The optical field through an optical instrument is band-limited. In 1961, Slepian et al. found that the spheroidal wavefunctions are useful to describe the band-limited functions. Since then, many investigators came to apply these functions in their own field. In this article, the important features of the apheroidal wavefunctions are summarized first, and then several optical problems which could be analysed by means of these functions are reviewed.
Recent developments in Scanning Electron Microscope (SEM) are reviewed compared with Conventional Electron Microscope (CEM). Resolution and contrast formation of several different operation modes in SEM (emissive, reflective, absorptive, transmission, cathodoluminescence, X-rays and Auger electrons) are discussed taking into account several factors ; electron spot size, signal to noise ratios and spreading effect in specimen. Particularly it is emphasized that the electron source of high brightness is necessary to get the high resolution. Field emission gun, LaBs cathode and pointed cathode are compared to the usual hairpin cathode. The principles of image formation in CEM and STEM are compared to each other by using the reciprocity theorem in wave optics. The contrast formed by crystallographic orientations is explained by using the dynamical theory of two beam approximation, and applications of SEM and STEM to the crystallographic studies are discussed with including observations of crystal defects. Applications of SEM to a number of fields in reseach and industry are described considering various modes of signal detections.
In this paper, we describe the photoconductivity of impurity-doped CdS thin films prepared by a solution spray technique. As impurity, Cu or Li was used and doping was performed by adding Cu(CH3COO)2 or LiOH into a spray solution. Both Cu or Li-doped CdS thin films have a high photosensitivity but the response time of these films is very different from each other. This is due to the difference in the capture cross section of hole traps for photoexcited holes in these films.
A 85Kr irradiation equipment has been devised for chemical reaction in the liquid phase. Irradiation is achieved by circulating the 85Kr gas in a reaction system, where the 85Kr gas forms bubbles in the liquid reactant. The dosimetry is carried out for the reaction system using aqueous solutions of methylene blue. The observed relationship between the absorbed dose rate in the reactant and the fractional void in the reaction vessel agrees well with the theoretically obtained relationship.
Studies have heed made on the effects of divalent metal ions (Hg2+, Cu2+, Pb2+, Ni2+, Co2+, Cd2+, Fe2+, Zn2+, Ba2+, Sr2+, and Mn2+) upon photographic and emission processes in cubic silver bromide grains (ca. 0.7μ) in emulsions. Among these metal ions, only divalent mercury and copper ions, which have the most positive and the second most positive redox potentials respectively caused a marked decrease of the emission intensity of the grains in emulsions at liquid nitrogen temperature which appeared at about 600nm, with a marked decrease of photographic speeds of the emulsions. These results suggest that the increase of photographic speeds are not caused by the electron traps provided by divalent mercury and copper ions.