighth embodiment. [Figure 18] FIG. 13 is a schematic configuration diagram showing another example of the laser head according to the eighth embodiment. [Figure 19] FIG. 13 is a schematic configuration diagram illustrating an example of a scanning optical system including an interchangeable unit according to a ninth embodiment. [Figure 20] 1 is an external view of an embodiment of the laser head of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0032] The present invention relates to a laser irradiation device and a laser irradiation system that include a small and lightweight laser head that efficiently removes coatings formed on the surface of a structure in a short time and that are configured to be transportable and movable to a work site. The present invention also includes a coating removal method that uses the laser irradiation device and the laser irradiation system. Here, the term "structure" refers to structures that are fixed in place and difficult to move, such as bridges, highways, elevated railway tracks, large tanks, and large equipment, as well as structures that can be moved to maintenance sites, such as aircraft, ships, and railroad vehicles. Furthermore, the term "structure" refers to piping installed in various facilities.

[0033] The present invention is primarily intended to remove coatings from the surfaces of these structures, but it can also be applied to surface preparation for open inspections of large tanks, surface modification treatments such as pre-welding treatments for large machinery and equipment, and the removal of dirt or rust from port facilities. It can also remove dirt and graffiti from concrete surfaces. Furthermore, it can also remove deposits, sediments, dirt, rust, and the like (hereinafter collectively referred to as deposits) from the inner surfaces of pipes. It is particularly preferred to use it to remove radioactively contaminated paint and deposits.

[0034] The laser irradiation device of the present invention includes at least a laser head, a laser oscillator, and a fiber for transmitting laser light output from the laser oscillator. The laser head is connected to the laser oscillator via the fiber and has an optical system for scanning the irradiation point of the laser light. Note that, depending on the situation, if the removed material generated from the laser irradiation point scatters, enters the laser head, and adheres to the optical system (lens), the adhered area may become hot and damage the optical system. For this reason, it is preferable to provide the laser head with a shielding member to protect the optical system from the removed material generated from the laser irradiation point.

[0035] The shielding member only needs to prevent the material to be removed from adhering to the optical system inside the laser head, and its shape and arrangement can be appropriately determined depending on the mode of laser light irradiation, the configuration of the laser head, etc. The shielding member is preferably disposed between the emission end face of the optical system and the surface to be treated. The shielding member may be cylindrical so as to cover the optical path of the laser light (see FIG. 3) or dome-shaped (see FIG. 16). It may also be plate-shaped so as to cover the exit port of the housing 32 (see FIG. 10). When the optical system is configured to be rotatable around the optical axis as described below, the shielding member may be provided to rotate together with the optical system or independently of the rotation of the optical system. The laser irradiation device of the present invention can also use a laser beam with a diverging cone shape. In this case, the exit port may be widened to allow the rotating laser beam to pass through, or the shielding member may be rotated in accordance with the rotation speed of the laser beam (see FIG. 3). It is particularly preferable to provide a single exit port of the shielding member on the optical axis and deflect the expanding cone-shaped laser beam toward the exit port of the shielding member, since this allows the expanding cone-shaped laser beam to be emitted from the small exit port without rotating the shielding member (see FIG. 15). The exit port in the shielding member for passing the laser beam may be configured as a physical opening, or may be configured as a translucent material that allows the laser beam to pass through, rather than a physical opening. The entire shielding member may be configured as a translucent material, in which case the exit port for the laser beam will be located at an appropriate position. It is also preferable that the shielding member be detachable so that it can be replaced when it becomes dirty.

[0036] Furthermore, if it is desired to prevent the removed material generated at the laser irradiation point from scattering around from an environmental conservation perspective, the laser irradiation device of the present invention may be provided with a suction source as needed, or the laser head may be provided with suction means for sucking the removed material. If the suction means is provided in the laser head, most of the removed material generated at the laser irradiation point will be collected by the suction means, but the removed material may be drawn to the output end of the optical system, and there is a risk that some of the removed material generated at the laser irradiation point will adhere to the optical system. For this reason, if the suction means is provided in the laser head, it is preferable to provide a shielding member as needed to protect the optical system from the removed material generated at the laser irradiation point.

[0037] Furthermore, the laser head may have an attachment attached to its tip, and can move while in contact with the surface of the structure. The attachment is preferably configured to be detachable.

[0038] The laser head is preferably portable so that an operator can operate it manually. Alternatively, the laser head may be mounted on a moving means (transport means). The moving means is not particularly limited as long as it can move the laser head relative to the surface to be treated. For example, the moving means may be configured to use a manipulator to move the laser head appropriately along the surface of the structure. Furthermore, the moving means may be a self-propelled or manually movable cart. In this case, the laser head can travel, for example, inside a pipe. The self-propelled moving means includes, in addition to the cart on which the laser head is mounted, a driving means (motor, engine, actuator, etc.), a driving force transmission means (roller, tire, caterpillar, etc.) that transmits the driving force from the driving means to the inner wall of the pipe, a remote control means (including a wireless or wired communication unit, a control unit for the driving means, etc.), and the like. When a manual moving means is configured, a wire or rod may be connected to the cart on which the laser head is mounted, and the laser head may be moved by an operator's operation. When the laser head is self-propelled or manually moved inside the pipe, it is preferable that the cart on which the laser head is placed is cylindrical to fit the inner diameter of the pipe (see Figures 17 and 18).

[0039] In the coating removal method using this laser irradiation device, it is preferable that the surface to be treated is positioned at the same focal length as the laser light or closer to the focal length. In particular, with the focal point as the reference (0), the laser head side (near distance) is negative and the far side (far distance) is positive, the surface to be treated is positioned so that it is preferably in the range of 0 to -30 mm, more preferably -5 to -25 mm.

[0040] The energy is most concentrated at the focus of the laser light, but conversely, the treatment area (spot diameter) becomes narrower, which reduces the paint removal processing ability. In some cases, the energy may be too strong and damage the underlying material or cause a fire. For this reason, by shifting the focus of the laser light from the surface of the structure in the optical axis direction (defocusing), the treatment area (spot diameter) can be widened and processing can be performed with an appropriate energy density.

[0041] Furthermore, when actually defocusing the laser beam, it was confirmed that defocusing it toward the negative side significantly improved paint removal performance compared to defocusing it toward the positive side. For example, when the surface to be treated was positioned 20 mm toward the positive side (far distance), smoke was emitted from the paint surface, and paint removal was uneven and insufficient. However, when the surface to be treated was positioned 20 mm toward the negative side (close distance), strong laser ablation occurred on the paint surface, enabling efficient paint removal. This is presumably because, when the laser beam is irradiated onto the material being removed that is flying away from the paint surface, the size of the laser beam near the focal position approaches the size of the material being removed, resulting in a moment when much of the laser power is blocked. Hereinafter, placing the irradiated surface in front of the focal point is referred to as "negative focus."

[0042] When the laser head is moved manually, it is difficult to maintain a constant distance from the surface to be treated. Therefore, it is preferable to configure the present laser irradiation device so that the distance to the surface to be treated is constant (preferably negative focus) depending on the length of the attachment of the laser head. Furthermore, the length of the attachment may be adjustable to adjust the amount of negative focus. Furthermore, the focal length of the laser light may be set appropriately, either in addition to or without an attachment, so that the amount of negative focus can be adjusted to match the focal length of the laser light to the state of the workpiece (coating film). Furthermore, instead of or in addition to the attachment, a surface distance measuring means may be provided to maintain the distance from the surface to be treated within a predetermined range.

[0043] The optical system of this laser head preferably employs a wedge prism rotatable around the optical axis and a rotary drive means for rotating it, thereby enabling the laser beam to be irradiated in a widening cone shape. When the target surface area is generally flat and the optical axis is approximately perpendicular to the surface, the continuous locus of the laser beam irradiation points on the surface forms a circle with the intersection of the optical axis and the surface as the center and the deflection amount of the wedge prism as the radius. Here, circular scanning of the laser beam irradiation points is referred to as "circular scanning," as opposed to conventional linear scanning. By holding the laser head for a certain period of time or moving it back and forth up and down or left and right as necessary, an operator can efficiently remove a specific area or a wide area of ​​coating by laser ablation in a short time.

[0044] Furthermore, the optical system of this laser head can also employ a wedge prism and deflection means that can rotate around the optical axis, allowing the laser beam to be projected in the shape of a diverging cone (which may be partially hollow). It is preferable to use a wedge prism as the deflection means, so that the continuous locus of the laser beam's irradiation point on the surface takes the form of a second circle whose radius is the deflection amount of the second wedge prism (second wedge prism) rolling continuously around a moving point on the circumference of a first circle whose radius is the deflection amount of the first wedge prism (first wedge prism). If the laser beam's irradiation point is continuously scanned for a certain period of time while the optical axis is fixed relative to the surface, the continuous locus can be regarded as a substantially circular ring or circular surface, enabling nearly uniform laser irradiation.

[0045] When changing the radius of the circle when circularly scanning laser light or the scanning method of the laser light, it is necessary to change the arrangement or configuration of the scanning optical system. However, in the present invention, the scanning optical system of the laser head is configured to have an interchangeable optical unit including various optical components and a main body portion including at least a driving means, and the interchangeable optical unit is configured to be detachable from the main body portion of the laser head with a simple operation, so that the irradiation conditions of the laser light can also be easily changed.

[0046] In the present invention, when an attachment is attached to the laser head, a closed space is formed between the housing of the laser head and the surface, preventing the scattering of removed coating material, including substances harmful to the environment and human body. By providing a suction means in addition to the attachment, the removed material can be sucked into the closed space. The attachment preferably has an extension mechanism that can be extended and retracted according to settings. This allows the distance from the housing to the surface to be maintained constant during work. Furthermore, to enable coating removal even on complex structures, at least a portion of the attachment is configured with a deformable joint and is provided with appropriate reflecting means. This allows the housing of the laser head to abut the surface at any angle relative to the normal to the surface. Furthermore, the attachment may be configured with a mirror for irradiating the laser light onto the side of a protrusion on the surface, allowing coating removal not only on flat surfaces but also on protrusions on the surface.

[0047] The laser irradiation device may also be configured to be connectable to a server via a network. In such a system, the server acquires information about the surface condition detected by a sensor mounted on the laser head, selects laser irradiation conditions suitable for coating film removal according to the surface condition, and transmits the selected conditions to the laser irradiation device.

[0048] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.

[0049] [Embodiment 1] The laser irradiation device of the first embodiment is a laser irradiation device including a small, lightweight, portable laser head that removes a coating film on the surface 20 of a structure and collects the removed material without scattering it.

[0050] 1 is a schematic diagram of a laser irradiation device according to a first embodiment. This laser irradiation device includes a laser oscillator 1, a fiber 2, a laser head 3, a suction hose 8, a suction source 9, and may also include a gas supply source 11 and a gas hose 12. The laser head 3 is small, lightweight, and portable, and is connected to the laser oscillator 1 via the fiber 2, making it easy to handle at the work site.

[0051] The laser oscillator 1, suction source 9, and gas supply source 11 are also devices configured to be transportable and movable, and may be mounted on various vehicles 100 (such as carts, vehicles, barges, and monoracks (including monorails and conveyors)). The laser irradiation device allows the irradiation conditions, such as laser output, focal position, beam width, and scanning speed, to be set appropriately according to the type and properties of the surface.

[0052] The laser oscillator 1 is composed of an excitation source, a laser medium, an optical resonator (mirror), and the like. The excitation source may be either a continuous wave (CW) type or a pulsed type, and an arc lamp, flash lamp, or the like may be used. A driving means for applying an excitation current or the like to drive the laser may also be provided depending on the light source used. A solid-state laser (such as a ruby ​​laser or a YAG laser) or a semiconductor laser (laser diode) is preferably used as the laser medium. It is particularly preferable to use a fiber laser as the solid-state laser. The laser medium is not particularly limited, and other lasers such as a gas laser (such as a CO2 laser or an excimer laser) or a liquid laser (dye laser) may also be used. The laser output from the laser oscillator 1 is transmitted to the laser head 3 via a transmission fiber 2.

[0053] Using a fiber laser to configure the laser oscillator 1 offers a variety of advantages. Fiber lasers primarily use fibers doped with rare-earth ions as the laser medium, enabling broader bandwidth optical amplification than solid-state lasers that use YAG crystals, etc. With a fiber laser, the fiber can be wound around the oscillator, making it possible to configure a small and lightweight laser oscillator that is easy to move and transport, and providing sufficient amplification even with a small gain per unit length.

[0054] Furthermore, fiber lasers have a larger fiber surface area / volume ratio than bulk solid-state lasers, providing excellent heat dissipation, allowing for a simple configuration using air cooling. Their small numerical aperture (NA) makes it easy to reduce the focused diameter. Fiber lasers also have shorter oscillation wavelengths and superior beam quality compared to CO2 lasers, allowing for a larger focal depth. Furthermore, the laser emitted from a fiber laser has a high coupling rate with the transmission fiber, allowing the laser to be transmitted with little loss even when the laser oscillator body is far from the surface.

[0055] In this way, with a fiber laser, the laser oscillator 1 itself can be carried to the vicinity of the surface (work location) of the structure and moved as needed to perform the paint film removal work. However, since it is the maneuverable laser head 3 that irradiates the surface with the laser, the laser oscillator 1 itself only needs to be positioned within the reach of the fiber 2.

[0056] Since the present invention is intended to remove a coating film from the surface of a workpiece rather than drilling or cutting holes in the workpiece, it is not necessary to obtain a high energy density with a single laser irradiation, and it is sufficient to obtain an energy density sufficient to remove the coating film with multiple laser irradiations. Therefore, in this embodiment, it is not necessary to use a high-output laser oscillator.

[0057] Furthermore, either a CW laser or a pulsed laser may be selected depending on the type of target structure or coating, the overall configuration of the device, etc. In particular, a CW laser requires more power than a pulsed laser to achieve the desired irradiation energy, but is preferred because of its low cost. The inventors have confirmed that, in terms of laser irradiation per unit time and unit area, a CW laser causes less thermal damage to the substrate or base material than a pulsed laser, and leaves a smoother surface after coating removal.

[0058] In this way, the use of a CW laser is preferable because it may facilitate painting after the coating removal. However, this embodiment is not limited to a CW laser, and either a CW laser or a pulsed laser may be selected depending on the target structure, the type of coating, the overall configuration of the device, etc.

[0059] The laser head 3 is a device that irradiates the surface 20 of a structure with a laser that is output by a laser oscillator 1 and transmitted through a fiber 2, removes the coating on the surface 20, and sucks up the removed material, and is configured to be easily maneuverable in the work area. The laser head 3 has an optical system 4, suction means 31 that sucks up the removed material 60, a housing 32 that houses these, and an attachment 5 that is attached to the tip of the housing 32. The laser head 3 may also have a shielding member (not shown) for protecting the optical system 4 from the removed material that is generated from the laser irradiation point.

[0060] In addition, the device may also include a gas spraying means 34 that sprays gas 70 near the irradiation point on surface 20, a control unit 35 that controls the optical system, etc., an operation unit 36 ​​to which operations from the operator are input, auxiliary irradiation means 37 that promotes ablation by irradiation with laser light, a sensor group 7 that includes a contact proximity sensor, a coating film visualization sensor, a vibration detection sensor, etc., and a power supply unit (not shown). The specific configuration of sensor group 7 will be described later using Figure 11.

[0061] The laser head 3 can appropriately set the intensity of the laser irradiation by changing the output of the laser oscillator 1. The laser head 3 is also configured so that the optical system 4 can appropriately set the irradiation conditions such as the focal position, beam width, and scanning shape according to the state and properties of the structure or surface.

[0062] The laser light 30 emitted from the laser head 3 preferably has an output of 100 to 2000 W and a wavelength of 500 nm or more, and more preferably has an output of 200 to 500 W and a wavelength of 1060 to 1100 nm. The energy density per unit time at the focal point can be appropriately designed depending on the surface material, condition, and irradiation time, but is preferably 1.25 × 10 -4 ~5×10 -4 J / μm 2 The spot diameter of the laser light may also be set appropriately depending on the relationship between the energy density and the size of the workpiece, but is preferably in the range of 20 to 200 μm in diameter.

[0063] The optical system 4 is composed of, for example, a combination of a focusing element, a reflecting element, a refractive element, a driving means, etc., and focuses the laser light emitted from the output end of the fiber 2 to irradiate the surface 20 with the laser light 30, and can also scan the irradiation point of the laser light 30 on the surface 20 in a linear or curved manner. The optical system 4 can be configured as appropriate, but in order to make the laser head small and simple, it is preferable to use a transparent refractive element to deflect the laser light. The specific configuration of the optical system 4 will be described later using Figures 3 and 5.

[0064] The housing 32 is preferably small and has a shape that provides a good grip so that it can be easily held by an operator.

[0065] When the surface 20 is irradiated with laser light 30, the irradiation point becomes high temperature and high pressure, causing ablation (melting and evaporation), which removes the coating. When the laser light is irradiated, a removed material 60 is generated near the irradiation point. In this embodiment, the laser head 3 is provided with suction means 31, so the removed material 60 is basically collected through the suction port 33 of the suction means 31. However, some of the removed material 60 may be attracted toward the optical system 4 and adhere to the lens of the optical system 4. For this reason, the laser head 3 is preferably provided with a shielding member (not shown) to protect the optical system 4 from the removed material generated at the laser irradiation point. The shielding member is preferably disposed between the output end face of the optical system 4 and the surface to be treated. The shielding member may be a plate-like member with an opening only in the optical axis portion, or a plate-like member (such as protective glass) that has no opening and is transparent to the laser light.

[0066] The attachment 5 is preferably detachably attached to the tip of the laser head housing 32 and fits tightly against the surface 20 to form a closed space. Here, the closed space is preferably a completely closed and sealed space, but a small gap may be provided. The attachment 5 may be configured to be movable while the laser head 3 is in contact with the surface 20, but is preferably configured to be able to contact curved surfaces as well. For example, the attachment 5 may be made of a flexible and deformable resin, or a sliding assisting means may be provided on the side of the tip of the attachment that contacts the surface. The sliding assisting means may be a tire or roller, or a brush-like or curtain-like member made of a flexible member may be provided.

[0067] Furthermore, it is preferable that the attachment 5 has an extension mechanism so that the distance d (see FIG. 2A) from the principal point of the scanning optical system 4 to the surface 20 can be appropriately set. The extension mechanism of the attachment 5 may be, for example, a zoom mechanism or autofocus mechanism of a general camera. The attachment 5 may have a deformable joint (flexible tube) formed in at least a part thereof so that the orientation of the optical axis L of the laser head 3 can be changed with respect to the normal to the surface 20.

[0068] In this laser head 3, the distance between the laser head 3 and the surface 20 can be appropriately set by the extension mechanism of the attachment 5 attached to the tip of the laser head 3. In addition, the focal length of the laser light 30 can also be appropriately set by the optical system 4.

[0069] 2A is an explanatory diagram showing the positional relationship between the focal point F and the irradiation point. As a result of extensive research, the present inventors have found that, rather than positioning the surface 20 at the focal point F of the laser light 30, the coating can be removed more efficiently by moving the position of the surface 20 from the focal point F to the negative side of the direction of the optical axis L (negative focus) and positioning the surface 20 to be treated in front of the focal point.

[0070] If the distance from the focal point F to the irradiation point (irradiation spot) P of the laser beam 30 on the surface 20 is Δf (defocus amount), the defocus amount (if negative) is determined by the relationship between the focal distance f from the principal point of the optical system 4 to the focal point F and the distance d from the principal point to the surface 20 (hereinafter referred to as the "surface-to-surface distance"). For ease of explanation, the surface-to-surface distance d and the focal distance f are assumed to originate from the exit end of the optical system 4 inside the housing 32 in the figure, but in reality, they originate from the principal point of the optical system. The defocus amount Δf is calculated by subtracting the focal distance f from the distance d, and is preferably set in the range of 0 to -30 mm, more preferably in the range of -5 to -25 mm. When the laser beam is deflected, the surface to be treated is preferably positioned in the range of 0 to -30 mm from the focal point along the optical path of the deflected laser beam, more preferably in the range of -5 to -25 mm.

[0071] In this embodiment, the defocus amount Δf (in other words, the position of the focal point relative to the surface to be treated) can be set as appropriate by changing the surface-to-surface distance d, and the surface-to-surface distance d can be changed as appropriate when the laser head is in contact, for example, by an attachment 5 equipped with an extension mechanism. Furthermore, if the optical system 4 is configured to be able to change the focal length f as appropriate (a variable focus mechanism), the position of the focal point can be changed without using the extension function of the attachment while it is in contact. Furthermore, the defocus amount may be changed as appropriate using both the extension function of the attachment and the variable focus mechanism of the optical system.

[0072] Referring again to FIG. 1 , suction means 31 uses the negative pressure applied by suction source 9 to suck removed material 60 (dust and minute fragments of the coating) generated from the irradiation point of laser 30 through suction port 33. Suction source 9 is, for example, a pump that applies suction force, and may also include a processing chamber for processing the sucked removed material 60, an exhaust filter, etc. The removed material 60 sucked by suction means 31 is collected by suction source 9 through suction hose 8, and remaining harmless air and the like may be discharged through an exhaust filter. Suction means 31 sucks removed material 60 generated from the irradiation point of laser light through suction port 33 in the closed space formed by attachment 5.

[0073] The gas blowing means 34 blows gas supplied from the gas supply source 11 via the gas hose 12 onto the vicinity of the irradiation point of the laser light 30, and has the effect of guiding the removed matter 60 (including dust, minute fragments, smoke, etc. of the coating film) generated from the vicinity of the irradiation point due to ablation toward the suction port 33 of the suction means 31 so that the removed matter 60 does not become an obstacle to the laser irradiation, thereby ensuring that the laser light 30 is irradiated onto the surface. In addition, the gas blowing means 34 may be used, as necessary, to prevent or reduce contamination of the inside of the housing 32 and the output end surface (lens) of the optical system 4 by the removed matter.

[0074] The gas supply source 11 may be composed of, for example, a tank, a cylinder, and a compressor. The gas can be selected appropriately depending on the working environment, the surface condition, material, properties, etc. For example, dry air, nitrogen, carbon dioxide, an inert gas (e.g., helium, neon, argon, etc.), or a charged gas for static electricity prevention may be used. If there is a risk of toxic reactive gases being generated from the surface, it is preferable to supply nitrogen or an inert gas or an activated gas to neutralize the reactive gas in order to reduce the generation of such gases. Furthermore, the spraying is not limited to gases; liquids (including mist (steam)) may also be sprayed. Examples of liquids include water for heating the surface, a treatment agent for promoting ablation, and chemicals such as a substrate protectant after coating removal.

[0075] In addition, the fiber 2, suction hose 8, gas hose 12 and power cable (not shown) connecting the laser oscillator 1, suction source 9 and gas supply source 11 to the laser head 3 may be bundled into a single integrated cable 25 to enable the worker to easily handle the laser head 3 at the work site.

[0076] Furthermore, when irradiating laser light, the removed material generated near the irradiation point may be electrostatically charged. Such removed material tends to adhere to the lens of the optical system, potentially shortening the lens's lifespan. For this reason, it is preferable to provide an anti-static device in the laser head. As an anti-static device, for example, a gas spraying device may be used, and static electricity may be removed by supplying a gas containing ions from the gas spraying device in accordance with the charge amount of the removed material. As described above, a shielding member may be used to prevent the removed material from adhering to the optical system, and at least a portion of the shielding member may be provided with a conductive member to remove the electrostatically charged removed material. Alternatively, a member for removing static electricity may be provided at an appropriate position in the laser head, separate from the shielding member. The anti-static device may also supply a magnet to remove static electricity from the removed material flying around the optical system.

[0077] The auxiliary irradiation means 37 applies various energies to the vicinity of the irradiation point to assist ablation as needed (for example, when the coating on the surface 20 is thick and requires long-term laser irradiation for removal). The auxiliary irradiation means 37 may be configured to irradiate, for example, light, heat, ultrasound, microwaves, or laser. Specifically, a halogen lamp or metal halide lamp capable of heating by light irradiation, an ultrasonic heater, a magnetron microwave oscillator, or a carbon dioxide laser for surface heating can be used. The auxiliary irradiation means 37 can also be used as lighting for photographing the surface condition with a CCD camera (reference numeral 73 in FIG. 11).

[0078] The control unit 35 has the function of controlling the scanning mechanism of the optical system 4, the variable focus mechanism, the extension / retraction mechanism of the attachment 5, the suction means 31, the gas spraying means 34, the operation unit 36, the auxiliary irradiation means 37, etc. The control unit 35 may be configured to realize various processes by cooperation between hardware and programs, or may be configured by a dedicated processing circuit. In the figure, the control unit 35 is provided in the laser head main body, but it may also be provided separately from the laser head main body. For example, a terminal (see reference numeral 82 in FIG. 14) connected wirelessly or by wire may serve as the control unit and control the laser head 3.

[0079] The operation unit 36 ​​has a function of receiving operations from the operator and outputting the results to the control unit 35. It may also have a function of displaying the operation results, the coating removal status, laser parameters, etc. The operation unit 36 ​​is composed of, for example, various switches, knobs, a software keyboard, a display device, etc.

[0080] As described above, the laser irradiation device of the first embodiment can be used to remove coatings from surfaces at the work site and collect the removed material using a portable and mobile laser irradiation device. The use of a portable laser head connected to the laser oscillator via a fiber makes the coating removal work easy for the worker. Furthermore, the laser output and wavelength can be appropriately set according to the surface condition, enabling laser irradiation suitable for coating removal.

[0081] Furthermore, the optical system of this laser head allows for the appropriate setting of irradiation conditions, such as the focal position, beam width, and scanning speed, enabling laser irradiation suitable for coating removal. Furthermore, the suction means and attachment provided on the laser head allow for efficient suction of the removed coating while removing it without scattering it. By appropriately setting the surface-to-surface distance using the extension / retraction mechanism of the attachment, the amount of defocus can be adjusted according to the surface condition, enabling ablation suitable for coating removal.

[0082] Furthermore, this laser head attachment ensures an adequate space for suctioning the material to be removed, reducing the risk of the material concentrating and blocking the suction port. It also prevents leakage and scattering of the laser light, ensuring the safety of the worker. Since the worker moves the laser head while holding this attachment in contact with the surface, the distance d between the surfaces can be kept constant, allowing for efficient removal work.

[0083] Other embodiments of the optical system inside the laser head will be described below. First, as a second embodiment, the configuration of a laser head using one wedge prism in the scanning mechanism will be described (FIGS. 3 and 4), and then, as a third embodiment, the configuration of a laser head using a wedge prism and deflection means in the scanning mechanism will be described (FIGS. 5 to 7). However, the present invention is not limited to the following examples.

[0084] [Embodiment 2] In the second embodiment, the optical system uses a wedge prism that can rotate around the optical axis and a driving means for rotating it, and irradiates the laser light in a widening cone shape (side surface). The continuous locus of the laser light irradiation points on the surface forms a circle C1 whose center is the intersection of the optical axis and the surface and whose radius is the deflection amount of the wedge prism r1. Hereinafter, an optical system that can scan the irradiation points using a driving mechanism or the like is also referred to as a scanning optical system.

[0085] Furthermore, by having the operator hold the laser head for a certain period of time or move it back and forth up and down or left and right as needed, it is possible to efficiently remove coating from a specific area or a wide area by laser ablation in a short period of time.

[0086] 3 is a schematic diagram of the scanning optical system of the laser head of the second embodiment. This laser head 3A is connected to the laser oscillator 1 via a fiber 2 and can be handled at the work site. In this embodiment, the scanning optical system 4 includes a fiber connection unit 41, a focusing means 42, a first wedge prism 43, a support member 44, and a driving means 49.

[0087] The fiber connection unit 41 is an optical element (laser emission collimator (for example, a quartz lens)) attached to the emission end of the fiber 2, and emits the laser light transmitted through the fiber 2 as parallel light toward the focusing means .

[0088] The focusing means 42 is a focusing optical system composed of one or more lenses, and focuses the laser light output from the fiber connection part 41 to a high energy density, and irradiates the surface 20 with the laser light 30. The focusing means 42 can appropriately set the focal length, focal depth, and beam spot diameter of the laser light 30.

[0089] The first wedge prism 43 is an optical element that deflects the incident laser light at a deflection angle θ with respect to the optical axis L. The first wedge prism 43 (and the focusing means 42) are supported by a support member 44. In this embodiment, a wedge prism is used as an optical element for deflecting the optical path of the laser light. This simplifies the optical path of the laser light without repeated reflections compared to when an optical element such as a galvanometer mirror is used, allowing the laser head to have a small and simple configuration.

[0090] The driving means 49 rotates the first wedge prism 43 by rotating the support member 44 at a predetermined rotational speed ω around the optical axis L. The driving means 49 can be configured as appropriate, such as a motor or a rotary actuator, but in order to make the laser head small and simple, it is preferable to use a hollow motor that can be arranged around the optical axis.

[0091] According to the scanning optical system 4, the irradiation point P (including the irradiation spot) of the laser light 30 appears on the surface 20 at a position that is a distance r from the optical axis intersection point O. The distance r is a deflection amount that is based on the deflection angle θ of the first wedge prism 43, the distance from the first wedge prism 43 to the surface 20, and the like.

[0092] Furthermore, a shielding member 48 can be employed to protect the first wedge prism 43 and shield the removed material generated near the laser beam irradiation point. The shielding member 48 is fixed to the first wedge prism 43 or the support member 44 and is configured to be rotatable therewith, and has an opening at an appropriate position that allows the laser beam 30 deflected according to the deflection angle of the wedge prism to pass through. In this embodiment, a suction means (e.g., reference numeral 31 in FIG. 1 ) and an attachment (e.g., reference numeral 5 in FIG. 1 ) are not provided, and the removed material generated at the laser beam irradiation point P scatters to the surrounding area. However, by providing the shielding member 48, the wedge prism can be protected from the removed material that is peeled off from the surface 20 and flies toward it. Furthermore, a conductive member may be provided on at least a portion of the shielding member 48 to actively remove statically charged removed material. Furthermore, as a means for preventing static electricity, a gas spraying means (see symbol 34 in Figure 1 or Figure 11) may be used, and static electricity may be removed by supplying a gas containing ions from the gas spraying means in accordance with the amount of charge on the object to be removed.

[0093] In this embodiment, when removing a coating, it is sufficient to provide an energy density sufficient to remove the coating through multiple circular scans. Therefore, unlike conventional laser processing devices for drilling, cutting, spot welding, and other applications of metals, it is not necessary to align the focal point with the actual laser beam irradiation point. Furthermore, during circular scanning, the optical path length of the laser 30 is approximately the same at each point on the approximately circular trajectory. Therefore, unlike linear scanning, the distance between the focal point and the actual irradiation point does not change during rotational scanning, allowing for consistent irradiation energy. Furthermore, to effectively utilize the laser energy, it is preferable to set the focal point deeper than the surface (negative defocus). The focal depth may also be set to a certain depth. This allows for coating removal even on surfaces with protrusions, steps, or deep structures.

[0094] Figure 2B is a diagram illustrating the positional relationship between the focal point and the irradiation point when a laser beam is deflected. When a laser beam is deflected by a deflection angle θ relative to an optical axis L1 using an optical system 4 having a wedge prism, the focal point F1 and irradiation point P1 on the undeflected optical path L1 move to positions corresponding to F2 and P2 on a new optical path L2 with a deflection angle θ. Therefore, when setting the defocus amount Δf based on F2, the target surface to be treated is preferably positioned at P2, which is in the range of 0 to -30 mm relative to the focal point F2, and more preferably in the range of -5 to -25 mm. Note that Figure 2B uses the principal point S as the reference point for deflection for convenience in order to illustrate that the focal length f when the laser beam is deflected is aligned with the optical path of the deflected laser beam. However, in an actual optical system, this may differ from the principal point.

[0095] Furthermore, the laser head is brought into close contact with the surface by the attachment 5, so the distance from the scanning optical system to the surface is always constant. From this perspective, it is preferable to employ circular scanning, which does not change the optical path length. Furthermore, in this embodiment, the irradiation point of the laser light is rotated around the optical axis intersection point, so even if the laser light is reflected from the surface, there is no risk of the returning light entering the laser head and damaging the fiber 2. In addition, in this embodiment, an anti-static means is provided in the laser head, so that statically charged material to be removed does not adhere to the optical system, or static electricity can be removed from the material to be removed.

[0096] 4 is an explanatory diagram showing the trajectory of the laser irradiation point by the laser head of the second embodiment. When the optical axis L and the surface 20 are approximately perpendicular and the surface 20 is generally flat without any curvature or irregularities, the first wedge prism 43 rotates around the optical axis L at a rotational speed ω, and therefore the irradiation point P of the laser light becomes a moving point on the surface 20 that moves at the rotational speed ω on the circumference of a circle of radius r centered at the optical axis intersection O.

[0097] In other words, the irradiation point P traces a locus of a circle C (including a substantially circular shape) of radius r centered on the optical axis intersection point O. Therefore, when the laser head 3A of the second embodiment is used to irradiate the surface 20 of the structure with laser light 30, the coating film is removed by laser ablation along the circumference of the circle C on the surface 20. For ease of explanation, the circumference of the circle C is shown as a line with no width in the figure, but in reality, the laser light 30 has a width equal to the spot diameter. Furthermore, it is preferable to set the radius r to be 5 to 200 mm.

[0098] When the laser head 3 is moved at a constant speed in the up-down or left-right direction parallel to the surface 20, either automatically or manually, while performing a circular scan such as the shape of circle C, the locus of the irradiation spot P becomes substantially band-shaped. In this way, the irradiation spot P can be scanned almost uniformly across the surface 20, making it possible to efficiently remove a wide area of ​​the coating on the surface 20 in a short amount of time. In the figure, the laser head 3A is moved linearly in a specific direction, but it may also be moved in, for example, a U-shape, zigzag, arc, or spiral pattern depending on the type of structure, the condition of the surface, etc.

[0099] For ease of explanation, the figure shows a schematic shape of the circle C continuing in the direction of movement of the laser head. However, in reality, the irradiation point is scanned circularly while the laser head (i.e., the optical axis intersection) is moved, so the trajectory of the irradiation point P is not a continuous circle C, which is a closed curve, but rather has a coil-like shape, which is an open curve. More precisely, the trajectory of the irradiation point P is the trajectory of the end point of the radius vector r rotating at a rotational speed ω.

[0100] Specifically, for example, when the irradiation point P is on the Y axis at time t=0 and starts to rotate at an angular velocity ω (circular scanning only), the trajectory (Px, Py) of the irradiation point at time t is expressed by the following equation.

[0101] Px=rsinωt Py=rcosωt Furthermore, for example, if an operator moves the laser head at a constant speed V in the direction of a vector having an angle φ with respect to the X axis, the trajectory (Px, Py) of the irradiation point at time t is expressed by the following equation:

[0102] Px=rsinωt+Vtcosφ Py=rcosωt+Vtsinφ In particular, when moving the laser head horizontally (X-axis direction), the following occurs:

[0103] Px=rsinωt+Vt Py=rcosωt The figure also shows a case where the optical axis L and the surface 20 are approximately perpendicular, the surface 20 is flat, and the locus of the irradiation point P is approximately circular. When the laser head is held tilted with respect to the normal to the surface (i.e., when the optical axis L and the surface 20 are not approximately perpendicular), the locus of the irradiation point P becomes elliptical (including a shape that is approximately elliptical).

[0104] Furthermore, if the surface 20 is uneven or curved, the locus of the irradiation point P will be a distorted circle or ellipse. In these cases, strictly speaking, the optical path length of the laser light at each irradiation point on the locus will be different, and the actual irradiation point may deviate slightly from the preset focus. In this case, it is preferable to set the focal depth to a certain extent (within the range of the change in optical path length). This allows the desired energy density for coating removal to be cumulatively applied by multiple rotational scans.

[0105] If the locus of the irradiation point P is elliptical, strictly speaking, the optical path length of the laser light at each irradiation point on the locus will be different, and the preset focus may deviate from the desired position. In this case, it is preferable to set the focal depth to a certain extent (within the range of change in optical path length) in advance. By performing multiple rotational scans, the desired energy density for coating removal can be cumulatively applied, so there is no problem even if the optical path length changes to some extent.

[0106] In this way, with the laser head of the second embodiment, the irradiation point of the laser light is rotated and scanned in a circular pattern around the intersection of the optical axes, so that by moving the laser head appropriately, it becomes possible to perform a substantially planar scan, making it possible to efficiently remove a wide area of ​​coating in a short amount of time.

[0107] Furthermore, because a wedge prism is used as a scanning element for deflecting the optical path of the laser light, the optical path of the laser light is simpler and does not undergo repeated reflections compared to when optical elements such as a galvanometer mirror are used, allowing for a compact and simple scanning mechanism. This allows for a low-cost, compact laser head that can be easily handled in the workplace. Furthermore, since the optical path length does not change during such circular scanning, the laser head configuration can be simplified.

[0108] The focal depth may also be set to a certain extent, which enables coating removal processing on protrusions, steps, the surface of deep structures, and corners of structures. Furthermore, by performing multiple circular scans, the required energy density for laser ablation can be applied, allowing coating to be removed efficiently. Furthermore, with such circular scans, even if the laser light is reflected from the surface, there is no risk of the returning light entering the laser head and damaging the fiber 2.

[0109] [Embodiment 3] In the second embodiment, a single wedge prism was used in the scanning optical system. In contrast, in the third embodiment, the scanning optical system uses a wedge prism rotatable about the optical axis and a deflection means to irradiate the laser beam in the shape of a diverging cone (which may be partially hollow). The deflection means may be a reflective optical element such as a mirror, but it is preferable to use a transmissive optical element such as a wedge prism. The following describes the case where a wedge prism is used as the deflection means. The continuous locus of the laser beam irradiation point on the surface is shaped like a second circle whose radius is the deflection amount of the second wedge prism (second wedge prism) rolling continuously around a moving point on the circumference of a first circle whose radius is the deflection amount of the first wedge prism (first wedge prism). If the laser beam irradiation point is continuously scanned for a certain period of time while the optical axis is fixed relative to the surface, the continuous locus can be regarded as a substantially annular or circular surface, enabling approximately uniform laser irradiation.

[0110] 5 is a schematic diagram of the scanning optical system of the laser head of the third embodiment. In addition to the configuration of the laser head 3A of the second embodiment, this laser head 3B has a second wedge prism 45, a support member 46, and a transmission means 47 as additional components of the scanning optical system. Furthermore, if necessary, the laser head 3 may have a shielding member (not shown) for protecting the scanning optical system from debris generated from the laser irradiation point. In the laser head 3B of the third embodiment, components similar to those of the laser head 3A of the second embodiment are assigned the same reference numerals, and detailed description thereof will be omitted.

[0111] The second wedge prism 45 further deflects the optical path of the laser light by a deflection angle θ2 with respect to the optical path M (hereinafter also referred to as the rotation reference axis M) of the laser light deflected by the first wedge prism 43 by a deflection angle θ1 with respect to the optical axis L. The second wedge prism 45 is supported by a support member 46.

[0112] The transmission means 47 connects the support member 44 including the first wedge prism 43 with the support member 46 including the second wedge prism 45, and transmits the driving force from the drive means 49. The drive means 49 can be, for example, a gear mechanism that can set an appropriate rotation ratio.

[0113] In this embodiment, the first wedge prism 45 is rotated at a rotational speed ω1 by rotating the support member 44 around the optical axis L using the driving means 49, and further, the second wedge prism 45 is rotated at a rotational speed ω2 by rotating the support member 46 around the optical axis L via the transmission means 47 connected to the support member 46.

[0114] Furthermore, when considering surface 20 that is approximately perpendicular to optical axis L, when the two wedge prisms are rotated around optical axis L, intersection point Q between surface 20 and rotation reference axis M appears at a position on the surface that is a distance r1 from optical axis intersection point O. Then, illumination point R (including the illumination spot) appears at a position on the surface that is a distance r2 from intersection point Q.

[0115] The distance r1 is the amount of deflection based on the deflection angle θ1 of the first wedge prism 43 and the distance from the first wedge prism 43 to the surface 20, and the distance r2 is the amount of deflection based on the deflection angle θ2 of the second wedge prism 45 and the distance from the second wedge prism 45 to the surface 20, etc.

[0116] In the figure, a configuration has been described in which the drive means 49 directly applies a rotational drive force to the first wedge prism 43, and the transmission means 47 indirectly applies the rotational drive force from the drive means 49 to the second wedge prism 45, but this is not limiting. Different rotational drive forces may be applied separately to each wedge prism by two drive means, or a rotational drive force directly applied from the drive means to the transmission means may be applied to each wedge prism. Any configuration may be used as long as the first wedge prism 43 and the second wedge prism 45 can rotate at different rotational speeds.

[0117] 6 is an explanatory diagram showing an example of the trajectory of a laser irradiation point on a processing plane according to the third embodiment. This figure illustrates a case in which the optical axis L and the surface 20 are substantially perpendicular, and the surface 20 is generally flat without any curvature or irregularities. Since the rotation reference axis M is a radius vector that rotates around the optical axis L at a rotational speed of ω1, the intersection point Q between the rotation reference axis M and the surface 20 is a moving point that moves at a rotational speed of ω1 on the circumference of a circle C1 of radius r1 centered at the optical axis intersection point O (hereinafter also referred to as moving point Q). The irradiation point R of the laser light is also a moving point that moves at a rotational speed of ω2 on the circumference of a circle C2 of radius r2 centered at the moving point Q.

[0118] For the sake of explanation, the figure schematically shows the locus of circle C2 when the rotation reference axis M rotates once, i.e., when the moving point Q on the circle C1 rotates once. Apparently, the circle C2 has a continuous shape with each point on the circle C1 as its center. However, in reality, as the moving point Q moves on the circle C1, the irradiation point R moves around it as its center. Therefore, the locus of the irradiation point R is not a continuous series of individual circles C2, which are closed curves, but rather has a shape like a coil loop, which is an open curve. More precisely, the locus of the irradiation point R is the locus of the end point of radius vector r2, which rotates at a rotational speed ω2 around the end point of radius vector r1, which rotates at a rotational speed ω1 around the optical axis intersection point O (i.e., the locus of the end point of vector r(r1+r2)).

[0119] It is preferable that the rotation speed ω2 is set to be sufficiently higher than the rotation speed ω1, and the ratio between the rotation speed ω1 and the rotation speed ω2 (rotation ratio ω2 / ω1) is set to be at least 9 / 2.

[0120] Furthermore, it is preferable to set the rotation ratio (ω2 / ω1) so that the initial position of the irradiation point R does not coincide with the position of the irradiation point R when the rotation reference axis M has made one or several revolutions. In this way, even if the rotation reference axis M has made several revolutions, the locus C2 of the irradiation point R will not overlap on the surface 20, making it possible to perform an almost uniform scan.

[0121] Furthermore, by moving the laser head 3B automatically or manually in the up / down or left / right directions parallel to the surface 20 at a constant speed while scanning the shape of the circle C2, the irradiation point R can be scanned almost uniformly over a specific range of the surface 20, and the coating film in a specific range on the surface 20 can be removed efficiently in a short period of time.

[0122] 7 is an explanatory diagram showing another example of the trajectory of the laser irradiation point by the laser head of the third embodiment. If the optical axis intersection point O is not moved and the shape of the circle C2 is scanned for a certain period of time, as shown in the figure, it is also possible to remove the coating film in the area of ​​the ring C3 with the circle C1 as the center curve.

[0123] In this way, the laser head of the third embodiment has the same effect as the second embodiment, and in addition, the laser head scans the irradiation point of the laser light on a circular or annular surface, so that it can efficiently remove a coating film in a specific area on the surface of a structure in a short time. This embodiment is suitable for removing a coating film around a protrusion such as a bolt, for example.

[0124] Furthermore, since the radius of the central curve C1 and the width of the ring C3 depend on r1 and r2, which correspond to the amount of deflection by each wedge prism, by appropriately setting r1 and r2, i.e., the deflection angle θ1 of the first wedge prism and the deflection angle θ2 of the second wedge prism, it is possible to set irradiation areas of rings of various sizes and shapes, and it is also possible to set a circular shape with no irradiated area in the center.

[0125] For example, when removing a coating film around a circular protrusion on a processing plane, if the deflection angles θ1 and θ2 are set so that |r2-r1| is the radius of the circular protrusion and an irradiated area is set, only the periphery of the circular protrusion can be scanned. Also, if r2≧r1 is set, it is possible to scan the entire circle without an irradiated area in the center, rather than a ring shape.

[0126] [Embodiment 4] As a fourth embodiment, an example of an interchangeable attachment that can be attached to the tip of a laser head will be described below. This attachment has a deformable joint and a mirror with an adjustable angle. This allows the laser head housing to be abutted against a surface at any angle relative to the normal to the surface. This makes it suitable for use in complex work locations where sufficient working space is not available, or for removing paint around protrusions such as bolts and from the sides of the protrusions themselves.

[0127] Fig. 8 is a schematic diagram of the laser head of the fourth embodiment. This attachment is detachable from the tip of the housing 32 of the laser head, and can be attached to the laser heads of the first to third embodiments. This figure shows an example in which it is attached to the tip of the housing of the laser head of the third embodiment (Fig. 5).

[0128] This attachment 5B has a deformable joint (flexible tube) 53 and is configured so that its shape can be deformed according to the angle with respect to the normal to the surface 20B. In the figure, the attachment 5B is configured so that the laser head 3C is approximately perpendicular to the normal to the surface 20B. The attachment 5B has a first mirror 51 and a second mirror 52 (see FIG. 9). However, the second mirror 52 may be removed depending on the application (for example, when it is not desired to irradiate the side surface of a protrusion with laser light). In addition, the laser head 3C may have a shielding member (not shown) to protect the scanning optical system from removed material generated from the laser irradiation point.

[0129] The first mirror 51 is configured so that the angle of the normal to the first mirror itself with respect to the optical axis L can be changed as needed. This allows the irradiation direction of the laser light to be changed from the optical axis La to the direction of the incident axis Lb, as shown in the figure. The angle between the optical axis La and the incident axis Lb can be set arbitrarily and is not particularly limited, but is preferably set to, for example, 90°. In this case, the trajectory of the irradiation point of the laser light on the surface 20B is the same as the trajectory on the surface 20 perpendicular to the optical axis L shown in FIG. 6.

[0130] FIG. 9 is a schematic diagram of a portion of the attachment of the fourth embodiment, showing the optical path of the laser beam from the laser head 3C. As shown in the figure, a protrusion 20C (e.g., a bolt) is present on the surface 20B, and the laser beam 30 is incident while rotating around a rotation reference axis Mb, which rotates around an incident axis Lb deflected by a first mirror 51. The laser beam 30 closer to the incident axis Lb is irradiated onto the top surface of the bolt 20C, while the laser beam 30 farther from the incident axis Lb is reflected by a second mirror 52 provided on the attachment 5B and irradiated onto the side of the bolt 20C. In this way, using this attachment, it is possible to easily remove paint around protrusions, which was previously difficult.

[0131] As described above, with the attachment of this embodiment, the laser head can be brought into contact with the surface in any orientation, allowing the worker to easily perform removal work without having to assume an awkward posture, even in narrow, complicated structures where handling is restricted. Furthermore, by attaching this attachment to the laser head of the third embodiment, the paint film around protrusions on the surface and the sides of the protrusions themselves can be efficiently treated.

[0132] Fig. 10 is an explanatory diagram showing yet another example of an attachment for the laser head of the fourth embodiment. In this example, an attachment including a reflecting mirror is attached to the tip of a laser head equipped with the scanning optical system shown in Fig. 3. This example has a simpler structure and can be used, for example, in narrow parts of structures, and can remove coatings, deposits, etc. from the surface of intricate parts that could not be achieved with conventional blasting methods.

[0133] The attachment 5C is connected to the tip of the laser head housing 32, and a reflecting mirror 51 is attached to the tip at a predetermined angle. The laser light 30 emitted in a conical shape from the scanning optical system of the laser head is reflected by the reflecting mirror 51, and the laser irradiation point is scanned in a substantially circular pattern on the inner surface of the narrow portion of the structure. A shielding member 48 is preferably attached to the output end of the scanning optical system to protect optical components (prisms, lenses, mirrors, etc.) arranged on the output end side from material removed from the laser irradiation point. The shielding member 48 is, for example, flat, has a laser light exit port 50, and is configured to rotate with the rotation of the scanning optical system.

[0134] Furthermore, in order to protect the reflecting mirror 51 from the removed material generated from the laser irradiation point, the attachment 5C may be provided with a gas spraying means 34 that supplies a gas flow to the reflecting mirror 51. The gas spraying means 34 sprays gas that is pressurized from a gas supply source (not shown) via a gas hose 12 onto the vicinity of the surface of the reflecting mirror 51, thereby preventing scattered removed material from adhering to the reflecting mirror 51.

[0135] [Embodiment 5] Hereinafter, an example in which a group of sensors and the like are provided in the laser heads of the first to fourth embodiments will be described.

[0136] 11 is a schematic diagram of a laser head according to the fifth embodiment. This laser head includes various sensors as a sensor group 7, such as a contact / proximity sensor 71, a surface condition sensor 72, a monitoring sensor 73, a vibration detection sensor 74, and a surface distance measurement sensor 75. It is not necessary to include all of the sensors in the sensor group 7; the sensors in the sensor group 7 may be selected and employed according to the purpose, or one sensor may serve multiple functions.

[0137] The contact / proximity sensor 71 is a sensor that detects when the attachment 5 comes into contact with or proximity to the surface 20. Such a sensor may be, for example, a pressure sensor attached to the tip of the attachment where it contacts the surface to be treated, or a sensor that measures the reflection intensity of the emitted radio waves, and may be configured to detect the contact or proximity of the attachment. The control unit 35 (which may be a management terminal (see reference numeral 82 in Figure 14) separate from the laser head; the same applies below) can also control the device to not permit laser light emission unless such a sensor detects it. This prevents the laser light from being accidentally emitted toward a surface other than the target surface for coating removal, ensuring the safety of workers. Furthermore, in the case of a sensor that measures the reflection intensity of the emitted radio waves, the device may be configured to permit laser light emission only when the reflection intensity exceeds a predetermined value. This prevents the laser light from being accidentally emitted toward the human body, etc.

[0138] The surface condition sensor 72 detects the underlying material of the surface 20 (steel plate, aluminum, etc.), the condition of the coating (lifting, thickness), the condition of rust (area, degree), and the presence of corrosive substances, dirt, and grease. It may also detect the amount of coating removed. Specifically, a radiation temperature sensor, a visible spectral image sensor, a near-infrared camera, etc. may be used. The monitoring sensor 73 may be, for example, a CCD camera or a CMOS camera. This allows a worker or a manager located remotely from the work site to observe the surface condition and the internal condition of the laser head, providing information for determining the necessary level of coating removal and the need for maintenance. The control unit 35 may also collect information regarding the surface condition detected by such sensors (hereinafter referred to as "surface condition information"). The control unit 35 may also control the display device of the operation unit 36 ​​to display this surface condition information. Alternatively, the surface condition information may be transmitted to a display device (reference numeral 82 in FIG. 14) connected to the laser head 3D main body via wireless or wired communication. The surface condition information may also be transmitted to a server connected to the laser irradiation device wirelessly or via a wire. The control unit 35 may change the laser irradiation conditions based on the detected surface condition information, or may reset the laser irradiation conditions based on instructions input by the operator based on the surface condition information. Furthermore, the control unit 35 may select laser irradiation conditions suitable for coating film removal at the site based on the acquired surface condition information, and change each setting of the laser irradiation device, including the laser head, based on the selected laser irradiation conditions.

[0139] Furthermore, a sensor capable of detecting toxic reactive gases may be provided inside the attachment (not shown). The control unit 35 may be configured to issue a warning to the operator and manager when it detects the generation of toxic gases.

[0140] The surface-to-surface distance measuring sensor 75 is a sensor that measures the distance to the surface using infrared rays or the like. The control unit 35 can set the focal point to a position suitable for coating removal based on the surface-to-surface distance detected by this sensor. Specifically, when the attachment 5 comes into contact, the control unit 35 controls the extension / contraction mechanism of the attachment 5 so that the surface 20 to be treated is positioned at or closer to the focal length of the laser light. The control unit 35 also controls the variable focus mechanism of the optical system so that the focal length of the laser light is equal to or longer than the measured surface-to-surface distance.

[0141] Furthermore, an irradiation means (such as a laser pointer) using a red laser may be used as the surface distance measuring means. FIG. 12 shows an example of the arrangement of laser pointers in the laser head, and FIG. 13 shows an example of indicating the focus using a laser pointer. In FIGS. 12 and 13, two laser pointers 77 are provided on the laser head as the surface distance measuring means (only the front one is shown in FIG. 12). Each laser pointer 77 is arranged so that its red laser beam 80 is emitted obliquely with respect to the optical axis of the scanning optical system 4 and intersects with the red laser beam from the other laser pointer 77 at a predetermined distance (position) s. In FIG. 12, the laser pointers 77 are arranged so that they intersect at position S on the optical axis L of the scanning optical system 4, which serves as a guide for the surface-to-surface distance and allows the center of the irradiation point of the laser beam to be identified. In this way, by setting the distance s to the desired surface-to-surface distance, the irradiation position of the laser head can be identified. Note that the red laser beams from the laser pointers 77 do not need to intersect on the optical axis of the scanning optical system 4; they may be arranged so that they intersect at another position (for example, a predetermined position directly in front of the laser pointer 77). Also, three or more laser pointers may be provided.

[0142] 13 shows how red laser light 80 from two laser pointers is emitted from two emission ports 78 provided on the tip cap of the laser head 3 and overlaps at position S. By irradiating the surface to be treated with red laser light using these two laser pointers, the operator can know the approximate surface distance from the principal point of the optical system to the surface when moving the laser head back and forth relative to the surface to be treated from the distance between the two light points from each laser pointer. For example, when the two light points coincide, it can be confirmed that the laser head is at an appropriate surface distance.

[0143] Referring to FIG. 11 , the vibration detection sensor 74 detects vibrations of the laser head 3D held by the operator and may be, for example, an acceleration sensor. Furthermore, the laser head 3D may include a vibration means 76 that vibrates the laser head body. The vibration means may be a vibration motor or an image stabilization mechanism installed in a general camera. During the coating removal operation, if the laser beam 30 is continuously irradiated on a specific area, there is a risk that only that area will be deeply excavated. When the magnitude of the vibration detected by the vibration detection sensor 74 falls below a predetermined threshold, the control unit 35 preferably uses the vibration means 76 to vibrate the laser head body 3D or the scanning optical system 4, thereby finely oscillating the irradiation point P of the laser beam and preventing the specific area from being excavated too deeply.

[0144] Furthermore, when the control unit 35 determines that the desired focal position has been obtained based on the measurement of the surface-to-surface distance by the surface-to-surface distance measuring sensor 75, it can notify the operator that the focal position is in the appropriate position by the vibration means 76 or the display device on the operation unit. Furthermore, when the control unit 35 determines that the focal position is not in the desired position based on the measured surface-to-surface distance, it may stop emitting the laser light. When an attachment is attached, the irradiation point of the laser light is usually not visible to the operator. This is preferable because the operator can confirm the optimal position by vibration or display.

[0145] In this embodiment, the fiber connection unit 41 (laser output collimator) may be configured to have a focusing function. Generally, a collimator has the function of converting incident light into parallel light. However, a focusing lens may be incorporated into this collimator to enable the output of focused laser light 30. This allows for a more compact and cost-effective laser head. Furthermore, since the fiber connection unit 41 (laser output collimator) is the final irradiation element of the fiber, heat is likely to accumulate therein. Therefore, to prevent overheating of the fiber connection unit 41, a cooling means 38 may be provided around the fiber connection unit 41. The cooling means 38 may be air-cooled or water-cooled. The cooling means 38 may be a gas blowing means 34 provided inside the housing 32, which blows gas pressure-fed from a gas supply source via the gas hose 12 onto the fiber connection unit 41. Furthermore, the gas spraying means 34 may fill the inside of the housing with a gas flow (purge gas) to prevent the removed material generated from the irradiation point P from flowing into the inside of the housing and contaminating the inside of the housing and the optical components of the scanning optical system 4. As described above, the gas spraying means 34 can also be used as an anti-static means, supplying a purge gas (e.g., containing ions) capable of removing static electricity into the inside of the laser head to remove charge from the removed material that has static electricity. Furthermore, in this embodiment, instead of or in addition to the gas spraying means 34, a shielding member (not shown) may be provided to protect the scanning optical system from the removed material generated from the laser irradiation point.

[0146] The laser irradiation device including the laser head having the various sensors of this embodiment may be connected to an external server via a network. The server stores various information acquired by the various sensors, selects various conditions for laser irradiation based on the various information, and can instruct the laser irradiation device in a remote location to select the optimal conditions. A system including a laser irradiation device will be described below.

[0147] [Embodiment 6] 14 is a schematic diagram showing the overall configuration of a laser irradiation system according to the sixth embodiment. The laser irradiation system interconnects a laser irradiation device installed at the work site with a server located in a remote location via a network, and sets laser irradiation conditions based on information on the coating condition acquired by the laser irradiation device, thereby achieving efficient coating work according to the condition of the structure surface.

[0148] This system comprises a laser irradiation device including a small and lightweight laser head 3 used at the work site, and a server, both of which are interconnected via a network. In the laser irradiation device, the laser head 3 used at the work site is connected to various devices mounted on a vehicle 100 located near the work site via an integrated cable 25 (including a fiber 2, a suction hose 8, a gas hose 12, and a power cable). The vehicle 100 is preferably a mobile vehicle, but may also be a ship, a barge, a cart configured to be movable via rails or cables, or a remotely controlled autonomous platform. The vehicle 100 is equipped with a laser oscillator 1, a suction source 9, and a gas supply source 11, as in FIG. 1, as well as a management terminal 82, a power supply unit 83, etc.

[0149] The management terminal 82 is a terminal for managing the laser irradiation device, and has functions such as obtaining information from various sensors mounted on the laser head 3 to create information regarding the surface condition (surface condition information), creating information regarding the maintenance and management of the laser irradiation device (hereinafter referred to as "device management information"), managing laser irradiation conditions, displaying various types of information, and communicating with a server 84 via a network. The management terminal 82 can be, for example, a control unit of the laser head 3, a personal computer, etc. The power supply device 83 supplies power to each device in the vehicle and the laser head 3.

[0150] The server 84 is a server that manages multiple laser irradiation devices, and has functions such as storing various information obtained from the management terminal 82 via the network 90, setting laser irradiation conditions for efficient coating removal according to the work location and target surface based on surface condition information, etc., transmitting such irradiation conditions to each laser irradiation device via the network 90, and maintaining and managing each laser device based on device management information.

[0151] The system may also include a management terminal 85. The management terminal 85 is a terminal for managing the server 84, and may be, for example, a personal computer. The management terminal 85 may be directly connected to the server 84, or may be connected to the server 84 and the management terminal 82 via a network. Managers can access the server 84 and the management terminal 82 of the laser irradiation device via the management terminal 85.

[0152] The network 90 may be any network that enables mutual communication between the management terminal 82 (or a communication device, not shown) of the laser irradiation device and the server 84. For example, a public telephone network, ISDN (short for Integrated Service Digital Network, also called a digital integrated service network), ADSL (Asymmetric Digital Subscriber Line), CATV (Community Antenna Television) network, optical fiber network, wireless LAN (Local Area Network), CS (Communication Satellite) broadcasting, mobile telephone network, etc. may be used.

[0153] The device management information includes, for example, identification information of the laser head 3 and other information, model, and usage status (date and time of use, cumulative usage time, frequency of use, conditions of use, part replacement history). The surface condition information includes information on the condition of the coating (coating thickness, area of ​​active film, rust and dirt state, adhesion (moisture)), the material of the base material (substrate), the shape of the target surface (flat, corner, protrusion), and the type of structure (bridge, tank, etc.). The surface condition information may also be associated with the laser irradiation conditions (laser output, laser wavelength, focal length, defocus amount, spot diameter, scanning mode (rotation speed, scanning speed), energy density, removal amount, etc.) used when actually removing the coating from the surface, information on the surface of the structure after laser irradiation, and weather conditions (temperature, humidity, etc.).

[0154] The server 84 of this system can select appropriate laser irradiation conditions according to the surface condition of each work site based on the acquired surface condition information and / or past laser irradiation results, and transmit the selected laser irradiation conditions to each laser irradiation device. The server 84 may also have a function to create a database by associating surface condition information with laser irradiation conditions. The server 84 may also be configured to transmit a signal to the laser irradiation device permitting or prohibiting laser light irradiation based on information from a group of sensors (such as attachment contact, surface distance, and surface condition). Furthermore, the server 84 may notify or manage the timing and content of maintenance based on device management information acquired from each laser device.

[0155] The laser irradiation device may acquire the laser irradiation conditions from the server 84 in response to an operation of the laser irradiation device itself, or the server 84 may provide the laser irradiation conditions to the laser irradiation device independently of the operation of the laser irradiation device. Specifically, when an operation of the laser irradiation device, such as transmission of surface condition information, a condition distribution request input by the worker, or power-on of the laser head, occurs, the server 84 acquires the surface condition information, selects appropriate laser irradiation conditions based on the surface condition information, and transmits the selected conditions to the laser irradiation device at the work site. Alternatively, the server 84 may acquire various information stored in the management terminal 82 of the laser irradiation device based on pre-registered identification information or the like, independently of the operation of the laser irradiation device, select appropriate laser irradiation conditions based on the information, and store the selected conditions in the management terminal 82 of the laser irradiation device. While the above description has been given of the case where the server 84 transmits the laser irradiation conditions, a configuration in which the management terminal 82 of the laser irradiation device acquires the laser irradiation conditions stored in the server 84 may also be adopted.

[0156] The management terminal 82 (or the control unit 35) may automatically set the irradiation device based on the acquired laser irradiation conditions. The acquired laser irradiation conditions may also be displayed, for example, on the display unit of the management terminal 82 or the operation unit 36 ​​of the laser head 3. Furthermore, the system may be configured so that various settings can be manually adjusted by an operator, allowing the laser irradiation conditions to be changed as appropriate in response to changes in the situation on-site. From the standpoint of safety management, it is preferable to limit the adjustable range (maximum output value, etc.).

[0157] Additionally, the manager may determine the paint removal grade based on surface condition information and visual observations using a camera, as necessary, and notify the workers at the work site of the grade. When repainting a structure, the required paint removal grade is classified as Class 1 to Class 4. For example, Class 1 completely removes the surface paint, rust, etc., completely revealing the metallic luster of the iron surface. Class 2 removes firmly adhered paint, as well as other paint, corrosion, oil, grease, dirt, and other foreign substances. Class 3 removes rust and loose paint, leaving the active film. Class 2 and Class 3 are common when repainting a structure, but in recent years, Class 1 is often used for structures with severe paint deterioration on the steel.

[0158] Thus, according to this embodiment, the server can select and instruct the laser irradiation device to select laser irradiation conditions suitable for removing the coating based on information detected by various sensors mounted on the laser head.

[0159] [Embodiment 7] This embodiment describes another example of circular scanning of laser light, in which the converging laser light is deflected to form a circular trajectory, and then deflected again in the direction of the optical axis, thereby irradiating the laser light so that the optical path intersects with the optical axis.

[0160] Fig. 15 is a schematic diagram showing an example of a laser head according to the seventh embodiment. This laser head 3E differs from the laser head 3B of the third embodiment shown in Fig. 5 in that the first wedge prism 43 and the second wedge prism 45 are fixed to a support member 44 so as to prevent a difference in rotation between the prisms, and in that a dome-shaped shielding member 48 having a laser emission port 50 on the optical axis is provided. In the laser head 3E of the seventh embodiment, components similar to those of the laser head 3B of the third embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

[0161] In this example, the first wedge prism 43 and the second wedge prism 45 are supported by a support member 44, and the driving force from the driving means 49 causes both the first wedge prism 43 and the second wedge prism 45 to rotate around the optical axis (at the same rotational speed).

[0162] The first wedge prism 43 deflects the optical path of the laser beam relative to the optical axis L at a deflection angle θ1 in a direction outward from the center of rotation (the optical axis L). Next, the second wedge prism 45 deflects the optical path of the laser beam relative to the deflected optical path M at a deflection angle θ2 in a direction toward the center of rotation (the optical axis L) (θ2>θ1). In this example, the laser beam that was once deflected outward with respect to the optical axis L is deflected inward again, so that the laser beams appear to intersect at the intersection point X due to the movement of the two prisms that rotate together. In other words, this example is configured to irradiate the laser beam 30 from the intersection point X at an angle (θ2-θ1) from the optical axis L.

[0163] According to this embodiment, the exit 50 of the shielding member 48 is positioned to correspond to the intersection X of the laser beams. This allows the exit 50 of the shielding member 48 to be small on the optical axis, thereby preventing the material removed from the irradiation point of the laser beam on the processing plane from entering the laser head while still irradiating the laser beam in a circular pattern. In this embodiment, a third wedge prism may be provided on the positive side (the side of the processing surface in the figure) and rotated at a different rotational speed than the first and second wedge prisms. In this case, a circular scanning mode such as that shown in FIG. 5 can be achieved. This embodiment is not configured to collect the material removed from the laser irradiation point P. However, if it is desired to prevent the material from scattering around, an attachment and suction means may be further provided.

[0164] Fig. 16 is a schematic diagram showing another example of the laser head of the seventh embodiment. The laser head 3F of this example is an additional configuration to the laser head 3E shown in Fig. 15, which includes an attachment 5 and suction means 31 having a suction port 33. The laser head of this example can protect the optical system of the laser head from the removed material generated from the irradiation point of the laser light, and can also collect the removed material without scattering it around.

[0165] [Embodiment 8] In one embodiment of the present invention, a modified example for removing deposits from the inside of a pipe is described. In this example, the laser beam is not irradiated circularly onto a flat surface to be treated, but is irradiated circularly to match the inner diameter of the pipe. This example is particularly suitable for removing deposits containing radioactive materials from secondary cooling pipes in nuclear reactors.

[0166] 17 is a schematic diagram showing an example of a laser head according to the eighth embodiment. The laser head 3G of this example includes a wedge prism 43, a support member 44, a driving means 49, a fiber connection unit 41, a suction means 31 having a suction port 33, and a moving means 110. Since the laser head 3G is inserted into a small-diameter pipe for use, it is preferable that it be as small as possible, and it is preferable that the fiber connection unit 41 be capable of supplying high-energy laser light directly from the output end without using a focusing means.

[0167] The main body (41, 43, 44, 49) of the laser head 3G is mounted on moving means 110A that can travel automatically or manually inside the pipe 20, and the suction means 31 is mounted on moving means 110B that is arranged in the direction of travel of the laser head main body. The moving means 110A and 110B each have, for example, rollers 112 for travel and an appropriate driving means (not shown), and can move along the inside of the pipe. The moving means 110A and 110B are preferably configured to be movable by remote control.

[0168] Furthermore, it is preferable that the moving means 110A and 110B are provided with sealing means 114 that can come into close contact with the surface inside the pipe. The sealing means is made of rubber or resin packing, a brush, etc. This seals the space between the moving means 110A and the moving means 110B, making it possible to prevent harmful materials removed by laser irradiation from scattering.

[0169] Laser head 3G is moved inside the pipe by moving means 110A, and emits laser light 30 in a circular pattern aligned with the inner diameter of pipe 20. That is, the irradiation point P of the laser light is scanned so as to trace a circular locus with a radius r corresponding to half the inner diameter of the pipe, thereby efficiently removing deposits 22 inside the pipe. Moving means 110B carrying suction means 31 moves in accordance with moving means 110A carrying the laser head main body, and removed material 60 produced from the irradiation point of laser light 30 is collected by suction means 31.

[0170] FIG. 18 is a schematic diagram showing another example of the laser head according to the eighth embodiment. The laser head 3H of this example differs from the example shown in FIG. 17 in that a reflecting mirror 43B is used instead of a wedge prism and a suction unit 31 is provided on the main body of the laser head. The reflecting mirror 43B is provided at the tip of the laser head and rotated by a driving unit 49. In this laser head 3H, the laser beam 30 emitted from the fiber connection unit (laser output collimator) 41 is reflected at a predetermined angle θ by the rotating reflecting mirror 43B. The reflected laser beam 30 travels rearward from the tip of the laser head. The irradiation point P of the laser beam scans along a circular locus with a radius r corresponding to half the inner diameter of the pipe, thereby efficiently removing deposits 22 inside the pipe. The removed material 60 resulting from the irradiation point of the laser beam 30 is collected by a suction unit 31 mounted on a moving unit 110.

[0171] In this example, the laser head can travel inside the pipe and the irradiation point of the laser light can be scanned in a circular pattern to match the inner diameter of the pipe, making it possible to efficiently and safely remove adhesions inside the pipe, which was previously difficult.

[0172] 17 illustrates a configuration in which one wedge prism is used as the scanning optical system, and FIG. 18 illustrates a configuration in which one reflecting mirror is used as the scanning optical system, but the laser head of the eighth embodiment is not limited to such a configuration. The laser head of FIG. 17 or 18 may be combined with the configurations of other embodiments (for example, FIG. 1, FIG. 3, FIG. 5, FIG. 8, FIG. 15, FIG. 16, etc.).

[0173] [Embodiment 9] In this embodiment, a laser head including an interchangeable optical unit will be described. Fig. 19(A) is a schematic diagram of a scanning optical system (when connected) including an interchangeable optical unit in a laser head of the ninth embodiment, and Fig. 19(B) is a schematic diagram of the scanning optical system when the interchangeable optical unit is detached (when separated). The scanning optical system of the laser head of this embodiment is configured by connecting an interchangeable optical unit 190 including at least a focusing or deflecting optical element and a main body portion 191 including at least a driving means 49 (see Fig. 19(A)). The interchangeable optical unit 190 is configured to be detachable from the main body portion 191 of the laser head with a simple operation (see Fig. 19(B)), allowing the irradiation conditions of the laser light to be easily changed.

[0174] The interchangeable optical unit 190 is a unit that includes various optical components (e.g., one or more of a wedge prism, a condenser lens, a reflecting mirror, etc.), and at least a portion or all of the interchangeable optical unit 190 is rotatable by a driving force applied by a driving means 49. In FIG. 19 , the interchangeable optical unit 190 is configured with a support member 44 that rotatably holds a lens holder main body 44A, a lens cap 44B, a joint cap 44C, etc. Various optical components are stored within the lens holder main body 44A, and the front end is closed by the lens cap 44B and the rear end is closed by the joint cap 44C. Optical components whose conditions need to be changed may be placed in the interchangeable optical unit, and other optical components may be placed in the main body portion 191. The lens cap 44B has an opening through which laser light passes. The joint cap 44C has an opening through which laser light passes, and is configured to engage with a connecting member 49B of the main body portion 191 and transmit the rotational force of the driving means. Therefore, at least a portion of the interchangeable optical unit 190 can be rotated by the driving force applied from the driving means 49, but can be separated from the main body part 191 including the driving means 49 by a simple operation and can be removed from the laser head.

[0175] A laser emission port 50 for emitting laser light is provided at the tip of the interchangeable optical unit 190. The laser light emitted from the interchangeable optical unit 190 is scanned, for example, in a circular pattern by various optical members housed in the lens holder main body 44A, and is then irradiated from the laser emission port 50 toward the surface to be treated. To prevent the material to be removed from entering the optical unit 190, gas supplied from a gas supply source (not shown) may be ejected from the laser emission port 50. Instead of or in addition to the laser emission port 50, a gas ejection port 34B may be provided around the laser emission port 50 to eject gas supplied from the gas supply source (not shown). The interchangeable optical unit 190 may also be provided with a laser pointer (reference numeral 77 in FIG. 12 ) and a laser pointer hole (reference numeral 78 in FIG. 12 ). The main body 191 includes a hollow motor 49A, which is a driving means 49, a connecting member 49B, and the like.

[0176] As a method of connecting the interchangeable optical unit 190 and the main body portion 191, for example, the joint cap 44C of the interchangeable optical unit 190 and the connecting member 49B of the main body portion 191 may be fixed via a hook or the like, and the driving force of the driving means 49 may be transmitted to the interchangeable optical unit 190 via the connecting member 49B and the joint cap 44C.

[0177] Alternatively, the interchangeable optical unit 190 may be connected to the main body 191 by fixing the support member 44 to the housing 32 of the main body 191 with the joint cap 44C and the connecting member 49B engaged so as to be able to transmit rotational motion. In this case, the lens holder main body 44A can be configured to rotate inside the support member 44 via a sliding means such as a bearing while the support member 44 is fixed to the housing 32 of the main body 191. Note that, before connecting the interchangeable optical unit 190 to the main body 191, it is preferable to attach an additional component (such as a laser pointer) to the interchangeable optical unit 190 in advance.

[0178] As described above, in this embodiment, an interchangeable optical unit is employed, and various laser beam irradiation modes can be realized by selecting and installing an appropriate unit according to the purpose (type, condition, size, etc. of the workpiece). Specifically, if a unit including one wedge prism is selected, circular scanning as shown in FIG. 4 can be realized. If a unit including two wedge prisms (with a difference in rotational speed) is selected, annular scanning as shown in FIG. 6 or FIG. 7 can be realized. If a unit including two wedge prisms (with no difference in rotational speed) is selected, circular scanning as shown in FIG. 15 can be realized.

[0179] Furthermore, by selecting an appropriate unit from among multiple units including wedge prisms with gradually varying deflection angles, a circular scan with a desired radius r can be achieved according to the purpose. Furthermore, various irradiation conditions can be changed by providing the scanning optical system with an adjustable focal length and deflection angle. For example, by appropriately changing the interchangeable optical unit and changing the deflection angle, the size of the circular scan (e.g., diameter 10 cm, 5 cm, 3 cm, etc.) can be changed while maintaining approximately the same inter-surface distance. Changing the focal length changes the desired inter-surface distance, thereby changing the size of the circular scan (e.g., diameter 10 cm, 5 cm, 3 cm, etc.). The size of the circular scan (e.g., diameter 10 cm, 5 cm, 3 cm, etc.) can be determined depending on the area of ​​the surface to be treated. For large areas, a large circular scan can be used, and for small areas such as narrow spaces, a small circular scan can be used.

[0180] Furthermore, when irradiating laser light of the same energy, changing the size of the circular scan also changes the energy density at the irradiation position. Therefore, the size of the circular scan can be changed by selecting an interchangeable optical unit depending on the desired energy density to be imparted to the surface to be treated. Furthermore, the size of the circular scan can be changed depending on the specified output of the laser oscillator used, thereby adjusting the energy density of the laser irradiation imparted to the surface to be treated, thereby reducing the risk of imparting excessive energy. Furthermore, an interchangeable optical unit can be selected depending on the condition of the surface to be treated. For example, when performing type 3 cleaning to remove surface rust or loose paint, an interchangeable optical unit capable of large circular scans can be selected so that the energy density of the laser irradiation is reduced. Using an interchangeable optical unit in this manner facilitates maintenance of optical components. Various attachments (such as the symbol 5 in FIG. 1 or FIG. 11, the symbol 5B in FIG. 8, and the symbol 5C in FIG. 10) can also be attached to the laser head including the interchangeable optical unit of this embodiment.

[0181] [Example 1] As an example of the present invention, a laser head was designed as follows. The laser head was 43 cm long, 7 cm in diameter, and weighed 1400 g. In the laser head having first and second wedge prisms, the focal length was set to 150 mm, and the beam spot diameter at the focal point was set to 0.04 mm (40 μm). The laser light input to the laser head was of the continuous wave type, with an average output of 200 W and a wavelength of 1070 nm. The laser head with an attachment was brought into contact with a flat steel plate on which a coating film of 30 to 50 μm in thickness had been formed, and the surface of the steel plate was irradiated with the laser light approximately perpendicularly. Using this laser head, a laser beam was emitted at a rate of 8 m per hour. 2 It was possible to remove the coating with a work efficiency of 100%.

[0182] [Example 2] As another embodiment of the present invention, a laser head employing an interchangeable optical unit was designed. Figure 20 shows the external appearance of an embodiment of a laser head employing an interchangeable optical unit. Figures 20(A), (B), (C), and (D) are a side view, a top view, a perspective view seen from the front end, and a perspective view seen from the rear end of the laser head, respectively. This laser head is 35 cm long, 8.5 cm high, 6 cm wide, and weighs 1.6 kg. The interchangeable optical unit 190 includes a focusing lens, a wedge plate, and a protective glass (part of the shielding member). It is detachable from the main body 191 and is connected to the drive means of the main body 191 via a connecting member so that driving force can be transmitted.

[0183] 19 , the joint cap 44C of the interchangeable optical unit 190 is connected to the connecting member 49B of the main body portion 191 so as to be able to transmit rotational motion, and the outer housing 44 of the interchangeable optical unit 190 itself is fixed to the housing 32 of the main body portion 191. The lens holder main body 44A that stores the optical elements in the interchangeable optical unit 190 is configured to rotate along the inside of the housing 44 of the interchangeable optical unit 190 via bearings. When attaching the interchangeable optical unit 190 to the main body portion 191, the joint cap 44C is engaged with the connecting member 49B, and the interchangeable optical unit 190 is inserted while being turned in one direction. When removing the interchangeable optical unit 190 from the main body portion 191, the interchangeable optical unit 190 is pulled out while being turned in the opposite direction to when it was attached. The interchangeable optical unit 190 is 4 cm long, 8.5 cm high, and 6 cm wide, and weighs 200 to 300 g when including one wedge prism.

[0184] As described above, according to each embodiment of the present invention, by scanning the laser irradiation point on the surface of a structure, it is possible to efficiently remove paint films in a short time. Furthermore, the focal position can be appropriately set using the extension mechanism of the attachment, etc., so that the irradiation energy, spot diameter, etc. can be selected according to the surface condition. Unlike conventional blasting methods, the present invention does not involve physical contact with the surface and uses a quiet laser, so there is little noise impact on the surrounding environment. Furthermore, according to one aspect of the present invention, by employing various attachments, it is possible to remove paint films and deposits from intricate areas, around protrusions, narrow areas, inside pipes, etc., which were difficult to treat using conventional methods.

[0185] Although the first to ninth embodiments have been described, the scope of application of the present invention is not limited to each of the embodiments. For example, a plurality of embodiments can be combined, and partial configurations of each embodiment (such as the attachment, the shielding member, the suction means, the scanning optical system, the laser pointer and its irradiation hole, and the configuration of the supply port of the gas supply means) can be combined with each other. [Explanation of symbols]

[0186] 1. Laser oscillator 2 Fiber 3 laser heads 4. Scanning optical system 5 Attachments 7 Sensors 9 Suction source 11 Gas supply source 20 surface 30 Laser Light 31 Suction means 32 Cabinet 33 Suction port 34 Gas spraying means 35 Control Unit 36 Operation section 38 Shielding material 100 vehicles

Claims

1. A method for removing deposits on a surface of a structure by irradiating a circular laser beam from a laser irradiation device that focuses a laser beam output from a laser oscillator and irradiates the surface of the structure in accordance with the inner diameter of a pipe, the method comprising: The laser irradiation device is moved forward of the tip of the laser irradiation device, and the laser light is irradiated so that the irradiation direction of the laser light is directed rearward of the tip of the laser irradiation device, so that the irradiation point of the laser light can be rotated on the surface of the structure. A method for removing deposits.

2. The laser irradiation device scans the surface of the structure in a predetermined direction while rotating the laser irradiation device so that the irradiation point of the focused laser light follows a substantially circular locus with a substantially constant radius.

2. The method for removing deposits according to claim 1.

3. The laser irradiation device includes a deflection means for deflecting the focused laser beam at a predetermined angle with respect to the optical axis, and the deflection means rotates the focused laser beam around the optical axis, thereby causing the irradiation point of the focused laser beam to rotate on the surface of the structure.

3. The method for removing deposits according to claim 1 or 2.

4. The method for removing adhesions according to any one of claims 1 to 3, characterized in that the laser irradiation device is moved relative to the structure so that the irradiation point of the laser light on the surface of the structure describes a circular locus with a radius of 5 to 200 mm.

5. A method for removing deposits on a surface of a structure by irradiating a circular laser beam from a laser irradiation device that focuses a laser beam output from a laser oscillator and irradiates the surface of the structure in accordance with the inner diameter of a pipe, the method comprising: the laser irradiation device comprises a first deflection means for deflecting the focused laser beam at a predetermined angle with respect to an optical axis of the focused laser beam, and a second deflection means for deflecting the laser beam deflected by the first deflection means at a predetermined angle; The laser irradiation device is moved forward of the tip of the laser irradiation device, and the laser light is irradiated so that the irradiation direction of the laser light is directed rearward of the tip of the laser irradiation device, so that the irradiation point of the laser light can be rotated on the surface of the structure. A method for removing deposits.

6. The laser irradiation device includes a laser head, The laser head is provided with the laser oscillator, an optical system that focuses the laser light output from the laser oscillator and irradiates it onto the surface of the structure, a shielding member that protects the optical system from material removed from the surface of the structure, and an exit port that is provided in the shielding member and opens into the optical path of the laser light that is irradiated onto the surface of the structure.

6. The method for removing deposits according to claim 1.

7. 7. The method for removing deposits according to claim 1, wherein the deposits on the surface of the structure are removed by moving the laser irradiation device linearly relative to the surface of the structure.

8. The method for removing adhesions according to any one of claims 1 to 7, characterized in that the surface of the structure is brought closer to the laser irradiation device by 5 to 25 mm than the focal position of the laser light, and a distance is maintained.

9. 9. The method for removing deposits according to claim 1, wherein the wavelength of the laser light is 500 nm or more.

10. 10. The method for removing deposits according to claim 1, wherein the removed matter resulting from the irradiation point of the laser light is sucked behind the tip of the laser irradiation device.

11. A method for removing adhesions according to any one of claims 1 to 9, characterized in that it comprises a suction means that is provided behind the tip of the laser irradiation device and is mounted on a moving means that moves the laser irradiation device within the surface of the structure.

12. A deposit removal device that removes deposits on the surface of a structure by irradiating a circular laser beam from a laser irradiation device that focuses a laser beam output from a laser oscillator and irradiates the surface of the structure in accordance with the inner diameter of a pipe, The laser irradiation device is moved forward of the tip of the laser irradiation device, and the laser light is irradiated so that the irradiation direction of the laser light is directed rearward of the tip of the laser irradiation device, so that the irradiation point of the laser light can be rotated on the surface of the structure. A deposit removal device characterized by:

13. The laser irradiation device includes an optical system that rotates and scans the focused laser light in a predetermined direction so that the irradiation point of the focused laser light follows a substantially circular locus with a substantially constant radius on the surface of the structure.

13. The deposit removal device according to claim 12.

14. The optical system includes a deflection means for deflecting the focused laser beam at a predetermined angle with respect to the optical axis, and the deflection means rotates the focused laser beam around the optical axis, thereby causing the irradiation point of the focused laser beam to rotate on the surface of the structure.

14. The deposit removal device according to claim 13.

15. The deposition removal device according to any one of claims 12 to 14, characterized in that the laser irradiation device is moved relative to the structure so that the irradiation point of the laser light on the surface of the structure describes a circular locus with a radius of 5 to 200 mm.

16. A deposit removal device that removes deposits on the surface of a structure by irradiating a circular laser beam from a laser irradiation device that focuses a laser beam output from a laser oscillator and irradiates the surface of the structure in accordance with the inner diameter of a pipe, the laser irradiation device comprises an optical system including a first deflection means for deflecting the focused laser beam at a predetermined angle with respect to an optical axis of the focused laser beam, and a second deflection means for deflecting the laser beam deflected by the first deflection means at a predetermined angle; The laser irradiation device is moved forward of the tip of the laser irradiation device, and the laser light is irradiated so that the irradiation direction of the laser light is directed rearward of the tip of the laser irradiation device, so that the irradiation point of the laser light can be rotated on the surface of the structure. A deposit removal device characterized by:

17. The laser irradiation device includes a laser head, The laser head is provided with the laser oscillator, an optical system that focuses the laser light output from the laser oscillator and irradiates it onto the surface of the structure, a shielding member that protects the optical system from material removed from the surface of the structure, and an exit port that is provided in the shielding member and opens into the optical path of the laser light that is irradiated onto the surface of the structure.

17. The deposit removal device according to claim 12.

18. 18. The deposit removal device according to claim 17, wherein the laser head is provided with an attachment that abuts against the surface of the structure and maintains a substantially constant distance between the laser head and the surface of the structure.

19. 19. The deposit removal device according to claim 18, wherein the attachment has an inner wall on the surface side of the structure, and the laser light irradiated onto the inner wall from the laser head is reflected toward the surface side of the structure.

20. 20. The deposit removal device according to claim 12, wherein the deposit on the surface of the structure is removed by moving the laser irradiation device linearly relative to the surface of the structure.

21. The laser irradiation device includes a laser head, The laser head includes a head body that houses the laser oscillator and a driving means that rotates and drives the optical system; an exchangeable optical unit that can be connected to the head body, that houses at least a part of the optical system, and that has an exit port for the laser light that is irradiated from the optical system; 20. The deposit removal device according to claim 13, further comprising:

22. 22. The deposit removal device according to claim 12, wherein the wavelength of the laser light is 500 nm or more.

23. 23. The deposit removal device according to claim 12, wherein the removed matter produced from the irradiation point of the laser light is sucked behind the tip of the laser irradiation device.

24. 23. The deposition removal device according to claim 12, further comprising a suction means mounted on a moving means for moving the laser irradiation device within the surface of the structure, the suction means being disposed rearward of the tip of the laser irradiation device.

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