Simple automatic fluid displacement measurement by time-of-flight laser sensing technology for volume calibrator need

The measurement of fluid displacement automatically is an urgent part to build an accurate calibrator of volume. The laser interferometer is the best accurate method, but it is not easy to be implemented. The primary standard of length quantity still refers to the speed of light in vacuum. Therefore, the application of laser to measure the fluid displacement length by time-of-flight technique is the simple best effort to achieve the sufficient accurate results and minimize human error. The emitter and receiver of laser with 940 nm wavelength are implemented to solve this task. The purpose of this research is to measure automatically a small fluid displacement by time-of-flight laser method to fulfill simply the accuracy need on volume calibrator. The measurement results indicated that this simple automatic method successfully achieved the accuracy of distance and displacement below 0.5% and 2%, respectively. However, the light refraction behavior on fluid must be taken into account which can affect 0.6% of accuracy. In addition, limit shield can be applied to improve the measurement accuracy.