Microplastic size-dependent turbidity detection using spectral decay in multiple self-mixing interference

Present detections of water turbidity lack analysis of the dependence on microplastic size. This work proposed the detection of water turbidity using spectral decay in multiple self-mixing interference. The experiments were conducted to detect water turbidity on the condition of different microplastic sizes. By accumulating the weak scattering of microplastics through multiple reflections in multiple self-mixing interference, the detection transformed reflected light into harmonic peaks of spectral line characterized by exponential spectral decay. The experimental results exhibited that the detection sensitivity was related to the microplastic size, and this work was suitable for detecting small-sized microplastics.