Holographic microscopy in low coherence

conference paper

English

Low coherence of the illumination substantially improves the quality of holographic and quantitative phase imaging (QPI) by elimination of the coherence noise and various artefacts and by improving the lateral resolution compared to the coherent holographic microscopy. Attributes of coherence-controlled holographic microscope (CCHM) designed and built as an off-axis holographic system allowing QPI within the range from complete coherent to incoherent illumination confirmed these expected advantages. Low coherence illumination also furnishes the coherence gating which constraints imaging of some spatial frequencies of an object axially thus forming an optical section in the wide sense. In this way the depth discrimination capability of the microscope is introduced at the price of restricting the axial interval of possible numerical refocusing. We describe theoretically these effects for the whole range of illumination coherence. We also show that the axial refocusing constraints can be overcome using advanced mode of imaging based on mutual lateral shift of reference and object image fields in CCHM. Lowering the spatial coherence of illumination means increasing its numerical aperture. We study how this change of the illumination geometry influences 3D objects QPI and especially the interpretation of live cells QPI in terms of the dry mass density measurement. In this way a strong dependence of the imaging process on the light coherence is demonstrated. The theoretical calculations and numerical simulations are supported by experimental data including a chance of time-lapse watching of live cells even in optically turbid milieu.

quantitative phase imaging; holographic microscopy; partial coherence; coherence gating; live cells

CHMELÍK, R.; PETRÁČEK, J.; SLABÁ, M.; KOLLÁROVÁ, V.; SLABÝ, T.; ČOLLÁKOVÁ, J.; KOMRSKA, J.; DOSTÁL, Z.; VESELÝ, P.

9. 3. 2016

978-1-62841-952-8

QUANTITATIVE PHASE IMAGING II

0277-786X

Proceedings of SPIE

9718

United States of America

971806-1

971806-7

7

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/9718/1/Holographic-microscopy-in-low-coherence/10.1117/12.2209465.pdf?SSO=1