Research On The Solar-Blind Pure Rotational Raman Lidar For The Measurement Of Atmospheric Temperatuer

Atmospheric temperature is an important atm ospheric ph ysical param eter,an.d its changes will directly aff'ect the survival of living organisms and production of human.Global warming in recent years and extreme weather are all closely related to atmospheric temperature.Therefore,daytime detection of atmospheric temperature i.s of great sign ifican ce for studying atmosph eric science,the correlation between global warming and extreme weather,weather f-orecasting and so on.In this thesis,a pure rotational Raman lidar is designed for the measurement of atmospheric temperature on daytime,in which the quadruple frequency of N'd:YAG pulsed laser with the wavelength of 266.0nm is selected as the transmitter wavelength.The spectra of the excited light and its corresponding pure rotational Raman signals are within the solar-blind region,therefore th ere is no effect of solar backgroun.d on the detection of atm osph eric tem perature using the technique of the pure rotational Raman lidar.In order to select the appropriate solar-blind pure rotational Raman lines to retrieve atmospheric temperature,the uncertainties of temperature measurement at different temperature pairs are calculated under three different extraction schemes.After comprehensive analysis by the comparison with the three schemes,in the high an d low quantum n umber channels of the Stokes branch,five pure rotation al Ram an lines of N2 and O2 centered at J=16 and three pure rotational Raman lines of N2 and O2 centered at J=5 are selected,an d in h.igh an d low quantum number ch an nels of the Anti-Stokes branch,five pure rotational Raman lines of N2 and O2 centered at J=18 and three p.ure rotational Raman lines of N2 and O2 are selected respectively as the extraction targets.In order to separate and extract these pure rotational Ram an lines with in solar-blind region with differen t tem perature sensitivity,a grating polychromator with double diffractions and a double-gratings polychromator with triple diffraction s are design ed as th e spectroscopic system of sloar-blind Ram an lidar.The structure,characteristics and the parameters of the grating polychromator with double diffractions are discussed in detail.Compared with the grating polychromator with double diffractions,the double-gratings polychromator with triple diffractions is constructed with a grating with double diffractions as the first spectroscopic and a grating with a single diffraction as the second spectroscopic,which can improve the suppression of the Mie-Rayleigh scattering signals.ZEMAX simulations show that the grating polychromator with double diffractions and the double-gratings polychromator with triple diffractions can separate and extract the solar-blind pure rotational Raman lines effectively.Finally,the system simulation and the performance analysis of the solar-blind pure rotational Raman lidar are carried out.By spectral analysis,it is found that both ozone absorption and fluorescence should be considered in the retrieval of atmospheric temperature.The simulation results show that the system with the analog detection mode has the capability of measuring atmospheric temperature up to a height of 2.5km,2.2km,1.9km,1.7km,1.6km,1.5km respectively at daytime,When the ozone concentrations are assumed to be 5 ?g/L,10?g/L,15?g/L,20?g/L,25?g/L,30?g/L respectively and the bioaerosol concentration is 1000 particles/L.