数字微镜器件在红外目标场景仿真器中的应用研究

发布时间：2018-07-25 14:47

【摘要】：作为半实物仿真实验系统的核心部件,红外目标场景仿真器主要是为半实物仿真系统提供动态的红外目标和背景环境,满足仿真实验所需要的场景条件需求。目前几种典型的红外目标仿真技术包括液晶光阀、红外CRT、激光二极管、电阻阵列和DMD等技术。相较于其它红外目标仿真技术,DMD型红外目标场景仿真器以其良好的性能和较低的成本优势而得到了比较深入的应用研究。本文通过调研DMD型红外目标场景仿真器发展现状,针对DMD型红外目标场景仿真器在实际应用中存在的问题,展开深入研究与具体分析。DMD芯片是由美国德州仪器(TI)公司于1987年发明的反射式空间光调制器,并被广泛应用于DLP投影显示,高清影院,光谱成像以及光刻等诸多领域。目前TI公司生产的DMD芯片工作波段为320~2500nm,其光学窗口的光谱透过率截止波长为2700nm。因此DMD应用于3~5μm和8~12μm波段时,需要对其表面的光学窗口进行更换,以保证DMD能在中波和长波红外波段正常工作。本论文选用Zn Se红外材料作为DMD光学窗口,首先对Zn Se窗口玻璃进行镀膜处理,镀膜完成后的Zn Se光学窗口在3~5μm波段的光谱透过率高于95%,在8~12μm波段的光谱透过率高于80%,然后针对DMD微镜片更换过程中要求的严苛环境和精细操作,依托实验室微纳加工工艺,完成了DMD芯片光学窗口的无损更换。经过实验测试,更换窗口后的DMD芯片可正常应用于3~5μm和8~12μm波段。DMD器件应用于红外波段时,DMD微镜片的衍射效应会引起系统成像对比度下降,并且随着入射波长的增大,衍射效应越来越显著。当其应用于8~12μm波段时,衍射效应造成系统对比度严重下降,使得DMD型红外目标场景仿真器成像性能无法满足仿真需求。为降低DMD微镜片的衍射效应,提高系统成像对比度,本文根据微镜片工作原理和结构特性,建立DMD微镜片二维衍射光栅衍射模型,利用标量衍射理论与矢量衍射理论仿真分析DMD微镜片在红外波段的衍射特性。首先利用标量衍射模型仿真计算得出:在3~5μm波段,照明光束以28°角度入射时,DMD型红外目标场景仿真器成像对比度最好。然后利用矢量衍射模型仿真计算在8~12μm波段,光束偏振态对DMD衍射光强分布影响,由仿真结果得出结论:在8~12μm波段,照明光束以TM线偏振光入射,入射角调整为48°,能明显降低衍射效应对DMD型目标场景仿真器成像对比度影响。为测量验证不同光束入射角和偏振态下DMD衍射特性,首先搭建DMD衍射特性测量系统,验证分析在8~12μm波段,DMD矢量衍射模型的正确性。然后结合系统成像质量因素的分析,定量测量分析DMD微镜片衍射效应和微镜片以及投影镜头自发辐射对系统成像对比度的影响。最后根据DMD衍射特性实验分析结果,对改进的DMD型红外目标场景仿真器成像对比度进行实验验证。由实验测量分析可知:在8~12μm波段,照明光束为TM线偏振光,光束以48°角度入射时,微镜片衍射效应对DMD型目标场景仿真器系统影响最小,系统成像对比度最好。研制了DMD型长波红外目标场景仿真器,首先根据DMD衍射模型的仿真计算和实验测量结果,设计相应的照明和投影光学系统,通过照明和投影光路空间结构的合理布局以及光束特性的调制,降低DMD衍射效应对系统成像质量的影响,提高系统对比度。其中照明光路选用直接照明的结构设计,既能使系统具有较高的光能利用率,又减小系统结构长度;投影镜头选用远心光路设计,保证了投影系统与照明系统的光瞳匹配和实现系统出射平行光。然后对研制的样机进行成像性能测试,经实验测量验证,在8~12μm波段,系统成像对比度为0.85左右,成像性能良好,可为半实物仿真系统提供高质量的长波红外目标场景条件。
[Abstract]:As the core component of the hardware in the loop simulation experiment system, the infrared target scene simulator mainly provides the dynamic infrared target and background environment for the hardware in the loop simulation system, and meets the requirement of the scene conditions required by the simulation experiment. At present, several typical infrared target simulation techniques include the liquid crystal light valve, the infrared CRT, the laser diode and the resistance. Compared with other infrared target simulation techniques, compared with other infrared target simulation techniques, the DMD infrared target scene emulator gets more in-depth application research with its good performance and lower cost advantage. This paper investigates the development status of the DMD infrared target scene simulator and applies the DMD infrared target scene emulator in practical application. The.DMD chip is a reflection type spatial light modulator invented by the American TI (TI) Company in 1987, and is widely used in many fields such as DLP projection display, high definition cinema, spectral imaging and photolithography. At present, the DMD chip produced by TI company is 320~2500nm, its light The cut-off wavelength of the spectral transmittance of the learning window is 2700nm., so when DMD is applied to the 3~5 m and 8~12 m bands, the optical window of the surface needs to be replaced to ensure that DMD can work normally in the medium wave and the long wave infrared band. In this paper, Zn Se infrared material is used as the optical window of DMD, and the plating of Zn Se window glass is first plated and plated. The spectral transmittance of the Zn Se optical window at the 3~5 mu m band is higher than 95%, and the spectral transmittance is higher than 80% at 8~12 / M band. Then, according to the harsh environment and fine operation required in the DMD microlens replacement process, the optical window of the DMD chip is replaced by the laboratory microprocessing technology. The DMD chip after changing the window can be used normally in the 3~5 and 8~12 M band.DMD devices to be applied to the infrared band. The diffraction effect of the DMD microlenses will cause the decline of the contrast of the system imaging, and the diffraction effect becomes more and more significant with the increase of the incident wavelength. When it is applied to the 8~12 in the M band, the diffraction effect causes the serious contrast of the system. The imaging performance of the DMD infrared target scene simulator can not meet the simulation requirements. In order to reduce the diffraction effect of the DMD microlenses and improve the contrast of the system imaging, this paper establishes the DMD micro lens two-dimensional diffraction grating diffraction model based on the working principle and structure characteristics of the microlenses, and uses the scalar diffraction theory and the vector diffraction theory to simulate the diffraction model. The diffraction characteristics of the DMD microlens in the infrared band are analyzed. First, it is obtained by the scalar diffraction model that the contrast degree of the DMD infrared target scene emulator is the best when the illumination beam is incident at the angle of 28 degrees in the 3~5 Mu band. Then the vector diffraction model is used to simulate the 8~ 12 U M band, and the beam polarization state is distributed to the intensity distribution of the DMD diffraction. From the simulation results, it is concluded from the simulation results that the illumination beam is polarized by the TM line and the incident angle is adjusted to 48 degrees in the 8~12 mu m band. The diffraction effect can obviously reduce the influence of the diffraction effect on the contrast degree of the DMD target scene emulator. In order to test and verify the DMD diffraction characteristics of the incident angles and polarization states of different beams, the DMD diffraction characteristic measurement system is set up first. Verify and analyze the correctness of the DMD vector diffraction model at 8~12 mu m band. Then combined with the analysis of the quality factors of the system imaging, the influence of the diffraction effect of DMD microlenses and the micro lens and the spontaneous radiation of the projective lens on the contrast of the imaging system are quantitatively measured. Finally, the improved DMD infrared infrared spectroscopy is based on the analysis results of the DMD diffraction specificity experiment. The contrast degree of the target scene simulator is verified experimentally. It is known from the experimental measurement that the illumination beam is polarized on the TM line in 8~12 mu m band, and when the beam is incident at 48 degrees, the micro lens diffraction effect has the least influence on the DMD target scene simulator system and the system imaging pair is the best. The DMD long wave infrared target scene is developed. According to the simulation calculation and experimental measurement results of the DMD diffraction model, the corresponding lighting and projective optical systems are designed. The influence of the DMD diffraction effect on the imaging quality of the system is reduced by the rational layout of the lighting and projection optical path spatial structure and the modulation of the beam characteristics, in which the contrast of the system is improved. The structure design of lighting can not only make the system have a high utilization rate of light energy, but also reduce the structure length of the system. The projection lens is designed by the far center light path, which ensures the matching of the pupil of the projection system and the lighting system and the realization of the system ejection parallel light. Then the performance test of the developed prototype is verified by experimental measurement, in 8~12 mu m The system has a good imaging performance of about 0.85, and can provide high quality long wave infrared target scene conditions for hardware in the loop simulation system.
【学位授予单位】：中国科学院长春光学精密机械与物理研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TJ765.4

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