Ryuichi Hioki

Coherence of Light from Random Medium

Theoretical descriptions are given of the statistics of the speckled diffraction patterns of diffused coherent light. The amplitude of light disturbance in a diffused source surface is expressed by a spatially continuous complex function. The spatial correlation of the phase angle of the amplitude is discussed and the space-averaged coherence area of phase is given. The coherence area of phase depends on the microscopic processes of the diffusion, but is at least of the square of the wavelength of light. The power spectral density of the diffraction pattern in terms of spatial frequency is shown to be proportional to the autocorrelation function of the intensity distribution of the diffused source and also to the coherence area of phase.

Formation and Dielectric Properties of Glass in the System As-Te

The regions of glass formation in the system As-Te, d.c. conduction and dielectric properties of glass obtained are investigated. Glasses are formed only by quenching. Measurements of the dielectric constant over 60 c/s to 3 Mc/s on glass show two sorts of separable dispersions. It is ascertained that one is due to the surface effect and the other due to the bulk effect. Activation energy derived from the temperature dependence of dielectric relaxation time in the latter, which is present at the higher frequencies, and that of d.c. conductivity are found to be equal. Moreover, e0, dielectric constant at f→0 when only the relaxation phenomenon at the higher frequencies is taken into account, is considerably high and seems to be almost temperature independent. These facts suggest that the dispersion at the higher frequencies is caused by inhomogeneous structure in bulk.

Speckled Diffraction Pattern and Source Effect on Resolution Limit in Holography

The Speckled Pattern in the Fourier-transform hologram with diffused illumination is described. The distortion term in the reconstructed image is shown to be proportional to the convolution of the intensity distribution of the object against itself, and the point spread function in the image is shown to be proportional to the convolution of the intensity distributions of the sources of the reference and of the reconstruction. The anisotropy in resolution by the source effect is shown with an experimental illustration.

Modification of the (U*, V*, W*) System

The (U*, V*, W*) system has been checked against the Munsell renotation system on the assumption that the latter provides an equispaced visual scale. As the result of the examination, it has been found that the formula for lightness index is in excellent agreement with the Munsell value function, in spite of its numerically simplified form and that the value effect appearing on the CIE 1960 UCS diagram is over corrected by making the chromaticness indexes depend upon the first power of W*. Twenty five times the 56-power of W* has been found to be more suitable for the weighting factors to be applied to the chromaticness indices. The value effect has been reduced to about 45% by the use of the modified chromaticness indices. On the basis of the modified system, a formula is proposed for computation of color differences for pairs of similar colors. In addition, a formula is proposed for specifying whiteness for practical purposes, based on the modified system.

On the Diffraction Loss of Optical Resonator

The oscillation characteristics are reported of a helium-neon laser equipped with a resonator which consists of two concave spherical reflectors with non-identical curvatures. Laser oscillations in resonator arrangements of the so-called high loss geometry are studied. The powers and the field patterns of the output beam are shown. An intuitive interpretation of the high loss in a confocal resonator is also given, and is compared with Fox and Lis treatment.