Hirotaka Ito

Active endoscope with SMA (Shape Memory Alloy) coil springs

This paper describes the development of an active endoscope which allows a large bending angle for practical application and has a simple structure for miniaturization. An active endoscope (image fiber with 4200 pixels and light guide fiber) 2 mm in outer diameter with a shape memory alloy (SMA) actuator was designed and fabricated. The practical specifications of the SMA coil spring were determined based on a design chart and equation. The active endoscope consists of a bending part, the SMA actuator, and an endoscope. The mechanical properties of the bending part were investigated. The shear modulus of the SMA at room temperature and in the parent phase were determined in designing the actuators.

Nonstoichiometry Effects and Their Additivity on Anomalous Photovoltaic Efficiency in Lead Lanthanum Zirconate Titanate Ceramics

(Pb 0.97 , La 0.03 )(Zr 0.52 , Ti 0.48 ) 1-0.03/4 O 3 ceramics doped with various amounts of Ta were sintered at 1200°C for 2 h and then heat-treated in nitrogen at 900°C for 1 h to investigate the nonstoichiometric effects on the anomalous photovoltaic effect (APE). In the samples pretreated in nitrogen, both the photovoltaic current and the photovoltage were increased by the doping of Ta, and showed maxima around 1.5 mol% of doped Ta. Similar photovoitaic change with various amounts of Ta was observed in the nitrogen-treated samples. They, however, showed markedly higher values of the photovoltaic current and voltage than those in the doped samples pretreated in nitrogen. From this result, additivity is confirmed to hold for the effect of Ta doping and that of nitrogen treatment on the APE, indicating the coexistence of two types of contributions to the APE through different mechanisms. The spectral responses showed peak shifts and curve extension of the photovoltaic current to different directions according to the two effects. The mechanisms of those effects were discussed.

Fiberscope-type environmental monitoring devices with binocular parallax accommodation mechanism for stereoscopic observation

A fiberscope-type environmental monitoring device is suitable for observation in narrow spaces that cannot be observed by conventional technology. The goal of developing this device is advanced functions such as stereoscopic and microscopic observation. The binocular parallax can be varied by bending the fiberscope. The position of the stereoscopic observation area is shifted by changing the binocular parallax. Therefore, the operator can observe the object without having to move the fiberscope back and forth and can also get optimum images on a 3D display by accommodation of the binocular parallax. Microactuators are necessary to accommodate the binocular parallax. This stereoscope consists of two fiberscopes, an SMA (shape memory alloy) coil spring, a bias spring plate, and two support plates, and is covered with a stainless steel pipe 5 mm in outer diameter. The fiberscope consists of an image fiber with 12,000 pixels and six light guide fibers. The outer diameter of the fiberscope is 1.3 mm. The wire diameter and the outer diameter of the SMA coil spring are 75 /spl mu/m and 300 /spl mu/m, respectively. The SMA coil spring is stretched and fixed to the tip of the fiberscopes. We devised a system for stereoscopic observation and an environmental monitoring device using two fiberscope. We also defined the stereoscopic parameters necessary for stereoscopic observation.