Eiji Toba

Fabrication of ruby sensor probe for the fiber-optic thermometer using fluorescence decay

Ruby single crystals have been grown successfully from the melt droplet on the sapphire crystal fibers as the sensor head directly coupled with optical fiber for the thermometer applications using fluorescence decay. In this fabrication process, droplets of slurry of ruby powders are formed on the end of the sapphire crystal fiber and are dried, sintered, and then melted and solidified in a floating-zone furnace. The photoluminescence (PL) lifetime of the ruby sensor head varies from τ=3.8 to 2.5 ms with the Cr3+ concentrations from 0.07 to 1.0 at. %. The ruby crystal with a Cr3+ concentration of 0.35 at. % is found to be the most suitable sensor head having the longest PL lifetime. The temperature coefficient of the fiber-optic thermometer equipment using the directly coupled ruby sensor head with a Cr3+ concentration of 0.35 at. % is −12.4 μs/K.

Fiber-optic thermometer using Cr-doped YAlO3 sensor head

Cr-doped YAlO3 phosphor crystals have been grown and characterized for applications in fiber-optic thermometers based on the temperature dependence of the photoluminescence (PL) lifetime. PL peaking at λ=735 nm is observed from the crystals following an excitation by a light-emitting diode at λ=520 nm. Long PL lifetime (τ=43.14 ms) is observed from Cr-doped YAlO3 at room temperature as compared with those of ruby (τ=4.2 ms) and spinel (τ=8.0 ms). The temperature coefficient (−0.075 ms/K) of Cr-doped YAlO3 is also larger than those of ruby (−0.010 ms/K) or spinel (−0.037 ms/K). YAlO3 is considered to be a sensitive sensor head material for fiber-optics thermometers.

Long afterglow phosphorescent sensor materials for fiber-optic thermometer

Long duration phosphorescent SrAl2O4 phosphors doped with various auxiliary activators (Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) have been evaluated for the fiber-optic thermometer application. In this thermometer, temperature was measured based on the temperature dependence of the lifetime and/or intensity of the afterglow phosphorescence which was dominated by the thermal excitation of trapped carriers. Characteristics of the long phosphorescent fiber-optic thermometer are quite different from those of the conventional thermometer using fluorescent lifetime of the phosphors. Lifetime and intensity of the afterglow phosphorescence from the long afterglow phosphorescent sensor heads show large positive temperature coefficients in the narrow temperature region around room temperature. Sensitivity and temperature range of the long phosphorescent fiber-optic thermometer depend strongly on the trap depth and the trap density of phosphors. Since the trap depth and the trap density vary with a...

Fiber-optic Thermometer Using Afterglow Phosphorescence from Long Duration Phosphor

A fiber-optic thermometer is developed based on the temperature dependence of the afterglow phosphorescence intensity which is dominated by the thermal excitation of trapped carriers using long duration phosphor, The intensity of afterglow phosphorescence from the long phosphorescent sensor head increases greatly and linearly with the temperature ranging from 270 to 320 K with the temperature coefficient of 1.3 % K−1. The long phosphorescent materials are potentially useful phosphors for the sensitive sensor head in fiber-optic thermometers.

Fibre-optic thermometer using sensor materials with long fluorescence lifetime

A fibre-optic thermometer using newly developed phosphor sensor materials is described. A highly sensitive fibre-optic fluorescence thermometer is developed using chromium ion (Cr3+) doped phosphor crystals with a longer lifetime than that of conventional ruby sensors. Long fluorescent europium doped strontium aluminate phosphors co-doped with various auxiliary activators (SrAl2O4:Eu2+, Ln3+, Ln = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), were also grown and evaluated. In the fibre-optic thermometer using Cr3+ doped phosphor, PL lifetime decreased at temperatures ranging from 270 K to 750 K. The sensitivity of the fibre-optic thermometer varies with the host materials of Cr3+ ions. In the fibre-optic thermometer using SrAl2O4:Eu2+, Ln3+ doped phosphor, the value and lifetime of afterglow phosphorescence from the SrAl2O4:Eu2+, Ln3+ phosphors varied greatly in the narrow temperature region because the afterglow phosphorescence was dominated by thermal excitation of trapped carriers. Since the trap depth and the trap density depend on auxiliary activator elements, the sensitivity and temperature range of the fibre-optic thermometer using SrAl2O4:Eu2+, Ln3+ phosphors varied with auxiliary activator elements of SrAl2O4:Eu2+, Ln3+ phosphors.

Comfort Pressure Evaluation of Men's Socks Using an Elastic Optical Fiber:

In this work, factor analysis is used to study six adjectives for defining comfort in Japanese mens socks. Comfort consists of three common factors: Factor A is related to a tight feeling at the sole of socks and a cramped feeling, factor B is related to a close tit feeling, and factor C is related to a tight feeling at the top of socks and a comfortable feeling. Because the comfortable feeling is closely related to the tight feeling at the top, a system is developed to measure the clothing pressure at the top of the socks using an elastic optical fiber. The relation between the subjective evaluation of comfort and the clothing pressure as measured by the experimental system is then examined by correlation analysis. Because the clothing pressure at the sock top has a positive correlation with the tight feeling at the top and a negative correlation with the comfortable feeling, mens socks are judged loose at their tops and comfortable as the clothing pressure at the top decreases.

Characteristics of sapphire fiber connected with ruby sensor head for the fiber-optic thermometer applications

The influences of fiber materials on the performance of the fiber-optic thermometers are evaluated using the thermal probes, in which the sapphire fiber and/or the silica fiber was connected mechanically with the ruby sensor head. The value of photoluminescence (PL) lifetime and its temperature coefficients for the ruby sensor head with sapphire fiber (/spl tau/ = 3.9 ms and -9.9 /spl mu/s/K) were slightly different from those using the silica fiber (/spl tau/ = 4.2 ms and -10.9 /spl mu/s/K), due to the background PL from the sapphire fibers. The influence of the PL from the sapphire fiber on the temperature measurements can be reduced successfully using a modified lifetime calculation based on the curve fitting of the PL decay with double exponential equation.

Characteristics of chromium doped spinel crystals for a fiber-optic thermometer application

Thermometer probe using the chromium doped spinel crystals, MgAl/sub 2/O/sub 4/:Cr/sup 3+/, has been fabricated and the wavelength dependences of PL lifetime are evaluated as compared with those using ruby crystals. Lifetimes and temperature coefficients of the spinel crystals (/spl tau/=10 ms, 37 /spl mu/s/K), which were typically 3 times larger than that of the ruby crystals (/spl tau/=4 ms, 10 /spl mu/s/K), varied from 4.74 ms to 1.65 ms with wavelength from 667.5 nm to 780 nm.

Optical Coherence Domain Mid-infrared Spectroscopy

The infrared spectroscopy is widely used as an analysis method of the chemical today. On the other hand, the technology that enables structural information acquisition in compound quality by OCT (Optical Coherence Tomography) develops, too. In this research, it aimed to develop measurement technique of non destructive and non contact of three dimension structure in a new technique for combining these. The measurement system was constructed by using low coherence light source and Michelson interferometer for the verification of principle, and in this thesis, it is a model sample in a known multilayer structure was used and examined. As a result, the possibility of obtaining the location information and element information on each level of model sample was able to be shown. It will aim at a three dimensional mapping in the future and it aims at doing qualitative and quantitative fault image measurement system achievement, and the application is developed

Determination of the Autocorrelation Function of Woven Fabrics Using Laser Speckle

When a rough surface is irradiated by a laser light and reflected or transmitted light is observed, a diffraction fringe with speckle is obtained at the observation plane. This diffraction fringe is called the speckle pattern. In the present study the static states of woven fabric surfaces were obtained as the autocorrelation functions from the speckle patterns. The functions indicate the following: 1) By the reflection method the surface configuration of a woven fabric can be determined; by the transmission method the state of plane arrangement of yarn can be determined. 2) Three funda mental weaves (plain weave, twill weave, and satin weave) can be discriminated. 3) The presence and sizes of periodic defects in the woven fabric can be detected.