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Proceedings Paper

Bond-selective phase contrast imaging (Conference Presentation)
Author(s): Ji-Xin Cheng

Paper Abstract

Phase-contrast microscopy detects the optical phase delayed by a specimen, especially by transparent ones. Modern phase imaging techniques are capable of quantifying the phase, enabling a large variety of applications. A missing feature of phase imaging, however, is the lack of chemical information. To fulfill this gap, we developed a bond-selective phase-contrast microscope based on chemical bond vibrational absorption of mid-infrared light. We report high spectral fidelity, nanosecond temporal resolution, submicron spatial resolution, and a speed of 50 frame/sec in a wide field scheme, limited by the camera. Our microscope utilizes a mid-infrared pulsed laser to induce a local temperature rise via absorption, resulting in a transient phase change of probe light that is directly related to the molecular spectroscopy information of the specimen. By tuning the delay between the pump and probe laser, the dynamics of the absorption and heat decay is acquired, adding another dimension of information. Our approach links the missing chemical information to phase contrast, which paves a new avenue for microscopic studies in biology and materials science.

Paper Details

Date Published: 4 March 2019
Proc. SPIE 10887, Quantitative Phase Imaging V, 108870E (4 March 2019); doi: 10.1117/12.2513362
Show Author Affiliations
Ji-Xin Cheng, Boston Univ. (United States)

Published in SPIE Proceedings Vol. 10887:
Quantitative Phase Imaging V
Gabriel Popescu; YongKeun Park, Editor(s)

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