In order to explain the infra-red sensitive behaviors of cubic Zn (S:Se) phosphors, a simple model which contains two types of infra-red sensitive centers, namely phosphorescence centers associated with a single trap and a double trap, has been proposed in the previous paper. In the present paper a model is assumed which is more generalized by taking into con-sideration the existence of two more types of isolated electron traps, namely a single trap and a double trap, and the probability of retrapping processes. The fundamental equations based on this model are approximately solved for several important cases. The comparison between the obtained conclusions and the experimental results reported in the previous paper shows that the theoretical consideration based on this model can explain the influence of added ZnSe upon the infra-red sensitive behaviors of Zn (S:Se) phosphors semi-quantitatively.
Colorimetrical studies on the interference color of crystal between Nicol prisms, when (i) the crystal is birefringent and an achromatic retardation is added thereto, (ii) crystal is active (crystal has the power of rotating the plane of polarization), and (iii) the birefringence of the crystal is a function of the wavelength, are given. It was found that in case of (ii), there exists extremely sensitive change of color with respect to the change of birefringence, called “hypersensitive color”. The fact that the loci of the interference color of the active crystal are ellipses, is also proved analytically.
It is a well known fact that the interference color, especially the “sensitive color”, is an efficient measure to estimate the thickness of a thin film. But the interference color of a thin layer on a dielectric base such as glass becomes the “sensitive color” only when its optical thickness is λ/4 or λ/2 according as the phase change at the surface of the base dielectrics is 0 or -π. If a thin layer is deposited on a metallic surface, the interference color becomes the “sensitive color” with any optical thickness as the phase change at the surface of the metal can be made at will by selecting a proper metal. The possibility of colorimetrical application of this proposition is studied. As the result of calculation, the theory of “hypersensitive color” was found to be of use in the case of a thin dielectric layer on metals. It was also found that the effects of dispersion of reflection at the metallic surface and multiple reflections within the thin layer are virtually negligibly small.
The specular gloss of paper was investigated with a new gloss meter which can be set for any desired incident angle between 45° and 75°. The gloss is so dependent upon the incident angle that the order of gloss for thirteen specimens examined changed with the incident angle used, it also varies considerably over the surface.
A test chart is projected obliquely, with an incident angle ranging between 30° and 75°, on a test specimen, the focusing plane of the image being varied from the specimen surface to 4.8mm from it. The resolution of the image is examined with a microscope in the direction of the specular reflection. Different varieties of paper, and glass plates, ground and polished, aluminium coated by vacuum evaporation, are used as test specimens. A quantity I/R is proposed for the gloss G, that is G=I/R, where I is the intensity of the specularly reflected light and R the resolvable limit of the interval of parallel lines in the image of the chart. With this quantity together with the value of gloss measured by Hunter's multi-purpose reflectmeter, the problem of gloss is discussed.
Analysis of the mechanism coupled range-finder for miniature cameras by focusing with coincidence of doubled images is given. Although it is not difficult to obtain a correct shape of the cam which is the most important part of the mechanism, the shape should be approxi-mated by a circle or a straight line when, in mass prodction, the accuracy in the working process and the cost are considered. With mathematical formulations, useful means and data for designing and producing the mechanism to obtain a uniform coupling accuracy in the whole range of the object distance and the differential characteristics of the mechanism are given especially in the case of a round cam.