發(fā)布時(shí)間：2017-12-27 08:46

  本文關(guān)鍵詞：連續(xù)波環(huán)形腔震衰減光譜測(cè)量技術(shù)研究　出處：《中國(guó)科學(xué)院研究生院(長(zhǎng)春光學(xué)精密機(jī)械與物理研究所)》2016年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 光學(xué)測(cè)量 激光吸收光譜技術(shù) 腔衰蕩光譜測(cè)量 光學(xué)無(wú)源諧振腔 模式匹配 痕量氣體濃度 超高反射率測(cè)量

【摘要】：光學(xué)諧振腔的光腔損耗主要分為以下幾個(gè)方面,包括:衍射損耗、幾何偏折損耗、反射不完全損耗、腔內(nèi)介質(zhì)的吸收損耗等。其中,衍射損耗包括因腔鏡大小產(chǎn)生的衍射損耗以及因腔鏡失調(diào)產(chǎn)生的附加衍射損耗;光線在腔內(nèi)往返傳播時(shí),可能從腔的側(cè)面偏折出去,這種損耗為幾何偏折損耗,穩(wěn)定腔內(nèi)傍軸光線的幾何損耗應(yīng)為零;利用腔鏡的反射不完全損耗的特點(diǎn),同樣通過(guò)探測(cè)諧振腔出射光強(qiáng)的衰減,得到腔鏡反射率的絕對(duì)值,該特點(diǎn)目前已得到廣泛關(guān)注,將成為腔鏡超高反射率值的測(cè)量的唯一手段。在超高反射率測(cè)量技術(shù)領(lǐng)域中具有絕對(duì)優(yōu)勢(shì);對(duì)由于腔內(nèi)介質(zhì)存在的吸收損耗的這一特點(diǎn),以及對(duì)于不同氣體“指紋”式的吸收譜線特性,根據(jù)朗伯比爾定律,通過(guò)測(cè)量諧振腔出射光強(qiáng)的變化來(lái)獲得腔內(nèi)待測(cè)氣體濃度值,相關(guān)的技術(shù)包括腔增強(qiáng)光譜技術(shù)和腔衰蕩光譜技術(shù)等。其中,腔震衰減光譜儀(CRDS,Cavity Ring-Down Spectrometer)是近年痕量氣體分析儀器技術(shù)發(fā)展突破的標(biāo)志。CRDS提供現(xiàn)有其它測(cè)試方法不可比擬的高性能比、適用苛刻現(xiàn)場(chǎng)應(yīng)用條件的通用氣體檢測(cè)手段。在此,本文根據(jù)國(guó)內(nèi)外的研究狀況,以連續(xù)波環(huán)形腔衰蕩光譜技術(shù)為重點(diǎn),就與該技術(shù)密切相關(guān)的重大問(wèn)題,包括環(huán)形腔結(jié)構(gòu)特性、光束特性、激光器與諧振腔頻率匹配、模式匹配、光軸對(duì)準(zhǔn)、激光帶寬特性以及掃描速度等問(wèn)題進(jìn)行了深入的研究,在此基礎(chǔ)上建立了完整的光譜測(cè)量系統(tǒng),并進(jìn)行了大量的實(shí)驗(yàn)應(yīng)用研究。并在此基礎(chǔ)上對(duì)影響測(cè)量精度的一系列因素進(jìn)行了深入研究。本文的主要內(nèi)容和得到的結(jié)論可以概括如下:(1)對(duì)由兩平面鏡一球面鏡構(gòu)成的高品質(zhì)無(wú)源腔的基于腔衰蕩光譜測(cè)量技術(shù)中若干問(wèn)題進(jìn)行了研究,具體包括:首先,對(duì)三角形環(huán)形腔的光束特性進(jìn)行了全面的分析,得到了腔內(nèi)循環(huán)光的光束特性、頻率特性以及偏振特性,為環(huán)形腔的應(yīng)用打下了堅(jiān)實(shí)的理論基礎(chǔ),為后續(xù)的測(cè)量系統(tǒng)的設(shè)計(jì)提供了良好的理論指導(dǎo);其次,為了降低高斯光束與諧振腔耦合過(guò)程中,失調(diào)量和失配量對(duì)基于無(wú)源諧振腔測(cè)量技術(shù)精度的影響,采用高斯光束變換規(guī)律、模式耦合有關(guān)理論以及光束傳播坐標(biāo)變換等相關(guān)理論,就失調(diào)量和失配量對(duì)基模耦合效率的影響分別進(jìn)行分析和模擬,并據(jù)此給出了一般情況下兩個(gè)參考量同時(shí)存在時(shí)基模耦合效率的表達(dá)式;再次,從光束傳輸坐標(biāo)變換的角度,分析了由多個(gè)平面鏡所構(gòu)成的諧振腔的共軛光軸存在條件,得出了奇數(shù)平面鏡諧振腔僅當(dāng)平面鏡間具有高精度的相同垂直度時(shí)才存在閉合光軸,而偶數(shù)平面鏡諧振腔總是存在閉合光軸的結(jié)論,并給出了腔共軛軸隨腔鏡方向失調(diào)而產(chǎn)生的角度變化關(guān)系。給出了諧振腔的設(shè)計(jì)參數(shù)以及依據(jù)。具體分析了由兩個(gè)平面鏡和一個(gè)球面鏡構(gòu)成的三角形環(huán)形諧振腔的閉合共軛光軸存在的問(wèn)題,結(jié)果表明,當(dāng)不同的鏡子出現(xiàn)角度偏差時(shí),腔內(nèi)仍然存在閉合的共軛光軸,并給出了對(duì)應(yīng)的腔軸變化以及新諧振面的位置及方向,由此說(shuō)明由于球面鏡的加入降低了諧振腔共軛軸存在性對(duì)平面鏡間高精度平行度的要求,為基于高品質(zhì)光學(xué)無(wú)源腔的光譜測(cè)量技術(shù)的高精度裝調(diào)工作提供了理論指導(dǎo);最后,本文沒(méi)有從頻率匹配的角度來(lái)考慮入射光的頻率特性,因?yàn)楹?jiǎn)單的頻率匹配不能更好的為入射激光的頻率特性提出更好的限制性分析,為了更便于后續(xù)對(duì)激光器選型的參數(shù)確定,將從光學(xué)疊加原理,分別從時(shí)域和頻域兩個(gè)角度進(jìn)行分析,給出了腔內(nèi)光干涉過(guò)程,更好的為分析腔內(nèi)光場(chǎng)特性提供了理論依據(jù),以便更為方便對(duì)可能遇見(jiàn)的問(wèn)題進(jìn)行理論分析。(2)在充分的理論分析的基礎(chǔ)上建立了連續(xù)波環(huán)形腔衰蕩光譜技術(shù)測(cè)量方案。針對(duì)環(huán)形腔的理論分析結(jié)果,對(duì)連續(xù)波腔衰蕩光譜系統(tǒng)的整體測(cè)量系統(tǒng)設(shè)計(jì)、控制系統(tǒng)設(shè)計(jì)、電路設(shè)計(jì)以及軟硬件的實(shí)現(xiàn)進(jìn)行了介紹。本文設(shè)計(jì)的系統(tǒng)具有以下的優(yōu)點(diǎn)和創(chuàng)新,其中,以分布反饋式激光器(dfb)為光源,利用其溫度、電流調(diào)諧特性實(shí)現(xiàn)激光波長(zhǎng)的調(diào)諧從而實(shí)現(xiàn)“關(guān)斷”,省略了與光開關(guān)的相關(guān)器件;測(cè)量系統(tǒng)以三角形環(huán)形腔作為諧振腔,減少了直接返回到激光器的光學(xué)面,省去了光隔離器;控制系統(tǒng)中采用高精度的波長(zhǎng)計(jì)完成激光器頻率的調(diào)節(jié)和鎖定,在保證精度的前提下,省略了常用的基于相位調(diào)制鎖定光學(xué)諧振腔所用的一系列激光器與諧振腔的鎖定裝置。在建立的測(cè)量系統(tǒng)基礎(chǔ)上對(duì)相關(guān)設(shè)計(jì)參數(shù)進(jìn)行了確定,并對(duì)測(cè)量系統(tǒng)中的各個(gè)器件進(jìn)行性能測(cè)試,較為主要的結(jié)果為激光器的調(diào)諧關(guān)斷時(shí)間為2μs內(nèi);pzt腔長(zhǎng)調(diào)節(jié)范圍為2.5nm,調(diào)整頻率為1khz;波長(zhǎng)計(jì)在波長(zhǎng)為1000nm時(shí)其絕對(duì)精度可達(dá)±0.2pm,可滿足高精度激光波長(zhǎng)標(biāo)定的要求,以上指標(biāo)滿足測(cè)量系統(tǒng)的理論要求。(3)對(duì)調(diào)腔式連續(xù)波環(huán)形腔衰蕩光譜系統(tǒng)的特點(diǎn)及搭建實(shí)現(xiàn)進(jìn)行了深入研究。以所述的理論為基礎(chǔ),在考慮光源光譜線寬的情況下,就光源光譜線寬的特性提出兩種裝調(diào)校準(zhǔn)方案:基于法布里伯羅干涉儀法和基于多維象限探測(cè)器探測(cè)諧振腔出射光的調(diào)節(jié)回路,搭建了調(diào)腔式環(huán)形腔衰蕩光譜系統(tǒng),特點(diǎn)是該系統(tǒng)具有光軸校準(zhǔn)的閉合控制能力。對(duì)所設(shè)計(jì)的諧振腔在相關(guān)光學(xué)軟件上進(jìn)行模擬分析,得到其衍射損耗與腔鏡位置對(duì)應(yīng)的變化關(guān)系;得到了腔出射光斑特性與腔長(zhǎng)失調(diào)量之間的對(duì)應(yīng)關(guān)系;得到了腔鏡大小的限制以及其基膜模式分布特性,為諧振腔的裝調(diào)提供了指導(dǎo)。更主要的是針對(duì)軟件中不能給出的諧振腔的腔軸位置的問(wèn)題進(jìn)行了補(bǔ)充分析,得到了諧振腔鏡角度失調(diào)對(duì)腔內(nèi)閉合光軸的位置的影響,并進(jìn)行了理論研究和數(shù)值模擬,得到了腔軸的位置變化與入射光的方向位置變化關(guān)系,并進(jìn)行了初步的實(shí)驗(yàn)研究,驗(yàn)證了三角形環(huán)形腔腔參數(shù)設(shè)計(jì)的合理性,降低了三角形環(huán)形腔的裝調(diào)難度。(4)對(duì)連續(xù)光波環(huán)形腔衰蕩光譜技術(shù)影響探測(cè)精度的誤差因素進(jìn)行了初步研究。這些因素包括對(duì)激光器調(diào)諧掃描速度等問(wèn)題進(jìn)行了系統(tǒng)的分析,為了更方便描述激光器掃描速度的限制,在此引入了兩個(gè)參數(shù),掃描速度參數(shù)??c a v c a v??W?v?和帶寬參數(shù)κ,并對(duì)腔出射光譜與?的數(shù)值模擬,得到了當(dāng)?1時(shí),腔衰蕩光譜更接近單e指數(shù)衰減;對(duì)激光器帶寬特性對(duì)測(cè)量的影響,得到了????時(shí),腔出射線型中尖峰特性平穩(wěn),使得衰蕩線型更趨于光滑的單e指數(shù)衰減;主要分析了壓強(qiáng)對(duì)氣體吸收特性的影響,以H2S氣體為例,給出了如何確定目標(biāo)氣體的“無(wú)干擾”波段以及最佳操作壓力的確定方法,為氣體的探測(cè)最佳參數(shù)的確定提供了參考。(5)對(duì)腔體長(zhǎng)~200 mm、總腔長(zhǎng)~410mm環(huán)形腔衰蕩光譜系統(tǒng)進(jìn)行了實(shí)驗(yàn)研究,搭建了連續(xù)波激光器環(huán)形腔衰蕩光譜測(cè)量系統(tǒng)。鑒于腔衰蕩光譜技術(shù)的應(yīng)用均是建立在對(duì)腔損耗值進(jìn)行精確測(cè)量的基礎(chǔ)上,本文將該測(cè)量系統(tǒng)應(yīng)用于常溫常壓,無(wú)“干擾氣體”吸收的反射鏡超高反射率的測(cè)量上。利用高純氮?dú)鈱?duì)空腔進(jìn)行反復(fù)沖洗,消除干擾氣體的吸收光譜的影響得到反射鏡的反射率更精確的測(cè)量值,最后確定反射鏡的反射率在6046.972cm-1頻率處的反射率精確值。此外,還對(duì)該系統(tǒng)在痕量氣體濃度探測(cè)領(lǐng)域的應(yīng)用進(jìn)行了研究,并對(duì)影響測(cè)量精度的因素進(jìn)行了詳細(xì)分析。
[Abstract]:The optical cavity loss of optical resonator is mainly divided into the following aspects, including diffraction loss, geometric deflection loss, incomplete reflection loss, and absorption loss of cavity medium. Among them, the diffraction loss including the diffraction loss caused by mirror size and due to misalignment of cavity mirrors generated additional diffraction loss in the cavity; the light travels, probably from the cavity side out deflection, the loss of geometric deflection losses, the cavity loss near the geometric axis light consumption should be zero; the mirror reflection incomplete loss of the same through the detection of resonant cavity light attenuation, the absolute value of the reflectivity obtained, the characteristics of the present have been widely concerned, will become the only means to measure the value of the ultra high reflectivity mirror. Has the absolute advantage in high reflectivity measurement technology in the field of; because of the characteristics of the absorption medium in the cavity, and the absorption spectrum characteristics of different gas "fingerprint", according to Longbow Bill's law, to obtain the measured gas concentration cavity by measuring the resonant cavity light intensity changes, related technology including the cavity enhanced spectroscopy and cavity ringdown spectroscopy etc.. Among them, CRDS (Cavity Ring-Down Spectrometer) is a symbol of the breakthrough of the development of trace gas analysis instruments in recent years. CRDS provides an unparalleled high performance ratio and a general gas detection method for harsh field application conditions that are incomparable with other existing testing methods. Then, according to the research status at home and abroad, with the continuous wave ring cavity ringdown spectroscopy to focus on major issues closely related to the technology, in-depth research including the structure characteristics, ring beam and laser resonator with frequency matching, pattern matching, optical axis alignment, laser scanning and bandwidth characteristics the speed problem is established based on the spectral measurement of a complete system, and the application of a large number of experiments. On the basis of this, a series of factors that affect the accuracy of measurement are studied. The main contents of this paper and conclusions can be summarized as follows: (1) the high quality passive cavity is composed of two plane mirrors a spherical mirror cavity ringdown spectroscopy measurement technology based on some problems are studied, including: first, the beam characteristics of the triangular ring cavity is analyzed. The obtained beam the characteristics, frequency characteristics and optical cavity of circular polarization, a solid theoretical foundation for the application of ring resonators, and provides theoretical guidance for the design of the measurement system is good in the future; secondly, in order to reduce the Gauss beam and resonator coupling process, misalignment and mismatch effect on passive resonator measurement the technical precision based on the Gauss beam transformation rules, mode coupling theory and related beam propagation coordinate transformation theory, influence of misalignment and mismatch of mode coupling efficiency points Don't analyze and simulation, and gives a general expression reference volume two exist at the same time the fundamental mode coupling efficiency; thirdly, the beam propagation coordinate transformation angle, analyzes the existing condition of the conjugate axis resonant cavity is composed of a plurality of plane mirror, the odd mirror cavity only when the same the verticality with high precision plane mirror between the optical axis and is closed, even the plane mirror cavity there is always closed the optical axis of the conclusion, and gives the relationship between the change of cavity mirror with conjugate axis direction disorders and angle. The design parameters and basis of the resonant cavity are given. The paper analyzed the existing closed conjugate ring resonator optical axis triangle composed of two plane mirror and a spherical mirror. The results show that, when the angle deviation of different mirror, the cavity axis still exists conjugate closed, and gives the corresponding change of cavity axis and new resonance surface position and direction, thus because of adding spherical mirror reduces the existence of a plane mirror between the high precision parallel degree requirements resonator conjugate axis, to provide theoretical guidance for high precision alignment work spectral measurement technique based on high quality optical cavity; finally, this paper from the perspective of frequency, the frequency characteristic of incident light, because simple frequency matching can not be better for the frequency characteristics of the incident laser proposed restriction analysis better, in order to facilitate the subsequent selection of the laser parameters determined from the optical stack The principle of the addition is analyzed from two angles of time domain and frequency domain respectively, and the process of intracavity optical interference is given, which provides a theoretical basis for analyzing the characteristics of the optical field in the cavity, so as to facilitate the theoretical analysis of the problems that may be encountered. (2) on the basis of sufficient theoretical analysis, a continuous wave ring ring cavity ring down spectroscopy measurement scheme is set up. According to the theoretical analysis results of the ring cavity, the design of the whole measurement system, the control system design, the circuit design and the realization of hardware and software of the continuous wave cavity ring down spectroscopy system are introduced. This system has the following advantages and innovation, among them, using a distributed feedback (DFB) laser as light source, wavelength of the laser, the temperature tuning characteristics of tunable current so as to realize the "turn off", omitting related devices and optical switch; measuring system based on triangle ring cavity as resonant cavity is reduced direct return to the optical surface laser, eliminating the optical isolator; control system with high precision laser wavelength meter complete frequency adjustment and locking, under the premise of ensuring accuracy, locking phase modulation lock light resonance cavity with a series of laser resonator based on commonly used and omitted. Based on the established measurement system, the relevant design parameters are determined, and the performance of each component in the measurement system is tested. The main result is the laser turn off.
【學(xué)位授予單位】：中國(guó)科學(xué)院研究生院(長(zhǎng)春光學(xué)精密機(jī)械與物理研究所)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TN248
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本文編號(hào)：1341009