CCD Camera for Intermediate Voltage Electron Microscopes

中压电子显微镜用 CCD 相机

• 批准号: 7099774
• 负责人: KENNETH H DOWNING
• 金额: $ 35.22万
• 依托单位: UNIVERSITY OF CALIF-LAWRENC BERKELEY LAB
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-01 至 2010-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7099774
• 关键词: bioimaging /biomedical imaging; biomedical equipment development; charge coupled device camera; electron microscopy

DESCRIPTION (provided by applicant): Charge-coupled device (CCD) cameras have found wide application in electron microscopy. They provide much faster availability of image and diffraction data than photographic film, and this improvement in turnaround time has allowed a tremendous increase in the efficiency of specimen evaluation, microscope operation and automation, and data recording. For some types of work the data collected with a CCD is of higher quality than that recorded on film. However, the CCD performance is seriously compromised when the microscope is operated much above 100 kV, due to the decrease in efficiency of the scintillator. The higher voltages result in a decrease of the signal level and introduction of noise, as well as an increase in lateral scattering of the electrons within the scintillator, which decreases the resolution. Together these effects can produce a detective quantum efficiency (DQE) which is far below that of film, and indeed too low for work such as low-dose imaging of proteins. The use of Intermediate Voltage Electron Microscopes (IVEMs) operating at 300 - 400 kV is increasing as the many advantages of the higher accelerating voltage become more widely recognized, so the CCD performance on these microscopes is becoming more of a limitation. We are building a new CCD camera system designed to overcome the poor performance of CCD cameras on IVEMs by decelerating the electrons before they reach the camera. We mount the CCD so that it can be floated to around 200 kV, so that when the microscope is operated at 300 kV we obtain the advantages of the IVEM but the camera should perform as well as on a 100 kV microscope. Further improvements will be made to the scintillator to produce even better signal and resolution characteristics than currently available. This advance will, in turn, allow us to utilize the newest, very large format CCDs that are fabricated with smaller pixels. These adaptations will produce substantial benefits in work ranging from high-resolution structural studies of proteins and viruses to the three dimensional study of cell ultrastructure.

描述（由申请人提供）：电荷耦合器件（CCD）相机已在电子显微镜中得到广泛应用。与照相胶片相比，它们提供的图像和衍射数据的可用性要快得多，并且周转时间的改进大大提高了样本评估、显微镜操作和自动化以及数据记录的效率。对于某些类型的工作，使用 CCD 收集的数据比胶片上记录的数据质量更高。然而，当显微镜在远高于 100 kV 的电压下运行时，由于闪烁体效率的降低，CCD 性能会受到严重影响。较高的电压会导致信号电平降低并引入噪声，以及闪烁体内电子横向散射的增加，从而降低分辨率。这些效应共同产生的探测量子效率 (DQE) 远低于胶片，而且对于低剂量蛋白质成像等工作来说确实太低。随着更高加速电压的许多优点得到越来越广泛的认可，在 300 - 400 kV 下工作的中压电子显微镜 (IVEM) 的使用越来越多，因此这些显微镜上的 CCD 性能越来越受到限制。我们正在构建一种新的 CCD 相机系统，旨在通过在电子到达相机之前对其进行减速来克服 IVEM 上 CCD 相机的较差性能。我们安装 CCD，使其可以浮动到 200 kV 左右，这样当显微镜在 300 kV 下运行时，我们可以获得 IVEM 的优势，但相机的性能应与 100 kV 显微镜上一样好。闪烁体将得到进一步改进，以产生比目前更好的信号和分辨率特性。反过来，这一进步将使我们能够利用采用更小像素制造的最新、超大幅面 CCD。这些适应将为从蛋白质和病毒的高分辨率结构研究到细胞超微结构的三维研究等工作带来巨大的好处。