Precision cameras

Structure of OjPtFg (cub.).—Thin-walled, 0-5 mm. quartz capillaries were charged in a dry-box with the sublimed material, and sealed. A 14-32 cm. General Electric precision camera (Straumanis loading) and Cu-A radiation from a nickel filter were used. The photographs were indexed on a cubic unit cell with a = 10-032 0-002 A, F = 1010 A , = 4-20, Z =... 

X-Ray powder photographs were obtained using a General Electric Precision camera (Straumanls loading) with graphite - monochromatized CuK( radiation. Finely powdered samples were sealed into 0.3-0.5 mm thin-walled quartz capillaries as described under Raman spectra. 

Y-Ray powder samples were prepared in 0-3 mm. quartz capillaries in the manner usual for volatile material and powder photographs were taken at various temperatures. Higher temperatures were achieved by blowing hot air over the capillary mounted on a standard 14-32 cm. diam. General Electric Precision camera. The temperature was controllable to 1°, and was recorded throughout the ex-... 

X-Ray powder photographs were recorded from samples packed in 0. 3 to 0. 5 mm quartz capillaries (Charles Supper Co., Natick, Mass.) using a 45 cm circumference General Electric Precision Camera with Ni filtered CuK, radiation. Raman spectra were obtained using a... 

X-ray Powder Diffraction Photographs (XRDP) were obtained using Ni-filtered Cu Ka radiation using General Electric Co. Precision Cameras (circumference 45 cm, Straumanis loading). 

X-ray powder diffraction samples were prepared as previously described, the X-ray dtffraciton pattern (XRDP) being recorded on film using Ni-filtered Cu Ka radiation (General Electric Co. precision camera. Straumanis loading). The program ERaCEL- was used for the refinement of the lattice parameters which incorporates the Nelson-Riley extrapolation function.- The AgMFfi salts (M = Os. Ir, Ru) show... 

Powdered samples were contained in thin-walled quartz capillaries of 0.7 mm diameter. A General Electric Precision camera of 45 cm nominal circumference was used with Ni filtered Cu radiation... 

Powder patterns were taken on a General Electric Precision Camera with a 45 cm circumference, and with use of Ni-filtered CuK or Zr-filtered MoK radiation. 

A precision camera uses a coupling between the motions of the crystal and the screened film to give an undistorted pattern, enabling the determination of the unit cell dimensions, which are then set in the computer controlled four-circle diffractometer (Figure 12.26), where the crystal is positioned in the goniometer head and the diffraction intensity is measured with a photomultiplier. 

It has been said that the Precision camera records the undistorted reciprocal lattice. There are two t3rpes of Precision cameras. The one is due to de Jong and Boumann and the other is due to Buerger. The Precession camera developed by Buerger is quite different and difficult to visualize and so, the Boumann method is first described here. 

During testing a depth resolution of 50-80 micron and a lateral resolution of 20-40 micron was achieved. The spatial resolution was limited not mainly hy source or camera properties, but by the accuracy of compensation of the instrumental errors in the object movements and misalignments. According to this results a mote precision object rotation system and mote stable specimen holding can do further improvements in the space resolution of microlaminography. 

Laminographical approaches can be used for layer-by-layer visualization of the internal microstructure for the flat objects (multilayers, PCBs etc.), that caimot be reconstructed by computerized tomography because of the limited possibilities in rotation. Depth and lateral spatial resolutions are limited by the tube, camera and rotation accuracy. Microfocus X-ray tubes and digital registration techniques with static cameras allow improving resolution. Precision object manipulations and more effective distortion corrections can do further improvement. 

At still shorter time scales other techniques can be used to detenuiue excited-state lifetimes, but perhaps not as precisely. Streak cameras can be used to measure faster changes in light intensity. Probably the most iisellil teclmiques are pump-probe methods where one intense laser pulse is used to excite a sample and a weaker pulse, delayed by a known amount of time, is used to probe changes in absorption or other properties caused by the excitation. At short time scales the delay is readily adjusted by varying the path length travelled by the beams, letting the speed of light set the delay. 

High-purity lead oxide is used to make precision glasses needed for lasers, low-dose X-ray machines, fiber optic probes, medical camera systems, and low-light military equipment such as night vision scopes and goggles. 

Even if in the near future those problems could be partially resolved in some commercial CCD cameras the main problem of precision measurement (up to 1 %)of all ED intensities -and specially the weakest ones - with a CCD camera will still remain in the future. For instance, accuracy in... 

Figure. 5 Graphical user interface of the CCD camera that permits the user define interactively the area of interest to be scanned of ED pattern for precise measurement of intensities.

Electron diffractometry system with the combination of the precession technique can be very perspective experimental instrumentation for precise structural investigations. The technique can now be adapted in a commercial TEM (previously applied uniquely to electron diffraction cameras) taking advantage of the small beam size and can measure reflections in the ED pattern with same required precision for structure analysis. 

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