Fiber bragg grating strain sensor for structure surface

The invention discloses a fiber bragg grating strain sensor for a structure surface, a metal sheet is composed of sheet branches in three directions, an angle between two adjacent sheet branches is 45 degrees, the three sheet branches are located on the same plane, a fiber bragg grating adopts a double-grating fiber and two single-grating fibers, and the double-grating fiber and the single-grating fiber are arranged on the same plane. The double-grating optical fiber is composed of a large-wavelength grating and a small-wavelength grating, the double-grating optical fiber and the two single-grating optical fibers are arranged in grooves of the slice branches respectively, the metal tube is connected with the outer ends of the slice branches provided with the double-grating optical fiber, and the small-wavelength grating is arranged in the metal tube in a penetrating mode. The sensor is reasonable in structure, strain monitoring of a certain point of the structure in three directions can be achieved, meanwhile