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https://www.readbyqxmd.com/read/29048748/accuracy-of-fetal-sex-determination-in-the-first-trimester-of-pregnancy-using-3d-virtual-reality-ultrasound
#1
Hein Bogers, Maria S Rifouna, Anton H J Koning, Margreet Husen-Ebbinge, Attie T J I Go, Peter J van der Spek, Régine P M Steegers-Theunissen, Eric A P Steegers, Niek Exalto
PURPOSE: Early detection of fetal sex is becoming more popular. The aim of this study was to evaluate the accuracy of fetal sex determination in the first trimester, using 3D virtual reality. METHODS: Three-dimensional (3D) US volumes were obtained in 112 pregnancies between 9 and 13 weeks of gestational age. They were offline projected as a hologram in the BARCO I-Space and subsequently the genital tubercle angle was measured. Separately, the 3D US aspect of the genitalia was examined for having a male or female appearance...
October 19, 2017: Journal of Clinical Ultrasound: JCU
https://www.readbyqxmd.com/read/29048040/compressive-correlation-holography
#2
Rachit Saluja, G R K S Subrahmanyam, Deepak Mishra, R V Vinu, Rakesh Kumar Singh
We propose and demonstrate a compressive sensing (CS) framework for correlation holography. This is accomplished by adopting the principle of compressive sensing and thresholding in the two-point intensity correlation. The measurement matrix and the sensing matrix that are required for applying the CS framework here are systematically extracted from the random illuminations of the laser speckle data. Reconstruction results using CS, CS with thresholding, and intensity correlation are compared. Our study reveals that liminal CS requires far fewer samples for the reconstruction of the hologram and has wide application in image reconstruction...
August 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29048039/nonvolatile-plasmonic-holographic-memory-based-on-photo-driven-ion-migration
#3
Shuangyan Liu, Shencheng Fu, Xiuxiu Han, Xinnong Wang, Ruiya Ji, Xintong Zhang, Yichun Liu
Stability of data storage is essential for optical information processing. TiO2 nanoporous films loaded with small-sized Ag nanoparticles thus attracted much attention due to their fast and polarization-sensitive photochemical response, which is able to realize optical phase modulation and high-density optical memory. However, little attention was given to the modulation of the silver ion migration, which plays a key role in anti-erasure of the recorded hologram. In this paper, the strong coupling of two phase gratings was achieved by long-term recording in the Ag-TiO2 film irradiated with a pair of coherent left- and right-hand circular polarization lights from a Blu-ray (∼405  nm) laser...
August 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29048025/one-step-real-virtual-combined-reflection-hologram-a-4f-relay-approach
#4
Jian Su, Yingqing Huang, Yibei Chen, Xiaoyu Jiang, Xingpeng Yan
The production of conventional optical reflection holograms can be classified into the one-step method or the two-step method. In the one-step method, only the diverging light of an object can be recorded, and the reconstructed scene is a virtual one behind the recording medium. In the two-step method, the diverging light or the converging light can be recorded alternatively. However, the process is complicated considering double exposures. The object is first imaged by a 4f system, and then the interference patterns are recorded by single exposure...
August 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29048023/generalized-sequential-four-step-phase-shifting-color-digital-holography
#5
Takanori Nomura, Kazuma Shinomura
A generalized sequential four-step phase-shifting color digital holography is proposed. As an arbitrary phase-shift quantity is independent from wavelengths, it can be used for four-step phase-shifting color digital holography. Furthermore, no constraint on the phase-shifting quantities or statistical property on the hologram is required in the proposed method. Experimental results using a reflective object are shown to confirm the proposed phase-shifting digital holography.
August 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29047904/cooperative-execution-of-auto-focusing-metrics-in-digital-lensless-holographic-microscopy-for-internal-structured-samples
#6
Carlos Trujillo, Jorge Garcia-Sucerquia
The cooperative execution of two metrics to automatically determine the best focal plane in digital lensless holographic microscopy (DLHM) is presented. This proposal is comprised of two stages: first, a quick coarse search over the whole reconstruction range by using Dubois's metric allows the finding of a range in which the best focal plane can be found. In a second stage, the modified enclosed energy (MEE) metric is used within the found range in the former stage to finely determine the best focal plane...
July 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29047852/advanced-modeling-of-a-moderate-resolution-holographic-spectrograph
#7
Eduard Muslimov, Gennady Valyavin, Sergei Fabrika, Nadezhda Pavlycheva
In the present article we consider an accurate modeling of a spectrograph with a cascade of volume-phase holographic gratings. The proposed optical scheme allows us to detect spectra in an extended wavelength range without gaps, providing relatively high spectral resolution and high throughput. However, modeling and minimization of possible cross-talk between gratings and stray light in such a scheme represents a separate task. We use analytical equations of the coupled-wave theory together with rigorous coupled-wave analysis to optimize the gratings parameters and further apply the latter together with a non-sequential ray-tracing algorithm to model propagation of beams through the spectrograph...
May 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29047816/multiple-3d-object-decryption-based-on-one-interference-using-two-phase-only-functions
#8
Wei-Na Li, Sang-Min Lee, Sang Keun Gil, Nam Kim
We propose a multiple-3D-object decryption scheme based on one interference using two beams that are from two different phase-only functions. It takes advantage of off-axis digital holography to extract the optical fields of multiple 3D objects, and respectively utilize single different decryption keys to decrypt multiple 3D objects in the decryption procedure. The advantages of the proposed scheme include the following: each 3D object can be decrypted discretionarily without decrypting a series of other objects earlier; no iterative algorithm is involved; and the decrypted image of each object can be successfully clearly distinguished...
August 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/29047808/optical-elements-containing-semitransparent-wavelike-films
#9
Anatoly M Smolovich, Valery Chernov
Novel optical elements containing semitransparent wavelike films embedded into the bulk of transparent material, which form a reflection image without transmitted light distortion, are studied. The dynamic theory of light diffraction by a locally periodic multilayer semitransparent wavelike film is developed. A simple analytical formula for near Bragg diffraction order intensity is obtained for the case when only one diffraction order lies within the hologram angular selectivity. The phase modulation of light transmitted through the optical element containing wavelike films is estimated for single-layer and multilayer wavelike films with an arbitrary shape of surface...
August 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/29047744/full-color-holographic-3d-display-using-slice-based-fractional-fourier-transform-combined-with-free-space-fresnel-diffraction-erratum
#10
Zhen Zhang, Siqing Chen, Huadong Zheng, Zhenxiang Zeng, Hongyue Gao, Yingjie Yu, Anand K Asundi
We have addressed some errors in our recent work [Appl. Opt.56, 5668 (2017)APOPAI0003-693510.1364/AO.56.005668]. Especially, we note that the formulae for reconstruction of phase-only holograms are different from the formulae for amplitude holograms. So Eqs. (9) and (12) must be modified.
September 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29047732/generation-of-perfect-polarization-vortices-using-combined-gratings-in-a-single-spatial-light-modulator
#11
Tonglu Wang, Shiyao Fu, Feng He, Chunqing Gao
Perfect polarization vortices (PPVs) are a type of vector beam with a diameter independent of the polarization order. In this paper, an experimental method is proposed to generate PPVs with an anisotropic polarization distribution. First, a specially designed hologram is generated on a liquid-crystal spatial light modulator (SLM) to obtain Bessel-Gaussian (BG) beams. Second, the BG beams are transformed into PPVs in the Bessel region by an interferometer, which includes a polarized beam splitter, two reflectors, and several lenses...
September 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29047721/bessel-function-expansion-to-reduce-the-calculation-time-and-memory-usage-for-cylindrical-computer-generated-holograms
#12
Yusuke Sando, Daisuke Barada, Boaz Jessie Jackin, Toyohiko Yatagai
This study proposes a method to reduce the calculation time and memory usage required for calculating cylindrical computer-generated holograms. The wavefront on the cylindrical observation surface is represented as a convolution integral in the 3D Fourier domain. The Fourier transformation of the kernel function involving this convolution integral is analytically performed using a Bessel function expansion. The analytical solution can drastically reduce the calculation time and the memory usage without any cost, compared with the numerical method using fast Fourier transform to Fourier transform the kernel function...
July 10, 2017: Applied Optics
https://www.readbyqxmd.com/read/29047709/full-color-holographic-3d-display-using-slice-based-fractional-fourier-transform-combined-with-free-space-fresnel-diffraction
#13
Zhen Zhang, Siqing Chen, Huadong Zheng, Zhenxiang Zeng, Hongyue Gao, Yingjie Yu, Anand K Asundi
The fractional Fourier transform (FRT) has been used for computing holograms in holographic displays due to its continuity of describing wave diffraction in the near field and far field. In this study, we propose a method to realize a full-color holographic 3D display with combined use of the FRT and the free-space Fresnel diffraction. A slice-based optical configuration and the calculation algorithm of the FRT are proposed for generating phase-only holograms of full-color 3D objects. Sequential phase-only holograms are generated for reducing the speckle noise of reconstructed images by the time-averaging effect...
July 10, 2017: Applied Optics
https://www.readbyqxmd.com/read/29047576/modeling-of-light-emitting-diode-wavefronts-for-the-optimization-of-transmission-holograms
#14
Daniela Karthaus, Markus Giehl, Oliver Sandfuchs, Stefan Sinzinger
The objective of applying transmission holograms in automotive headlamp systems requires the adaptation of holograms to divergent and polychromatic light sources like light-emitting diodes (LEDs). In this paper, four different options to describe the scalar light waves emitted by a typical automotive LED are regarded. This includes a new approach to determine the LED's wavefront from interferometric measurements. Computer-generated holograms are designed considering the different LED approximations and recorded into a photopolymer...
June 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29047557/generating-superimposed-bessel-beams-with-a-volume-holographic-axicon
#15
Alvie J Asuncion, Raphael A Guerrero
Quasi-Bessel beams (QBB) with different profiles are generated with an axicon-telescope system. Beam profiles are found to vary with different axicon-telescope distance δ. QBBs are stored as volume holograms in a photorefractive crystal. Reconstructions of the QBBs are focused by the recording axicon to produce superimposed Bessel beams (SBBs) with oscillating cores. SBBs formed through this method have different oscillation periods that range from 4.3 to 6.1 cm. We demonstrate that periodicity is dependent on δ...
May 10, 2017: Applied Optics
https://www.readbyqxmd.com/read/29044431/computational-imaging-of-sperm-locomotion
#16
Mustafa Ugur Daloglu, Aydogan Ozcan
Not only essential for scientific research, but also in the analysis of male fertility and for animal husbandry, sperm tracking and characterization techniques have been greatly benefiting from computational imaging. Digital image sensors, in combination with optical microscopy tools and powerful computers, have enabled the use of advanced detection and tracking algorithms that automatically map sperm trajectories and calculate various motility parameters across large data sets. Computational techniques are driving the field even further, facilitating the development of unconventional sperm imaging and tracking methods that do not rely on standard optical microscopes and objective lenses, which limit the field of view and volume of the semen sample that can be imaged...
August 1, 2017: Biology of Reproduction
https://www.readbyqxmd.com/read/29041735/analysis-of-spurious-diffraction-orders-of-computer-generated-hologram-in-symmetric-aspheric-metrology
#17
Yiwei He, Xi Hou, Fan Wu, Xinxue Ma, Rongguang Liang
Computer-generated hologram (CGH) has been widely used as a wavefront compensator in symmetric aspheric metrology. As a diffractive element, it generates different diffraction orders, but only the 1st-order diffraction is used to test aspheric surface. The light from spurious diffraction orders (SDO) will produce many high-frequency fringes in interferogram and reduce measurement accuracy. In this paper, we regard the CGH null system as an imaging system and develop an aberration model in Seidel formalism to analyze the SDO...
August 21, 2017: Optics Express
https://www.readbyqxmd.com/read/29041733/real-and-virtual-propagation-dynamics-of-angular-accelerating-white-light-beams
#18
Christian Vetter, Angela Dudley, Alexander Szameit, Andrew Forbes
Accelerating waves have received significant attention of late, first in the optical domain and later in the form of electron matter waves, and have found numerous applications in non-linear optics, material processing, microscopy, particle manipulation and laser plasma interactions. Here we create angular accelerating light beams with a potentially unlimited acceleration rate. By employing wavelength independent digital holograms for the creation and propagation of white light beams, we are able to study the resulting propagation in real and virtual space...
August 21, 2017: Optics Express
https://www.readbyqxmd.com/read/29041701/compact-single-shot-four-wavelength-quantitative-phase-microscopy-with-polarization-and-frequency-division-demultiplexing
#19
Behnam Tayebi, Jae-Ho Han, Farnaz Sharif, Mohammad Reza Jafarfard, Dug Young Kim
We present a novel single-shot four-wavelength quantitative phase microscopy (FW-QPM). Four lasers operating at different wavelengths are multiplexed with a pair of dichroic mirrors and a polarization beam splitter in a three-mirror quasi-common-path interferometer. After a single-shot interference pattern is obtained with a monochrome camera, four holograms of different wavelengths were demultiplexed from it in the frequency domain with polarization- and frequency-division multiplexing. Polarization-division demultiplexing scheme uses polarization dependent visibility changes in an interference pattern, and it plays a critical role in making only two interference patterns exist within a single quadrant in the frequency domain...
August 21, 2017: Optics Express
https://www.readbyqxmd.com/read/29041695/resolution-enhancement-in-in-line-holography-by-numerical-compensation-of-vibrations
#20
Tatiana Latychevskaia, Hans-Werner Fink
Mechanical vibrations of components of the optical system is one of the sources of blurring of interference pattern in coherent imaging systems. The problem is especially important in holography where the resolution of the reconstructed objects depends on the effective size of the hologram, which is on the extent of the interference pattern, and on the contrast of the interference fringes. We discuss the mathematical relation between the vibrations, the hologram contrast and the reconstructed object. We show how vibrations can be post-filtered out from the hologram or from the reconstructed object assuming a Gaussian distribution of the vibrations...
August 21, 2017: Optics Express
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