本文關(guān)鍵詞： 蒙特卡羅模擬 光纖 橢球反射鏡 復(fù)合拋物面聚光器 無創(chuàng)生化分析　出處：《中國科學(xué)院研究生院（長春光學(xué)精密機(jī)械與物理研究所）》2012年碩士論文　論文類型：學(xué)位論文

【摘要】：近紅外光譜技術(shù)是血液無創(chuàng)生化分析能夠獲得應(yīng)用的最具潛力的方法之一。但是,由于人體皮膚組織中的水對光的吸收非常強(qiáng),并且血液中各種化學(xué)成分的含量較低,致使由它們引起的吸收光譜信號很微弱,給無創(chuàng)生化分析帶來了困難。為了解決此問題,本論文通過增大光學(xué)系統(tǒng)集光效率的方法來增加近紅外光譜分析系統(tǒng)的光通量,從而有助于提高光譜儀器的信噪比。 論文首先介紹了近紅外無創(chuàng)生化分析的研究現(xiàn)狀,分析了當(dāng)前存在的技術(shù)難點(diǎn),包括光譜信號微弱、背景干擾及血流容積的周期性變化。針對第一個問題,擬采用設(shè)計(jì)高效聚焦光學(xué)系統(tǒng)的方法作為解決途徑,提出對分別由光纖、橢球反射鏡、復(fù)合拋物面聚光器構(gòu)成的幾種光學(xué)系統(tǒng)的聚焦效果進(jìn)行研究。 闡述了蒙特卡羅模擬方法原理,結(jié)合三層皮膚組織模型,研究了光在皮膚組織中的傳播規(guī)律。在波長范圍為1000nm-2350nm內(nèi),模擬計(jì)算了光子傳播的路徑長度、穿透深度、散射次數(shù)以及漫反射光能量,并討論了入射-出射距離對出射光子能量的影響。根據(jù)以上蒙特卡羅模擬結(jié)果對光纖探頭的結(jié)構(gòu)進(jìn)行了設(shè)計(jì),并利用光學(xué)軟件仿真計(jì)算了光纖收集到的漫反射光能量及照度分布。 根據(jù)橢球反射鏡的聚光特點(diǎn),在幾何光學(xué)理論的基礎(chǔ)上計(jì)算了焦面上的物體經(jīng)橢球鏡反射后像點(diǎn)坐標(biāo)方程,并基于此方法優(yōu)化了橢球反射鏡最佳聚光效果時的結(jié)構(gòu)參數(shù)。采用光線追跡方法,分析了橢球反射鏡聚焦光能特征,與無光學(xué)收集系統(tǒng)相比,橢球反射鏡對人體漫反射光的利用率提高了5.4倍。 分析了復(fù)合拋物面聚光器(CPC)反射光線隨結(jié)構(gòu)參數(shù)變化特點(diǎn),優(yōu)化設(shè)計(jì)了CPC-凹面鏡系統(tǒng)結(jié)構(gòu)參數(shù)。首次提出了一種雙復(fù)合拋物面聚光系統(tǒng),通過比較標(biāo)準(zhǔn)型和截短型CPC聚光性能變化,優(yōu)化出集光效果最佳時的結(jié)構(gòu)參數(shù),并分別模擬研究了這兩種光學(xué)系統(tǒng)對人體漫反射光的聚焦情況。與無光學(xué)收集系統(tǒng)相比,截短型CPC-凹面鏡系統(tǒng)對人體漫反射光的利用率提高了15.1倍,截短型雙復(fù)合拋物面聚光系統(tǒng)對人體漫反射光的利用率提高了32.6倍。 本文研究的幾種聚光系統(tǒng)均能有效地將漫反射光會聚至探測器上,有助于提高無創(chuàng)生化分析系統(tǒng)的信噪比及整體分析精度。
[Abstract]:Near-infrared spectroscopy (NIR) is one of the most promising methods for non-invasive biochemical analysis of blood. However, because of the strong absorption of light by water in human skin, and the low content of various chemical components in blood, The absorption spectrum signal caused by them is very weak, which brings difficulties to non-invasive biochemical analysis. In order to solve this problem, this paper increases the luminous flux of the near infrared spectrum analysis system by increasing the optical system's light collection efficiency. It is helpful to improve the signal-to-noise ratio of the spectrometer. This paper first introduces the research status of NIR noninvasive biochemical analysis, and analyzes the existing technical difficulties, including weak spectral signals, background interference and periodic changes of blood flow volume. The focusing effect of several optical systems composed of optical fiber ellipsoidal mirror and compound parabola concentrator is studied by using the method of designing high efficiency focusing optical system. In this paper, the principle of Monte Carlo simulation is described, and the propagation of light in skin tissue is studied in combination with a three-layer skin tissue model. In the wavelength range of 1000nm-2350nm, the path length and penetration depth of photon propagation are simulated and calculated. The scattering times and diffuse reflected light energy are also discussed. The influence of incident-exit distance on the emission photon energy is discussed. Based on the above Monte Carlo simulation results, the structure of optical fiber probe is designed. The energy and illuminance distribution of diffuse reflected light collected by optical fiber are simulated by optical software. According to the characteristics of ellipsoidal reflector, the image point coordinate equation of the object on the focal plane reflected by the ellipsoid mirror is calculated on the basis of geometric optics theory. Based on this method, the structure parameters of the ellipsoidal mirror are optimized. The focused light energy characteristics of the ellipsoidal mirror are analyzed by using the ray tracing method, which is compared with the non-optical collecting system. The utilization ratio of ellipsoidal mirror to diffuse reflected light is 5.4 times higher. In this paper, the characteristics of the reflected light of the compound paraboloid concentrator (CPC) are analyzed, and the structural parameters of the CPC- concave mirror system are optimized. A dual compound parabolic condenser system is proposed for the first time. By comparing the change of condensing performance between standard and truncated CPC, the structure parameters of the best light gathering effect are optimized, and the focusing conditions of the two optical systems on diffuse reflected light of human body are simulated and studied respectively. Compared with the non-optical collection system, the structure parameters of the two optical systems are simulated. The utilization ratio of the truncated CPC- concave mirror system for diffuse reflected light is increased by 15.1 times, and that of the truncated double-compound parabolic condenser system is increased by 32.6 times. In this paper, several condensed light systems can effectively converge diffuse reflected light onto the detector, which is helpful to improve the signal to noise ratio and the overall analytical accuracy of the non-invasive biochemical analysis system.
【學(xué)位授予單位】：中國科學(xué)院研究生院（長春光學(xué)精密機(jī)械與物理研究所）
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：R318.6;O433

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