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Light Sci Appl. 2016 Apr 8;5(4):e16060. doi: 10.1038/lsa.2016.60. eCollection 2016 Apr.

Pixel super-resolution using wavelength scanning.

Luo W1,2,3, Zhang Y1,2,3, Feizi A1,2,3, Göröcs Z1,2,3, Ozcan A1,2,3,4.

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Electrical Engineering Department, University of California, Los Angeles, CA 90095, USA.
Bioengineering Department, University of California, Los Angeles, CA 90095, USA.
California NanoSystems Institute (CNSI), University of California, Los Angeles, CA 90095, USA.
Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.


Undersampling and pixelation affect a number of imaging systems, limiting the resolution of the acquired images, which becomes particularly significant for wide-field microscopy applications. Various super-resolution techniques have been implemented to mitigate this resolution loss by utilizing sub-pixel displacements in the imaging system, achieved, for example, by shifting the illumination source, the sensor array and/or the sample, followed by digital synthesis of a smaller effective pixel by merging these sub-pixel-shifted low-resolution images. Herein, we introduce a new pixel super-resolution method that is based on wavelength scanning and demonstrate that as an alternative to physical shifting/displacements, wavelength diversity can be used to boost the resolution of a wide-field imaging system and significantly increase its space-bandwidth product. We confirmed the effectiveness of this new technique by improving the resolution of lens-free as well as lens-based microscopy systems and developed an iterative algorithm to generate high-resolution reconstructions of a specimen using undersampled diffraction patterns recorded at a few wavelengths covering a narrow spectrum (10-30 nm). When combined with a synthetic-aperture-based diffraction imaging technique, this wavelength-scanning super-resolution approach can achieve a half-pitch resolution of 250 nm, corresponding to a numerical aperture of ~1.0, across a large field of view (>20 mm2). We also demonstrated the effectiveness of this approach by imaging various biological samples, including blood and Papanicolaou smears. Compared with displacement-based super-resolution techniques, wavelength scanning brings uniform resolution improvement in all directions across a sensor array and requires significantly fewer measurements. This technique would broadly benefit wide-field imaging applications that demand larger space-bandwidth products.


holographic imaging; on-chip microscopy; pixel super-resolution; wavelength scanning; wide-field imaging

Conflict of interest statement

The authors declare no conflict of interest.

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