We proposed and demonstrated a practical method for simultaneous measurement of the refractive index and the thickness of a transparent plate, based on the low coherence interferometry. This paper suggests that our method is applicable for birefringence measurement using unpolarized light source. Small birefringence of thin medium such as LiTaO₃ crystal is measured with high accuracy, by introducing dispersion compensation into the low coherence interferometry.

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In order to study contact-free levitation systems for micromachines, our group has developed a levitation system with a millimeter-sized cylindrical rotor. The system consists of a rotor (2.0mmφ×8mm, 95mg), a pair of electromagnets for levitation, two pair of photo diodes for sensing, and an analog PD controller. The photo diodes detect axial displacements and rotation speeds of the rotor. The rotor and the electromagnets are so small that the rotor in the radial direction is passively stabilized. This paper describes closed-loop frequency responses, follow-up control characteristics, impulse responses, and rotation decay characteristics. From the results, it is found that the levitating rotor makes a very quick response because of the small mass 95mg, and that photo diodes are useful for sensing rotation speeds, and that the levitation system is applicable to frictionless micromechanisms.

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A high sensitive miniature piezoresistive force sensor utilizing combination of three-axis stress components has been developed. This work aims to develop a force sensor which acts as a sensing unit assembled in a new miniature high pressure sensor. By using a force transmission rod, forces are applied to piezoresistors on a Si diaphragm of the sensor. Resistance changes of the piezoresistors depend on combination of stress components generated by the applying forces. FEM stress analysis was carried out, in order to investigate dependence of stress components on dimensions and Young's modulus of the rod, and diaphragm thickness. A sensor structure to obtain large resistance changes of the piezoresistors was found by utilizing valid combination of three-axis stress components according to the analysis. As an experimental result, an output voltage more than 140mV/5V at 150N was obtained.

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Peristaltic motion system like earthworm are proposed and developed. This system consist of several flexible units. The unit has the flexible body made of silicone gel, the plates made of silicon at both edge of the unit, an SMA coil actuator, which are in the center of the body and are connected to the plates, and the circuit including a D register and a switch for driving the SMA actuator fabricated on the plate. As the units are connected serially each other, the structure of the peristaltic motion system and the shift register to transfer the driving signal are constructed. The simple system was fabricated. The driving circuit was made out of the units. The plates were steel washers. The speed of 0.21mm/s was obtained when the clock frequency, the driving current for the SMA actuators were 3Hz and 400mA, respectively. This system is useful for the motion mechanism for the micromachine which move in the narrow pipes.

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The recovery process of stiction-failed micro-cantilevers with excimer laser irradiation has been investigated experimentally and numerically. Micro-cantilevers with various lengths have been prepared with standard surface micromachining process. KrF laser is used for experiment, and the influence of the laser parameters on the recovery yield have been examined experimentally. The laser fluence has strong impact on the recovery yield of the stiction-failed micro-cantilevers. The recovery yield does not exhibit significant dependence on the repetition rate and the number of pulses. Temperature rise of the cantilevers is numerically calculated by solving a set of energy conservation equations that includes the non-equilibrium nature of the carriers and the crystal lattice in the cantilevers. The carrier temperature rise becomes lower than the femtosecond laser irradiation case, and thus the carrier induced recovery process is not expected to occur. The lattice temperature rise becomes significant at the time scale of the laser pulse width. Lattice temperature difference between the front and rear surface of the cantilever also becomes significant. The lattice temperature may have strong influence on the recovery yield.

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Sensing properties of mixed LB films used as odor sensors were studied. They are constructed of some organic materials like phospholipids and proteins as sensing films deposited on a QCM, and are used mainly to detect volatile organic compounds such as benzene, hexane, hexanone, etc. The use of the mixtures made possible the deposition stable and reproducible. Besides, it permitted to combine the characteristics of the substances and to control the response patterns as the proportion was changed. Furthermore, the use of calixarenes with a supramolecular structure as a “host-guest” characteristic layer deposited by the LB technique was adequate when looking for an increase of the sensitivity and selectivity due to the size and shape recognition characteristics of this molecule.

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Characteristics of near-axis scattered light were investigated to get optical imaging of biological body. In the Monte Carlo simulation and time-resolved measurement, shapes of light pulse emitted from a tissue-like scattering object were analyzed. The near-axis scattered light was detectable in terms of its intensity and angular characteristic.

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