This paper describes a laser three-focus velocimeter for measurement of particle size and velocity to make the system compact and portable. An array of independently driven laser diodes is used to obtain the stable output of the laser beams without the thermal interference between the laser diodes and to exclude ambiguity of velocity direction. The method measuring velocity and size of a transparent and spherical particle is shown. The optical characteristics are analyzed. Using a flow of glass beads, it is confirmed that this velocimeter is a useful tool for measuring particle size and velocity simultaneously.

A fiber heterodyne interferometer probe free from external disturbance, which can measure small displacement of an object as a pressure transducer or a vibrational object, is described. The phase fluctuation in the fiber due to external disturbance is excluded using a reference beat signal of light beams from a reflection mirror on a graded index rod lens. A graded index-type multimode fiber connected to one end of a single-mode fiber by arc fusion splicing is used to improve acceptance of the light. The characteristics of the fiber probe are also described.

Approach to speed control using temperature characteristics of ultrasonic motor ~~ 50 [Idlz] 1 10 [Vm,] 0.5 [kgf-cm] 1 .0 [W] 200 [rpml 1 .O [kgf-cm] 1 .O [kgf-cm] 263-328 IK1 Abstract-Ultrasonic motors have some special unique features, such as high-torque under low-speed operation, compact size, and no electromagnetic noise. Ultrasonic motors would be expected to apply an element of the artificial muscle. The driving principle of the ultrasonic motor is based on friction force between a rotor and a stator. Therefore, it is difficult to drive the ultrasonic motor at a constant speed, because the generation of heat by friction changes the friction force. In this study, we proposed speed controllers of the ultrasonic motor, considering the temperature rise of the ultrasonic motor. From the results, these methods were proved the most effective for the speed control of the ultrasonic motor in experiments.

As a functional type fiber temperature sensor has a long sensing fiber for a range of measurands, the phase sensitivity is high for temperature change. An optical heterodyne interferometer has been used to measure small phase variation in the temperature sensor. However, the interferometer has suffered from external disturbance because the reference light has a different path from the measurement arm. This paper describes an optical fiber temperature sensor using heterodyne interferometory to enable free from external disturbance easily. The measurement arm is made loop to remove the reference arm. A stabilizied transverse Zeeman laser (STZL) is used to exclude the phase fluctuation due to the phase difference between the measurement path and the reference path. The STZL has the leak frequncy components. The leakage causes the periodic nonlinearity of the heterodyne interferometer and decreases the accuracy of the interferometer. The relation between the cross talk due to the leakage and the measured phase error is analyzed with considering initial phase difference between polarization components of the STZL beam. From the analyzed result it is found that the cross talk can be measured from amplitude modulation of beat signal. To reduce crosstalk term, the leakage is decreased by phase compensation method using a quarter-wavelength plate, and the cross talk term is cancelled by a new fringe distribution method.In the temperature sensor, the reduction of the non-linearity is confirmed experimentaly.

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