Design And Optimization Of Scanning Solid-cavity F-P Interferometer

Atmospheric temperature is one of important physical parameters for the description of atmospheric state.The high-precision measurement of atmospheric temperature at day and night will constantly improve service capability for production and life.For example,The reliable technical support can be provided for improving the accuracy of weather forecasting,curbing environmental pollution,studying the countermeasures of greenhouse effect,and utilizing meteorological resources and making economic policies.As an active remote sensing technique with high spatiotemporal resolution and detection sensitivity,Lidar has been widely used for atmospheric temperature detection,especially detecting temperature profiles in low layer,beause of the ultra-high spectral resolution and relatively strong Rayleigh scattering signal.The hyperspectral lidar is easy to obtain a high signal-to-noise ratio and has the potential for the all-time detection.At present,the detection of atmospheric temperature by using hyperspectral Lidar based on Rayleigh scattering is mainly focused on relative detection.That is to say,the response functions and calibration procedures will be required for temperature retrieval.In this dissertation,according to the characteristics of Rayleigh scattering spectrum,a scanning solid-cavity Fabry-Perot interferometer is optimally designed for the absolute detection of atmospheric temperature,which can achieve the incident spectrum continuously changing by using an electro-optic crystal as Fabry-Perot cavity.The design parameters of device are as follows:the electro-optical crystal of KD*P with the length of 8.5mm acts as solid-cavity medium of scanning Fabry-Perot interferometer,the designed free spectral region with 11.5GHz,3dB bandwidth of 150MHz at the central wavelength of 354.7nm,the cavity reflectivity of 96%,and every voltage interval of 15.5V.In order to verify the accuracy of design results,a numerical simulation of Rayleigh scattering spectrum based on standard atmosphere model and S6 model is performed.The detection uncertainty of atmospheric temperature is up to 2.8K.In order to optimize the dynamic filtering performance of the scanning solid-cavity F-P interferometer,the relationship between the refractive index of electro-optic crystal and modulation voltage is measured by employing the digital holographic interferometry.By comparing the experimental data with the theoretical modulation data,they are in good agreement.In order to verify the dynamic filtering performance of the scanning solid-cavity F-P interferometer and confirm whether it meets the design requirements,the influence of cavity surface defects on the transmission spectrum was first analyzed.The transmission spectrum of the interferometer was measured through experiments,and the filter performance was determined.In the experiments,the test optical paths were built by the cage structure.At the same time,the temperature control of the solid-cavity with 0.02 C accuracy is achieved.The resonance wavelength of the scanning solid-cavity F-P interferometer was measured to be 354.72913nm,and the full width at half maximum was 386MHz,it was in good agreement with the design parameters.The result shows that the device can realize the fine detection of Rayleigh spectrum,and can be used for reference for the study of similar hyperspectral Lidar system,and provides a feasible solution for the land-based and spaceborne applications of hyperspectral Lidar.