<title>Optics design for internal autoconverge in a single-lens light-valve projector</title>

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.

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

Scientific Reports ◽

10.1038/s41598-020-78964-1 ◽

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.

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Manipulation of light transmission from stable magnetic microrods formed by the alignment of magnetic nanoparticles

RSC Advances ◽

10.1039/d0ra09511g ◽

2021 ◽

Vol 11 (4) ◽

pp. 2390-2396

Author(s):

Yoon Ji Seo ◽

Hyung Gyu Lee ◽

Jun Seok Yang ◽

Hwanyeop Jeong ◽

Jeonghun Han ◽

...

Keyword(s):

Magnetic Field ◽

Magnetic Nanoparticles ◽

Light Transmission ◽

Smart Window ◽

Light Valve

Magnetic microrods were synthesised from magnetic nanoparticles by alignment using a magnetic field. The transparency difference was maximised and the anisotropic features of the rods were used as a light valve to control the transparency of a smart window.

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Ultrawide-angle and high-efficiency metalens in hexagonal arrangement

Scientific Reports ◽

10.1038/s41598-020-72668-2 ◽

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.

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