Digital Holographic Interferometry for Ethylene Glycol Quality Control

David E Onsombi, Geoffrey Rurimo, Jack Kihiko, and Stephen M Njoroge
2026-09-15 10 views 0 downloads

 

Digital holographic interferometry is a non-contact, full-field optical technique for quantifying sample-induced phase variations in transparent liquids. It offers a non-destructive approach for assessing composition-related changes in ethylene glycol. In this study, a Mach–Zehnder off-axis digital holographic interferometry system was constructed using a 632.8 nm helium–neon laser as the coherent illumination source. The laser output was assessed for power stability, after which the beam was spatially filtered and used to record holograms of pure ethylene glycol and ethylene glycol–water mixtures containing 0.1–80% v/v water. The holograms were reconstructed using Fourier-domain sideband filtering. Using the stabilized reconstructed dataset and literature refractive-index data as an external phase-order constraint, the literature-constrained optical path-difference estimate increased from 1.269 µm at 0.1% v/v water to 778.811 µm at 80% v/v water, demonstrating a concentration-dependent optical response. The developed system provides a proof-of-concept basis for literature-constrained, full-field ethylene glycol composition monitoring.

 

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