High-resolution imaging system with an annular aperture of coded phase masks for endoscopic applications

Author(s):

Nitin Dubey, Joseph Rosen, and Israel Gannot

Abstract:

“Partial aperture imaging is a combination of two different techniques; coded aperture imaging and imaging through an aperture that is only a part of the complete disk, commonly used as the aperture of most imaging systems. In the present study, the partial aperture is a ring where the imaging through this aperture resolves small details of the observed scene similarly to the full disk aperture with the same diameter. However, unlike the full aperture, the annular aperture enables using the inner area of the ring for other applications. In this study, we consider the implementation of this special aperture in medical imaging instruments, such as endoscopes, for imaging internal cavities in general and of the human body in particular. By using this annular aperture, it is possible to transfer through the internal open circle of the ring other elements such as surgical tools, fibers and illumination devices. In the proposed configuration, light originated from a source point passes through an annular coded aperture and creates a sparse, randomly distributed, intensity dot pattern on the camera plane. A combination of the dot patterns, each one recorded only once, is used as the point spread hologram of the imaging system. The image is reconstructed digitally by cross correlation between the object intensity response and the point spread hologram.”

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Publication: Optics Express

Issue/Year/DOI: Vol. 28, Issue 10, pp. 15122-15137
DOI: 10.1364/OE.391713

Non-iterative phase hologram generation with optimized phase modulation

Author(s):

Lizhi Chen, Hao Zhang, Liangcai Cao and Guofan Jin

Abstract:

“A non-iterative algorithm is proposed to generate phase holograms with optimized phase modulation. A quadratic initial phase with continuous distributed spectrum is utilized to iteratively optimize the phase modulation in the reconstruction plane, which can be used as an optimized phase distribution for arbitrary target images. The phase hologram can be calculated directly according to the modulated wave field distribution in the reconstruction plane. Fast generation of the phase holograms can be achieved by this non-iterative implementation, and the avoidance of the random phase modulation helps to suppress the speckle noise. Numerical and
optical experiments have demonstrated that the proposed method can efficiently generate phase holograms with quality reconstructions.”

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Publication: Optics Express

Issue/Year/DOI: Vol. 28, Issue 8, pp. 11380-11392
DOI: 10.1364/OE.391518

Three-Dimensional Holographic Reconstruction of Brain Tissue Based on Convolution Propagation

Author(s):

Rania M. Abdelazeem and Doaa Youssef and Jala El-Azab and Salah Hassab-Elnaby and Mostafa Agour

Abstract:

” In this study, a dynamic holographic projection system for brain tissue and its anatomical structures extracted from Magnetic Resonance (MR) plane slice is reported. Computer holograms are calculated using a modied Gerchberg-Saxton (GS) iterative algorithm where the projection is based on the plane wave decomposition. First, brain anatomy includes white matter (WM), grey matter (GM) and brain tissue are extracted. Then, phase holograms using the proposed method are generated. Finally, single phase hologram for the whole brain anatomy is generated and is optically reconstructed by a phase-only spatial light modulator (SLM) at dierent depths. The obtained results revealed that the three-dimensional holographic projection of MR brain tissue can aid to provide better interpretation of brain anatomical
structure to achieve better diagnostic results.”

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Publication: Journal of Physics: Conference Series
Issue/Year/DOI: Vol. 1472
DOI: 10.1088/1742-6596/1472/1/012008

Holographic near-eye display with continuously expanded eyebox using two-dimensional replication and angular spectrum wrapping

Author(s):

Myeong-Ho Choi, Yeon-Gyeong Ju and Jae-Hyeung Park

Abstract:

“Holographic near-eye displays present true three-dimensional images with full
monocular depth cues. In this paper, we propose a technique to expand the eyebox of the
holographic near-eye displays. The base eyebox of the holographic near-eye displays is determined
by the space bandwidth product of a spatial light modulator. The proposed technique replicates
and stitches the base eyebox by the combined use of a holographic optical element and high order
diffractions of the spatial light modulator, achieving horizontally and vertically expanded eyebox.
An angular spectrum wrapping technique is also applied to alleviate image distortions observed
at the boundaries between the replicated base eyeboxes.”

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Publication: Optics Express

Issue/Year/DOI: Vol. 28, Issue 1, pp. 533-547
DOI: 10.1364/OE.381277

Endogenous SHG and 2PEF coherence imaging of substructures in neurons in 3D

Author(s):

Carlos Macias-Romero, Claire Teulon, Marie Didier, and Sylvie Roke

Abstract:

“Neuronal morphology, long-distance transport and signalling critically depend on the organization of microtubules in the cytoskeleton. Second harmonic generation (SHG) imaging has been recognized as a potentially powerful tool for in situ label-free neuroimaging with specific sensitivity to microtubules. We study here the structural organization of microtubules in living neurons using a wide-field multiphoton microscope that performs 3D imaging using a structured illumination. This microscope allows label-free high throughput imaging of living mammalian neurons. We show that we can image structural correlations by taking advantage of the structured illumination and the coherence of the emitted light. The result allows us to study the microtubule organization throughout the development of the neuron and to differentiate between the regions of the cytoskeleton in the matured neuron.”

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Publication: Optics Express
Issue/Year/DOI: Vol. 27, Issue 3, pp. 2235-2247 (2019)
DOI: 10.1364/OE.27.002235

Raman imaging through multimode sapphire fiber

Author(s):

Sunan Deng, Damien Loterie, Georgia Konstantinou, Demetri Psaltis, and Christophe Moser
Abstract:

“We report on a sapphire fiber Raman imaging probe’s use for challenging applications where access is severely restricted. Small-dimension Raman probes have been developed previously for various clinical applications because they show great capability for diagnosing disease states in bodily fluids, cells, and tissues. However, applications of these sub-millimeter diameter Raman probes were constrained by two factors: first, it is difficult to incorporate filters and focusing optics at such small scale; second, the weak Raman signal is often obscured by strong background noise from the fiber probe material, especially the most commonly used silica, which has a strong broad background noise in low wavenumbers (<500-1700 cm−1). Here, we demonstrate the thinnest-known imaging Raman probe with a 60 μm diameter Sapphire multimode fiber in which both excitation and signal collection pass through. This probe takes advantage of the low fluorescence and narrow Raman peaks of Sapphire, its inherent high temperature and corrosion resistance, and large numerical aperture (NA). Raman images of Polystyrene beads, carbon nanotubes, and CaSO4 agglomerations are obtained with a spatial resolution of 1 μm and a field of view of 30 μm. Our imaging results show that single polystyrene bead (~15 µm diameter) can be differentiated from a mixture with CaSO4 agglomerations, which has a close Raman shift." Link to Publications Page

Publication: Optics Express
Issue/Year/DOI: Vol. 27, Issue 2, pp. 1090-1098 (2019)
DOI: 10.1364/OE.27.001090

Deep speckle correlation: a deep learning approach toward scalable imaging through scattering media

Author(s):

Yunzhe Li and Yujia Xue and Lei Tian

Abstract:

“Imaging through scattering is an important yet challenging problem. Tremendous progress has been made by exploiting the deterministic input–output “transmission matrix” for a fixed medium. However, this “one-to-one” mapping is highly susceptible to speckle decorrelations – small perturbations to the scattering medium lead to model errors and severe degradation of the imaging performance. Our goal here is to develop a new framework that is highly scalable to both medium perturbations and measurement requirement. To do so, we propose a statistical “one-to-all” deep learning (DL) technique that encapsulates a wide range of statistical variations for the model to be resilient to speckle decorrelations. Specifically, we develop a convolutional neural network (CNN) that is able to learn the statistical information contained in the speckle intensity patterns captured on a set of diffusers having the same macroscopic parameter. We then show for the first time, to the best of our knowledge, that the trained CNN is able to generalize and make high-quality object predictions through an entirely different set of diffusers of the same class. Our work paves the way to a highly scalable DL approach for imaging through scattering media.”

Link to Publications Page

Publication: Optica

Issue/Year/DOI: Optica Volume 5, Issue 10 pp. 1181-1190 (2018)
DOI: 10.1364/OPTICA.5.001181

Single-shot memory-effect video

Author(s):

Xiaohan Li and Andrew Stevens and Joel A. Greenberg and Michael E. Gehm

Abstract:

“Imaging through opaque scattering media is critically important in applications ranging from biological and astronomical imaging to metrology and security. While the random process of scattering in turbid media produces scattered light that appears uninformative to the human eye, a wealth of information is contained in the signal and can be recovered using computational post-processing techniques. Recent studies have shown that statistical correlations present in the scattered light, known as ‘memory effects’, allow for diffraction-limited imaging through opaque media without detailed knowledge of (or access to) the source or scatterer. However, previous methods require that the object and/or scatterer be static during the measurement. We overcome this limitation by combining traditional memory effect imaging with coded-aperture-based computational imaging techniques, which enables us to realize for the first time single-shot video of arbitrary dynamic scenes through dynamic, opaque media. This has important implications for a wide range of real-world imaging scenarios.”

Link to Publications Page

Publication: Scientific Reports

Issue/Year/DOI: Scientific Reports 8, Article number: 13402 (2018)
DOI: 10.1038/s41598-018-31697-8

Multiple-plane image formation by Walsh zone plates

Author(s):

Federico Machado, Vicente Ferrando, Fernando Giménez, Walter D. Furlan, and Juan A. Monsoriu

Abstract:

“A radial Walsh filter is a phase binary diffractive optical element characterized by a set of concentric rings that take the phase values 0 or π, corresponding to the values + 1 or −1 of a given radial Walsh function. Therefore, a Walsh filter can be re-interpreted as an aperiodic multifocal zone plate, capable to produce images of multiple planes simultaneously in a single output plane of an image forming system. In this paper, we experimentally demonstrate for the first time the focusing capabilities of these structures. Additionally, we report the first achievement of images of multiple-plane objects in a single image plane with these aperiodic diffractive lenses.”

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Publication: Optics Express

Issue/Year/DOI: Optics Express Volume 26, Issue 16
DOI: 10.1364/OE.26.021210

Lensless Stokes holography with the Hanbury Brown-Twiss approach

Author(s):

Darshika Singh and Rakesh Kumar Singh

Abstract:

“The recording and reconstruction of the Stokes parameter is of paramount importance for the description of the vectorial interference of light. Polarization holography provides a complete vectorial wavefront, however, direct recording and reconstruction of the hologram is not possible in a situation where the object is located behind the random scattering layer. The Stokes holography plays an important role in such situations and makes use of the Fourier transform relation between the Stokes parameters (SPs) at the scattering plane and the generalized Stokes parameters (GSPs) of the random field. In this paper, we propose and experimentally demonstrate the Stokes holography with the Hanbury Brown-Twiss (HBT) interferometer. We also propose and implement a lensless Fourier configuration for the Stokes holography. This permits us to reconstruct the wavefront from the GSPs at any arbitrary distance from the scattering plane. The application of the proposed technique is experimentally demonstrated for the 3D imaging of two different objects lying behind the random scattering medium. Depth information of the 3D objects is obtained by digitally propagating the generalized Stokes parameters to a different longitudinal distance. The quality of the reconstruction is assessed by measuring the overall visibility, efficiency, and PSNR of the reconstruction parameters.”

Link to Publications Page

Publication: Optics Express

Issue/Year/DOI: Optics Express, Vol. 26, Issue 8, pp. 10801-10812 (2018)
DOI: 10.1364/OE.26.010801

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