A three-ports micro ER valve has been fabricated by photolithography, which is made of a patterned resist film between two-glass plates coated ITO electrode pattern. And one inlet channel (height h 1/4 0.1 mm, width w 1/4 2 mm) of the ER suspension diverges into two outlet channels having ER valves, so that the inflow of the ER suspension from the inlet port is divided into two outflows to the two outlet ports by synchronously controlling a pair of ER valves installed in the outlet channels. The PWM control strategy is applied to a pair of ER valves to change the flow rates, as proposed in our previous paper. The PWM control of each outlet micro ER valve can realize the almost same changing characteristics of flow rate with the duty ratio as that of a conventional valve. The switching characteristics of a pair of ER valves have been investigated by measuring the flow rates from both outlet ports and visualizing the micro-flow behavior of ER suspension in the ER valves.

A diode-pumped solid-state (DPSS) laser, such as a Nd:YAG green laser, has become smaller in size , lower in cost and higher in performance. Therefore, the DPSS lasers are widely used in many industries. For a laser interferometers and secondly length standards, stable light sources are in demand. We have developed 532 nm iodine-stabilized DPSS lasers used for the applications. The lasers have following features ; compact design (D 280×W 170×H 120 mm), high power (3 mW) , high stability ( < 1×10-10 : allann deviation k=1 at τ=1 sec), and easy operation.

Laser interferometers are widely used to measure highly sensitive length and displacement, e.g., in which refractive index fluctuations of air adversely affect measurement accuracy. To compensate for these effects, the two-wavelength interferometer studied has not yet proved practical in industrial use. We studied the interferometer’s performance and practicality, using uncertainty analysis to extract its features. Based on our results, we developed a two-wavelengthMichelson interferometer with wavelengths of 1064 nm and 532 nm. It was calibrated and evaluated using a highprecision laser interferometer whose optical path was in a vacuum. Results confirmed measurement accuracy of 100 nm/50 mm (k=2) under unstable air conditions - superior to a traditional laser interferometer.

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