optical focusing
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2022 ◽  
Vol 165 ◽  
pp. 108398
Author(s):  
Qingbing Chang ◽  
Yingxiang Liu ◽  
Jie Deng ◽  
Shijing Zhang ◽  
Weishan Chen

2021 ◽  
Author(s):  
Zixiang Wei ◽  
Tulsi Dabodiya ◽  
Jian Chen ◽  
Qiuyun Lu ◽  
Jiasheng Qian ◽  
...  

Surface-bound nanomaterials are widely used in clean energy techniques from lithium batteries, solar-driven evaporation in desalination to hydrogen production by photocatalytic electrolysis. Reactive surface nanodroplets may potentially streamline the process of fabrication of a range of surface-bound nanomaterials invoking biphasic reactions at interfaces. In this work, we demonstrate the feasibility of reactive surface nanodroplets for in-situ synthesis and anchoring of nanocaps of metal oxides with tailored porous structures. Spatial arrangement and surface coverage of nanocaps are predetermined during the formation of reactive nanodroplets, while the crystalline structures of metal oxides can be controlled by thermal treatment of organometallic nanodroplets produced from the biphasic reactions. Notably, tuning the ratio of reactive and non-reactive components in surface nanodroplets enables the formation of porous nanocaps that can double photocatalytic efficiency in the degradation of organic contaminants in water, compared to smooth nanocaps. In total, we demonstrate in-situ fabrication of four types of metal oxides in the shape of nanocaps. Our work shows that reactive surface nanodroplets may open a door to a general, fast and tuneable route for preparing surface-bound metal oxides. This fabrication approach may help develop new nanomaterials needed for photocatalytic reactions, wastewater treatment, optical focusing, solar energy conversion and other clean energy techniques.


2021 ◽  
Author(s):  
Muntasir Mahmud ◽  
Md Shafiqul Islam ◽  
Mohamed Younis ◽  
Gary Carter

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1107
Author(s):  
Yeh-Wei Yu ◽  
Wen-Li Wang ◽  
Yong-Sheng Lin ◽  
Han-Shin Ko ◽  
Shih-Hsin Ma ◽  
...  

We applied a digital holographic detection technique to detect the scratches on glass surfaces with scattering noise. In the experiment, scratches with widths of 1.67 µm were generated on the front sides of the glass slides, and three different gray levels were painted on the back sides of the glass slides to generate the scattering noise. It demonstrated that the digital holographic detection method can enhance the image contrast of the scratch under high scattering noise. The high defocus tolerance promises a detection process without optical focusing and thus benefits the high-speed automatic optical inspection.


2021 ◽  
Author(s):  
Jian Wang ◽  
Hanpeng Liang ◽  
Jiawei Luo ◽  
Ye Bolin ◽  
Yuecheng Shen

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Zhongtao Cheng ◽  
Lihong V. Wang

AbstractFocusing light into scattering media, although challenging, is highly desirable in many realms. With the invention of time-reversed ultrasonically encoded (TRUE) optical focusing, acousto-optic modulation was demonstrated as a promising guidestar mechanism for achieving noninvasive and addressable optical focusing into scattering media. Here, we report a new ultrasound-assisted technique, ultrasound-induced field perturbation optical focusing, abbreviated as UFP. Unlike in conventional TRUE optical focusing, where only the weak frequency-shifted first-order diffracted photons due to acousto-optic modulation are useful, here UFP leverages the brighter zeroth-order photons diffracted by an ultrasonic guidestar as information carriers to guide optical focusing. We find that the zeroth-order diffracted photons, although not frequency-shifted, do have a field perturbation caused by the existence of the ultrasonic guidestar. By detecting and time-reversing the differential field of the frequency-unshifted photons when the ultrasound is alternately ON and OFF, we can focus light to the position where the field perturbation occurs inside the scattering medium. We demonstrate here that UFP optical focusing has superior performance to conventional TRUE optical focusing, which benefits from the more intense zeroth-order photons. We further show that UFP optical focusing can be easily and flexibly developed into double-shot realization or even single-shot realization, which is desirable for high-speed wavefront shaping. This new method upsets conventional thinking on the utility of an ultrasonic guidestar and broadens the horizon of light control in scattering media. We hope that it provides a more efficient and flexible mechanism for implementing ultrasound-guided wavefront shaping.


Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4584
Author(s):  
Sun-Je Kim ◽  
Changhyun Kim ◽  
Youngjin Kim ◽  
Jinsoo Jeong ◽  
Seokho Choi ◽  
...  

Recently, optical dielectric metasurfaces, ultrathin optical skins with densely arranged dielectric nanoantennas, have arisen as next-generation technologies with merits for miniaturization and functional improvement of conventional optical components. In particular, dielectric metalenses capable of optical focusing and imaging have attracted enormous attention from academic and industrial communities of optics. They can offer cutting-edge lensing functions owing to arbitrary wavefront encoding, polarization tunability, high efficiency, large diffraction angle, strong dispersion, and novel ultracompact integration methods. Based on the properties, dielectric metalenses have been applied to numerous three-dimensional imaging applications including wearable augmented or virtual reality displays with depth information, and optical sensing of three-dimensional position of object and various light properties. In this paper, we introduce the properties of optical dielectric metalenses, and review the working principles and recent advances in three-dimensional imaging applications based on them. The authors envision that the dielectric metalens and metasurface technologies could make breakthroughs for a wide range of compact optical systems for three-dimensional display and sensing.


2021 ◽  
Vol 103 (6) ◽  
Author(s):  
R. Richberg ◽  
S. S. Szigeti ◽  
A. M. Martin

2021 ◽  
pp. 2000594
Author(s):  
Rongkang Gao ◽  
Zhiqiang Xu ◽  
Liang Song ◽  
Chengbo Liu

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