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Aaron M Michalko, James R Fienup
Transverse translation diverse phase retrieval (TTDPR), a ptychographic image-based wavefront-sensing technique, is a viable method for optical shop testing due to its high accuracy and relatively simple experimental arrangement. However, when measuring a reflective optic, a normally hard-edged translating illumination will become soft-edged due to diffraction, which may reduce the accuracy of TTDPR by suppressing fine structures in measured data. In this Letter, we quantitatively explore the wavefront-sensing accuracy of TTDPR in the presence of soft-edged translating illumination...
March 15, 2018: Optics Letters
Scott W Paine, James R Fienup
For large amounts of wavefront error, gradient-based optimization methods for image-based wavefront sensing are unlikely to converge when the starting guess for the wavefront differs greatly from the true wavefront. We use machine learning operating on a point-spread function to determine a good initial estimate of the wavefront. We show that our trained convolutional neural network provides good initial estimates in the presence of simulated detector noise and is more effective than using many random starting guesses for large amounts of wavefront error...
March 15, 2018: Optics Letters
Jian Su, Xingpeng Yan, Xiaoyu Jiang, Yingqing Huang, Yibei Chen, Teng Zhang
Based on our proposed method for holographic stereogram printing using effective perspective images' segmentation and mosaicking (EPISM), we analyze the reconstructed wavefront errors, and establish the exit pupil function model of proposed printing system. To evaluate the imaging quality, the optical transfer function (OTF) of the holographic stereogram is modelled from the aspect of frequency response. The characteristic of the OTF with respect to the exit pupil size and the aberration are investigated in detail...
March 14, 2018: Scientific Reports
Timothée Proix, Viktor K Jirsa, Fabrice Bartolomei, Maxime Guye, Wilson Truccolo
Recent studies have shown that seizures can spread and terminate across brain areas via a rich diversity of spatiotemporal patterns. In particular, while the location of the seizure onset area is usually invariant across seizures in an individual patient, the source of traveling (2-3 Hz) spike-and-wave discharges during seizures can either move with the slower propagating ictal wavefront or remain stationary at the seizure onset area. Furthermore, although many focal seizures terminate synchronously across brain areas, some evolve into distinct ictal clusters and terminate asynchronously...
March 14, 2018: Nature Communications
Sean T Vittadello, Scott W McCue, Gency Gunasingh, Nikolas K Haass, Matthew J Simpson
The fluorescent ubiquitination-based cell cycle indicator, also known as FUCCI, allows the visualization of the G1 and S/G2/M cell cycle phases of individual cells. FUCCI consists of two fluorescent probes, so that cells in the G1 phase fluoresce red and cells in the S/G2/M phase fluoresce green. FUCCI reveals real-time information about cell cycle dynamics of individual cells, and can be used to explore how the cell cycle relates to the location of individual cells, local cell density, and different cellular microenvironments...
March 13, 2018: Biophysical Journal
M Sanz, J A Picazo-Bueno, J García, V Micó
We report on a novel layout capable of dual-mode imaging in real time with different magnifications and resolution capabilities in lensless microscopy. The concept is based on wavelength multiplexing for providing two illuminations with different wavefront curvatures: one is collimated, allowing a large field of view (FOV) with a poor resolution limit, and the other is divergent, to achieve a better resolution limit (micron range) over a small FOV. Moreover, our recently reported concept of MISHELF microscopy [M...
March 13, 2018: Lab on a Chip
Okan Yurduseven, Daniel L Marks, Thomas Fromenteze, David R Smith
We present a reconfigurable, dynamic beam steering holographic metasurface aperture to synthesize a microwave camera at K-band frequencies. The aperture consists of a 1D printed microstrip transmission line with the front surface patterned into an array of slot-shaped subwavelength metamaterial elements (or meta-elements) dynamically tuned between "ON" and "OFF" states using PIN diodes. The proposed aperture synthesizes a desired radiation pattern by converting the waveguide-mode to a free space radiation by means of a binary modulation scheme...
March 5, 2018: Optics Express
Mooseok Jang, Yu Horie, Atsushi Shibukawa, Joshua Brake, Yan Liu, Seyedeh Mahsa Kamali, Amir Arbabi, Haowen Ruan, Andrei Faraon, Changhuei Yang
Recently, wavefront shaping with disordered media has demonstrated optical manipulation capabilities beyond those of conventional optics, including extended volume, aberration-free focusing and subwavelength focusing. However, translating these capabilities to useful applications has remained challenging as the input-output characteristics of the disordered media ( P variables) need to be exhaustively determined via O ( P ) measurements. Here, we propose a paradigm shift where the disorder is specifically designed so its exact input-output characteristics are known a priori and can be used with only a few alignment steps...
2018: Nature Photonics
Enrique Barragán-Garza, Douglas D Koch, Luis G Vargas, Alan Lang, Adam Roy
PURPOSE: To assess the clinically acceptable range of inlay decentration with respect to the light-constricted pupil center and the coaxially sighted corneal light reflex (CSCLR) for an inlay (Raindrop Near Vision Inlay; ReVision Optics, Inc., Lake Forest, CA) that reshapes the anterior corneal surface. METHODS: In this retrospective, observational cohort study of 115 patients with emmetropic or low hyperopic presbyopia who were implanted with a shape-changing corneal inlay, visual acuity, task performance (in good and dim light), reports of halos and glare, and satisfaction data were collected from the preoperative and 3-month postoperative examinations...
March 1, 2018: Journal of Refractive Surgery
Ikhyun Jun, David Sung Yong Kang, Dan Z Reinstein, Samuel Arba-Mosquera, Timothy J Archer, Kyoung Yul Seo, Tae-Im Kim
PURPOSE: To comparatively investigate the clinical outcomes, vector parameters, and corneal aberrations of small incision lenticule extraction (SMILE) with a triple centration technique and corneal wavefront-guided transepithelial photorefractive keratectomy (PRK) for the correction of high astigmatism. METHODS: This retrospective, comparative case series study included 89 eyes (89 patients) that received treatment for myopia with high astigmatism (≥ 2.50 diopters) using SMILE with a triple centration technique (SMILE group; 45 eyes) and corneal wavefront-guided transepithelial PRK (transepithelial PRK group; 44 eyes)...
March 1, 2018: Journal of Refractive Surgery
Fredrick A South, Yuan-Zhi Liu, Andrew J Bower, Yang Xu, P Scott Carney, Stephen A Boppart
In many optical imaging applications, it is necessary to correct for aberrations to obtain high quality images. Optical coherence tomography (OCT) provides access to the amplitude and phase of the backscattered optical field for three-dimensional (3D) imaging samples. Computational adaptive optics (CAO) modifies the phase of the OCT data in the spatial frequency domain to correct optical aberrations without using a deformable mirror, as is commonly done in hardware-based adaptive optics (AO). This provides improvement of image quality throughout the 3D volume, enabling imaging across greater depth ranges and in highly aberrated samples...
March 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Xianfeng Xu, Zhiwei Zhang, Zecheng Wang, Jing Wang, Kaiyun Zhan, Yulei Jia, Zhiyong Jiao
A robust digital holography recording design is presented to complete the work of switching between in-line and off-axis recording methods. We precisely supervise the off-axis angle in off-axis holography, so that the original reconstructed image can be separated by a minimum off-axis angle. In the design, we can also monitor and remove the negative effects of the reference tilt error in phase-shifting digital holography. Compared with the conventional digital holographic recording configuration, a supervising unit is introduced to control and to monitor the angle between the reference beam and object beam...
March 1, 2018: Applied Optics
Dan Yue, Haitao Nie, Ye Li, Changsheng Ying
Wavefront sensorless (WFSless) adaptive optics (AO) systems have been widely studied in recent years. To reach optimum results, such systems require an efficient correction method. This paper presents a fast wavefront correction approach for a WFSless AO system mainly based on the linear phase diversity (PD) technique. The fast closed-loop control algorithm is set up based on the linear relationship between the drive voltage of the deformable mirror (DM) and the far-field images of the system, which is obtained through the linear PD algorithm combined with the influence function of the DM...
March 1, 2018: Applied Optics
Yao Li, Yongying Yang, Chen Wang, Yuankai Chen, Yihui Zhang, Jian Bai
A polarization point diffraction interferometry (PPDI) system, adopting a specially designed even aspheric quarter-wave plate (EAQWP) in the test path, is proposed for low-reflectivity and high-numerical-aperture spherical surface testing. In terms of the low-reflectivity mirror measurement, the obtained poor fringes contrast, which can significantly affect the measurement accuracy, can be improved by the polarization characteristic of the EAQWP. Simultaneously, the wavefront distortion, especially larger in high-numerical apperture (NA) measurement, can be greatly reduced attributable to the even aspheric surface design instead of the plane...
March 10, 2018: Applied Optics
Longjie Fang, Haoyi Zuo, Zuogang Yang, Xicheng Zhang, Jinglei Du, Lin Pang
We propose an idea using a simulated annealing algorithm for amplitude modulation to focus light through disordered media. Using 4096 independently controlled segments of an incident wavefront, the intensity of the target signal is enhanced 73 times over the original intensity of the same output channel. The simulated annealing algorithm and existing amplitude control algorithms for focusing through scattering media are compared experimentally. It is found that the simulated annealing algorithm achieves the highest enhancement when the number of iterations required for optimization is the same...
March 10, 2018: Applied Optics
Elisabeth M J P Mouws, Eva A H Lanters, Christophe P Teuwen, Lisette J M E van der Does, Charles Kik, Paul Knops, Ameeta Yaksh, Jos A Bekkers, Ad J J C Bogers, Natasja M S de Groot
BACKGROUND: The influence of underlying heart disease or presence of atrial fibrillation (AF) on atrial excitation during sinus rhythm (SR) is unknown. We investigated atrial activation patterns and total activation times of the entire atrial epicardial surface during SR in patients with ischemic and/or valvular heart disease with or without AF. METHODS AND RESULTS: Intraoperative epicardial mapping (N=128/192 electrodes, interelectrode distances: 2 mm) of the right atrium, Bachmann's bundle (BB), left atrioventricular groove, and pulmonary vein area was performed during SR in 253 patients (186 male [74%], age 66±11 years) with ischemic heart disease (N=132, 52%) or ischemic valvular heart disease (N=121, 48%)...
March 8, 2018: Journal of the American Heart Association
Ying Bi, Xiping Xu, Sing Yee Chua, Eddy Mun Tik Chow, Xin Wang
Laser sensing has been applied in various underwater applications, ranging from underwater detection to laser underwater communications. However, there are several great challenges when profiling underwater turbulence effects. Underwater detection is greatly affected by the turbulence effect, where the acquired image suffers excessive noise, blurring, and deformation. In this paper, we propose a novel underwater turbulence detection method based on a gated wavefront sensing technique. First, we elaborate on the operating principle of gated wavefront sensing and wavefront reconstruction...
March 7, 2018: Sensors
Alan She, Shuyan Zhang, Samuel Shian, David R Clarke, Federico Capasso
Focal adjustment and zooming are universal features of cameras and advanced optical systems. Such tuning is usually performed longitudinally along the optical axis by mechanical or electrical control of focal length. However, the recent advent of ultrathin planar lenses based on metasurfaces (metalenses), which opens the door to future drastic miniaturization of mobile devices such as cell phones and wearable displays, mandates fundamentally different forms of tuning based on lateral motion rather than longitudinal motion...
February 2018: Science Advances
Martin Y Sohn, Bryan M Barnes, Richard M Silver
Accurate optics-based dimensional measurements of features sized well-below the diffraction limit require a thorough understanding of the illumination within the optical column and of the three-dimensional scattered fields that contain the information required for quantitative metrology. Scatterfield microscopy can pair simulations with angle-resolved tool characterization to improve agreement between the experiment and calculated libraries, yielding sub-nanometer parametric uncertainties. Optimized angle-resolved illumination requires bi-telecentric optics in which a telecentric sample plane defined by a Köhler illumination configuration and a telecentric conjugate back focal plane (CBFP) of the objective lens; scanning an aperture or an aperture source at the CBFP allows control of the illumination beam angle at the sample plane with minimal distortion...
March 2018: Optik
Edward J Ciaccio, Nicholas S Peters, Hasan Garan
BACKGROUND: The mechanisms involved in onset, maintenance, and termination of atrial fibrillation are not well understood. A biophysical model could be useful to determine how the events unfold. METHOD: A two-dimensional cellular automaton consisting of 576 × 576 grid nodes was implemented to demonstrate the types of electrical activity that may occur in compromised atrial substrate. Electrical activation between nodes was made anisotropic (2:1), and the refractory period (RP) was adjusted from 74 to 192 ms in the spatial domain...
February 24, 2018: Computers in Biology and Medicine
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