在数控机床误差补偿、航空航天制造等领域的大型构件加工与装配现场,空气折射率的空间时变、非均匀分布特性严重影响大尺寸激光干涉测量的精度，使干涉测量结果的不确定性评估失去依据。针对此问题，本项目拟探索使用可调谐半导体激光器多特征吸收光谱在线重构非均匀空气介质折射率廓线的方法，揭示空气温度、相对湿度、CO2浓度等物理量对空气吸收光谱的影响规律，优化选择表征时变、非均匀空气折射率的特征吸收谱线。研究激光调谐、调制模式及其非线性特性对吸收光谱谱线的影响规律，优化可调谐激光调谐、调制参数。研究控制参数自适应调整策略，实现吸收谱线线形畸变的自校正方法。在此基础上，以温度、湿度等物理量为时变参数，研究沿测量光束路径空气折射率廓线时变非线性动态建模及其基于统计回归分析的反演方法，重构激光测量光束路径的空气折射率廓线，实现工业现场大尺寸干涉测量在线修正，提高干涉测量精度，提升精密测量设备对环境变化的鲁棒性。

For error compensation of NC machine tool and manufacturing and assembly of large work-pieces in aerospace industry, the accuracy of laser interferometer for large scale metrology is limited by in suit air refractive index distribution due to its characteristics of time-varying and non-uniform distribution. As a result, the interference measurement result uncertainty evaluation lost evidence. Aiming at this problem, this project aims to explore the tunable diode laser absorption spectroscopy to reconstruct profile of non uniform air refractive index by using multiple characteristic absorption spectrum and try to reveal the influence of the temperature, relative humidity, concentration of CO2 of air to absorption spectra of diode laser. Based on that, multiple feature absorption lines are selected to describe the time-varying non-uniform distribution of air refractive index. The influence of laser tuning, modulation parameters and its nonlinear effects on the harmonic of spectral line is studied to improve the accuracy of absorption spectrum measurement. The strategy of adjust adaptively control parameters is studied to realize the self-correction of profile distortion of spectral line. Then, a time-varying nonlinear dynamic model is used to describe the air refractive index profile along the path of measuring beam and the temperature, humidity and concentration of CO2 of air are used as time-varying parameters for this model. The inversion method based on statistical regression analysis will be studied to reconstruct profile of air refractive index. The online correction for large scale interferometry measurement at industrial site will be studied to improve the measuring accuracy and the robustness of precision measurement equipment to enviromental changes.