Photo-electric method

As, without the use of one of the photo-electric methods, it becomes completely impossible to measure extinction positions of such small parasitic birefringences, the present author relied on an indirect method by the use of revolving windows (217). As pointed out in Section 6.1.5, the windows of the rotor unit were put in a most suitable fixed position. This position is found in the following way ... 

Where automatic/electronic/photo-electric methods of inspection are used, the effectiveness of the equipment should be validated and its sensitivity monitored. 

Bergel, D.H. (1958) A photo-electric method for the determination of the elasto-viscous behavior of the arterial wall. J. Physiol, 141, 22-23. 

In methods involving image formation there is a common factor. Radiation normally propagated in rectilinear fashion, such as light or an electron beam, is interrupted by the particles under examination, and the pattern of the interruption can be observed in different ways, eg, optically or photo-electrically... 

Perkins and Andersen, 31 photo emission method (Barker), 41 potentiostatic scrape method, 38 piezo electric method (Gokstein), 42 rapid emergent method (Packham), 38... 

This method is similar to continuous flow method except that the rate of flow is continuously varied and the analysis is made at a fixed point along the observation tube. Since the rate of flow changes with time, the reaction mixtures arriving at observation point have different time. In the accelerated flow method the output from a photo electric colorimeter is fed to a cathode-ray oscilloscope, which sweeps out a complete time-concentration record which may be photographed. The method is useful for very rapid enzyme reactions and requires only small quantities of reactants. 

Essentially, the one-dimensional system comprises a photo-electrical transformer in which reflected and transmitted light are collected by lenses and converted into electrical signals. A surface defect results in a light level different from that of the normal signal and as evaluation can be rapid such methods are suitable for assessing faults arising, for example, on fast-moving production lines for film. 

It is not possible within the scope of this collection of methods to deal with the theoretical processes in the interaction of radioactive emitters with matter (e.g. ionization, photo-electric effect, Compton effect, pair creation), the construction and operation of detectors, the structure and circuitry of the measuring equipment, or the electrical evaluation of the signals received. The reader should consult the specialized radiochemical literature. 

Plastics can be used to make erasable printing media by a number of different techniques. Photo changing dyes could be incorporated into the structure of the plastics. The printer could change the dye to the colored form to read, and the material can be bleached with another unit that would reverse the photo coloring process. An ionic type plastic can be incorporated into the plastics and used to color the printed area by the use of an indicator type reaction with an organic acid or base. Another method would be to use a thermal printer in conjunction with liquid crystal type materials that would alter the state of the liquid crystals in the printed areas. Applying heat and electrical fields to the printed sheet would erase the printing. 

ANALYZER (Reagent-Tape). The key to chemical analysis by this method is a tape (paper or fabric) that has been impregnated with a chemical substance that reacts with the unknown to form a reaction product on the tape which lias some special characteristic, e.g., color, increased or decreased opacity, change in electrical conductance, or increased or lessened fluorescence. Small pieces of paper treated with lead acetate, for example, have, been used manually by chemists for many years to determine the presence of hydrogen sulfide in a solution or in the atmosphere. This basic concept forms the foundation for a number of sophisticated instruments that may pietreat a sample gas, pass it over a cyclically advanced tape, and, for example, photo-metrically sense the color of the exposed tape, to establish a relationship between color and gas concentration. Depending upon tile type uf reactiun involved, the tape may he wet or dry and it may be advanced continuously or periodically. Obviously, there are many possible variations within the framework of this general concept. 

Detector elements 11 are formed on a ceramic substrate 1. Each detector element includes a photosensitive zone 9, an output terminal 4 and a common terminal S. The detector elements are arranged in an array protruding from a common metal line 3, which is connected to a terminal pad 6. The terminal electrodes and the common metal line are formed on a comb-like patterned photo-conductive layer 2. An aperture plate 7 of silicon or ZnS having apertures 8 formed therein by an anisotropic etching method is prepared. The purpose of the aperture plate is to restrict the field of view of the photosensitive zones. An auxiliary electrode 30 is formed on the aperture plate. When the aperture plate is assembled with the substrate using an adhesive, the auxiliary electrode is pressed against the common metal line and the common terminal, which together reduce the electrical resistance. 

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