DIFFRACTION GRATING REFLECTED WAVELENGTH MEASURING METHOD AND DEVICE, AND PHYSICAL QUANTITY MEASURING METHOD AND DEVICE

摘要

PROBLEM TO BE SOLVED: To measure the wavelength and physical quantity of light reflected by a diffraction grating with high accuracy. SOLUTION: Pulse light having a designated wavelength obtained by modulating output light of a wide band light source 1 by an external modulator 2 enters from one end of an optical fiber having a diffraction grating FBG in the midway of an optical path, reflected light returned from the diffraction grating FBG to one end of the optical fiber is received through a wavelength inclined type optical filter 5 having a designated wavelength transmission characteristic by a photo detector 6, and the light intensity of the reflected light is measured to obtain the wavelength of reflected light from the light intensity of the reflected light.