Quantitative Phase Imaging using a Frequency Comb for Speckle-Less Cellular Motion Measurement

Quantitative Phase Imaging (QPI) is a label-free imaging technique widely applied for investigating cellular properties (e.g., physical thickness and refractive index) [1]. Because it is based on the interference of light, the coherence of light source is a prerequisite. However, coherent illumination unavoidably encounters speckle noises, so several techniques have introduced low spatially or/and low temporally coherent light sources [2-4]. Nevertheless, those techniques have suffered from difficulties in system complexity and limited performances. Here, we proposed a speckle-less QPI using coherence-controlled frequency-comb (FC) as a light source. Since a frequency comb enables a lower phase noise in wide time scales, frequency-comb-referenced (FCR) QPI can help measuring dynamic motions at cellular level in live biological samples.