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1、摘 要摘 要红外光谱仪是用于红外光谱测量与分析的检测仪器，广泛应用于石油化工、生物医学、食品安全和环境监测等领域。在这些应用中很多时候需要体积较小、方便移动的检测仪器用于现场分析。为了满足这一需求，众多科研机构和企业研制出了多种轻便、紧凑的红外光谱仪。它们中的大部分是通过缩小光学系统的尺寸实现仪器的小型化。这会使光学系统的通光孔径和有效焦距（或动镜移动的距离）都相应减小，导致光谱仪的性能明显下降。相比之下，基于平板波导技术的小型化方法，不仅能够有效地减小光学系统尺寸，而且不会导致光谱仪性能下降，同时系统中没有运动部件，很适合用于设计现场分析用途的小型红外光谱仪。现有的平板波导红外光谱仪中所用的
2、核心部件为平板波导和柱面光栅，其加工难度大、制作成本高，限制了它们的推广。本论文提出了一种基于中空平板波导的红外光谱仪小型化方法，采用中空平板波导结构和平面光栅分光结构，降低了加工难度和制作成本。通过试验样机的研制和测试，证明了该小型化方法是有效和可行的，所设计的小型红外光谱仪性能能够满足现场分析应用的要求。本论文的主要研究工作有以下几个方面：1. 光栅光谱仪理论研究。从光栅光谱仪的工作原理出发，分析了红外光谱仪中使用的红外辐射源和红外探测器的特性；进一步研究了平面衍射光栅的色散性能；根据光栅光谱仪的像差理论，深入分析了光谱带宽和分辨率的影响因素，为平板波导红外光谱仪的研制提供理论依据。2.
3、平板波导光谱仪光学系统设计。针对平板波导光谱仪的特点，将光学系统的设计分解为分光结构的设计和平板波导结构的设计。为使光谱仪结构尽量紧凑，分光结构采用像差和尺寸都比较小的交叉非对称Czerny-Turner结构，对其像差进行了深入分析，理论推导出球差、慧差、像面弯曲的校正公式，并按照设计指标完成分光结构的设计。根据非成像光学设计理论，深入研究了平板波导结构的聚光特性，分析其对狭缝放大率、狭缝弯曲半径、光线反射次数等的影响，在此基础上实现了高聚光比、小尺寸中空平板波导结构的设计。在Zemax软件中，使用Ref、Pick up和ZPL功能建立完整的光学系统模型，确保优化时不会出现结构异常的光学系统；
4、以探测器接收到的能量和RMS Spot Y为优化目标，通过优化得到光学效率最高、总体像差最小的光学系统；并对其进行了公差分析确保光学系统加工制造的可行性。3. 平板波导光谱仪样机研制。针对现场应用中轻便、抗振的要求，对光学系统进行了一体化设计。根据中空平板波导光谱仪的结构特点，精心设计了可拆卸、模块化的光学调整机构，以实现各光学元件的精确定位，并能在胶合工艺结束后顺利移除。设计了专门的机械装置，用于上、下平面反射镜的夹持与定位；设计了狭缝固定装置，实现了狭缝和柱面准直透镜的固定及狭缝的调整；采用1:1打印的光学图纸实现了柱面成像透镜及其它光学元件的粗定位；创造性地设计了两用调整装置，既可工作在
5、柔性模式下用于柱面反射镜的调整，又可工作在刚性模式下用于平面光栅和探测器的调整。在此基础上，设计了胶合工艺流程，完成了所有光学元件的胶合。针对液体和薄膜的红外光谱检测需求，设计了平板波导光谱仪的衰减全反射附件。4. 平板波导光谱仪样机性能测试与分析。通过分析确立了平板波导光谱仪中光波长与探测器像元位置的线性关系，并采用双波长定标法对试验样机进行波长定标。在此基础上进行了光谱实测实验，测量了氨气和六氟化硫气体的透过率谱以及甲基硅油和磷酸三乙酯的衰减全反射谱，并与傅里叶变换红外光谱仪的测量结果进行了对比分析，验证了试验样机的性能。对样机的杂散光进行了分析，设计了光栅多次衍射杂散光的抑制装置，通过精
6、心设计滤光片的参数和摆放位置，最大限度地抑制了光栅多次衍射杂散光，改善了样机的信噪比。结果表明平板波导光谱仪体积小、质量轻、性能高，能满足现场快速分析的应用需求。关键词：小型红外光谱仪 光学设计 平板波导 光栅多次衍射杂散光 一体化设计IIAbstractAbstractInfrared spectrometer is an instrument for measuring and analyzing infrared spectra, which is widely used in petrochemical, biomedicine, food safety and environment
7、al monitoring. These applications sometimes need small and portable instrument for on-site analysis.To meet this demand, many research institutions and companies have developed a variety of lightweight and compact infrared spectrometers, most of which are miniaturized by reducing the size of optical
8、 system. Correspondingly, the aperture size and the effective focal length (or the moving distance of the movable mirror) are decreased, resulting in significantly decreased performance of the spectrometers. By contrast, the miniaturization method based on planar waveguide technology not only can ef
9、fectively reduce the size of the optical system, but also can keep the performance of the spectrometer unchanged. This method is suitable for designing miniature infrared spectrometer with no moving parts for on-site analysis. The core components of the existing planar waveguide infrared spectromete
10、r are planar waveguide and cylindrical grating, which are difficult to process and have high cost. These disadvantages limit the using of these spectrometers.This paper presents a miniaturization method of infrared spectrometer based on hollow planar waveguide and plane grating to reduce the process
11、ing difficulty and the cost. By developing and testing the prototype of the planar waveguide infrared spectrometer, the effectivity and feasibility of this method is proved, and the performance of the prototype can satisfy the requirements of field applications.The main research work of this paper h
12、as the following parts:1. Theoretical study of grating spectrometer. Based on the principle of grating spectrometer, the features of infrared radiation and infrared detectors used in infrared spectrometer are analyzed; the dispersion properties of plane diffraction grating are studied; the factors t
13、hat influence the spectral bandwidth and resolution are deeply analyzed according to the aberration theory of grating spectrometer. These provide a theoretical basis for developing a planar waveguide infrared spectrometer.2. Optical design of planar waveguide infrared spectrometer. According to the
14、characteristics of planar waveguide infrared spectrometer, the design of the optical system is decomposed into two parts, planar waveguide structure and dispersive structure. A cross-asymmetric Czerny-Turner structure of small aberration and size is chosen as the dispersive structure to make the spe
15、ctrometer compact, and the correction conditions of spherical aberration, coma, field curvature are deduced based on in-depth analysis of its aberrations. The non-imaging optical design theory is used to study the converging characteristic of the planar waveguide structure, analyze its impact on the
16、 magnification of slit, bending radius of slit, the times of light reflection, and complete the design of a high concentration ratio, small size hollow planar waveguide structure. In Zemax software, a complete model of the optical system is established using Ref, Pick up and ZPL functions, ensuring that no abnormal structure would appear when the optical system is optimized; a good optical system with high efficiency and small total aberrati
