本文選題：大氣氣溶膠 + 吸收系數(shù)��； 參考：《中國科學(xué)技術(shù)大學(xué)》2017年博士論文

【摘要】：大氣氣溶膠粒子的光吸收雖一般比較微弱,但對地球大氣輻射收支平衡、激光大氣傳輸?shù)染哂兄匾绊�。目�?大氣氣溶膠粒子吸收系數(shù)的精確測量越來越受到重視,已經(jīng)成為一個(gè)研究熱點(diǎn)與技術(shù)難點(diǎn)。光熱干涉技術(shù)通過測量氣溶膠粒子光吸收熱擴(kuò)散效應(yīng)產(chǎn)生的折射率變化,實(shí)現(xiàn)了自然懸浮狀態(tài)下氣溶膠粒子吸收特性的直接獲取,有效規(guī)避了粒子散射光的影響,同時(shí)干涉測量又具有極高探測靈敏度,因此光熱干涉技術(shù)被認(rèn)為是一種極具發(fā)展?jié)摿Φ拇髿鈿馊苣z粒子吸收系數(shù)測量手段。本文針對大氣氣溶膠吸收特性的光纖式光熱干涉測量技術(shù)進(jìn)行了深入研究,闡明了光熱干涉技術(shù)測量原理,包括光熱效應(yīng)、光相位調(diào)制及光相位解調(diào)等,并根據(jù)實(shí)際大氣氣溶膠吸收特性測量需求,研制了一套光纖式光熱干涉實(shí)驗(yàn)裝置,完成了不同吸收特性樣品的初步測量。本文主要研究結(jié)果及創(chuàng)新點(diǎn)如下:(1)利用氣溶膠粒子吸收的光熱效應(yīng),從熱傳導(dǎo)方程出發(fā),建立了激勵(lì)光加熱氣溶膠的"光-熱-折射率-相位"轉(zhuǎn)化過程的理論模型,構(gòu)造了大氣氣溶膠粒子吸收系數(shù)與干涉儀輸出相位差之間的直接聯(lián)系。(2)提出了同步載波復(fù)原的方法,有效的消除了相位生成載波調(diào)制解調(diào)算法中干涉信號與混頻信號的載波延遲問題;利用參考光路解決了光源直接頻率調(diào)制導(dǎo)致的伴生調(diào)幅現(xiàn)象;完成了基于相位生成載波調(diào)制解調(diào)算法的光熱干涉解調(diào)與控制軟件的編寫、優(yōu)化與驗(yàn)證測試,具備了氣溶膠吸收激勵(lì)光能量生成誘導(dǎo)相位起伏的全過程在線研究能力。(3)設(shè)計(jì)并研制了一套可用于大氣氣溶膠吸收特性測量的光纖式光熱干涉實(shí)驗(yàn)裝置;采用特制光纖準(zhǔn)直器與高反鏡實(shí)現(xiàn)了共光路光纖式斐索干涉結(jié)構(gòu),僅通過普通單模光纖就消除了系統(tǒng)偏振衰落現(xiàn)象;結(jié)合一體化光熱干涉腔,有效增強(qiáng)了裝置的抗干擾能力,提升了光熱耦合效率和探測靈敏度。(4)闡明了光纖式光熱干涉實(shí)驗(yàn)裝置的標(biāo)定原理并利用二氧化氮標(biāo)準(zhǔn)氣體對裝置進(jìn)行了標(biāo)定;以含碳?xì)馊苣z作為待測樣品,二氧化氮標(biāo)準(zhǔn)氣體與高純氮?dú)庾鳛閷φ諛悠?完成了氣溶膠吸收特性的初步測量,所得實(shí)驗(yàn)結(jié)果均與理論分析結(jié)果相符,為大氣氣溶膠吸收特性的進(jìn)一步研究奠定了技術(shù)基礎(chǔ)。
[Abstract]:Although the light absorption of atmospheric aerosol particles is generally weak, it has an important effect on the balance of the earth's atmospheric radiation budget and laser atmospheric transmission.At present, more and more attention has been paid to the accurate measurement of atmospheric aerosol particle absorption coefficient, which has become a research hotspot and technical difficulty.By measuring the refractive index change of aerosol particle photoabsorption thermal diffusion effect, the photothermal interferometry can directly obtain the aerosol particle absorption characteristics in the natural suspension state, and effectively avoid the influence of particle scattering light.At the same time, the interferometry has high detection sensitivity, so the photothermal interferometry is considered as a promising method for measuring the absorption coefficient of aerosol particles in the atmosphere.In this paper, the optical fiber photothermal interferometry for atmospheric aerosol absorption is studied, and the principle of photothermal interferometry is expounded, including photothermal effect, optical phase modulation and optical phase demodulation.According to the requirement of the measurement of atmospheric aerosol absorption characteristics, a set of optical fiber photothermal interference experimental device has been developed, and the preliminary measurement of the samples with different absorption characteristics has been completed.The main results and innovations of this paper are as follows: (1) based on the photothermal effect of aerosol particle absorption, a theoretical model of photothermal refractive index phase transformation of aerosol excited by photothermal heating is established from the heat conduction equation.The direct relation between the atmospheric aerosol particle absorption coefficient and the interferometer output phase difference is constructed.The problem of carrier delay between interference signal and mixed signal in phase-generated carrier modulation and demodulation algorithm is effectively eliminated, and the associated amplitude modulation phenomenon caused by direct frequency modulation of light source is solved by reference light path.The software of photothermal interference demodulation and control based on phase-generated carrier modulation and demodulation algorithm is written, optimized and validated.An optical fiber photothermal interference experimental device is designed and developed to measure the absorption characteristics of aerosol.Using special fiber collimator and high mirror, the common optical path fiber-optic Fieso interference structure is realized. The polarization fading phenomenon of the system is eliminated only by ordinary single-mode fiber, and the anti-interference ability of the device is effectively enhanced by combining the integrated photothermal interference cavity.The calibration principle of the optical fiber photothermal interference experimental device is clarified, and the calibration of the device is carried out by using nitrogen dioxide standard gas, and the carbon-containing aerosol is used as the sample to be measured.Nitrogen dioxide standard gas and high purity nitrogen were used as control samples to measure the absorption characteristics of aerosol. The experimental results were in agreement with the theoretical analysis results, which laid a technical foundation for the further study of the absorption characteristics of atmospheric aerosols.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：X513;O439

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