For measuring high-frequency and intense ultrasonic fields, a miniature sensor with a durable structure has a great demand recently. The authors propose a new fabrication method of the small acoustic sensor which is composed of a micro optical cavity of 100 μm long at the end of an optical fiber. The deformation or the refractivity change of the cavity by sound wave is measured by monitoring the reflected light intensity at another end of the fiber. In this report, the fabrication technique of the sensing part is first described. Then, we examine the basic properties for measuring ultrasound in water. It is shown experimentally that megahertz ultrasonic field can be measured successfully by the prototype micro probe with a good spatial resolution.

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It is favorable for the bolometer material used as an uncooled infrared detector device to have large TCR (temperature coefficient of resistance) near room temperature. La_1-xCa_xMnO_z (LCMO) not only shows colossal magnetoresistance, but also has large TCR for the bolometer material. LCMO thin films deposited on LaA10₃ in several conditions by laser ablation method and were measured their resistivities to estimate TCR and analyzed their mechanism for the oxygen deficiency effect. As a result, we have got thin films which show large TCR by changing oxygen pressure in verger and anneal temperature. The oxygen deficiency effect clarifies to us that it is possible to apply LCMO thin films to bolometer materials.

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This paper deals with inspection method of railway track irregularities by acceleration. These irregularities are inspected by a track inspection car. There are two methods for inspection of track vertical or horizontal irregularities, they are the differential method and the inertial measuring method. Track irregularities inspection method now in use is the mid-chord offset method on inspection car of conventional lines. The inertial measuring method is rare for practical use, because it has demerit with output wave distortion. In this paper, the inspection method is suggested without this demerit, that is directly obtained mid-chord offset irregularities from acceleration. From the result of test on conventional line, we obtain as follows: (1) Characteristics of midchord offset method and inertial measuring method are analyzed and problems in those method are clarified . (2) We propose new inertial inspection method with characteristic of mid-chord offset method. (3) The precision of this inspection method is 0.5mm and the difference between this inspection method and convention mid-chord offset method is 0.7mm.

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We have developed a multichannel taste sensor with lipid membranes which can detect and quantify the basic taste substances in aqueous solution. The aim of the present study is to increase selectivity to adsorptive taste substances (bitter, umami and astringent taste substances) for quantification of taste by improving measuring methods. High selectivity to adsorptive taste substances is obtained by CPA measurement algorithm (CPA: Change of membrane Potential caused by Adsorption). High repeatability is also obtained by developing a cleaning technique of taste sensor.

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An emission microscope, which has two electrostatic lenses, has been made at our laboratory in order to observe magnified emission patterns for a FEA (field emission array). The electrostatic lens system consists of a bipotential lens and an Einzel lens (a three electrode static lens). The lenses focus the emission patterns on a phosphor screen placed at 315mm from the center plate of the Einzel lens. The total magnification is 100. The microscope enables to separate the field electron emission from each individual cathode as bright spots on the phosphor screen. It is found that the electron beam from slightly non-concentric structure of the individual cathode deviates from the optical axis and gives a comet-like tailed spot. The luminance of the spots fluctuates like pulses.

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In order to design and develop electric power apparatus it is important to analyze electrical discharges, and a measurement of an electric field is greatly helpful to it. There are some methods for measuring the electric field. Among them a Pockels sensor is based on an optical method and has many advantages.
There is a request to miniaturize a sensor from a view point of spatial resolution. An optical waveguide technique has been successfully introduced in Pockels sensor to achieve the spatial resolution of micrometers.
As a senor for measuring electric field in space it must be confirmed about two characteristics. One is limitation of its caliblation in non-uniform fields and the other is its operation with space charges. Pockels sensors except for what in fixed envirornment must be calibrated under uniform field and it is surmised there is limitation. In consideration of discharge measurement charge attachiment on Pockels sensor is inevitable. In this paper these two points are examined.

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A new 39 channel SQUID magnetometer system with 3D second-order gradiometer has been developed for research use in order to measure the biomagnetic fields. This is the total hardware system consisting of 39 SQUID sensors with detecting coils, readout electronics, two liquid helium dewars for MEG and MCG, a gantry, and a magnetically shielded room.
The noise characteristics of frequency domain of three components were measured. The power spectra of the noise field normal component are about 15fT/√Hz at 10Hz and under 10fT/√Hz at white noise. The power spectrums of the noise field tangential component are about 12fT/√HZ at 10Hz and under 10fT/√Hz at white noise. An alpha rhythm occurring from a subject's head was recorded with the amplitude of about 500fT at about 10Hz. We could measure the mixed AEF and SEF overlapping in time using this system. From these results, the system has a sufficient ability to measure weak magnetic fields from the brain.

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This paper proposes two new kinds of two dimensional micro magnetic sensor arrays, which are designed for a position sensor in a micro superconducting magnetic conveyance system with feedback control. One is a magnetic switch array with a nickel cantilever structure fabricated by electro-plating. Another one is a Hall sensor array consisted of so-called a MOS-Hall element, which is a MOS device in fact, but works as a Hall element. We have fabricated these two different types of sensor arrays by micromachining process, and tested their performances. The sensing principle, fabrication process and experimental results are reported.

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