Fundamental study for measuring microflow with Michelson interferometer enhanced by external random signal

We propose a measuring technique for microflow based on the stochastic resonance phenomenon. The minute changed signal from the microflow hidden within the threshold of multi-threshold imaging sensors, such as CCDs, can be reconstructed using an external random signal. The differences in optical path length fringes of a Michelson interferometer were enhanced by scattered light using a micro Brownian particle solution. In this paper, we investigate the required characteristics of the external random signal numerically and experimentally. The feasibility of the proposed method was experimentally confirmed. The number of pixels required to reconstruct the signal was smaller than expected owing to internal and environmental noise signals. We show that the standard deviation of the external random signal plays an important role in enhancing the accuracy of the measurement.