Research On High Precision Infrared Laser Wavelength Measurement Technology

The remote sensing technology based on Fourier Transform Spectrometer has been widely used and became a trend in the field of meteorological observation.The remote sensing instrument based on Fourier Transform Spectrometer will be installed on the new generation geostationary and polar orbiting meteorological satellite. The accuracy of spectrum is an important index of the remote sensing instrument based on Fourier Transform Spectrometer and it affects the inversion precision of the air's temperature and humidity. In order to guarantee the spectral accuracy of the remote sensing instrument, spectral calibration is required. The wavelength of the stabilized laser chosen as the calibration source should be accurately measured. The dissertation researches on the precision measurement techniques for the calibration source used in the remote sensing instrument and the research has strong practical engineering value.The measurement techniques for laser wavelength have been comprehensive researched and analyzed, and the laser wavelength measurement technique based on Michelson interferometer has been chosen to measure the wavelength of the calibration laser used in the remote sensing instrument. The effects of the stabilization of reference laser, the misalignment of reference laser and measured laser, the counting error of the interference fringes, the refractive index of air and the error caused by laser diffraction on the laser wavelength measurement technique based on Michelson interferometer have been discussed. The methods which can deduce the measurement error of the laser wavelength have been proposed. A technical plan which can meet the requirement of calibration laser used in the remote sensing instrument has been worked out.The stabilization of reference laser has a direct effect on the measurement result of laser wavelength. The laser stabilization techniques have been analyzed and frequency modulation spectroscopy is chosen to stabilize the wavelength of DFB semiconductor laser. The laser stabilization method without phase shift has been proposed which improves the stabilization system's adaptability to the modulation frequency and eliminates the tedious process of phase adjustment.The refractive index of air must been used in the precision computation of laser wavelength as the measurement result is affected by the refractive index of air.And the algorithms of the refractive index of air have been discussed in the dissertation. The algorithm of Rueger is updated and the performance of the updated algorithm has been improved without changing the complexity of the algorithm too much.The counting method of interference fringes has been improved which makes full use of the optical path difference of the interferometer. The improved counting method also improves the measurement precision of laser wavelength.According to the research, the laser wavelength measurement technique based on Michelson interferometer can meet the measurement requirement of the calibration laser in the remote sensing instrument. The research result of the dissertation has practical value to the spectral calibration of the Fourier transform spectrometer based on the satellite.