Characteristics of the light reflected from textile fabrics made of viscose spun rayon are investigated with a goniometric spectrophotometer, and the following results are obtained. 1. Most part of the reflected light is the internally scattered light, that is the light which has penetrated into the fabrics and come out of it after many refractions and reflections, and the rest is the light merely reflected from the surfaces of fibres (the surface reflected light). 2. The surface reflected light comprises almost as much specular reflected light as diffused light, multiply reflected on the surface of the fabric without penetrating into it. 3. The surface structure of individual fibres as well as the texture of the specimen have complicated effects upon the properties of the surface reflected light; specimens prepared under different conditions give different goniometric curves. 4. The surface of the fibres is made of rectangular elementary facets with area of about 1×10_??_17μ2 each and there are numerous small irregularities of about 0.17 μ on each elementary facet. 5. Owing to the Jentzsch effect, the surface reflected light increases rapidly with the angle of incidence of above a certain critical value.
Automatic recording lens interferometer has been built by applying photoelectric method of determining polarized light by means of ADP polarization modulators. Optical arrangement of the apparatus is a modification of the wavefront shearing lens inter-ferometer proposed by M. Francon and M. Jordery. A point source is placed on the focus of a test lens. Light emitted from the source is colli-mated by the test lens and the wavefront of the collimated beam is deformed from plane by the aberration inherent to the lens. Small portion of the collimated beam collected through an opening is linearly polarized by a polarizer. The polarized beam is divided into two components and laterally displaced each other by a Savart's plate to produce small phase difference between them. The phase difference is proportional to the inclination of wavefront of the beam and is deter-mined photoelectrically by the polarization modulating technique. By scanning the collimated beam along a diameter of the test lens with the shearing polari-meter head, inclination of the wavefront at each point is determined and the derivative curve of the wavefront aberration of a lens is drawn.
Recently, many kinds of semiconductor photoelectric devices have been developed such as cadmium sulphide photoconductive cell, germanium photo-transistor, selenium photovoltaic cell, lead sulphide photoconductive cell, etc. A lead sulphide photoconductive cell is well known for its high photoelectric sensitivity in near infrared region of about 0.8 micron-2.7 micron, and it is the most useful detector in near infrared region. In practice, it is used as a detector of near infrared spectrophotometer, as a infrared receiver of infrared homing device, infrared radar, infrared telephone, and so on. Through studies on the method of manufacturing lead sulphide cell, the writer has determined the manufacturing methods which ensure high photoelectric sensitivity and stable performance re-producibility of over 80%. The oxidation method of evaporated lead sulphide is the most critical and important problem of cell manufacture. The temperature of the evaporation substrate is controlled by 40°C hot water circulating cooler. Air is used for oxidation and the result is better than when oxygen is used. Evaporation is processed between acquadag electrodes with impedance as controlling measure. In the course of study on methods of oxidation, the writer obtained a new type lead sulphide cell which is characterized by its low impedance of under 20 kilo-ohms (usually over 300-500 kilo-ohms) and good spectral response in the region of 2.5-3.0 micron. Several photoelectric characteristics of these lead sulphide cells and some typical examples of lead sulphide cell input head circuit are described, and a brief discussion on the mechanism of photoconductivity of oxidized lead sulphide evaporated film is given. The result obtained with the cell when used as a detector of near infrared spectrophotometer is given.
This paper presents a new technique of determining the grain size distribution by autocorrela-tion function. Grain size distribution of silver halide is known to be valuable for determining the basic characteristics of photographic emulsion such as its sensitivity, graininess and so on. This distribution is usually being obtained by laborious measurement of each grain size with a rule. But, by the use of autocorrelation method, it can be obtained quickly. The relation between autocorrelation function and grain size distribution is obtained analytically on the assumption that the distribution is lognormal, grains are scattered at random and are spherical. A pair of slide is made from electron micrograph of grain and the autocorrelation function of grain pattern is obtained from the slide by using a Kretzmer type optical autocorrelator. Good agreement for practical use is obtained between the grain size distribution measured by using autocorrelator and that measured by using a rule.
Speed of response is one of th most important characteristics of photoelectric converters. Usual method of estimating this response is to use a chopped light through a rotating sector. But, for high speed, the response cannot be measured by such a rotating sector method because unre-alizably high speed rotation becomes necessary. To make up for this, a circular disc with a num-ber of slits along its periphery is being used. Yet, the lack in uniformity of shapes and spacing of the slits limits the measuable maximum frequency to about 10 K. C. This limit is extended by the following flying-spot scanning method. (1) A part of a photosensitive surface is covered by an opaque mask so as to get sharp boundaries of illuminated and unilluminated regions. (2) This photosensitive surface is scanned by a flying spot across the boundary lines and its response is amplified and reproduced on a cathode ray oscillograph against time scale synchronized with the period of the scanning flying spot. (3) From the traced or photographed curve taken on oscillograph, the frequency response of the photosensitive surface can be calculated by the use of one or two derived equations. Two more methods, both experimentally easily realizable, are descrided, by which the same results as above can be obtained. Measurements and analyses made on a gold evaporated germanium photo-diode and a selenium photovoltaic cell are given as examples, the results obtained agreeing satis-factorily with the speed of response estimated by other methods.
Lichtenberg figures are obtained on negative color films (ASA 32 and 50) and their variations in size, form and color by lowering of pressure of the surrounding gas are studied. On positive dendritic figures, radius of the figure increases and streamers broaden with bluish violet tint (yellowish orange on color negative films) as the pressure is reduced. These tendencies are the same for all negative circular fan-shaped figures, but the rate of increase of the radius is more remarkable on the negative figures than on the positive. Red streamers on the periphery (cyan-blue on color negative films), become more conspicuous as the pressure is further reduced, while they are only faintly observable at normal atmospheric pressure. In consideration of the multilayer structure of color film, it is inferred that the positive figures are developed only in the top layer of the emulsion and that the negative figures are of such structure that the foremost edges of their streamers reached the very bottom of the layer. As for the relation between the rate of increase in size of the figures and the pressure, the ratio of the rates R+/R- decreases and approaches to 1 as the pressure is reduced but is larger than 2 under normal pressure. These tendencies observed on color films are different from those observed by Stekolnikof and Riaschenzef on black and white dry plates. Under low pressures of the order of 7 cm Hg and at applied crest voltage of 11.0 kV, the color of the streamers of either sign is very weak bluish violet and no trace of red streamers at the tips of negative figures is found. Under these conditions, the above shows that the figures of either sign can be regarded as developed only in the top layer of the emulsion which is in contact with the electrode bars.
As was described inthe preceding paper (this Journal, Vol. 30, No. 2, p. 86 (1961)), the scratch made by a steel point on a glass surface is composed of two regions: the “fractured” and the “abnormal region.” The latter is not different from the original surface when observed by the naked eye, but its physical as well as chemical properties have been modified rather drastically through severe stress during scratch formation. The “abnormal region” is different in refractive index and is more easily attacked by diluted hydrofluoric acid as compared with the original glass. These “abnormalities”, however, completely disappear when annealed. When a plane surface of a glass sheet is scratched it becomes convex owing to the expansion caused by scratch formation. If the o;iginal scratches are invisible, i-e., if they are composed of the “abnormal region” exclusively, the sheet recovers from deformation on annealing. The deformation due to “secondary cracks” in the scratch is not influenced by annealing. When a glass surface is coated by glue, and the glue film is desiccated by heating, thin flakes of glass are stripped accompanying the crack formation in the glue film. This “glue coating method” can be conveniently applied to the study of nature of the scratch. Stripping can start from visible “secondary cracks” as well as from the “abnormal regions” of the scratch. When annealed, however, the latter can no longer be the cause of stripping. It is believed that the so-called “latent scratches” are nothing but the “abnormal regions”.