DEVELOPMENT OF SLOW SCAN CAMERA & INTERFACE

这个核心研发项目的目标是开发一个系统， NCMIR IVEM在分辨率、速度、 为用户提供电子读出装置 与使用下一代2k x 2k的胶片相当或更好 CCD成像系统。 这个子项目对此非常重要 研究计划。 它将使我们能够改善图像采集 计算机化三维重建的速度和精度， 厚生物标本的可视化。 我们最近 完成了新的透镜耦合相机系统。 它已经安装 正在进行测试。 这有五个部分 项目：1）液晶屏开发：两项美国专利 （#5，401，964和#5，594，253）已发给我们，包括一个刚刚 1997年1月发布。 一种基于薄箔的P20荧光屏， 由格兰特科学公司根据我们的 专利设计。 该设计首次被描述和表征， 1994（Fan和Ellisman，Ultramicroscopy 55：7 - 14，1994）并优化 1996年（Fan等，Ultramicroscopy 66：11 - 19，1994）; 2）透镜耦合 系统，由光学研究协会根据我们的 规格，并由廷斯利实验室制造，是 已交付并已安装在IVEM上。 设计目标是 对光学设计师和制造商都具有挑战性， 廷斯利不得不在透镜首次交付后进行修改， 由于该透镜未能满足我们的光学系统中的一些设计目标， 台架试验 性能显著改善后， 改性 调制传递函数（MTF）为55% 奈奎斯特频率，并且在整个视场中几乎是平坦的， 其是直径超过10厘米的区域。 整体光 透过率为83%，超过80%的设计目标。 的 光学系统的分辨率和中继效率与 该系统提供的分辨率 超过了光纤耦合系统的可能性; 3） 采用的CCD芯片在技术上比 市售，并作为合作项目的一部分提供。 麻省理工学院的林肯实验室和美国空军的研究工作。 该设备采用了非常先进的技术，并有8高带宽 可以并行读出的端口。 虽然只有四个港口 在我们的实现中使用，我们仍然会实现实质性的 与我们目前的1k x 1k设备相比， 成像阵列的尺寸是我们目前CCD成像仪的2倍以上; 4） 设计了与CCD摄像机控制器的计算机接口， 切实贯彻 该接口采用基于Unix的工作站耦合 DataCube MV200图像处理器控制摄像机， 解复用并组装图像。 新的图形界面 设计用于相机。 5)机械一体化 相机组件是使用一套3D Solid 建模/2D CADCAM软件工具。 整个系统最初 在3D中建模，以允许可视化和验证 建设前的整合。 从最终的优化模型中， 为施工制作了工程示意图。 的 该系统的部件包括：真空兼容的下降法兰 其支撑和定位闪烁体屏和含铅玻璃 窗口，可调透镜支撑硬件，机械隔离， 陀螺仪摄像机支撑外壳， CCD芯片的定心和调整，自动旋转，以及 精确对焦，以及一个相机外壳适配器， 交换2kx2k和1kx1k摄像头。 初步测试 表明该成像系统的整体性能 比胶片敏感得多，比 400 keV的光纤耦合CCD系统（数据来自亚利桑那州 大学）。 正在开始进行进一步的定量评价 与亚利桑那大学的约翰·斯宾塞博士和左健明博士合作 州立大学。 我们还计划探索使用应用程序 专用集成电路（ASIC）探测器作为CCD的替代品 用于TEM成像。 ASIC检测器由Xuong博士开发 UCSD的Nguyen-Huu及其同事， 应用. 我们最近测试了该装置的电子 在80 - 400 keV的能量范围内的检测（Fan等人，在综述中， Ultramicroscopy，1997），结果非常令人鼓舞。 一个 基于ASIC的成像系统将具有许多优势， 基于CCD的成像系统（见第4A2.2节）。 Xuong博士将 在这个项目上与我们合作。

The objective of this core TR&D project is to develop a system for the NCMIR IVEM with the necessary enhancements in resolution, speed and sensitivity to provide users with an electronic readout device comparable to or better than film using a next generation of 2k x 2k CCD imaging system . This subproject is very important to this research program. It will allow us to improve the image acquisition rate and precision for computerized 3-D reconstruction and visualization of thick biological specimens. We have recently completed the new lens coupled camera system. It has been installed on the IVEM and is undergoing testing. There are five parts to this project: 1) scintillating screen development: two US patents (#5,401,964 and #5,594,253) have been issued to us including one just issued in January, 1997. A thin foil-based P20 phosphor screen has been made for this system by Grant Scientific according to our patented design. The design was first described and characterized in 1994 (Fan and Ellisman, Ultramicroscopy 55:7-14, 1994) and optimized in 1996 (Fan et al, Ultramicroscopy 66:11-19, 1994) ; 2) Lens coupling system, designed by Optical Research Associates according to our specifications, and manufactured by Tinsley Laboratories, was delivered and has been installed on the IVEM. The design goal was challenging for both the optical designer and the manufacturer, and Tinsley had to make a modification after the lens was first delivered, as the lens failed to meet some of the designed goals in our optical bench test. The performance was significantly improved after the modification. The mod EMulation transfer function (MTF) is 55% at the Nyquist frequency, and is nearly flat across the entire field of view, which is an area over 10 cm in diameter. The overall light transmittance is 83%, exceeding the design goal of 80%. The resolution and relay efficiency of the optical system match well with that of the scintillating screen and the system delivers resolution exceeding that possible with a fiber-optically coupled system; 3) The CCD chip being employed is technologically more advanced than what is commercially available and was provided as part of a collaborative research effort with MIT's Lincoln Laboratory and the US Air Force. This device employs very advanced technology and has 8 high bandwidth ports which may be read out in parallel. Although only four ports are being used in our implementation, we will still achieve a substantial speedup as compared to our current 1k x 1k device, yet are able to image an array more than 2x the size of our current CCD imager; 4) The computer interface to the CCD camera controller has been designed and implemented. The interface employs a Unix-based workstation coupled to DataCube MV200 image processor to control the camera and to demultiplex and assemble the image. A new graphical interface has been designed for use of the camera. 5) Mechanical integration of the camera components was designed in house using a suite of 3D Solid Modeling/2D CADCAM software tools. The complete system was initially modeled in 3D to allow for visualization and validation of total integration prior to construction. From the final, optimized model, engineering schematics were generated for construction. The components of the system include: a vacuum compatible drop flange which supports and positions the scintillator screen and leaded glass window, adjustable lens support hardware, a mechanically isolated, gyroscopic camera support housing which allows for sub-micron centering and adjustment of the CCD chip, automated rotation, and precision focusing, and a camera housing adapter which allows quick swapping of the 2kx2k and 1k x1k camera heads. Preliminary tests indicate that the overall performance of this imaging system is considerably more sensitive than film and better than a fiber-optically coupled CCD system at 400 keV (Data from Arizona State University). A further quantitative evaluation is beginning conducted in collaboration with Drs. John Spence and Jian Ming Zuo at Arizona State University. We also plan to explore the use of an Application Specific Integrated Circuit (ASIC) detector as an alternative to a CCD for TEM imaging. The ASIC detector was developed by Dr. Xuong Nguyen-Huu of UCSD and co-workers for X-ray crystallography applications. We have recently tested the device for electron detection in the energy range of 80-400 keV (Fan et al, in review by Ultramicroscopy, 1997), and the results are very encouraging. An ASIC-based imaging system will possess many advantages over the CCD-based imaging systems (see Section 4A2.2). Dr. Xuong will collaborate with us on this project.