Authors:

Agustin Lopez Zapata

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About Paper:

Fluctuation spectroscopy of dynamic speckle measures intracellular transport by detecting Doppler frequency shifts produced by a broad range of cellular motions related to different mechanisms and functions that maintain cellular healthiness. The scale in which these speeds occur require a stable enough system capable of resolving subtle frequency offsets. This work utilizes a common-path interferometric system with a low-coherence NIR source, based on a Fresnel biprism geometry, which enhances stability by ensuring the signal and reference traverse the same optical path. Mechanical disturbances influence is therefore minimized, allowing to measure ultra-low frequency shifts. This technique yields image-domain autocorrelations that reveal dynamic speckle fluctuations by performing the Fourier reconstruction of the self- referencing speckle fields. The sensitivity extension to frequencies below 1 mHz grants this approach to unfold a new window into slow biological processes, such as cytokinesis and cell crawling. These advancements lay the groundwork for future applications in live tissue studies and drug response monitoring, though such applications remain under active investigation. Keywords: Biodynamic Imaging; Digital Holography; Dynamic Light Scattering; Common-Path Interferometry

Source:

Purdue University / 2025

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Co-authors:

Agustin Lopez Zapata