Abstract: A power converter includes first and second arms, each having switching elements, and performs power conversion between a DC system and an AC system. An AC circuit breaker and a current control circuit are connected in series between the AC system and the power converter. The current control circuit includes a current-limiting resistor and a disconnector connected in parallel. A controller instructs a disconnector to close after an initial charge of the power converter and opens the AC circuit breaker when an impedance of a line between a first node located on a first end side of the current control circuit and a second node located on a second end side of the current control circuit is not less than a first threshold and an accumulated value of a current flowing through the current control circuit within a certain period of time is not less than a second threshold.

Abstract: A non-destructive inspection method of inspecting an inspection target using multiple different types of non-destructive inspection means that include one non-destructive inspection means and at least one other non-destructive inspection means. The method includes determining a marking position on the inspection target in a detection result by the one non-destructive inspection means, causing a device to store the marking position, and fixedly forming a mark on the inspection target corresponding to the marking position. The mark is detectable by the other non-destructive inspection means. The method further includes causing the other non-destructive inspection means to inspect an inspection target including the mark. The method further includes contrasting detection results by the multiple different types of non-destructive inspection means in reference to the mark which is the marking position.

Abstract: A non-destructive inspection method of inspecting an inspection target using multiple different types of non-destructive inspection means that include one non-destructive inspection means and at least one other non-destructive inspection means. The method includes determining a marking position on the inspection target in a detection result by the one non-destructive inspection means, causing a device to store the marking position, and fixedly forming a mark on the inspection target corresponding to the marking position. The mark is detectable by the other non-destructive inspection means. The method further includes causing the other non-destructive inspection means to inspect an inspection target including the mark. The method further includes contrasting detection results by the multiple different types of non-destructive inspection means in reference to the mark which is the marking position.

Abstract: A non-destructive inspection method for inspecting an object to be inspected using a plurality of different types of non-destructive inspection means is shown. The method includes the following, fixedly forming common marks that can be detected by any of the plurality of non-destructive inspection means on the object to be inspected; then detecting the object to be inspected including the marks by the plurality of non-destructive inspection means respectively; and comparing the detection results by the plurality of non-destructive inspection means using the marks as positional references.

Abstract: Disclosed is a light spot forming element which is capable of forming a minute stabilized light spot efficiently and is easy to handle. For this purpose, there is provided a light spot forming element wherein a laser oscillation unit which has a periodic refractive index distribution and is employed as a laser resonator, and a focusing unit that receives the light emitted by this laser oscillation unit and forms a light spot by focusing this received light are formed on the same substrate.

Abstract: Disclosed is an optical recording head which is provided with a surface emitting laser that emits laser light which is efficiently introduced into a waveguide through a grating coupler (diffraction grating). Specifically disclosed is an optical recording head which is provided with a surface emitting laser comprising at least a light source, and a waveguide that is connected thereto through a diffraction grating and irradiates a recording medium with the light from the light source. The light source has a two-dimensional photonic crystal structure in the surface that faces the waveguide. Regions of the two-dimensional photonic crystal structure other than the region facing the diffraction grating are converted, and the region facing the diffraction grating serves as a surface emitting.

Abstract: An object of the present invention is to provide a three-dimensional photonic crystal which allows an internal formation of a defect structure with an arbitrary shape and size. Multiple holes extending to two different directions are formed obliquely to a base body surface in order to form a first crystal and a second crystal. Base body left between the holes are made to be rods. Moreover, a connection crystal layer is formed by a part of rods having a size different from that of the rods in the first crystal and the second crystal. The connection crystal layer is held between the first crystal and the second crystal and they are fused. In a three-dimensional photonic crystal thus obtained, the rod becomes a point defect. The shape and size of the point defect can be arbitrarily set in any directions within the connection crystal layer. The shape and size of the point defect can also be controlled by adjusting the thickness of the connection crystal layer.

Abstract: One objective of the present invention is to provide a laser device which is capable of scanning beams of a laser light of high output power at a high speed without using mechanical scanning mechanisms. A plurality of the upper electrodes 33 is linearly arranged in the photonic crystal laser provided with an active layer 21 and a two-dimensional photonic crystal layer 23 which are held between upper electrodes 33 and a lower electrode 27. A current is introduced from one upper electrode 33 or the plurality of the upper electrodes 33 disposed adjacently. Therefore, the active layer 21 generates light and the light is intensified by diffraction in the two-dimensional photonic crystal layer 23, so that a stronger laser light is emitted to the outside from around the upper electrodes 33 into which a current is introduced. When the current-injected upper electrodes are sequentially switched, a laser light scan is performed in the direction of the array of the upper electrodes.

Abstract: One objective of the present invention is to provide a laser device which is capable of scanning beams of a laser light of high output power at a high speed without using mechanical scanning mechanisms. A plurality of the upper electrodes 33 is linearly arranged in the photonic crystal laser provided with an active layer 21 and a two-dimensional photonic crystal layer 23 which are held between upper electrodes 33 and a lower electrode 27. A current is introduced from one upper electrode 33 or the plurality of the upper electrodes 33 disposed adjacently. Therefore, the active layer 21 generates light and the light is intensified by diffraction in the two-dimensional photonic crystal layer 23, so that a stronger laser light is emitted to the outside from around the upper electrodes 33 into which a current is introduced. When the current-injected upper electrodes are sequentially switched, a laser light scan is performed in the direction of the array of the upper electrodes.

Abstract: An object of the present invention is to provide a three-dimensional photonic crystal which allows an internal formation of a defect structure with an arbitrary shape and size. Multiple holes extending to two different directions are formed obliquely to a base body surface in order to form a first crystal and a second crystal. Base body left between the holes are made to be rods. Moreover, a connection crystal layers is formed by a part of rods having a size different from that of the rods in the first crystal and the second crystal. The connection crystal layer is held between the first crystal and the second crystal and they are fused. In a three-dimensional photonic crystal thus obtained, the rod becomes a point defect. The shape and size of the point defect can be arbitrarily set in any directions within the connection crystal layer. The shape and size of the point defect can also be controlled by adjusting the thickness of the connection crystal layer.