Showing papers by "Satoshi Kawata published in 1988"
TL;DR: A new optical chemical sensor was developed for chemical sensing based on light-excited surface plasmon measurement, which can be compact and simple, because of the absence of mechanical moving parts, by using multichannel angular light intensity detection with a photodiode array and a Fourier transform optical setup.
Abstract: A new optical chemical sensor was developed for chemical sensing based on light-excited surface plasmon measurement. Concentration of the chemical species is found in liquid or gas without the help of a reagent but by measuring the resonance condition of the surface plasmon on the sensing metal surface. The resonance condition is given by the dielectric constant of the sample faced on the metal. The developed sensor can be compact and simple, because of the absence of mechanical moving parts, by using multichannel angular light intensity detection with a photodiode array and a Fourier transform optical setup. Experimental results are shown for measurement of ethanol concentration in water. The detection limit for ethanol in water was 10(-4) wt./wt. by the experiments with the developed system.
338 citations
TL;DR: In this paper, an optical sensor based on surface plasmon resonance (SPR) for water measurement in process has been developed, which is made in a simple and compact way, by the use of a laser diode as a point light source, providing an angularly spread (convergent) beam incident to the sensing part with imaging optics.
Abstract: An optical sensor based on surface plasmon resonance (SPR) for water measurement in process has been developed. The optical setup of this sensor is made in a simple and compact way, by the use of a laser diode as a point light source, providing an angularly spread (convergent) beam incident to the sensing part with imaging optics. Multichannel detection by a photodiode array and the Fourier transform optical setup eliminates the need for a mechanical angle scanner or a rotary stage in the system, resulting in a reduction in the size, the weight, and the cost of the sensor. Water concentrations in ethanol were measured by this sensor. Water concentrations of from 0.3% to 10% were obtained. Temperature dependence of the sensor and the method for compensation are discussed.
92 citations
TL;DR: A new reconstruction algorithm with a nonnegative constraint that utilizes a priori knowledge of nonnegativity of absorbance or optical density of three-dimensional sample distribution to drastically improves the longitudinal resolution in tomography reconstruction.
Abstract: In part I of this series we proposed a new principle of tomographic imaging using an optical microscope devised with a support-constraint reconstruction algorithm [ J. Opt. Soc. Am. A4, 292 ( 1987)]. In this paper we describe a new reconstruction algorithm with a nonnegative constraint that utilizes a priori knowledge of nonnegativity of absorbance or optical density of three-dimensional sample distribution. This method drastically improves the longitudinal resolution in tomography reconstruction, which was the most serious problem with the developed microscope tomography principle. Compared with conventional nonnegative-constrained iterative reconstruction algorithms, the algorithm developed here essentially reduces computation-time and memory-capacity requirements because it includes conjugate directional searching and gradient projection based on the Kuhn–Tucker condition, guaranteeing the convergence of the algorithm within a finite (the smallest) number of iterations. Results of experiments with a biological specimen, using the proposed algorithm, demonstrate an evident improvement of longitudinal resolution with a computation time only three times longer than that of the fastest nonconstrained algorithm.
45 citations