By applying Lyot's principle to z-cut quarz, a variable color filter has been designed which has a uniform and high saturation for all colors. The optimum thickness of the quartz plate has been determined by colorimetric calculation. Loci of color by this filter plotted on C. I. E. chromaticity diagram are given.
High efficiency neutral half-mirrors and prisms are obtained by replacing metallic films of beam-splitting mirrors and prisms with multi-layer all dielectric films. Calculated and observed reflectances and transmittances of beam-splitters thus made and other multi-layer films are given. The calculations were performed by means of Smith chart, the results of which show good agreement with those of the observed in the visible region of spectrum.
A zero-dispersion photoelectric spectrophotometer capable of measuring directly the trichro-matic coefficient, the effective light intensity to photographic films etc. has been designed and built. Every effort has been made to render it light, compact and portable with ease and rapidity of manipulation. Specially designed center diaphragms are used in place of usual center slit. The outfit consists of a double-monochrom ator as the main part, a telescope system, a receptor of light, an electric source and a tripod.