Abstract: An apparatus and method for detecting composite material damage due to impact by using distributed optical fiber are disclosed. In the apparatus and method for detecting composite material damage due to impact by using distributed optical fiber, the position and level of damage occurring in a composite material due to low-velocity impact can be effectively and economically detected by measuring the residual strain of optical fiber distributed on the surface of the composite material or inside the composite material. In the apparatus and method for detecting composite material damage due to impact by using distributed optical fiber, there is no need to always operate a sensor in real time, so that detection errors due to temporary failures, malfunctions, etc. of the sensor, as well as a problem of constantly supplying power to the sensor, can be essentially removed.

Abstract: The present invention relates to an optical fiber BOCDA sensor. A purpose of the present invention is to provide an optical fiber BOCDA sensor which uses two phase codes to control a correlation peak position, thereby further simplifying control design and device configuration and improving spatial resolution to enhance a sensing performance and detection accuracy in comparison with the prior art.

Abstract: The present invention relates to an optical fiber BOCDA sensor. A purpose of the present invention is to provide an optical fiber BOCDA sensor which uses two phase codes to control a correlation peak position, thereby further simplifying control design and device configuration and improving spatial resolution to enhance a sensing performance and detection accuracy in comparison with the prior art.

Abstract: An apparatus and method for detecting composite material damage due to impact by using distributed optical fiber are disclosed. In the apparatus and method for detecting composite material damage due to impact by using distributed optical fiber, the position and level of damage occurring in a composite material due to low-velocity impact can be effectively and economically detected by measuring the residual strain of optical fiber distributed on the surface of the composite material or inside the composite material. In the apparatus and method for detecting composite material damage due to impact by using distributed optical fiber, there is no need to always operate a sensor in real time, so that detection errors due to temporary failures, malfunctions, etc. of the sensor, as well as a problem of constantly supplying power to the sensor, can be essentially removed.

Abstract: The present invention relates to an FBG sensor for measuring a maximum strain of an object being measured, a method for manufacturing the sensor, and a method of using the sensor. To this end, provided is the FBG sensor for measuring a maximum strain, comprising: an optical fiber (130) having an FBG sensor (150) therein; a first metallic foil (120) contacting the optical fiber (130) on one surface thereof; a second metallic foil (120) which comes into surface-contact with the one surface; an adhesive layer (140) provided between the first and second metallic foils (100, 120); a means for measuring a residual strain of the first and second metallic foils (100, 120) through the FBG sensor (150); and a means for calculating a maximum strain on the basis of the measured residual strain and a sensitivity coefficient (Csen) obtained through experimentation.

Abstract: The present invention relates to an FBG sensor for measuring a maximum strain of an object being measured, a method for manufacturing the sensor, and a method of using the sensor. To this end, provided is the FBG sensor for measuring a maximum strain, comprising: an optical fiber (130) having an FBG sensor (150) therein; a first metallic foil (120) contacting the optical fiber (130) on one surface thereof; a second metallic foil (120) which comes into surface-contact with the one surface; an adhesive layer (140) provided between the first and second metallic foils (100, 120); a means for measuring a residual strain of the first and second metallic foils (100, 120) through the FBG sensor (150); and a means for calculating a maximum strain on the basis of the measured residual strain and a sensitivity coefficient (Csen) obtained through experimentation.

Abstract: The present invention is effective in that automatically corrected temperature can be measured using one light source and one optical detector.

Abstract: The present invention is effective in that automatically corrected temperature can be measured using one light source and one optical detector.

Abstract: Provided is a physical quantity measuring method using a Brillouin optical fiber sensor. An optical fiber is set on a structure and a pair of pulse lights having different pulse widths is selected. The pulse lights are sequentially transmitted through the optical fiber to obtain back scattering lights and Brillouin gain spectra. The Brillouin gain spectra are compared to each other to calculate a normalized spectrum and a Brillouin frequency is acquired based on the normalized spectrum. The Brillouin frequency is multiplied by a conversion factor of a corresponding physical quantity of the structure to obtain the physical quantity. Accordingly, a portion of the optical fiber from which a sensing signal can be acquired is shortened to improve spatial resolution.

Abstract: A transmission-type extrinsic Fabry-Perot interferometric optical fiber sensor and a method used for integrity monitoring of structures and measuring strain and temperature are provided. The transmission-type extrinsic Fabry-Perot interferometric optical fiber sensor includes first single-mode optical fiber and second single-mode optical fiber, laser device, and optical detector. The first single-mode optical fiber is inserted into an end of a capillary quartz-glass tube and the second single-mode optical fiber is inserted into the other end of the capillary quartz-glass tube. Air gap is formed between the first single-mode optical fiber and the second single-mode optical fiber in the capillary quartz-glass tube. Gap length of the air gap changes in response to magnitude and direction of transformation of the capillary quartz-glass tube. The laser device launches light into an end of the first single-mode optical fiber.