An optical fiber high-precision absolute distance measurement technology incorporating white-light interferometry and single-wavelength interferometry

An optical fiber high-precision absolute distance measurement technology that incorporates white-light interferometry and single-wavelength interferometry is presented, which is suitable for measuring static or quasistatic local absolute distance as well as remote absolute distance. The sensing head which is a grin lens and is connected to an optical fiber Michelson interferometer with optical fiber can be installed conveniently in the sensing field to sense the measured absolute distance. The optical fiber Michelson interferometer is used to demodulate the optical path. The white light interferometric signal of the Michelson interferometer is used to determine the amplitude of the absolute distance, while the value of the absolute distance is measured precisely with a single wavelength interferometric signal which is obtained with a fiber Bragg grating reflecting a single wavelength from the white light interferometric signal. The measurement resolution that is determined by the single wavelength interferometry is less than 1 nm. And the measurement range that is determined by the coherent length of the light reflected by the fiber Bragg grating is about 12 mm. The linear correlation coefficient of the experimental results of absolute distance measurement is 0.999 which indicates that the linearity of the measurement system is very good.