Abstract: The present invention provides a filter composed of two layers of materials with different expansion coefficients. The difference between a length added to a whole section length of an outer low-expansion coefficient metal sleeve by a temperature change and a length added to a length of a whole section of high-expansion coefficient cylindrical coil spring arranged therein by the temperature change causes a stress-releasing or stress-increasing effect on the whole section of pre-tensioned high-expansion coefficient cylindrical coil spring arranged therein, so that a structure capable of compensating the wavelength shift of the fiber Bragg's grating filter caused by temperature by increasing or decreasing the refractive index is achieved.

Abstract: An apparatus includes a sensing screw capable of providing synchronous both pre-drawing of fiber Bragg grating and pre-tightening of bolt with induced characteristics to detect feedback control of large scale public engineering structures or precise equipments to facilitate fabrication of precise elements to achieve more precise control and record fabrication processes. Through the sensing screw apparatus a precision system structure can be formed to meet expectation of improved product quality and comprehensive recording of complete production process and physical characteristics at important points of the production process. The invention can provide instant onsite status and accumulate data or make parameter pre-action to avoid error accumulation, thereby improve production yield or safety of large scale structures.

Abstract: An optical fiber sensing spring of the present invention includes a longer cylindrical tension coil spring, a shorter cylindrical compression coil spring and a longer cylindrical tension coil spring that are connected in series to form a spring having the same inner and outer diameters. A single-mode optical fiber manufactured with a long section of fiber grating is placed in the manufactured spring. This section of the fiber grating is tensed to two ends of the cylindrical compression coil spring having a predetermined gauge length, and the force applied is released. A pre-tensing method for providing a maximum tolerable compression strain and manufacturing technology for this sensing element are then achieved. Thus, the self-tensed optical fiber sensing spring structure satisfies a standard 0.9 mm outer diameter, is fully spring jacketed by the full spring jacketing and protection layer, and forms a linear stress-strain relationship in an elasticity stretched elastic region.

Abstract: An apparatus includes a sensing screw capable of providing synchronous both pre-drawing of fiber Bragg grating and pre-tightening of bolt with induced characteristics to detect feedback control of large scale public engineering structures or precise equipments to facilitate fabrication of precise elements to achieve more precise control and record fabrication processes. Through the sensing screw apparatus a precision system structure can be formed to meet expectation of improved product quality and comprehensive recording of complete production process and physical characteristics at important points of the production process. The invention can provide instant onsite status and accumulate data or make parameter pre-action to avoid error accumulation, thereby improve production yield or safety of large scale structures.