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Seeing the Unseen with Localized Optical Contrast

Suran, Swathi and Bharadwaj, Krishna and Raghavan, Srinivasan and Varma, Manoj M (2016) Seeing the Unseen with Localized Optical Contrast. In: Conference on Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications XIII, FEB 15-17, 2016, San Francisco, CA.

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Official URL: http://dx.doi.org/10.1117/12.2212028


Optical wide-field imaging of sub-diffraction limit nanostructures is of interest in a wide array of applications. In applications where the nanostructures to be visualized are well isolated, a high enough optical contrast is sufficient to detect these. Here we demonstrate a technique to visualize nanoscale features, such as grain boundaries in Chemical Vapor Deposited (CVD) single layer graphene, which are just a few atom length defects, using regular bright field optical microscopy. This remarkably low lateral length scale was imaged using of a special thin film structure consisting of a water-soluble thin film layer deposited on a metal substrate, which produces a strong color change as a function of the film thickness. Small local water transport differences in the graphene layer result in thickness variation of the underlying thin film due to its solubility in water and produces color contrast readily observable under a normal bright-field optical microscope with the naked eye. We demonstrate the use of this technique for direct optical visualization of grain boundaries in graphene as wide as 2-5 nm and sub-100 nm photoresist lines. By using super-resolution image processing algorithms, we may be able to detect structure even smaller in size than currently achieved. We believe that this technique can be extended to single molecule detection.

Item Type: Conference Proceedings
Series.: Proceedings of SPIE
Additional Information: Copy right for this article belongs to the SPIE-INT SOC OPTICAL ENGINEERING, 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA
Department/Centre: Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited: 28 Oct 2016 07:31
Last Modified: 28 Oct 2016 07:31
URI: http://eprints.iisc.ac.in/id/eprint/55179

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