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远紫外感应式阳极光子计数成像探测器研究

Study of Far-ultraviolet Photon Counting Imaging Detector Based on Induced Charge Position Sensitive Anode

【作者】 韩素立

【导师】 陈波;

【作者基本信息】 中国科学院研究生院(长春光学精密机械与物理研究所) , 光学工程, 2014, 博士

【摘要】 极光主要是由太阳风和磁尾中的带电粒子沿地球磁场线注入高纬度地区和大气的中性成分相互作用产生的。极光的在远紫外(Far-ultraviolet, FUV)波段包括:HI121.6nm (Lyman-)、OI130.4nm、OI135.6nm和N2的140nm~180nm LBH(Lyman-Birge-Hopfield)波带。其中,N2LBH辐射强度分布能够反映极光椭圆区的形态,确定极光椭圆区的边界和地磁亚暴发生的时间和位置,并且能通过对图像的反演获得太阳EUV波段辐射通量等信息。因此需要研制一台广角极光成像仪,对极光FUV辐射中的N2分子辐射的LBH带(140nm~180nm)进行成像观测,获得太阳活动的相关信息。远紫外光子计数成像探测器作为广角极光成像仪的核心器件,本论文对其设计优化、成像性能检测、辐射定标等方面展开研究,为实际工程研制提供理论依据。研究内容有以下几点。(1)研究FUV光子计数成像探测器的部件组成及其工作原理,分析非晶态半导体薄膜对感应电荷读出方式光子计数探测器成像性能的影响,优化半导体薄膜相关参数。根据Fick第二定律推导了半导体薄膜方块电阻和电子云扩散时间的函数关系,确定了非晶态半导体薄膜方块电阻范围(30MΩ/□~2700MΩ/□),并进行了实验验证。(2)为了满足成像要求,优化探测器的性能,对远紫外光子计数成像探测器进行了性能评价研究。对微通道板的增益进行了测评,分析了不同电压下的增益,优化了探测器的工作电压。对成像探测器的空间分辨率、暗噪声、动态范围等成像性能进行了测试。(3)完成FUV光子计数成像探测器的量子效率定标研究,利用性能稳定的氘灯光源照射光子计数成像探测器,对远紫外光子计数成像探测器进行辐射定标,确定入射光子数和图像的灰度值随波长的变化关系。(4)采用后期图像处理算法提高成像质量,优化性能。采用基于Lucy-Richardson(L-R)的图像盲卷积恢复算法对探测器所成图像进行处理,重建后探测器所成图像的空间分辨率由0.5mm提高到0.4mm。

【Abstract】 Aurora is generated by high-energy particles from the solar wind along theearth s magnetic field lines injecting into the high latitudes of the earth andinteracting with the main components of the atmosphere. Aurora spectral radiation infar-ultraviolet (FUV) includes HI121.6nm (Lyman-), OI130.4nm, OI135.6nm andthe LBH (Lyman-Birge-Hopfield) of N2from140nm to180nm. The intensitydistribution of N2LBH radiation can show the shape of aural ellipse area, determinethe boundary of aural ellipse area, occurrence time and location of the magneticsub-storms, also obtain radiation characteristics of solar EUV spectra through theinversion of the image. Therefore, a wide field aurora imager is developed forimaging and observing N2molecule LBH radiation intensity distribution(140nm~180nm) to obtain the relevant information of solar activity. Far-ultravioletphoton counting imaging detector is the core of the wide field aurora imager, so thispaper mainly researches on the optimization design, imaging performance test andthe calibration of the Far-ultraviolet photon counting imaging detector. The maincontents are concluded as follows:(1) Study on the components of the FUV photon counting imaging detector andtheir working principle. Analysis of the influence for the semiconductor thin film tothe performance of the photon counting imaging detector based on induced chargereadout and optimization of parameters of the semiconductor thin films. The relationship of sheet resistance of the semiconductor and the electron diffusion timewas derived according to FIck s second law and the range of the sheet resistance(30MΩ/□~2700MΩ/□) was also obtained and vertified by experiment.(2) Performance measurement and evaluation was implemented to meet theimaging requirements and optimize the performance of the detector. The gain wasalso obtained at different voltage.The resolution test, dark counts and dynamic rangewere also measured.(3) The radiation calibration of the photon counting detector was studied. Thequantum efficiency at different wavelength, different incident angle was analyzedand measured. A stable deuterium lamp was used to calibration the photon detectorto determine the relationship between the gray scale of the image and the incidentnumber of the photons changing with wavelength.(4) The image processing algorithm can improve the imaging quality of theimage. Using the blind deconvolution algorithm based on L-R to process theobtained images, the resolution was improved from0.5mm to0.4mm.

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