並進三自由度差動式光学変位センサの出力特性の解析と改善

抄録

The characteristics of a differentially-operated optical displacement sensor developed for wind-tunnel using magnetic suspension are studied both analytically and experimentally. The target sensor measures the three-dimensional displacement of the suspended object (floator) from the variations of the shadow of the floator. It is composed of eight optical systems. First, the output characteristics of the fabricated sensor are measured. As to linearity, it is good in the direction of light (x-axis) but inferior in the other directions (y and z axes). In addition, interferences among the axes are observed. Because the differences in characteristics among the optical systems cause such errors, adjustments by software are carried out. They reduce the nonlinearity and interferences. However, residual errors still remain. To clarify the reasons, the output characteristics are studied analytically by investigating the movement of the shadow of the floator and the variations of the illuminated area on the lenses. The results suggest that nonlinearity and interaxial interferences exist on some extent in the sensor, which was observed in the experiments.