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: Vol. 1472
DOI: 10.1088/1742-6596/1472/1/012008

Microchannels inside bulk PMMA generated by femtosecond laser using adaptive beam shaping

Author(s):

Roth, Gian-Luca; Rung, Stefan; Esen, Cemal & Hellmann, Ralf

Abstract:

“In this contribution, we report on the generation of internal microchannels with basically unlimited channel length inside of PMMA bulk material by femtosecond laser. A precisely controllable and stable circular channel cross section is obtained by using a spatial light modulator to compensate the writing depth depending spherical aberration. Furthermore, the generation of a rotatable elliptical input beam by adaptive optics ensures a fitting of the beam shaping to the writing direction. In this study, we report on both, the effect of the ellipticity of the input beam and the effect of a correction of the spherical aberration on the circularity of the resulting internal microchannels. Moreover, we demonstrate the application of this writing technique by creating microfluidic testing structures inside of a transparent standard polymer.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 28; Number 4; Pages 5801; 2020
DOI: 10.1364/oe.384948

Maximum information states for coherent scattering measurements

Author(s):

Bouchet, Dorian; Rotter, Stefan & Mosk, Allard P.

Abstract:

“The use of coherent light for precision measurements has been a key driving force for numerous research directions, ranging from biomedical optics to semiconductor manufacturing. Recent work demonstrates that the precision of such measurements can be significantly improved by tailoring the spatial profile of light fields used for estimating an observable system parameter. These advances naturally raise the intriguing question of which states of light can provide the ultimate measurement precision and of how such states can be identified in an experiment. Here, we introduce a general approach to determine optimal coherent states of light for estimating any given parameter, regardless of the complexity of the system. Our analysis reveals that the light fields delivering the ultimate measurement precision are eigenstates of a Hermitian operator which quantifies the Fisher information based on the system’s scattering matrix. To illustrate this concept, we experimentally show that these maximum information states probe the phase of an object that is hidden by a disordered medium with a precision improved by an order of magnitude as compared to unoptimized states. Our results enable precision measurements in arbitrarily complex systems, with promising perspectives for metrology and imaging applications.”

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Publication: arXiv
Issue/Year: arXiv, 2020
DOI: 10.48550/arXiv.2002.10388

Precise position- and angular-controllable optical trapping and manipulation via a single vortex-pair beam

Author(s):

Wen, Jisen; Gao, Binjie; Liu, Dadong; Zhu, Guiyuan & Wang, Li-Gang

Abstract:

“Optical trapping and manipulation using laser beams play a key role in many areas including biology, atomic science, and nanofabrication. Here, we propose and experimentally demonstrate the first use of a vortex-pair beam in optical trapping and manipulation. We successfully trap two spherical microparticles simultaneously by a single vortex-pair beam. Precisely position-controllable manipulation of the trapped spherical microparticles is realized by adjusting the off-axis distance of the vortices on the initial phase plane of the vortex-pair beam. Based on the feature of the vortex-pair beam, as an optical wrench, the high-precision angular-controllable rotation of the cylindrical microrod is achieved by rotating the initial phase structure. Our result provides a rich control on the trapping of microparticles and has greatly important applications in biological area, and optically driven micromachines or motors.”

Link to Publications Page

Publication: arXiv
Issue/Year: arXiv, 2020
DOI: 10.48550/arXiv.2002.06860