Laue camera

Figure 16 Sample holder assembly of a monochromatic Laue camera. 1, Brass sample holder 2, collimator 3, beam stop 4, orienting arm 8, part attached to the cold tip of the cryocooler and holding the cold shroud 16, thermocouple. (From Ref. 132.)...

Any device designed to hold a specimen and photographic film to record diffracted beams is called an x-ray camera, even though it bears little resemblance to cameras used for photography by visible light. Laue cameras are so simple to construct that homemade models are not uncommon. 

Fig. 5-1 Combination transmission and back-reflection Laue camera. In this camera the Polaroid cassette (at right) and the cassette for ordinary film (at left) are interchangeable either can be used for transmission or for back reflection. (Courtesy of Blake Industries, Inc.)...

Fig. 5-3 Back-reflection Laue camera. The sectored disc on the front of the cassette would be removed for a Laue photograph the purpose of this disc and of the drive motor at left is described in Sec. 6-9. (Courtesy of Philips Electronic Instruments, Inc.)...

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. 

After the orientation of a crystal has been determined by the Laue method, it is sometimes necessary to cut the crystal along some selected plane. A more massive goniometer-holder than that of Fig. 5-7 is then required such a holder can be rentoved from the track of the Laue camera and transferred to a similar track on the cutting device without disturbing the orientation of the crystal. 

The crystal-setting procedure illustrated in Fig. 8-21 can be carried out whether or not the indices of the various poles are known. If the Laue pattern of a crystal is difficult to solve, any spot on it can be indexed by using a Laue camera and a diffractometer in sequence [8.4]. In addition, a goniometer is required that fits both instruments. The procedure is as follows ... 

By the procedure of Fig. 8-21, rotate the pole to be indexed to the center of the projection. The corresponding rotation on the goniometer will make the unknown plane hkl) normal to the incident beam of the Laue camera. 

The calculated spectrum (see chapter 4) is modified at the long wavelength end by absorption due to beam line windows or any airpaths in the Laue camera. Also, the short wavelengths are cut off if a reflecting mirror is used (and this may be the case for focussing or to aid more precise definition of spot multiplicity). 

The surfaces of NCH and the nylon 6 test specimens were scraped around the center to a depth of 0.5 mm. The surfaces of other NCH and nylon 6 test specimens (3 mm thick) were scraped to a depth of 1 mm. X-ray diffraction photographs of these test specimens were taken using Laue cameras. Specifically, the surfaces and insides of these test specimens were subjected to X-ray diffraction photography in the through , edge and end directions, and the orientations of the crystals were examined [25]. 

Laue camera is the simplest of all the devices for the structure determination of crystals as it consists of a collimator to narrow down the general radiation... 

Following such an idea, Tanaka et al. [2009) performed X-ray diffraction and Raman scattering spectroscopy, but no signatures of crystallization have been obtained. We may also envisage some oriented amorphous structures [as in Fig. 3.10), but experiments using a Laue camera, which took two-dimensional diffraction patterns for transmitted X-ray beams, could not detect any anisotropy. [Some oriented structure may exist, but the degree of orientation seems to be smaller than 10%, which is an experimental limit of the X-ray measurement for small samples.) For wrinkled a-Se films... 

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