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Proceedings Paper

High-speed line-scanning confocal holographic microscopy for quantitative phase imaging (Conference Presentation)
Author(s): Changgeng Liu; Sebastian Knitter; Zhilong Cong; Ikbal Sencan; Hui Cao; Michael A. Choma

Paper Abstract

We present a high speed, phase-sensitive, line-scanning reflectance confocal interference microscope. We achieved rapid confocal imaging using a fast line-scan camera and quantitative phase imaging using off-axis digital holography on a 1D, line-by-line basis. In our prototype system, a He-Ne laser (~1.2 mW) was used to demonstrate the principle of operation. Using a 20 kHz line scan rate (1024 pixels per line scan), we achieved a video-rate frame rate of 20 Hz for 1024x500 pixel en-face confocal images (20 MHz total pixel rate). By using an objective lens of a NA 0.65, we achieved an axial and lateral resolution of ~3.5 micrometers and ~0.8 micrometers, respectively. By z-stack imaging of a custom silicon target with a stepped structure, we confirmed that the axial sectioning of the interference microscope is similar to that of a traditional line-scan confocal microscope (our microscope with the reference arm blocked). The utility of phase-sensitive holographic detection in line-scan confocal was demonstrated in two ways. First, using a custom axial height phantom fabricated using chrome deposition, we demonstrated variations in phase corresponding to heights in the 100 nm range with a contrast-to-noise ratio of ~31 dB. Second, we demonstrate digital refocusing of an out-of-focus holographic image. The mechanism of confocality in our line-scan system is 1D physical pinholing. Our ongoing work aims to add an additional mechanism of confocality by using low spatial coherence sources to impose interferometric pinholing.

Paper Details

Date Published: 27 April 2016
PDF: 1 pages
Proc. SPIE 9718, Quantitative Phase Imaging II, 971820 (27 April 2016); doi: 10.1117/12.2212033
Show Author Affiliations
Changgeng Liu, Yale School of Medicine (United States)
Sebastian Knitter, Yale Univ. (United States)
Zhilong Cong, Yale School of Medicine (United States)
Ikbal Sencan, Yale School of Medicine (United States)
Hui Cao, Yale Univ. (United States)
Michael A. Choma, Yale School of Medicine (United States)

Published in SPIE Proceedings Vol. 9718:
Quantitative Phase Imaging II
Gabriel Popescu; YongKeun Park, Editor(s)

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