Preventing Falls in Older Multifocal Glasses Wearers by Providing Single-Lens Distance Glasses

2011 ◽  
pp. 194-207
Author(s):  
Mark Haran ◽  
Stephen Lord ◽  
Ian Cameron ◽  
Rebecca Ivers ◽  
Judy Simpson ◽  
...  
Keyword(s):  
Single Lens

scholarly journals Universal Stokes’s nanomechanical viscometer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Komal Chaudhary ◽  
Pooja Munjal ◽  
Kamal P. Singh
Keyword(s):  
Electric Field ◽  
Real Time ◽  
Sample Volume ◽  
Capillary Waves ◽  
Small Sample ◽  
Medical Applications ◽  
Rapid Measurement ◽  
Single Lens ◽  
Universal Applicability ◽  
Small Sample Volume

AbstractAlthough, many conventional approaches have been used to measure viscosity of fluids, most methods do not allow non-contact, rapid measurements on small sample volume and have universal applicability to all fluids. Here, we demonstrate a simple yet universal viscometer, as proposed by Stokes more than a century ago, exploiting damping of capillary waves generated electrically and probed optically with sub-nanoscale precision. Using a low electric field local actuation of fluids we generate quasi-monochromatic propagating capillary waves and employ a pair of single-lens based compact interferometers to measure attenuation of capillary waves in real-time. Our setup allows rapid measurement of viscosity of a wide variety of polar, non-polar, transparent, opaque, thin or thick fluids having viscosity values varying over four orders of magnitude from $$10^{0}{-}10^{4}~\text{mPa} \, \text{s}$$ 10 0 - 10 4 mPa s . Furthermore, we discuss two additional damping mechanisms for nanomechanical capillary waves caused by bottom friction and top nano-layer appearing in micro-litre droplets. Such self-stabilized droplets when coupled with precision interferometers form interesting microscopic platform for picomechanical optofluidics for fundamental, industrial and medical applications.

scholarly journals Frequency-diverse multimode millimetre-wave constant-ϵr lens-loaded cavity

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
M. A. B. Abbasi ◽  
V. F. Fusco ◽  
O. Yurduseven ◽  
T. Fromenteze
Keyword(s):  
Signal To Noise Ratio ◽  
Cost Effective ◽  
Doa Estimation ◽  
Frequency Diversity ◽  
Millimetre Wave ◽  
Single Lens ◽  
Dielectric Lens ◽  
Diversity Principle ◽  
First Time ◽  
Multi Mode

AbstractThis paper presents a physical frequency-diverse multimode lens-loaded cavity, designed and used for the purpose of the direction of arrival (DoA) estimation in millimetre-wave frequency bands for 5G and beyond. The multi-mode mechanism is realized using an electrically-large cavity, generating spatio-temporally incoherent radiation masks leveraging the frequency-diversity principle. It has been shown for the first time that by placing a spherical constant dielectric lens (constant-ϵr) in front of the radiating aperture of the cavity, the spatial incoherence of the radiation modes can be enhanced. The lens-loaded cavity requires only a single lens and output port, making the hardware development much simpler and cost-effective compared to conventional DoA estimators where multiple antennas and receivers are classically required. Using the lens-loaded architecture, an increase of up to 6 dB is achieved in the peak gain of the synthesized quasi-random sampling bases from the frequency-diverse cavity. Despite the fact that the practical frequency-diverse cavity uses a limited subset of quasi-orthogonal modes below the upper bound limit of the number of theoretical modes, it is shown that the proposed lens-loaded cavity is capable of accurate DoA estimation. This is achieved thanks to the sufficient orthogonality of the leveraged modes and to the presence of the spherical constant-ϵr lens which increases the signal-to-noise ratio (SNR) of the received signal. Experimental results are shown to verify the proposed approach.

scholarly journals Ultrawide-angle and high-efficiency metalens in hexagonal arrangement

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Chun-Yuan Fan ◽  
Chia-Ping Lin ◽  
Guo-Dung J. Su
Keyword(s):  
High Efficiency ◽  
Numerical Aperture ◽  
Vital Role ◽  
Optical Systems ◽  
Wide Field ◽  
Wide Angle ◽  
Camera Systems ◽  
Single Lens ◽  
Hexagonal Arrangement ◽  
Virtual And Augmented Reality

Abstract Wide-angle optical systems play a vital role in imaging applications and have been researched for many years. In traditional lenses, attaining a wide field of view (FOV) by using a single optical component is difficult because these lenses have crucial aberrations. In this study, we developed a wide-angle metalens with a numerical aperture of 0.25 that provided a diffraction-limited FOV of over 170° for a wavelength of 532 nm without the need for image stitching or multiple lenses. The designed wide-angle metalens is free of aberration and polarization, and its full width of half maximum is close to the diffraction limit at all angles. Moreover, the metalens which is designed through a hexagonal arrangement exhibits higher focusing efficiency at all angles than most-seen square arrangement. The focusing efficiencies are as high as 82% at a normal incident and 45% at an incident of 85°. Compared with traditional optical components, the proposed metalens exhibits higher FOV and provides a more satisfactory image quality because of aberration correction. Because of the advantages of the proposed metalens, which are difficult to achieve for a traditional single lens, it has the potential to be applied in camera systems and virtual and augmented reality.

Automatic geometry correction in a single-lens light valve projector

1993 ◽  
Author(s):  
Rodney J. Kugizaki ◽  
Delmer Curtis ◽  
James Turner
Keyword(s):  
Single Lens ◽  
Light Valve ◽  
Geometry Correction

Reverse Engineering Using Close Range Photogrammetry for Additive Manufactured Reproduction of Egyptian Artefacts and Other Objets d’art

2014 ◽  
Author(s):  
John Kaufman ◽  
Allan E. W. Rennie ◽  
Morag Clement
Keyword(s):  
Laser Scanning ◽  
Computer Software ◽  
Operating Conditions ◽  
Digital Data ◽  
Image Capture ◽  
Processing Power ◽  
Single Lens ◽  
Close Range ◽  
Geometric Representations ◽  
Objective Being

Photogrammetry has been in use for over one hundred and fifty years. This research considers how digital image capture using a medium range Nikon Digital SLR camera, can be transformed into 3D virtual spatial images, and together with additive manufacturing (AM) technology, geometric representations of the original artefact can be fabricated. The research has focused on the use of photogrammetry as opposed to laser scanning (LS), investigating the shift from LS use to a Digital Single Lens Reflex (DSLR) camera exclusively. The basic photogrammetry equipment required is discussed, with the main objective being simplicity of execution for eventual realisation of physical products. As the processing power of computers has increased and become widely available, at affordable prices, software programs have improved, so it is now possible to digitally combine multi-view photographs, taken from 360°, into 3D virtual representational images. This has now led to the possibility of 3D images being created without LS intervention. Two methods of digital data capture are employed and discussed, in acquiring up to 130 digital data images, taken from different angles using the DSLR camera together with the specific operating conditions in which to photograph the objects. Three case studies are documented, the first, a modern clay sculpture, whilst the other two are 3000 year old Egyptian clay artefacts and the objects were recreated using AM technology. It has been shown that with the use of a standard DSLR camera and computer software, 2D images can be converted into 3D virtual video replicas as well as solid, geometric representation of the originals.

scholarly journals MACS J0416.1–2403: Impact of line-of-sight structures on strong gravitational lensing modelling of galaxy clusters

2018 ◽  
Vol 614 ◽  
pp. A8 ◽  
Author(s):  
G. Chirivì ◽  
S. H. Suyu ◽  
C. Grillo ◽  
A. Halkola ◽  
I. Balestra ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Gravitational Lensing ◽  
Line Of Sight ◽  
Mass Distributions ◽  
Strong Gravitational Lensing ◽  
Cluster Mass ◽  
Critical Curves ◽  
Single Lens ◽  
Best Fitting ◽  
Modelling Techniques

Exploiting the powerful tool of strong gravitational lensing by galaxy clusters to study the highest-redshift Universe and cluster mass distributions relies on precise lens mass modelling. In this work, we aim to present the first attempt at modelling line-of-sight (LOS) mass distribution in addition to that of the cluster, extending previous modelling techniques that assume mass distributions to be on a single lens plane. We have focussed on the Hubble Frontier Field cluster MACS J0416.1–2403, and our multi-plane model reproduces the observed image positions with a rms offset of ~0.′′53. Starting from this best-fitting model, we simulated a mock cluster that resembles MACS J0416.1–2403 in order to explore the effects of LOS structures on cluster mass modelling. By systematically analysing the mock cluster under different model assumptions, we find that neglecting the lensing environment has a significant impact on the reconstruction of image positions (rms ~0.′′3); accounting for LOS galaxies as if they were at the cluster redshift can partially reduce this offset. Moreover, foreground galaxies are more important to include into the model than the background ones. While the magnification factor of the lensed multiple images are recovered within ~10% for ~95% of them, those ~5% that lie near critical curves can be significantly affected by the exclusion of the lensing environment in the models. In addition, LOS galaxies cannot explain the apparent discrepancy in the properties of massive sub-halos between MACS J0416.1–2403 and N-body simulated clusters. Since our model of MACS J0416.1–2403 with LOS galaxies only reduced modestly the rms offset in the image positions, we conclude that additional complexities would be needed in future models of MACS J0416.1–2403.

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