Laser Irradiation System

Abstract

To provide a laser irradiation system excellent in rectilinear propagation performance or condensation performance of a laser beam.SOLUTION: A laser irradiation system is provided with: a laser irradiation device 1 provided with a laser irradiation part 12 for emitting a laser beam Lb; a structure 4 on which the laser irradiation part 12 is attached so as to project from a surface 41; and a temperature difference suppression mechanism for reducing temperature differences between an air temperature near the structure 4 and an air temperature in an area along an irradiation line of the laser beam Lb on the structure 4. The temperature difference suppression mechanism can also serve as a convection suppression mechanism that suppresses generation of upward flow Ud toward the irradiation line of the laser beam Lb from the structure 4. The convection suppression mechanism is, for example, an air blow device 55 for generating an air flow FL along the surface 41.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present disclosure relates to a laser irradiation system including a laser irradiation device that emits a laser beam. [Background technology]

[0002] Patent Document 1 discloses a laser irradiation device including a light source, a laser irradiation unit, and an optical system that guides a laser from the light source to the laser irradiation unit. The laser irradiation device is installed on a structure such as a building or a mobile object on the ground. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6654028 Summary of the Invention [Problem to be solved by the invention]

[0004] In a laser irradiation system equipped with a laser irradiation device, it is desirable to eliminate as many factors as possible that hinder the straightness or focusing of the laser beam in order to improve the accuracy of target irradiation. For example, the temperature distribution of the atmosphere along the laser beam's ray affects the straightness or focusing of the laser beam.

[0005] An object of the present disclosure is to provide a laser irradiation system that has excellent straightness and focusing properties of a laser beam. [Means for solving the problem]

[0006] A laser irradiation system according to one aspect of the present disclosure includes a laser irradiation device having a laser irradiation unit that emits a laser beam, a structure to which the laser irradiation device is attached so that the laser irradiation unit protrudes, and a temperature difference suppression mechanism that reduces the temperature difference between the air temperature in the vicinity of the structure and the air temperature in a region on the structure along the ray of the laser beam. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a laser irradiation system that has excellent straightness and focusing properties of a laser beam. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a side view showing a simplified laser irradiation system including a laser irradiation device installed on a ground structure. [Figure 2] FIG. 2 is a side view of the laser irradiation device. [Figure 3] FIG. 3 is a perspective view of the laser irradiation device. [Figure 4] FIG. 4 is a schematic diagram for explaining factors that affect the straightness and focusing of a laser beam. [Figure 5] FIG. 5 is a side view showing the laser irradiation system according to the first embodiment of the present disclosure. [Figure 6] FIG. 6 is a side view showing another example of the first embodiment. [Figure 7A] FIG. 7A is a side view of the laser irradiation system according to the second embodiment, and is a cross-sectional view taken along line VIIA-VIIA of FIG. 7B. [Figure 7B] FIG. 7B is a top view of the laser irradiation system according to the second embodiment. [Figure 8] FIG. 8 is a cross-sectional side view of the laser irradiation system according to another example of the second embodiment. [Figure 9] FIG. 9 is a side view showing a laser irradiation system according to the third embodiment. [Figure 10] FIG. 10 is a side view showing an example in which the laser irradiation system of the present disclosure is mounted on a moving body. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of a laser irradiation system according to the present disclosure will be described in detail with reference to the drawings. The laser irradiation system according to the present disclosure is a laser system for irradiating a target with a high-power laser to neutralize the target or for transmitting energy to the target. The target of the system is, for example, a flying or vehicular harmful object. The harmful object may be, for example, a flying or vehicular harmful bird or animal. The target may also be an air vehicle or aerial vehicle, such as an aircraft having a propulsion system and fixed wings, or an aircraft having single or multiple rotors. The target air vehicle or aerial vehicle may be an aircraft, including an unmanned aerial vehicle.

[0010] [System Configuration] 1 is a side view schematically illustrating the configuration of a laser irradiation system S according to an embodiment of the present disclosure. The laser irradiation system S includes a laser irradiation device 1 installed on a structure 4 on the ground. The laser irradiation device 1 is equipped on the structure 4. The structure 4 is a building fixed to the ground G. The structure 4 has a surface 41 facing upward, and the laser irradiation device 1 is attached to the structure 4 so that a portion of the laser irradiation device 1 protrudes from the surface 41.

[0011] The laser irradiation device 1 includes a laser oscillator 11, a laser irradiation unit 12, and a support mechanism 13. The laser oscillator 11 is a light source that generates a laser beam Lb. The laser irradiation unit 12 emits the laser beam Lb to the outside. The laser irradiation unit 12 irradiates the laser beam Lb oscillated by the laser oscillator 11 while guiding the laser beam Lb in a desired direction. The support mechanism 13 is a mechanism that supports the laser irradiation unit 12 so that it can rotate and tilt.

[0012] The laser oscillator 11 is installed inside the structure 4. Meanwhile, the laser irradiation unit 12, which emits the laser beam Lb to the outside, is attached to the structure 4 via a support mechanism 13 so as to protrude from the surface 41 of the structure 4. FIG. 1 shows the state in which the laser irradiation unit 12 is oriented in the X-axis direction, which is the left direction on the page, and the laser beam Lb is emitted in the X-axis direction. Because the laser irradiation unit 12 can rotate and tilt as described above, the X-axis direction changes depending on the orientation of the laser irradiation unit 12. The surface 41 of the structure 4 is a surface that extends along a line obtained by projecting the ray of the laser beam Lb onto a horizontal plane. Because the laser irradiation unit 12 can rotate using the support mechanism 13, the surface 41 of the structure 4 also changes depending on the direction of the ray of the laser beam Lb. In the embodiment of the present disclosure, for the sake of convenience in the following description, the direction in which the laser beam is emitted is defined as the X-axis direction, the extension direction of the tilt axis 33a of the support mechanism 13 (described later) as the Y-axis direction, and the extension direction of the rotation axis 31a of the support mechanism 13 as the Z-axis direction. In addition, the direction of the line obtained by projecting the ray of the laser beam Lb onto a horizontal plane is defined as the ray direction.

[0013] The laser beam Lb generated by the laser oscillator 11 can be of any type as long as it is a high-power laser beam, but an iodine laser or a fiber laser is suitable. An iodine laser is a type of gas laser generated by a chemical reaction between excited oxygen and iodine. When an iodine laser is used, the laser oscillator 11 is, for example, a device including an excited oxygen generator that generates excited oxygen, an iodine supplying device that supplies iodine that reacts with the excited oxygen generated by the excited oxygen generator, and a laser resonator that generates laser oscillation through a chemical reaction between the excited oxygen and iodine. A fiber laser is a type of electrically driven laser that generates laser oscillation using an optical fiber doped with a laser-active element and has advantages such as high-efficiency oscillation and high beam quality. When a fiber laser is used, the laser oscillator 11 is, for example, a device including a semiconductor laser as an excitation light source, a coupler that couples the semiconductor laser light to an optical fiber doped with an active element that serves as a medium, and a laser resonator that extracts laser light from the optical fiber in a state excited by the semiconductor laser.

[0014] 2 and 3 are a side view and a perspective view showing the details of the laser irradiation unit 12 and the support mechanism 13. Laser irradiation part The laser irradiation unit 12 includes a housing 21, an optical module 22, an irradiation window 23, a tracking camera 24, and a photographing window 25.

[0015] The housing 21 is a roughly rectangular cylindrical housing that houses the optical module 22 and the tracking camera 24. The optical module 22 is a group of optical components that condense and direct the laser beam Lb output from the laser oscillator 11 in a desired direction, and is composed of optical elements including transmissive and reflective optical elements. Examples of transmissive optical elements include a condensing lens or a refractive lens, and examples of reflective optical elements include a concave mirror or a convex mirror. The irradiation window 23 is a transparent member made of a glass plate or the like that can transmit the laser beam Lb output from the optical module 22. The irradiation window 23 is attached to the front end surface 21a of the housing 21, which is the exit of the laser beam Lb. The tracking camera 24 is an imaging device that photographs a target to capture and track the target. The imaging window 25 is a transparent member made of a glass plate or the like that is attached to the front end surface 21a of the housing 21 to capture an image into the tracking camera 24.

[0016] The laser irradiation unit 12 irradiates a laser beam from an optical module 22 through an irradiation window 23 while being attitude-controlled so as to point at a target captured by a tracking camera 24 .

[0017] The irradiation window 23 and the imaging window 25 are airtightly attached to the front end surface 21a of the housing 21. In other words, the inside of the housing 21 is sealed. A dry gas is sealed inside this sealed housing 21. The dry gas fills the inside of the housing 21 and removes air, thereby reducing the amount of water vapor and impurities remaining inside the housing 21. This prevents water vapor from absorbing the laser beam Lb passing through the housing 21, and ultimately prevents the refractive index of the laser beam Lb from changing due to a temperature rise associated with the absorption.

[0018] The support mechanism 13 is a so-called two-axis gimbal mechanism. The laser irradiation unit 12 supported by the support mechanism 13 can rotate as indicated by arrow A1 and tilt as indicated by arrow A2 in Figures 2 and 3. In this embodiment, the rotation indicated by arrow A1 is rotation around the Z-axis parallel to the vertical axis, which is the up-and-down direction of the structure 4. In this embodiment, the tilt indicated by arrow A2 is rotation around the Y-axis perpendicular to the Z-axis. The rotation indicated by arrow A1 is achieved by operation of a Z-axis motor provided in the support mechanism 13, and the tilt indicated by arrow A2 is achieved by operation of a Y-axis motor provided in the support mechanism 13.

[0019] Specifically, the support mechanism 13 includes a base 31, a rotating body 32, and a pair of support legs 33 that support the laser irradiation unit 12 from both sides in the Y-axis direction. The base 31 is a disk-shaped platform fixed to the surface 41 of the structure 4. The rotating body 32 is a disk-shaped rotating body disposed on the base 31. The rotating body 32 is pivotally supported on the base 31 via a pivot 31a extending in the Z-axis direction. The pair of support legs 33 are members that protrude upward in the Z-axis direction from the rotating body 32, and are disposed so as to sandwich the laser irradiation unit 12 from both sides. Each support leg 33 pivotally supports the laser irradiation unit 12 via a tilting shaft 33a extending in the Y-axis direction.

[0020] In response to the rotation of the rotating body 32, the laser irradiation unit 12 rotates around the Z axis together with the support leg 33. Furthermore, the tilting operation causes the laser irradiation unit 12 to rotate around the Y axis relative to the support leg 33. The laser irradiation unit 12 is supported by the support mechanism 13 in a state in which it can rotate and tilt in this way, so that the front end surface 21a, on which the irradiation window 23 and the photographing window 25 are arranged, can be directed in all directions.

[0021] The laser irradiation unit 12 and the laser oscillator 11 are connected via an optical path 18 simply shown in FIG. 3. The optical path 18 is a path for introducing the laser beam Lb oscillated from the laser oscillator 11 into the optical module 22 inside the laser irradiation unit 12. When irradiating the target with the laser beam Lb, the laser beam Lb is introduced from the laser oscillator 11 into the optical module 22 through the optical path 18. The laser beam Lb introduced into the optical module 22 is led out to the outside through the irradiation window 23.

[0022] [Factors inhibiting the propagation of the laser beam] FIG. 4 is a schematic diagram for explaining the influencing factors on the straightness and condensing property of the laser beam Lb. The straightness and condensing property of the laser beam Lb deteriorate due to wandering caused by atmospheric fluctuations on the propagation path after being led out of the laser irradiation device 1 and wavefront distortion within the beam cross-section. The atmospheric fluctuations are mainly caused by convection generated based on the air temperature difference between the propagation path of the laser beam Lb and its surrounding area. As shown in FIG. 4, among the surfaces 41 of the structure 4, let the air temperature in the vicinity area AR1 of the structure near the propagation path of the laser beam Lb be T1, and the air temperature in the laser ray area AR2, which is the area along the ray of the laser beam Lb on the surface 41, be T2. If T1 = T2, or T1 ≒ T2, no significant convection will occur.

[0023] On the contrary, when there is a temperature distribution of air temperature such as T1 > T2 or T1 < T2, air convection occurs. For example, when the surface 41 of the structure 4 is heated by solar heat and a state of T1 > T2 is formed, an upward airflow from the surface 41 towards the ray of the laser beam Lb is generated. In the initial stage when convection such as an upward airflow occurs, as schematically shown in FIG. 4, large turbulent flows Tu1 and Tu2, which are masses of turbulent flows with different air densities, are generated, and these break up to generate small turbulent flows Tu3 and Tu4. Finally, a state where the large turbulent flows Tu1 and Tu2 and the small turbulent flows Tu3 and Tu4 are mixed occurs. In FIG. 4, for ease of understanding, the large turbulent flows Tu1 and Tu2 and the small turbulent flows Tu3 and Tu4 are described separately.

[0024] The large turbulences Tu1 and Tu2 are turbulence units larger in scale than the cross section of the laser beam Lb, and each can be treated as a single temperature distribution unit. The small turbulences Tu3 and Tu4 are turbulence units smaller in scale than the cross section of the laser beam Lb, and each can be treated as a single temperature distribution unit. The large turbulence Tu1, which has a certain air density, and the large turbulence Tu2, which has a different air density, exhibit different refractive indices. Therefore, when the laser beam Lb passes through an area where the large turbulences Tu1 and Tu2 are occurring, the laser beam Lb is refracted at the boundary between the large turbulences Tu1 and Tu2. This causes the entire laser beam Lb to wander. When wandering occurs, the straightness of the laser beam Lb deteriorates.

[0025] On the other hand, when the laser beam Lb passes through an area where small turbulences Tu3 and Tu4 are occurring, collisions with these small turbulences Tu3 and Tu4 cause wavefront distortion of the traveling laser wave in the beam cross section. This wavefront distortion generates beam components traveling in various directions, making it difficult to focus the laser beam Lb to a single point even with an optical lens. Naturally, this also deteriorates the focusing ability of the laser beam Lb. From the above perspective, in order to suppress atmospheric fluctuations that cause wandering and wavefront distortion in the beam cross section, it is preferable that the laser irradiation system S be equipped with a structure that minimizes the air temperature difference |T1-T2|. Various embodiments of a temperature difference suppression mechanism that reduces the temperature difference between the air temperatures T1 and T2 are exemplified below.

[0026] [First embodiment] In the first embodiment, an example is shown in which the temperature difference suppression mechanism is made of a heat input suppression layer that suppresses heat input due to sunlight to the surface 41 of the structure 4. Fig. 5 is a side view showing a laser irradiation system S1 equipped with an example of the heat input suppression layer. The laser irradiation system S1 is equipped with an infrared reflective paint 51 applied to the surface 41 of the structure 4 as the heat input suppression layer. The infrared reflective paint 51 reflects infrared rays, which are a heating component contained in sunlight, and serves to suppress a temperature rise in the surface 41.

[0027] The surface 41 is a surface exposed to the atmosphere around the laser irradiation unit 12. When the surface 41 acquires a temperature different from that of the atmosphere, it is within a range that generates significant air convection in the region along the ray direction of the laser beam Lb. In this embodiment, the laser irradiation unit 12 is rotatable around the Z axis, so the range of the surface 41 also changes with changes in the X-axis direction along which the laser beam Lb is emitted. In other words, there are multiple possible ray directions of the laser beam Lb. The surface 41 can be set based on one of the possible ray directions of the laser beam Lb, or based on multiple or all of the possible ray directions. While FIG. 5 shows an example in which the surface 41 is a simple flat surface, surfaces consisting of inclined surfaces, curved surfaces, uneven surfaces, etc., also fall within the category of the surface 41 as long as they satisfy the above-mentioned conditions. The definition of the surface 41 here also applies to the embodiments described below.

[0028] In this embodiment, the infrared reflective paint 51 is applied to at least a region of the surface 41 located below the laser beam Lb in the Z-axis direction. When the laser irradiation unit 12 rotates 360 degrees, the infrared reflective paint 51 is applied to the entire surface 41. However, even when the laser irradiation unit 12 can only rotate 360 degrees or less, it is desirable to provide a coating of the infrared reflective paint 51 on the entire surface 41. This is because even if the area directly below the laser beam Lb's radiation line is covered with the infrared reflective paint 51, the uncoated portion of the surface 41 may become heated and generate an updraft directly below the radiation line. The infrared reflective paint 51 can be, for example, a general-purpose paint containing infrared-reflective pigments or ceramic chips mixed with a binder resin. The infrared reflective paint 51 may also have heat insulation properties in addition to its infrared reflection properties. This heat insulation properties further suppress temperature rise of the surface 41.

[0029] FIG. 6 is a side view showing a laser irradiation system S2 equipped with another example of the heat input suppression layer. The laser irradiation system S2 includes, as the heat input suppression layer, a plurality of infrared reflective plates 52 laid on the surface 41 of the structure 4. In this embodiment, the infrared reflective plates 52 are rectangular flat plates capable of reflecting infrared rays. However, the shape of the infrared reflective plates 52 can be appropriately changed depending on the shape of the surface 41. Examples of the infrared reflective plates 52 that can be used include plates made of an infrared reflective material and plates with an infrared reflective paint applied to the surface of a base plate. The multiple infrared reflective plates 52 are densely packed on the surface 41 to prevent the surface 41 from heating up due to solar heat irradiation. As with the infrared reflective paint 51, it is desirable to lay the infrared reflective plates 52 over the entire surface of the surface 41.

[0030] Note that the present disclosure also encompasses the use of a solar cell panel as the infrared reflecting plate 52. Commercially available solar cell panels not only have the inherent photoelectric conversion function but also have a corresponding infrared reflecting function. Therefore, by installing a solar cell panel on the surface 41 of the structure 4, it is possible to suppress the temperature rise of the surface 41. Another advantage is that the power generated by the solar cell panel can be used as a power source for various electrical devices equipped in the structure 4, such as lighting equipment, air conditioning equipment, or batteries that are ancillary devices for the laser irradiation device 1.

[0031] According to the first embodiment described above, the formation of a heat input suppression layer such as the infrared reflective paint 51 or the infrared reflective plate 52 suppresses the input of solar heat to the surface 41 of the structure 4. This makes it possible to suppress the occurrence of convection due to the air temperature distribution on the propagation path of the laser beam Lb immediately after it is emitted from the laser irradiation unit 12. This makes it possible to provide laser irradiation systems S1 and S2 that can maintain the linearity and focusing ability of the laser beam Lb even under conditions where the surface 41 of the structure 4 is exposed to sunlight.

[0032] [Second embodiment] In the second embodiment, an example is shown in which the temperature difference suppression mechanism is composed of a cooling mechanism or a heating mechanism for the structure 4. Fig. 7A is a cross-sectional view of a laser irradiation system S3 equipped with an example of the cooling mechanism as seen from the Y-axis direction, and Fig. 7B is a top view of the laser irradiation system S3. Fig. 7A is a cross-sectional view taken along line VIIA-VIIA of Fig. 7B. The laser irradiation system S3 is equipped with a cooling pipe 53 arranged inside near the surface 41 of the structure 4 as the cooling mechanism. By cooling the structure 4, the cooling pipe 53 prevents the temperature of the surface 41 of the structure 4 from increasing even if solar heat is input to the surface 41 of the structure 4, thereby suppressing thermal radiation into the atmosphere.

[0033] The cooling pipe 53 is a pipe for circulating a refrigerant. The refrigerant is any liquid or gas capable of heat exchange, such as water. The cooling pipe 53 is arranged near the bottom of the surface 41 so as to be able to cool substantially the entire surface 41. The cooling pipe 53 has an inlet pipe 531 at one end serving as an inlet for the refrigerant and an outlet pipe 532 at the other end serving as an outlet for the refrigerant. The refrigerant introduced from the inlet pipe 531 exchanges heat with the structure 4 while flowing through the cooling pipe 53, cooling the structure 4, and is then discharged from the outlet pipe 532. In this embodiment, the cooling pipe 53 is serpentine, i.e., the inlet pipe 531 is located at the top right and runs leftward to approximately the left end of the structure 4. When the cooling pipe 53 reaches approximately the left end of the structure 4, the pipe changes direction 180 degrees and runs rightward to approximately the right end. Thereafter, the cooling pipe 53 is arranged so that the direction of the pipe changes 180 degrees each time it reaches approximately the right or left end of the structure 4 or the periphery of the laser irradiation device 1, and is arranged so as to cover approximately the entire surface 41 of the structure 4, and finally returns to the outlet pipe 532 on the upper right side arranged around the inlet pipe 531. However, the positions of the inlet pipe 531 and the outlet pipe 532 and the path arrangement of the cooling pipe 53 are arbitrary, as long as the pipe is arranged so that approximately the entire surface 41 of the structure 4 can be cooled. Alternatively, the surface 41 may be divided into multiple areas, and the cooling pipes 53 may be arranged so that each of the multiple areas can be cooled individually. In this case, it is possible to selectively cool an area below the irradiation direction of the laser beam Lb.

[0034] The inlet pipe 531 and the outlet pipe 532 are connected by a circulation pipe 533. A pump 534 and a chiller 535 are incorporated in the circulation pipe 533. The pump 534 pumps the refrigerant and circulates the refrigerant in the cooling pipe 53 and the circulation pipe 533 that form a circulation path. The chiller 535 cools the refrigerant that has exchanged heat with the structure 4 and is led out from the outlet pipe 532 with heat to a required temperature. The refrigerant returned to the appropriate temperature by the chiller 535 is introduced into the inlet pipe 531 again. Thus, the structure 4 that can be heated by solar heat or the like can be cooled by the flow of the refrigerant in the cooling pipe 53. In the present embodiment, the refrigerant of the cooling mechanism is also cooled using the chiller 535 for cooling the laser irradiation device 1, but a separate chiller for cooling the refrigerant of the cooling mechanism may be provided.

[0035] The cooling mechanism is an example of a temperature difference suppression mechanism when solar heat is input to the surface 41 of the structure 4 and T1>T2. However, the surface 41 of the structure 4 may be lower in temperature than the atmosphere by, for example, radiative cooling, and an air temperature difference of T1<T2 may occur and convection may occur. In this case, the cooling pipe 53 may be treated as a heating pipe and a heating medium such as hot water may be circulated through the heating pipe. Alternatively, the configuration may be such that the refrigerant flow system and the heating medium flow system can be switched and connected to the cooling pipe 53. Further, a temperature measuring device for measuring the temperatures of T1 and T2 may be installed on the surface 41 of the structure 4 and on the radiation line of the laser beam Lb. When the temperatures of T1 and T2 are measured and T1>T2 cooling when T1<T2 heating As such, the cooling and heating of the surface 41 of the structure 4 may be switched based on the measured T1 and T2.

[0036] FIG. 8 is a cross-sectional view of a laser irradiation system S4 according to another example of the second embodiment, as viewed from the Y-axis direction. The laser irradiation system S4 includes a cooling mechanism for directly exchanging heat between the surface 41 of the structure 4 and the coolant W. Specifically, the laser irradiation system S4 includes a spray nozzle 54 for discharging the coolant W as the heat exchange mechanism. The coolant W is any liquid capable of exchanging heat with the surface 41 of the structure 4, such as water. The coolant W discharged from the spray nozzle 54 directly cools the surface 41 through heat exchange with the surface 41. This allows the surface 41 to be cooled even if solar heat is input to the surface 41, thereby suppressing heat radiation into the atmosphere. The spray nozzle 54 may be a type that sprays the coolant W in a fountain-like manner or a type that sprays the coolant W in a mist-like manner. Alternatively, a perforated pipe with multiple spray holes may be used instead of the spray nozzle 54. The spray nozzle 54 or the perforated pipe is disposed at least in a region of the surface 41 that is located below the direction of the laser beam Lb. When the laser irradiation unit 12 rotates 360 degrees, the spray nozzle 54 or the perforated pipe is disposed over the entire surface 41.

[0037] A plurality of spray nozzles 54 are attached to the structure 4 at a predetermined pitch so as to protrude slightly from the surface 41. The laser irradiation system S4 further includes a spray pipe 541 and a manifold unit 542. The spray pipe 541 supplies the coolant W from a supply source of the coolant W to the spray nozzles 54. The manifold unit 542 distributes the coolant W supplied from the spray pipe 541 to the plurality of spray nozzles 54 at uniform pressure. The spray pipe 541 incorporates a pump 543 that pressurizes the coolant W and a liquid temperature regulator 544 that adjusts the temperature of the coolant W to a required temperature. The liquid temperature regulator 544 may be configured to be heatable as needed so that the coolant W serves as a heat transfer medium. Alternatively, the coolant W may be configured to be switchable between on and off, so that the coolant W is sprayed only from the spray nozzles 54 located below the irradiation direction of the laser beam Lb.

[0038] According to the second embodiment described above, even if the temperature of the structure 4 becomes higher or lower than the temperature of the propagation path of the laser beam Lb, the structure 4 can be cooled or heated by the cooling mechanism or heating mechanism, such as the cooling pipe 53 or the spray nozzle 54. Therefore, it is possible to suppress the occurrence of convection due to the air temperature distribution on the propagation path of the laser beam Lb immediately after emission, and it is possible to maintain the straightness or focusing of the laser beam Lb.

[0039] [Third embodiment] In the third embodiment, an example is shown in which the temperature difference suppression mechanism is a convection suppression mechanism that suppresses the generation of an air current heading from the structure 4 toward the ray of the laser beam Lb. Fig. 9 is a side view showing a laser irradiation system S5 equipped with an example of the convection suppression mechanism. The laser irradiation system S5 is equipped with an air blowing device 55 as the convection suppression mechanism, which generates an air current FL between the surface 41 of the structure 4 and the ray of the laser beam Lb. The air blowing device 55 blows away the ascending air current Ud heading from the surface 41 toward the ray of the laser beam with the air current FL, thereby suppressing the generation of an air temperature distribution.

[0040] The air blowing device 55 includes a blowing fan and a drive motor for rotating the fan. The air blowing device 55 generates an air flow FL in the direction pointed by the front end surface 21a of the laser irradiation unit 12, i.e., in the same direction as the ray of the laser beam Lb. The air blowing device 55 rotates in sync with the laser irradiation unit 12 so that the air flow FL can be generated along the ray even when the laser irradiation unit 12 rotates. To enable synchronous rotation, the air blowing device 55 is mounted on the rotating body 32 of the support mechanism 13.

[0041] When the surface 41 of the structure 4 is heated by solar heat or the like, and the air temperature near the surface 41 becomes higher than the air temperature on the ray of the laser beam Lb, an updraft Ud is generated as shown in FIG. 9. This updraft Ud creates atmospheric turbulence on the ray of the laser beam Lb. To suppress the occurrence of this atmospheric turbulence, the air blower 55 generates an airflow FL to replace the air on the surface 41. This eliminates or reduces the temperature difference between the air temperature near the surface 41 and the air temperature on the ray of the laser beam Lb. Note that it is desirable that the airflow FL is not a gentle breeze, but a strong wind strong enough to dispel the updraft Ud, for example, a wind speed of about 5 m / s or more.

[0042] The air blowing device 55 may have a function to prevent the air flow FL generated by the air blowing device 55 and the updraft Ud blown away by the air flow FL from affecting the ray of the laser beam Lb. For example, a louver capable of adjusting the direction of the air flow FL is attached to the outlet of the air blowing device 55. By operating the louver, the direction of the air flow FL and the blown updraft Ud can be adjusted so as not to affect the ray of the laser beam Lb.

[0043] 9, a plurality of air blowing devices 55 may be fixedly installed at appropriate positions on the surface 41. Furthermore, instead of the air blowing devices 55, an air suction device that sucks air near the surface 41 may be used. Furthermore, in addition to the air blowing devices 55, the infrared reflective paint 51 or infrared reflective plate 52 of the first embodiment, or the cooling pipe 53 of the second embodiment may be installed on the surface 41 of the structure 4 in a combined manner.

[0044] According to the fourth embodiment described above, the air on the surface 41 of the structure 4 is replaced by the air blowing device 55 or the air suction device, and the temperature difference between the air temperature near the surface 41 and the air temperature on the ray of the laser beam Lb can be eliminated or reduced. Therefore, it is possible to suppress the occurrence of convection due to the air temperature distribution on the propagation path of the laser beam Lb immediately after emission, and it becomes possible to maintain the straightness or focusing of the laser beam Lb.

[0045] [Example of a moving structure] In the above embodiment, an example has been shown in which the structure 4 is a building fixed to the ground G. The laser irradiation system of the present disclosure can also be mounted on a mobile body. FIG. 10 is a side view showing an example in which the laser irradiation system is mounted on a vehicle 40 as the mobile body. The vehicle 40 includes a container 42 loaded on the bed of the vehicle body and a cabin 43 in which the driver rides.

[0046] The laser irradiation device 1 is mounted on a container 42. The laser oscillator 11 of the laser irradiation device 1 is disposed inside the container 42, while the laser irradiation unit 12 is attached so as to protrude upward from the top surface 421 of the container 42. As described above, the laser irradiation unit 12 can be rotated by the support mechanism 13, and emits a laser beam Lb toward the front of the vehicle 40, for example, as illustrated in FIG.

[0047] In the embodiment of FIG. 10, the temperature difference between the air temperature in the area AR3 near the top surface 421 of the container 42 and the area AR4 near the top surface 431 of the cabin 43 and the air temperature in the area along the ray of the laser beam Lb becomes a problem. If the temperature difference becomes large, atmospheric fluctuation occurs, which adversely affects the propagation of the laser beam Lb. Therefore, the measures of the first, second, and third embodiments described above are applied to the top surfaces 421 and 431 to suppress the occurrence of atmospheric fluctuation.

[0048] Specifically, a temperature difference suppression mechanism is installed, such as applying infrared reflective paint 51 (FIG. 5) or laying infrared reflective plates 52 (FIG. 6) on the upper surfaces 421 and 431, disposing cooling pipes 53 directly below the upper surfaces 421 and 431 (FIGS. 7A and 7B), arranging spray nozzles 54 (FIG. 8), or installing an air blower 55 that generates airflow FL along the upper surfaces 421 and 431 (FIG. 9). These temperature difference suppression mechanisms can favorably maintain the linearity and focusing ability of the laser beam Lb emitted by the laser irradiation device 1 mounted on a moving body such as the vehicle 40. Note that, to solve the problems of the present disclosure, each of the temperature difference suppression mechanisms described above may be used alone, or any combination of temperature difference suppression mechanisms may be applied.

[0049] Summary of this disclosure The specific embodiments described above include disclosures having the following configurations.

[0050] A laser irradiation system according to one aspect of the present disclosure includes a laser irradiation device having a laser irradiation unit that emits a laser beam, a structure to which the laser irradiation device is attached so that the laser irradiation unit protrudes, and a temperature difference suppression mechanism that reduces the temperature difference between the air temperature in the vicinity of the structure and the air temperature in a region on the structure along the ray of the laser beam.

[0051] Atmospheric conditions affect the propagation of the laser beam. For example, the complex temperature distribution created in the surrounding atmosphere due to the incidence of solar heat on a structure leads to refractive index disturbances, adversely affecting the straightness and focusing of the laser beam. In particular, if factors that deteriorate the straightness exist near the laser beam's emission point, the impact increases in proportion to the propagation distance. In the above-described laser irradiation system, the temperature difference suppression mechanism suppresses the temperature difference between the air temperature near the structure and the air temperature on the laser beam's path above the structure. In other words, the atmosphere in the area through which the laser beam propagates immediately after being emitted from the laser irradiation unit can be maintained in a state where temperature distribution is unlikely to occur. Therefore, a laser irradiation system can be provided that can maintain high levels of straightness and focusing of the laser beam regardless of weather conditions.

[0052] In the above laser irradiation system, the structure may have a surface extending in the direction of the laser beam, and the temperature difference suppression mechanism may be configured to include a heat input suppression layer that suppresses heat input to the surface.

[0053] According to this laser irradiation system, the formation of the heat input suppression layer suppresses the input of solar heat to the surface of the structure, thereby suppressing the occurrence of air temperature distribution along the propagation path of the laser beam immediately after emission and maintaining the straightness and focusing of the laser beam.

[0054] In the above laser irradiation system, the heat input suppression layer may be configured to be made of an infrared reflective paint applied to the surface, or to be made of an infrared reflective plate laid on the surface.

[0055] These laser irradiation systems can suppress the heat input from sunlight to the surface of a structure using simple methods such as applying infrared-reflective paint or installing infrared-reflective plates.

[0056] Furthermore, it is desirable that the infrared reflective plate is a solar cell panel. This embodiment has the advantage that not only can heat input to the surface of the structure be suppressed, but also that the generated electricity of the solar cell panel can be used as a power source for the electric equipment or the battery attached to the laser irradiation system equipped in the structure.

[0057] In the above laser irradiation system, the temperature difference suppression mechanism may be configured to include a cooling mechanism or a heating mechanism for the structure.

[0058] With this laser irradiation system, even if the structure becomes hotter or colder than the surrounding air, the cooling mechanism or heating mechanism can cool or heat the structure. Therefore, it is possible to suppress the occurrence of air temperature distribution along the propagation path of the laser beam immediately after emission, and it is possible to maintain the straightness and focusing of the laser beam.

[0059] In the laser irradiation system, it is desirable that the cooling mechanism or the heating mechanism comprises a pipe disposed inside the structure and a refrigerant or a heating medium circulating through the pipe. In this configuration, the structure that can be heated can be cooled by circulating the refrigerant through the cooling pipe.

[0060] Alternatively, the structure may have a surface extending in the direction of the laser beam, and the cooling mechanism may be a mechanism for exchanging heat between the surface and a coolant. In this configuration, the surface can be cooled, for example, by flowing cooling water directly onto the surface.

[0061] In the above laser irradiation system, the temperature difference suppression mechanism may be a convection suppression mechanism that suppresses the generation of an air current that flows from the structure toward the ray of the laser beam.

[0062] For example, an updraft, which occurs when the air temperature near the surface of a structure is higher than the air temperature on the laser beam's ray, causes thermal fluctuations in the air and adversely affects the straightness of the laser beam. According to the laser irradiation system described above, the convection suppression mechanism suppresses the air current from the structure toward the laser beam's ray, thereby maintaining the straightness and focusing of the laser beam.

[0063] It is desirable that the structure has a surface extending in the direction of the laser beam's radiation, and that the convection suppression mechanism be an air blowing device that generates an air flow along the space between the surface and the laser beam's radiation. In this configuration, the air flow from the air blowing device can blow away the air flow heading from the surface of the structure toward the laser beam's radiation, thereby making it possible to prevent the occurrence of air temperature distribution.

[0064] In the above laser irradiation system, the structure may be a building fixed on the ground or a mobile body equipped with a laser irradiation device. According to the present disclosure, a laser irradiation system having excellent straightness and focusing properties of a laser beam can be provided, regardless of whether the structure is a building or a mobile body. [Explanation of symbols]

[0065] 1. Laser irradiation device 12 Laser irradiation unit 4 Structures 40 Vehicles (moving structures) 41 Surface 42 containers 421 Top surface (front surface) 43 Cabin 431 Top surface (front surface) 51 Infrared reflective paint (heat input suppression layer) 52 Infrared reflection plate (heat input suppression layer) 53 Cooling piping (cooling mechanism) 54 Spray nozzle (heat exchange mechanism) 55 Air blower (convection suppression mechanism) S1~S5 Laser irradiation system Lb laser beam T1, T2 air temperatures W Coolant FL Air Flow Ud Updraft (air current moving in the direction of the line of fire)

Claims

1. a laser irradiation device including a laser irradiation unit that emits a laser beam; a structure having a surface extending in the direction of the laser beam, and to which the laser irradiation device is attached so that the laser irradiation portion protrudes from the surface; a temperature difference suppression mechanism that reduces a temperature difference between the air temperature in the vicinity of the structure and the air temperature in a region along the ray of the laser beam on the structure; A laser irradiation system comprising:

2. 2. The laser irradiation system according to claim 1, The temperature difference suppression mechanism comprises a heat input suppression layer that suppresses heat input to the surface.

3. 3. The laser irradiation system according to claim 2, The heat input suppression layer is formed of an infrared reflective paint applied to the surface.

4. 3. The laser irradiation system according to claim 2, A laser irradiation system, wherein the heat input suppression layer is an infrared reflective plate laid on the surface.

5. 5. The laser irradiation system according to claim 4, A laser irradiation system, wherein the infrared reflecting plate is a solar panel.

6. 2. The laser irradiation system according to claim 1, A laser irradiation system, wherein the temperature difference suppression mechanism comprises a cooling mechanism or a heating mechanism for the structure.

7. 7. The laser irradiation system according to claim 6, A laser irradiation system, wherein the cooling mechanism or the heating mechanism comprises a pipe disposed inside the structure, and a refrigerant or a heating medium circulating within the pipe.

8. 7. The laser irradiation system according to claim 6, A laser irradiation system, wherein the cooling mechanism or the heating mechanism is a mechanism for heat exchange between the surface and a cooling liquid.

9. 2. The laser irradiation system according to claim 1, The temperature difference suppression mechanism comprises a convection suppression mechanism that suppresses the generation of an air current that flows from the structure toward the line of incidence of the laser beam.

10. 10. The laser irradiation system according to claim 9, The laser irradiation system, wherein the convection suppression mechanism comprises an air blowing device that generates an air flow between the surface and the ray of the laser beam.

11. The laser irradiation system according to any one of claims 1 to 10, A laser irradiation system, wherein the structure is a building fixed on the ground.

12. The laser irradiation system according to any one of claims 1 to 10, A laser irradiation system, wherein the structure is a mobile body equipped with a laser irradiation device.

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