Lateral position correction in ptychography using the gradient of intensity patterns

Author(s):

Priya Dwivedi and Sander Konijnenberg and Silvania Pereira and Paul Urbach

Abstract:

“Ptychography, a form of Coherent Diffractive Imaging, is used with short wavelengths (e.g. X-rays, electron beams) to achieve high-resolution image reconstructions. One of the limiting factors for the reconstruction quality is the accurate knowledge of the illumination probe positions. Recently, many advances have been made to relax the requirement for the probe positions accuracy. Here, we analyse and demonstrate a straightforward approach that can be used to correct the probe positions with sub-pixel accuracy. Simulations and experimental results with visible light are presented in this work.”

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Publication: Ultramicroscopy

Issue/Year/DOI: Ultramicroscopy, Volume 192, September 2018, Pages 29-36
DOI: 10.1016/j.ultramic.2018.04.004

Non-iterative method for phase retrieval and coherence characterization by focus variation using a fixed star-shaped mask

Author(s):

A. P. Konijnenberg and Xingyuan Lu and Leixin Liu and W. M. J. Coene and Chengliang Zhao and H. P. Urbach

Abstract:

“A novel non-iterative phase retrieval method is proposed and demonstrated with a proof-of-principle experiment. The method uses a fixed specially designed mask and through-focus intensity measurements. It is demonstrated that this method is robust to spatial partial coherence in the illumination, making it suitable for coherent diffractive imaging using spatially partially coherent light, as well as for coherence characterization.”

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Publication: Optics Express

Issue/Year/DOI: Optics Express, Vol. 26, Issue 7, pp. 9332- 9343 (2018)
DOI: 10.1364/OE.26.009332

Superresolution far-field imaging of complex objects using reduced superoscillating ripples

Author(s):

Xiao Han Dong and Alex M. H. Wong and Minseok Kim and George V. Eleftheriades

Abstract:

“Superoscillation is a phenomenon where a wave oscillates locally faster than its highest Fourier component. While previous reports have shown attractive possibilities for a superoscillation-based far-field superresolution imaging device, it has also been recognized that a high-energy “sideband” region coexists with the superresolution features. This sideband causes strong restrictions and necessitates trade-offs in achievable resolution, viewing area, and sensitivity of the imaging device. In this work, we introduce a new class of superoscillation waveform—which consists of a diffraction-limited hotspot surrounded by low-energy superoscillating sidelobe ripples. This waveform alleviates the aforementioned trade-off and enables superresolution imaging for complex objects over a larger viewing area while maintaining a practical level of sensitivity. Using this waveform as the point spread function of an imaging system, we demonstrate the successful superresolution of Latin letters without performing scanning and/or post-processing operations.”

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Publication: Optica

Issue/Year/DOI: Optica, Vol. 4, Issue 9, pp. 1126-1133 (2017)
DOI: 10.1364/OPTICA.4.001126

Resolving images by blurring: superresolution method with a scattering mask between the observed objects and the hologram recorder

Author(s):

Yuval Kashter and A. Vijayakumar and Joseph Rosen

Abstract:

“An important quest in optical imaging has been, and still is, extending the resolution of imaging systems beyond the diffraction limit. We propose a superresolution technique in which the image is first blurred by a scattering mask, and then recovered from the blurry data with improved resolution. We introduced a scattering mask into the space between the observed objects and the objective lens of a Fresnel incoherent correlation holography (FINCH) system to demonstrate the method. Optical waves, containing high spatial frequencies of the object, which are usually filtered out by the limited system aperture, were introduced into the system due to the scattering nature of the scattering mask. As a consequence, both the effective numerical aperture and the spatial bandwidth of the system were enlarged. The image resolution could therefore be improved far beyond the resolution limit dictated by the limited numerical aperture of the system. We demonstrated the technique using a modified FINCH system and the results were compared with other systems, all having the same aperture dimensions. We showed a resolution enhancement in comparison to conventional FINCH and regular imaging systems, with the same numerical apertures. The theoretical and experimental data presented here establishes the proposed method as an attractive platform for an advanced superresolution system that can resolve better than conventional imaging systems.”

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Publication: Optica

Issue/Year/DOI: Optica, Vol. 4, Issue 8, (2017)
DOI: 10.1364/OPTICA.4.000932

Computational super-resolution phase retrieval from multiple phase-coded diffraction patterns: simulation study and experiments

Author(s):

Vladimir Katkovnik and Igor Shevkunov and Nikolay V. Petrov and Karen Egiazarian

Abstract:

“In this paper, we consider computational super-resolution inverse diffraction phase retrieval. The optical setup is lensless, with a spatial light modulator for aperture phase coding. The paper is focused on experimental tests of the super-resolution sparse phase amplitude retrieval algorithm. We start from simulations and proceed to physical experiments. Both simulation tests and experiments demonstrate good-quality imaging for super-resolution with a factor of 4 and a serious advantage over diffraction-limited resolution as defined by Abbe’s criterion.”

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Publication: Optica

Issue/Year/DOI: Optica , Vol. 4, Issue 7, (2017)
DOI: 10.1364/OPTICA.4.000786

Plasmonic computing of spatial differentiation.

Author(s):

Zhu, Tengfeng and Zhou, Yihan and Lou, Yijie and Ye, Hui and Qiu, Min and Ruan, Zhichao and Fan, Shanhui

Abstract:

“Optical analog computing offers high-throughput low-power-consumption operation for specialized computational tasks. Traditionally, optical analog computing in the spatial domain uses a bulky system of lenses and filters. Recent developments in metamaterials enable the miniaturization of such computing elements down to a subwavelength scale. However, the required metamaterial consists of a complex array of meta-atoms, and direct demonstration of image processing is challenging. Here, we show that the interference effects associated with surface plasmon excitations at a single metal-dielectric interface can perform spatial differentiation. And we experimentally demonstrate edge detection of an image without any Fourier lens. This work points to a simple yet powerful mechanism for optical analog computing at the nanoscale.”

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Publication: Nature Communications

Issue/Year/DOI: Nature Communications volume 8, Article number: 15391 (2017)
DOI: 10.1038/ncomms15391

New microscopy technique based on position localization of scattering particles

Author(s):

Stefano Luigi Oscurato and Fabio Borbone and Robert Charles Devlin and Federico Capasso and Pasqualino Maddalena and Antonio Ambrosio

Abstract:

“We introduce the Holographic – Single Scatterer Localization Microscopy in which we combine dynamical laser speckle illumination with centroid localization of backscattered light spots in order to localize isolated scattering particles. The reconstructed centroid images show very accurate particle localization, with precision much better than the width of diffraction-limited image of the particles recorded by the CCD. Furthermore, the method provides an improved resolution in distinguishing two very close scattering objects compared to the standard laser scanning techniques and can be assimilated to a confocal technique in the ability of light background rejection in three-dimensional disposition of scattering objects. The illumination is controlled via a digital holography setup based on the use of a spatial light modulator. This allows not only a high level of versatility in the illumination patterns, but also the remarkable characteristics of absence of moving mechanical parts, typical of the laser scanning techniques, and the possibility of strongly miniaturizing the setup.”

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Publication: Optics Express

Issue/Year/DOI: Optics Express Vol. 25, Issue 10, pp. 11530-11549 (2017)

DOI: 10.1364/OE.25.011530

 

Spectrum and space resolved 4D imaging by coded aperture correlation holography (COACH) with diffractive objective lens

Author(s):

A. Vijayakumar and Joseph Rosen

Abstract:

“In this Letter, we present an advanced optical configuration of coded aperture correlation holography (COACH) with a diffractive objective lens. Four-dimensional imaging of objects at the three spatial dimensions and with an additional spectral dimension is demonstrated. A hologram of three-dimensional objects illuminated by different wavelengths was recorded by the interference of light diffracted from the objects with the light diffracted from the same objects, but through a random-like coded phase mask (CPM). A library of holograms denoted point spread function (PSF) holograms were prerecorded with the same CPM, and under identical conditions, using point objects along different axial locations and for the different illuminating wavelengths. The correlation of the object hologram with the PSF hologram recorded using a particular wavelength, and at a particular axial location, reconstructs only the object corresponding to the particular axial plane and to the specific wavelength. The reconstruction results are compared with regular imaging and with another well-established holographic technique called Fresnel incoherent correlation holography.”

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Publication:  Optics Letters

Issue/Year/DOI: Optics Letters Vol.42, Issue 5, pp. 947-950 (2017)
DOI: 10.1364/OL.42.000947

Imaging moving targets through scattering media

Author(s):

Michelle Cua and Edward (Haojiang) Zhou and Changhuei Yang

Abstract:

“Optical microscopy in complex, inhomogeneous media is challenging due to the presence of multiply scattered light that limits the depths at which diffraction-limited resolution can be achieved. One way to circumvent the degradation in resolution is to use speckle- correlation-based imaging (SCI) techniques, which permit imaging of objects inside scattering media at diffraction-limited resolution. However, SCI methods are currently limited to imaging sparsely tagged objects in a dark-field scenario. In this work, we demonstrate the ability to image hidden, moving objects in a bright-field scenario. By using a deterministic phase modulator to generate a spatially incoherent light source, the background contribution can be kept constant between acquisitions and subtracted out. In this way, the signal arising from the object can be isolated, and the object can be reconstructed with high fidelity. With the ability to effectively isolate the object signal, our work is not limited to imaging bright objects in the dark-field case, but also works in bright-field scenarios, with non-emitting objects.”

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Publication: Optics Express

Issue/Year/DOI: Optics Express Vol. 25, Issue 4, pp. 3935-3945  (2017)

DOI: 10.1364/OE.25.003935

 

Methods of Single-Channel Digital Holography for Three-Dimensional Imaging

Author(s):

R. Kelner and J. Rosen

Abstract:

“Digital holography is an effective tool for imaging three-dimensional (3-D) scenes or objects. In this paper, recently developed methods of single channel digital holography are reviewed: the joint object reference digital interferometer (JORDI), Fresnel incoherent correlation holography (FINCH), and Fourier incoherent single channel holography (FISCH).”

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Publication: IEEE Transactions on Industrial Informatics

Issue/Year/DOI: IEEE Transactions on Industrial Informatics ( Volume: 12, Issue: 1, Feb. 2016 )
DOI: 10.1109/TII.2015.2475247