To evaluate the stability of man-made structures such as bridges, high-rise buildings and dams and of regions prone to dangers such as bedrock collapse, we are planning the construction of a health monitoring system using a fiber Bragg grating (FBG). In this paper we discuss the use of an FBG and serrodyne modulation to perform dynamic strain measurements in order to detect Bragg wavelength shifts in combination with an unbalanced Mach-Zehnder interferometer. When a Bragg wavelength shift is measured as a phase difference, the pseudo-heterodyne effects of serrodyne modulation are represented in terms of the frequency ratio and serrodyne coefficient. As the frequency ratio shifts away from unity, it causes non-linear changes in electrically measured phase, as has been demonstrated by experimental measurements of the shift in wavelength of a swept narrowband signal reflected by a fiber Bragg grating. The shift coefficients of FBG Bragg wavelengths measured in this apparatus matched the values measured with a wavelength resolution of 1×10^-12m using an optical spectrum analyzer and an external cavity tunable diode laser, showing that the resolution of wavelength shift detection was 1×10^-12m or less.

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Arrayed ultrasonic transducers using the piezoelectric thin film (lead-zirconate-titanate film: Pb(Zr_0.52Ti_0.48)O₃ : PZT) having multilayer diaphragm structures are fabricated. The variation in resonant frequencies of conventional ultrasonic sensors is 7.3% in standard deviation, although those have the same structure. In order to reduce the variation of resonant frequency, membrane is coated by amorphous fluorocarbon polymer (FC) film (CYTOP, AGC). The variation in resonant frequencies of new ultrasonic sensors is 2.3% in standard deviation. The resonant frequency and Q-value and sensitivity of new ultrasonic sensors are estimated to be on the order of 56.9kHz and 28.3 and 114 μV/Pa, respectively. This amorphous fluorocarbon polymer film is effective for improvement of reception characteristic of ultrasonic sensor. This ultrasonic micro array sensor using the amorphous fluorocarbon polymer film is shown to be useful for three-dimensional object detection system.

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In this report, the spectral sensitivity was used for semiconductor junction analysis. This analysis is carried out by means of a photoconduction characteristic depend on the electric field strength in the material. The light absorption and the photoconduction current are in proportion, and the electric field strength in the material is known by way of comparing the photoconduction current to the light absorption. The material has different absorption coefficients each wave lengths, and has different complete light absorption lengths. Then, it is possible to select the analysis area at the material, if select appropriate wave length. From this analysis method, the electric field strength and the potential along thickness of the material can be evaluated. This analysis method was applied to evaluate the electric field strength on the ITO-ZnSe junction, and the potential distribution and the depletion layer were evaluated. As a result, it was found that ZnSe layer had space charges near the junction.

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Fiber Bragg Grating (FBG) strain-sensing system has been paid much attention for the advantages of its light weight, anti-explosion, and harmlessness for electromagnetic noise, but it has not been widely used in practical applications with the high price. We have developed a new concept of wavelength meter in which the transmission center wavelength is monitored by mechanically applying a certain strain to a scanning FBG. The accuracy and stability are found to be ±0.01 nm for 12 days running, which is enough for the most applications.

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Optically driven 3-wing mixers are designed, fabricated and applied to liquid mixing in a microchannel. Three-wing mixers are easily fabricated into the desired shape by photolithography based on a large wing angle, and they are stable against trapping and rotation. Two-liquid mixing is visualized by the variation in milk fat colloid density, and velocity vectors are obtained through a stable and fast rotation rate of 500 rpm, even in a flow of 67 μm/s.

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This paper describes a sensing technique to detect beam deflections caused by the two different vibration modes, i.e. bending and torsion modes of a micro cantilever, separately with two piezoresistor bridge circuits. Fabrication process to incorporate this detection circuitry into a two-dimensional optical microscanner together with the signal processing circuitry for self-sustaining vibrations are presented, which enables a compact feedback control of the two-dimensional optical scanning. Prototype optical scanners with this detection circuitry and magnetostirictive actuation have been fabricated with MEMS technology and tested to verify this technology.

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Surface polishing is required for small crystal blanks to eliminate frequency spurious generated by the infinite rectangular shape. From the productivity viewpoint, bi-convex or plano-cylindrical surface are generally used to realize the energy trapping at the central part of the blanks. So far barrel polishing is the common fabrication technology to obtain bi-convex surface, however, the surface is finished insufficiently and fabrication process takes longer time as the blank size becomes small. To solve this difficulty, two types of new surface micro-polishing mechanisms with fixed abrasive and arrayed blank arrangement are experimentally examined to obtain plano-cylindrical surface. The fastest finishing time of 10 s for a blank is achieved together with the spurious elimination.

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