叠盖电极技术在SPRITE 探测器上的应用

文中主要介绍了叠盖电极技术在SPRITE探测器上的实际应用，并给出了具体实验结果。选择适当的叠盖电极尺寸可以使SPRITE的响应率Rυ提高一倍以上，探测率D^*普遍提高30％左右，高的可达80％。实验结果表明，叠盖电极技术明显地提高了SPRITE器件的性能，是一种简便的提高SPRITE性能的新途径。     

A comparison of magnetic resonance imaging methods for fluid content imaging in porous media

Quantitative measurements are important for imaging fluid content in porous media. Conventional MRI methods suffer from contrast because of relaxation times in porous media, resulting in measurements of apparent fluid content, not the true fluid content. We compare four magnetic resonance imaging methods for fluid content imaging in several water‐saturated reservoir core plugs: frequency‐encoded spin echo, single point ramped imaging with T₁ enhancement, hybrid spin echo single point imaging (SE‐SPI), and T₂ mapping SE‐SPI. 1‐D profiles obtained with each method were compared in terms of image quality, image sensitivity, and quantification of water content. The image quality of short T₂ lifetime samples suffered from blurring in hybrid SE‐SPI images. Image sensitivity was the highest in the profiles obtained with frequency‐encoded spin echo. The quantification of frequency‐encoded spin echo, T₂ mapping SE‐SPI, and hybrid SE‐SPI suffered in core plugs with a significant population of short T₂ components because of T₂ attenuation. Overall, single point ramped imaging with T₁ enhancement was found to be the most general method for fluid content imaging. Copyright © 2013 John Wiley & Sons, Ltd.     

SPRITE探测器的电阻问题

ＳＰＲＩＴＥ探测器的电阻是一个重要的器件参数。研究了Ｈｇ１－ｘＣｄｘＴｅ材料组分和电阻率、芯片厚度和表面电导等因素对该电阻的影响，并就实验数据进行了比较结果表明：ＳＰＲＩＴＥ器件的室温电阻主要是受Ｈｇ１－ｘＣｄｘＴｅ材料组份和芯片厚度的影响。而其液氮温度电阻则主要是受芯片表面电导的影响。     

自动焊接技术在SPRITE探测器内引线联接工艺中的应用

为使自动金丝球焊接技术应用于碲镉汞红外器件的研制工艺，在大量试验的基础上，摸索出一套使用自动金丝球焊接技术进行了ＳＰＲＩＴＥ红外器件内引线焊接的可靠方法。文中还对自动焊接的精度和最小间距进行了探讨。     

Magnetic Resonance Imaging of Gases: A Single-Point Ramped Imaging with T1 Enhancement (SPRITE) Study

A pure phase-encoding MRI technique, single-point ramped imaging withT₁enhancement, SPRITE, is introduced for the purpose of gas phase imaging. The technique utilizes broadband RF pulses and stepped phase encode gradients to produce images, substantially free of artifacts, which are sensitive to the gasT₁andT^*:₂relaxation times. Images may be acquired from gas phase species with transverse relaxation times substantially less than 1 ms. Methane gas images,¹H, were acquired in a phantom study. Sulfur hexafluoride,¹⁹F, images were acquired from a gas-filled porous coral sample. High porosity regions of the coral are observed in both the MRI image and an X-ray image. Sensitivity and resolution effects due to signal modulation during the time-efficient acquisition are discussed. A method to increase the image sensitivity is discussed, and the predicted improvement is shown through 1D images of the methane gas phantom.     

Repetition time and flip angle variation in SPRITE imaging for acquisition time and SAR reduction

Single point imaging methods such as SPRITE are often the technique of choice for imaging fast-relaxing nuclei in solids. Single point imaging sequences based on SPRITE in their conventional form are ill-suited for in vivo applications since the acquisition time is long and the SAR is high. A new sequence design is presented employing variable repetition times and variable flip angles in order to improve the characteristics of SPRITE for in vivo applications. The achievable acquisition time savings as well as SAR reductions and/or SNR increases afforded by this approach were investigated using a resolution phantom as well as PSF simulations. Imaging results in phantoms indicate that acquisition times may be reduced by up to 70% and the SAR may be reduced by 40% without an appreciable loss of image quality.     

SPRITE探测器时空滤波特性分析

用ＳＰＲＩＴＥ探测器的脉冲响应（格林函数）描述了基于时间频率和空间频率变化的ＳＰＲＩＴＥ探测器光学传递函数（ＯＴＦ）、调制传递函数ＭＴＦ和相位传递函数（ＰＴＦ）,并由此分析了该探测器对红外辐射图像在时间域和空间域的联合滤波特性     

SPRITE探测器截止波长与HgCdTe材料组份的关系

根据探测器截止波长的变化,讨论和确定了ＨｇＣｄＴｅ材料组份的实际偏差量。从ＳＰＲＩＴＥ探测器截止波长的测量结果计算,对用布里奇曼、Ｔｅ溶剂和固态再结晶等三种体晶技术生长的长波ＨｇＣｄＴｅ材料,在１ｍｍ２的面积上,材料组份的偏差量均能优于±０．００１５ｍｏｌｅ,在１ｃｍ２的面积上,统计平均的组份偏差相应要增大约一个数量级。     

SPRITE探测器在小批量试生产阶段的维修性改善

国内外武器装备发展与应用的实践证明,开展维修性工作,改善维修性,对提高部队战斗力、节省装备寿命周期费用有着极其重要的作用。SPRITE探测器是红外热像仪中的关键重要部件,在其小批量试生产阶段从提高可靠性出发,对它的维修性进行了改善,取得了较好的社会效益和经济效益。     

叠盖电极高性能SPRITE探测器

由于扫出效应，载流子大量聚集在邻近电极的区域，但电极处的强复合作用使SPRITE读出区光生载流子数衰减很多，采用叠盖电极技术可以有效地阻载流子在地电极处的快速复合，读出区中光生非平衡载流子总数为无叠盖电极时的2.18倍，输出信号大幅度提高。该技术对现有工艺的改变极小，是一种比较现实的提高SPRITE探测器性能的有效办法。叠盖电极用于SPRITE探测器，可明显提高性能。