长波红外材料n型Hg_(1-x)Cd_xTe载流子寿命

测量了３种不同生长方法（加速坩埚旋转布里奇曼法、固态再结晶法和改进的布里奇曼生长大直径晶体法）制备的长波红外蹄镉汞晶体（块晶）载流子寿命的温度变化关系,与窄禁带半导体载流子复合机构的理论计算结果比较表明,优质晶体中是以带间碰撞复合为主。     

Ⅱ类热成像光机扫描技术的发展

根据武器系统的要求，缩小了军用热像仪扫描器的尺寸并减轻了其重量，指出改善空间分辨率是提高Ⅱ类热像仪性能的主要技术手段。认为采用限制孔径望远镜和变形光学系统是改善空间分辨率的简便而又经济的途径。     

Centric-scan SPRITE magnetic resonance imaging with prepared magnetisation

The combination of contrast preparation with centric-scan SPRITE imaging readout is investigated. The main benefit of SPRITE, its ability to image objects with short T2, is retained. We demonstrate T1 and T2 mapping as examples of magnetisation preparation followed by magnetisation storage and spatially resolved encoding. A strategy for selection of the most advantageous imaging parameters for contrast mapping is presented.     

Quantitative discrimination of water and hydrocarbons in porous media by magnetization prepared centric-scan SPRITE

MRI has considerable potential as a non-destructive probe of porous media, offering the possibility of rapid quantification of local oil and water content. This potential has not yet, however, been completely realized. In this paper, we explore a general magnetization preparation approach to the discrimination of water and oil in a model, representative, porous medium. These measurements have, as a common element, a centric scan pure phase encode readout based on the SPRITE methodology. Magnetization preparation permits facile T1, T2 and diffusion coefficient mapping as the basis for oil and water discrimination. Diffusion coefficient mapping proved to be the most robust approach to discrimination of oil and water. These methods are illustrated through static experiments and a dynamic immiscible fluid displacement experiment.     

线扩散函数法用于SPRITE探测器调制传递函数测试

在ＳＰＲＩＴＥ探测器的研制和生产检验中,对其调制传递函数（ＭＴＦ）进行测试,可以分析和评价探测器的空间分辨率。文中将线扩散函数法用于该方面的测试,描述了一般的光路安排和自动测试方案,而且考虑了测试用光学投影系统对探测器ＭＴＦ测试的影响,以及相应的测试、补偿方法。     

SPRITE探测器热成像系统的性能评价方法研究

文中介绍了ＳＰＲＩＴＥ探测器与一般离散阵列测器在性能评价方面的特殊性,建立了相应的性能评价模型,介绍了其中一些主要的处理方法,编制了热成像系统静态性能模软件包,通过计算机模拟结果与英国ＵＫＴＩＣＭ－Ⅱ的技术指标以国产系统测试结果的比较,证明了模型的可靠性和可行性。     

SPRITE MRI of bubbly flow in a horizontal pipe

Bubble flow is characterised by numerous phase interfaces and turbulence, leading to fast magnetic resonance signal decay and artefacts in spin-warp imaging. In this paper, the SPRITE MRI pulse sequence, with its potential for very short encoding times, is demonstrated as an ideal technique for studying such dynamic systems. It has been used to acquire liquid velocity and relative intensity maps of two-phase gas–liquid dispersed bubble flow in a horizontal pipe at a liquid Reynolds number of 14,500. The fluids were air and water and a turbulence grid was used to generate a dispersed bubble flow pattern. The SPRITE technique shows promise for future research in gas–liquid flow.     

Sectoral sampling in centric-scan SPRITE magnetic resonance imaging

A new approach to the construction of k-space trajectories for centric-scan SPRITE in both 2D and 3D is presented. All benefits of previous SPRITE methods are retained, most importantly the ability to image objects with short T*(2). This new approach gives more flexibility in the choice of number of interleaves with points more evenly distributed across k-space. All these improvements positively contribute to image quality and resolution, which can be also traded off against experimental speed. Sectoral sampling will have significant benefits for magnetisation preparation contrast imaging.     

Phantom materials for single point imaging pulse sequences

The popularity of pure phase encode MRI techniques, including single point imaging (SPI), is steadily increasing, particularly in instances where the samples of interest are solid-like, or for other reasons possess short effective transverse relaxation times, T2*. As the interest in these techniques grows, so too does the need for a phantom material which is representative of this class of samples. The characteristics of such a phantom should include chemical and physical stability, straightforward preparation, high signal to noise ratio and relaxation times which are both easily manipulated and representative. To this end, we have developed a gelatin/sucrose-based gel which addresses the above criteria and behaves as a very flexible short T2* phantom. An order of magnitude variation in T1 and T2 can be achieved over a reasonable range of sucrose concentration. Even larger changes can be achieved with the addition of further doping agents.