Development of multichannel optical sensor and visualization of vibration distribution

Abstract

A multi-channel optical sensor system was developed to measure vibrations simultaneously with high spatial resolution. As sensor elements, optical displacement sensor units were developed not to disturb the natural vibration. Each sensor unit, which consists of the optical fiber bundle and focusing lens, can detect the displacement of the object as the variation of the reflected light power. The sensor unit has a displacement resolution of 10 nm, a dynamic range of more than 90 dB, and a frequency band width of up to 80 kHz. Up to 64 sensor units can be arrayed as one sensor head, which realizes the simultaneous measurement of vibration distribution with the high spatial resolution of 4 mm. A calibrating function under the measurement circumstances was developed. Under calibration mode, the sensor array head is moved by a linear actuator, while the vibration of the object is stopped. Thus the calibrated data of each sensor unit can be obtained for the displacement magnitude. Measured vibration distributions can be monitored as the three-dimensional animations. With the system developed, several actuators for vibratory micro-injection were measured, and the system could reveal their detailed vibration distributions and could detect the existence of a failure portion of some actuator.