Doppler flow imaging of cytoplasmic streaming using spectral domain phase microscopy

Spectral domain phase microscopy SDPM is a function extension of spectral domain optical coherence tomography. SDPM achieves exquisite levels of phase stability by employing common- path interferometry. We discuss the theory and limitations of Doppler flow imaging using SDPM, demonstrate monitoring the thermal con- traction of a glass sample with nanometer per second velocity sensi- tivity, and apply this technique to measurement of cytoplasmic streaming in an Amoeba proteus pseudopod. We observe reversal of cytoplasmic flow induced by extracellular CaCl2, and report results that suggest parabolic flow of cytoplasm in the A. proteus pseudopod.