Comparative analysis and quantitative evaluation of the field of view and the viewing zone of single-shot phase-shifting digital holography using space-division multiplexing

We comparatively analyzed and quantitatively evaluated the field of view and the viewing zone of single-shot phaseshifting digital holography that uses space-division multiplexing, for the first time. We formulated the sampling intervals in the techniques in which the phase of the reference wave is spatially divided into two and four steps, and numerically simulated the areas. It was clarified that each area of the spatial two-step phase-shifting technique was twice as wide as that of the spatial four-step phase-shifting technique. We also experimentally investigated the areas. The ghost appeared for the spatial four-step technique when the object was between the boundary of the field of view of the spatial two-step technique and that of the spatial four-step technique, but did not appear for the spatial two-step technique.     

High-speed phase imaging by parallel phase-shifting digital holography

Parallel phase-shifting digital holography can obtain three-dimensional information of a dynamically moving object with high accuracy by using space-division multiplexing of multiple holograms required for phase-shifting interferometry. We demonstrated high-speed parallel phase-shifting digital holography and obtained images of the phase variation of air caused by a compressed gas flow sprayed from a nozzle. In particular, we found the interesting phenomenon of periodic phase distributions. Reconstructed images were obtained at frame rates of 20,000 and 180,000 frames per second.     

Sonoluminescence of Na atom from NaCl solutions doped with ethanol

Sonoluminescence spectra from argon-saturated NaCl solution were measured in the concentration range of 0.5-4 M at the frequency of 138 kHz. The line broadening of sodium atom emission was observed at various acoustic powers in the range from 1.8 to 16.2 W. The sodium D line showed a maximum intensity at a NaCl concentration of 2 M, which corresponded to the maximum production of OH radicals estimated by KI dosimetry. The effects of the addition of a small amount of ethanol on the line width and intensity were closely investigated at various acoustic powers. The sodium line width increases with ethanol concentration and also with power, whereas the line intensity is strongly quenched with increasing ethanol concentration. The results conclusively show that the sodium emission occurs in the gas phase within bubbles. The line broadening is due to interactions with high-pressure argon, and the maximum relative density of gas at bubble collapse was estimated to be 59.5 from the comparison with spectroscopic data. Further line broadening and quenching upon the addition of ethanol arise from collisions with gaseous products obtained from the decomposition of ethanol. The mechanism of sodium excitation is inferred to be as follows. Sodium ions enter bubbles as droplets, and salts are formed because of the high temperature within bubbles. Sodium atoms are generated by the dissociation of salts and then undergo electronic excitation by OH and H radicals.     

A convenient synthesis of olefins via deacylation reaction

A convenient and environmentally-friendly synthetic method of olefins via deacylation reaction is described. The reaction gives olefins by condensation of aldehydes with a variety of 1,3-dicarbonyl compounds in the presence of anhydrous potassium carbonate at room temperature in high yields (70-90%) in one step. The synthetic potential of this strategy can be used as an alternative procedure to the Wittig, Wittig-Horner reactions. The stereochemistry of the resulted olefins was determined by NOE experiment with correct radio frequency and X-ray analysis. The E/Z selectivity of the deacylation reaction depends on the α-substituents of the 1,3-dicarbonyl compounds.