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Proceedings Paper

Wavelength scanning achieves pixel super-resolution in holographic on-chip microscopy
Author(s): Wei Luo; Zoltan Göröcs; Yibo Zhang; Alborz Feizi; Alon Greenbaum; Aydogan Ozcan
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Paper Abstract

Lensfree holographic on-chip imaging is a potent solution for high-resolution and field-portable bright-field imaging over a wide field-of-view. Previous lensfree imaging approaches utilize a pixel super-resolution technique, which relies on sub-pixel lateral displacements between the lensfree diffraction patterns and the image sensor’s pixel-array, to achieve sub-micron resolution under unit magnification using state-of-the-art CMOS imager chips, commonly used in e.g., mobile-phones. Here we report, for the first time, a wavelength scanning based pixel super-resolution technique in lensfree holographic imaging. We developed an iterative super-resolution algorithm, which generates high-resolution reconstructions of the specimen from low-resolution (i.e., under-sampled) diffraction patterns recorded at multiple wavelengths within a narrow spectral range (e.g., 10-30 nm). Compared with lateral shift-based pixel super-resolution, this wavelength scanning approach does not require any physical shifts in the imaging setup, and the resolution improvement is uniform in all directions across the sensor-array. Our wavelength scanning super-resolution approach can also be integrated with multi-height and/or multi-angle on-chip imaging techniques to obtain even higher resolution reconstructions. For example, using wavelength scanning together with multi-angle illumination, we achieved a halfpitch resolution of 250 nm, corresponding to a numerical aperture of 1. In addition to pixel super-resolution, the small scanning steps in wavelength also enable us to robustly unwrap phase, revealing the specimen’s optical path length in our reconstructed images. We believe that this new wavelength scanning based pixel super-resolution approach can provide competitive microscopy solutions for high-resolution and field-portable imaging needs, potentially impacting tele-pathology applications in resource-limited-settings.

Paper Details

Date Published: 11 March 2016
PDF: 8 pages
Proc. SPIE 9699, Optics and Biophotonics in Low-Resource Settings II, 96990A (11 March 2016); doi: 10.1117/12.2211813
Show Author Affiliations
Wei Luo, Univ. of California, Los Angeles (United States)
Zoltan Göröcs, Univ. of California, Los Angeles (United States)
Yibo Zhang, Univ. of California, Los Angeles (United States)
Alborz Feizi, Univ. of California, Los Angeles (United States)
Alon Greenbaum, Univ. of California, Los Angeles (United States)
Aydogan Ozcan, Univ. of California, Los Angeles (United States)


Published in SPIE Proceedings Vol. 9699:
Optics and Biophotonics in Low-Resource Settings II
David Levitz; Aydogan Ozcan; David Erickson, Editor(s)

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