For the study of industrial X-ray, protection, a sensitive radiation integrating meter is required. The characteristic of the meter described, with the signal received in the third grid, is that the leakages in the first and second grids are reduced to minimum raising the sensitivity over 20 times of that of customary meters: 50μr is the full scale reading in the setting for the highest sensitivity when 350cm3 of air chamber is used. The circuit is stabilized because of the negative feed back; simplicity of the circuit makes the meter to be assembled small in size and portable.
Figures left on exposed but undeveloped photo-printing paper by electrical discharge over its surface was found by the author to be discernible to small details and reproducible. With this technique, experimental study is made how and under what conditions the discharge figure is formed on surface of organic substances. The figure is composed of groups of irregular streamers which grow nearly parallel to equipo-tential lines and are colored, the color being different by the kind of printing paper used. The growth of the figure starts with simultaneous discoloring of the straight region between the electrodes, from which the streamers develop laterally at a rate of 2_??_6mm/sec along equipotential lines, the specific surface resistance and potential gradient affecting the rate, and the applied wattage, voltage rise rate and gap length influencing the length of streamers. The range of specific resistance within which the reproducible figure appears is 105_??_109Ωcm; above 108Ωcm, the discharge tends to arcing and the irregularity of streamers increases. Extensive experiments are carried out concerning possible factors that may affect the discharge figure. As we have yet no satisfactory explanation as to either the mechanism of growth of the figure or the fundamental of the phenomenon, the data obtained will contribute to further studies.
For plastic two-step replica method, methacrylate resin film is used for the first step instead of conventional acetyl cellulose film to avoid large swelling in disolving process. Plastic three-step replica method is devised in which the first step is the application of wetted film of water-soluble and easily detachable plastics such a methocel, polyvinylalcohol, gelatine etc. on the specimen. As the second step, methacrylate resin film is used on the detached first film as in the above-mentioned improved two-step method. The third step is germanium shadowing and carbon evaporation on the second film. By these processes, the time required for completion of replica is shortened: 30 minutes for the two-step and 40 minutes for the three-step method. These methods are well suited to routine work, for the processes are easy and sure. Judged from discriminable minute striation on ceramic alumina, resolution of these replicas is found as good as that of customary replica. Details of preparation are briefly explained.
The aberration theory is important as the basis of optical design. From this standpoint, however. the expressions should be arranged more or less different from those which are arranged with the theoretical interest alone. Recent advance in optical systems has made third order theories too insufficient and fifth order theories have been developed by many authors. But, the practical expressions seem to be still required from the standpoint of optical design. The author tries to establish the practical expressions, starting from the Herzberger-Focke's fifth order theory. Herzberger-Focke's theory is noticeable for its clear physical meaning. But, it has a few defects for practical purposes, that is: i) it does not use the “reduced coordinates”, and then, it is difficult to apply it to the optical systems, comprising many refracitive surfaces. ii) it uses the “exit-pupil coordinates” instead of the “entrance-pupil coordinates” and also does not usually fit to the practical work. In this paper, the author applies the two transformations to the Herzberger's expressions, that is, from the “Herzberger coordinates” to the “reduced coordinates” and, from the “exit-pupil co-ordinates” tothe “entrance-pupil coordinates”. Upon this, the author defines the new symbols of the aberration coefficients, which correspond to the Berek's symbols.
A method is devised for growing ZnS crystals by sublimation. Large single crystals, about 1g_??_10g in weight, are synthesized by the following procedures. Polycrystals of easy grain growth are first prepared from a charge of ZnS powder by sublimation and recrystalization in a steep temperature gradient zone of a furnace. These polycrystals are piles of needle-like or rod-like grains with growth surfaces of the same orientation. The grains grow larger by heat treatment in saturated vapor of ZnS and single crystals are cleaved from the polycrystals. Chemical components of the single crystals are not always in stoichiometric relation; hence impurity levels arise. The weight percentage of Zn in ZnS increases as the growth temperature of the crystals becomes higher. Grain growth is discussed. When the vapor is cooled and recrystalized to be polycrystals in a zone with steep temperature gradient, the grains grow faster in the direction of temperature gradient. The grain boundaries in such a case are presumably very unstable and grains grow with ease by heat treatment. It is the reason why steep temperature gradient is needed in the recrystalization zone. Grains grow parallel to (1120) plane with the planes belonging to (1120) zone as the surfaces of growth. The grains with c-axes directing to temperature gradient are eaten away easily by the others as grain growth proceeds.
ADP crystal has a remarkable photo-electric property which is being used for instantaneous optical shutter, tuned color filter and so on. Application of this crystal to optical purposes demands excellent surface polish, but, the crystal being hygroscopic and soft, the polishing is not easy. For obtaining a practical method of polishing the crystal, examinations are made on the following items: (1) Several solvents as polishing media. (2) Properties of rosin, pitch and wax, the basic constituents of pitch compound. (3) Polishing properties of various pitch compounds. (4) Other polishing methods, e. g. water polish. (5) Polished surface. Lapping on soft pitch lap with cerium oxide and ethyl alcohol has been found as the best polishing method for ADP crystal.