Point collimation camera

In addition to point-focus apparatus there are scattering devices with an extremely elongated cross-section of the primary beam. Historically this geometry has been developed as a compromise between ideal collimation and insufficient scattering power. Their practical importance is decreasing as more powerful point-collimated sources become available. Kratky camera (Alexander [7], p. 107-110) and Rigaku-Denki camera (BaltA Vonk [22], p. 83) are the most frequent representatives of slit-focus devices. 

X-Ray Scattering. A small angle X-ray scattering camera with a point collimation has been used for the determination of Bragg spa-cings of many liquid crystal samples. Temperature wa monitored between 20° and 30°C, and the samples were contained into a capillary tube. The measurements were made by the photographic method on the first two reflections. 

In the following, a description of an improved Kratky-camera [73] will be discussed together with an extended discussion of the treatment of data. This device is capable of measuring latex particles up to a diameter of 200 nm and reaches the q-range provided by SAXS-cameras which work in point collimation and use synchrotron radiation (cf. below [73]). 

X-ray low- and wide-angle diffraction studies of the liquid crystalline phases were performed in a manner previously reported [lOj. The low-angle camera was a point-collimated... 

The wide angle X-ray scattering (WAXS) regime was collected nsing an evacnated Statton camera (Warhus, DE) with point-collimated X-ray beam via two pinholes (0.05 mm), separated by 15 cm at Cu Ka wavelength 1.5418 A. In order to examine scattering from dry membranes, SPTES-50, SPTES-60, SPTES-70, and... 

To obtain a diffraction pattern a Laue camera must be correctly oriented with respect to the x-ray tube. This alignment requires that the collimator axis point directly at the focal spot on the tube target and make an angle of about 6° with the face of the target. The camera is moved relative to the tube until the primary beam, observed on a small fluorescent screen held near the collimator exit, is of maximum intensity and circular, not elliptical, in section. 

It is often necessary to know exactly where the incident x-ray beam strikes the specimen, as, for example, when one wants to obtain a pattern from a particular grain, or a particular part of a grain, in a polycrystalline mass. This is sometimes a rather difficult matter in a back-reflection camera because of the short distance between the film and the specimen. One method is to project a light beam through the collimator and observe its point of incidence on the specimen with a mirror or prism held near the collimator. An even simpler method is to push a stiff straight wire through the collimator and observe where it touches the specimen with a small mirror, of the kind used by dentists, fixed at an angle to the end of a rod. 

As far as the glare source is concerned, the required luminous flux caimot be provided by an isotropic point source. Instead, the light has to be collimated to a certain extent and deliberately directed into the camera system. To achieve this, the glare source has to be aligned. 

---