X-ray small angle camera with block-collimation system an instrument of colloid research
X-ray small angle camera with block-collimation system an instrument of colloid research
复制标题
带块准直系统的X射线小角度相机是胶体研究的仪器
DOI：
10.1007/bf01410252
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发表时间：
1984
影响因子：
2.4
通讯作者：
H. Stabinger
中科院分区：
文献类型：
--
作者：
O. Kratky;H. Stabinger
摘要1.在X射线小角度研究中，通常采用线形截面的原束。已知最长的是三狭缝相机，它有两个平行的光阑来限定初级光束，第三个光阑限制第二个光阑引起的寄生散射。2.三个光阑的正确相互调节的困难通过块准直系统来避免，其中初级光束由三个物体（2个块和1个边缘）引导。基本原理是第一块（中间块）的非常光滑的上表面与第二块（桥）的同样完美的平面底面在它们的相互延伸中精确重合。第三个光阑，即边缘，控制带状主光束的宽度，并位于两个模块前面作为入口狭缝，这是最接近X射线管。3. 1954年的基本概念得到了保留，但是，小角度相机的整个设备已经被修改。只有最早的专业类型，积木相机，已在一个全面的通信（1958年）描述;最近开发的类型只知道从短期通信和制造商的前景，A。帕尔KG.本工作的主要议题是最近最重要的类型，紧凑型相机的描述。尽管积木式相机的各个部件以相互可调节的方式安装在某种光学轨道上，但是紧凑型相机的除了检测器狭缝和检测器之外的所有部件都容纳在抽真空的紧凑型刚性壳体中，而没有像积木式相机那样被穿透的箔或空气路径。一个重要的特征是将摄像机前端支撑在X射线管顶部，避免了摄像机和X射线管之间因热和机械影响而引起的微小移动。实验表明，在中、高分辨率（1000 μ m以上）下，散射强度的稳定性非常好。此外，应提及的独立运动的检测器狭缝和检测器，以及改进的光束引导块的表面的重合，从外部操作的真空包围的入口狭缝等。4.尝试的优化是为了获得最大的初级强度在给定的分辨率，测量的最小角度从散射测量是可能的。这种优化尝试通过改变两个实验参数来实现：从焦点的辐射的拾取角度的变化和在入口狭缝和桥之间的准直系统的中间块的位置。a）在理想焦点的假设下，计算了进入准直系统的初级能量与这两个变量的关系（无钨沉积，完美平面，纯表面发射），B）考虑到实验确定的由偏离理想焦点引起的初级光束的衰减。5.与常规方法相比，高分辨率（对应于最小的测量角度，其与布拉格值相比在1300至2000 μ m的范围内，取决于准直系统的缺陷程度）和通过一定的拾取角度和中间块的位置的组合的相当新的X射线管。此外，描述了一种被称为“集成相机”的原型，其中X射线管被内置到相机的伸长部分中并且因此以可调节的方式被集成到相机的伸长部分中。该仪器是专为极高的分辨率（几千埃），因为即使是最小的相对运动的X射线管和准直系统完全抑制。
Abstract1.For X-ray small angle research usually a primary beam of line shaped crosssection is applied. The longest known is the three-slit-camera with two parallel diaphragms defining the primary beam and the third one limiting the parasitic scattering caused by the second one.2.The difficulty of the correct mutual adjustment of the three diaphragms is circumvented by the block collimation system, where the primary beam is guided by three bodies (2 blocks and 1 edge). The essential principle is the exact coincidence of the extremely smooth upper surface of the first block (middle block) with the also perfectly plane bottom surface of the second block (bridge) in their mutual extension. The third diaphragm, the edge, controls the widths of the ribbon-shaped primary beam and is situated as entrance slit in front of the two blocks, this being closest to the X-ray tube.3.The basic concept from 1954 has been maintained, however, the entire apparatus of the small angle camera has been modified. Only the earliest professional type, the building block camera, has been described in a comprehensive communication (1958); the more recently developed types are only known from short communications and from prospects of the manufacturer, A. Paar KG. The main topic of the present work is the description of the most important recent type, the compact camera. Whereas the individual parts of the building block camera are mounted on some kind of optical rail in a mutually adjustable way, all parts of the compact camera except the detector slit and the detector are accomodated in an evacuated compact rigid housing without foils or air paths to be penetrated like for the building block camera. An important feature is the support of the front end of the camera on top of the X-ray tube avoiding those minor movements between camera and X-ray tube caused by thermal and mechanical influences. As shown by experiment, practically perfect stability of the scattering intensity at medium and high resolution (above 1000 Å) is obtained by these means. Moreover, the independent motion of detector slit and detector shall be mentioned, as well as the improved coincidence of surfaces of the beam — guiding blocks, operation of the vacuum surrounded entrance slit from outside etc.4.An attempt of an optimization is made with view to obtain maximum primary intensity at a given resolution, measured by the smallest angle from which on a scattering measurement is possible. This optimization was tried to be achieved by variation of two experimental parameters: Variation of the pick-up angle of the radiation from the focus and the position of the middle-block of the collimation system which is in between the entrance slit and the bridge. The primary energy entering the collimation system in dependence of the two variables has been calculateda)under the assumption of an ideal focus (no tungsten deposition, perfectly plane, pure surface emission),b)with consideration of the experimentally determined attenuation of the primary beam by deviations from an ideal focus.5.Intensity gains by more than a factor of 2 compared with the conventional method can be achieved in the case of high resolution (corresponding to smallest measuring angles which compare to Bragg's values in the range of 1300 to 2000 Å depending on the degree of imperfections of the collimation system) and a rather new X-ray tube by a certain combination of pick-up angle and position of the middle block.6.Finally, the problem of resolution is discussed on a mathematical basis. In addition, a prototype calles “integrated camera”, with the X-ray tube built into and thus integrated into an elongation part of the camera in a adjustable way, is described. This instrument is especially designed for extremely high resolution (some thousand Angstroms) since even smallest relative movements of X-ray tube and collimation system are completely suppressed.