Author Affiliations
Abstract
1 Zhejiang Lab, Research Center for Humanoid Sensing, Hangzhou, China
2 Zhejiang University, College of Optical Science and Engineering, International Research Center for Advanced Photonics, State Key Laboratory of Extreme Photonics and Instrumentation, Hangzhou, China
Imaging through multimode fiber (MMF) provides high-resolution imaging through a fiber with cross section down to tens of micrometers. It requires interferometry to measure the full transmission matrix (TM), leading to the drawbacks of complicated experimental setup and phase instability. Reference-less TM retrieval is a promising robust solution that avoids interferometry, since it recovers the TM from intensity-only measurements. However, the long computational time and failure of 3D focusing still limit its application in MMF imaging. We propose an efficient reference-less TM retrieval method by developing a nonlinear optimization algorithm based on fast Fourier transform (FFT). Furthermore, we develop an algorithm to correct the phase offset error of retrieved TM using defocused intensity images and hence achieve 3D focusing. The proposed method is validated by both simulations and experiments. The FFT-based TM retrieval algorithm achieves orders of magnitude of speedup in computational time and recovers 2286 × 8192 TM of a 0.22 NA and 50 μm diameter MMF with 112.9 s by a computer of 32 CPU cores. With the advantages of efficiency and correction of phase offset, our method paves the way for the application of reference-less TM retrieval in not only MMF imaging but also broader applications requiring TM calibration.
transmission matrix retrieval multimode fiber imaging through scattering Advanced Photonics Nexus
2023, 2(5): 056007
1 浙江大学 光电科学与工程学院, 浙江 杭州 310027
2 之江实验室 类人感知研究中心, 浙江 杭州 311100
全景内窥成像技术可有效减小体内器官的观察盲区，具有缩短手术时间、降低术中出血风险、改善手术预后、缩短术后恢复时间等多种优点，在微创手术和术前检查中有重要应用价值，是近年来的研究热点。本文从原理和产品应用两个方面对全景内窥成像技术进行了梳理。首先，综述了基于二维和三维成像的各种全景内窥成像技术，阐述了它们各自的实现方式，并分析了其关键指标和性能。其次，对比分析了由全景内窥成像技术衍生出来的胶囊内窥镜、全景结直肠镜等多种不同类型的产品，并展望了全景内窥成像技术的发展趋势和应用前景。
内窥镜 全景成像 3D重建 图像拼接 endoscope panoramic imaging 3D reconstruction image stitching
Author Affiliations
Abstract
1 State Key Laboratory for Manufacturing System Engineering and Shaanxi Key Laboratory of Photonics Technology for Information, School of Electronic Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China
2 School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Wettability is one of a solid surface’s fundamental physical and chemical properties, which involves a wide range of applications. Femtosecond laser microfabrication has many advantages compared to traditional laser processing. This technology has been successfully applied to control the wettability of material surfaces. This review systematically summarizes the recent progress of femtosecond laser microfabrication in the preparation of various superwetting surfaces. Inspired by nature, the superwettabilities such as superhydrophilicity, superhydrophobicity, superamphiphobicity, underwater superoleophobicity, underwater superaerophobicity, underwater superaerophilicity, slippery liquid-infused porous surface, underwater superpolymphobicity, and supermetalphobicity are obtained on different substrates by the combination of the femtosecond laser-induced micro/nanostructures and appropriate chemical composition. From the perspective of biomimetic preparation, we mainly focus the methods for constructing various kinds of superwetting surfaces by femtosecond laser and the relationship between different laser-induced superwettabilities. The special wettability of solid materials makes the femtosecond laser-functionalized surfaces have many practical applications. Finally, the significant challenges and prospects of this field (femtosecond laser-induced superwettability) are discussed.
Ultrafast Science
2022, 2(1): 9895418
Author Affiliations
Abstract
1 State Key Laboratory for Manufacturing System Engineering and Shaanxi Key Laboratory of Photonics Technology for Information, School of Electronic Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, People’s Republic of China
2 School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, People’s Republic of China
Underwater transportation of bubbles and gases has essential applications in manipulating and using gas, but achieving this function at the microscopic level remains a significant challenge. Here, we report a strategy to self-transport gas in water along a laser-induced open superhydrophobic microchannel with a width less than 100 μm. The femtosecond laser can directly write superhydrophobic and underwater superaerophilic microgrooves on the polytetrafluoroethylene (PTFE) surfaces. In water, the single laser-induced microgroove and water medium generate a hollow microchannel. When the microchannel connects two superhydrophobic regions in water, the gas spontaneously travels from the small region to the large area along this hollow microchannel. Gas self-transportation can be extended to laser-drilled microholes through a thin PTFE sheet, which can even achieve anti-buoyancy unidirectional penetration. The gas can overcome the bubble’s buoyance and spontaneously travel downward. The Laplace pressure difference drives the processes of spontaneous gas transportation and unidirectional bubble passage. We believe the property of gas self-transportation in the femtosecond laser-structured open superhydrophobic and underwater superaerophilic microgrooves/microholes has significant potential applications related to manipulating underwater gas.
femtosecond laser gas transportation superhydrophobicity underwater superaerophilicity water/gas separation International Journal of Extreme Manufacturing
2022, 4(1): 015002
1 云南电网有限责任公司昆明供电局, 云南 昆明 650000
2 重庆大学 电气工程学院, 重庆 400044
基于Pockels效应原理, 分别对交直流混合强电场传感器中的电光传感单元和电场调制机构进行了设计与测试。对电光传感单元结构进行合理设计, 选取并制备相关器件。搭建试验平台, 试验结果表明电光传感单元输入输出具有良好的线性度, 对电场波形的变化具有快速的响应且频率特性良好, 其性能满足测量调制后电场波形的需求。利用电光传感单元和电场调制机构组建传感器, 并测量了交直流混合强电场响应。
交直流电场 电压传感器 Pockels效应 电光传感单元 电场调制 AC and DC electric field voltage sensor Pockels effect electro-optical sensor unit electric field modulation
Author Affiliations
Abstract
1 Xi’an Jiaotong University, State Key Laboratory for Manufacturing System Engineering, Xi’an, China
2 Xi’an Jiaotong University, School of Electronic Science and Engineering, Shaanxi Key Laboratory of Photonics Technology for Information, Xi’an, China
3 Xi’an Jiaotong University, School of Mechanical Engineering, Xi’an, China
Nanochannel structures with a feature size deeply under the diffraction limit and a high aspect ratio hold huge biomedical significance, which is especially challenging to be realized on hard and brittle materials, such as silica, diamond, and sapphire. By simultaneously depositing the pulse energy on the surface and inside the sample, nanochannels with the smallest feature size of 18 nm (∼1 / 30λ) and more than 200 aspect ratios are achieved inside silica, the mechanism of which can be concluded as the surface assisting material ejection effect. Both the experimental and theoretical results prove that the coaction of the superficial “hot domain” and internal hot domain dominates the generation of the nanochannels, which gives new insights into the laser-material interacting mechanisms and potentially promotes the corresponding application fields.
femtosecond laser direct writing nanochannels spatially shaping surface assisting material ejection Advanced Photonics Nexus
2022, 1(2): 026004
1 西安交通大学 电子与信息工程学院，陕西省信息光子技术重点实验室，西安交通大学 机械制造系统工程国家重点实验室，西安 710049
2 西安交通大学 机械工程学院，西安 710049
仿生超疏水表面在油水分离、防结冰、自清洁等方面具有广阔的应用前景。但是由于其表面结构的脆弱所造成的不稳定性，使其在应用时受到较大限制。飞秒激光作为一种通用的微纳加工方法，在超疏水表面的制备中有许多明显的优势，并且适用于几乎任何硬质材料的加工。本文从浸润性的基本模型出发，分析了耐久型超疏水表面的特点，针对耐久型超疏水表面的飞秒激光制备方法以及应用进行了概述，从聚合物、玻璃以及金属等物质的超疏水表面的飞秒激光制备进行了归纳。对超疏水表面在油水分离、防结冰、自清洁等方面的应用研究进行了综述。最后总结了利用飞秒激光制备耐久型超疏水表面所面临的挑战。
耐久性 超疏水表面 飞秒激光 油水分离 抗冰 Durability Superhydrophobic Femtosecond laser Oil-water separation Anti-icing 
Author Affiliations
Abstract
1 Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan Universityhttps://ror.org/02xe5ns62, Guangzhou 510632, China
2 Research Center for Humanoid Sensing, Zhejiang Lab, Hangzhou 311121, China
3 State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering; International Research Center for Advanced Photonics, Zhejiang University, Hangzhou 311121, China
4 e-mail: liuxiaowei@zhejianglab.com
5 e-mail: yaoyucao@jnu.edu.cn
Achieving an axial superresolved focus with a single lens by simply inserting a modulation mask in the pupil plane is preferred due to its compact configuration and general applicability. However, lack of a universal theoretical model to manifest the superresolved focusing mechanism vastly complicates the mask design and hinders optimal resolution. Here we establish an interference model and find out that the axial resolution closely relates to the Gouy phase gradient (GPG) at the focal point. Using a GPG tuning-based optimization approach, the axial resolution of a ring-mask-modulated beam is readily improved to attain superresolved focal depth for multiple types of pupil function and polarization. In experiment, a focus with an axial resolution of 27% improved from the diffraction limit and 11% finer than the previously reported record is demonstrated for the radially polarized beam. In simulations, a spherical focus with 3D isotropic resolution and a superoscillation-like axial modulation behavior toward extremely high axial resolution is also presented. This approach can be applied for varied types of pupil function, wavelength, and polarization, and can be easily transferred to other traditional or superresolution microscopes to upgrade their axial resolution.
Photonics Research
2022, 10(11): 2502
1 云南电网有限责任公司昆明供电局，昆明 650000
2 重庆大学电气工程学院，重庆 400044
氢能的引入能有效提升配电网的供电可靠性，而电解水制氢是实现低碳转型的关键技术，开发高效的电解水催化剂势在必行。过渡金属氧化物储量大、催化活性高，是具有广阔应用前景的析氧反应催化剂。本文通过射频等离子体处理制备石墨烯上负载Co3O4析氧催化剂，XRD、Raman和XPS测试结果显示，二维结构石墨烯的引入加速表面电子迁移，增大了反应面积。等离子体处理促进了纳米粒子在石墨烯上的负载，利用等离子体刻蚀作用在催化剂表面制造出大量碳结构缺陷和氧空位结构，改善了活性位点分布，有效调控Co3O4电子结构，提高析氧催化活性。电化学测试表明，本文中合成的Co3O4@rGO在电流密度为50 mA·cm-2时的过电位为410 mV，动力学反应速率较快，表现出优于商业IrO2的析氧催化活性。
等离子体 石墨烯 氧空位 电催化 析氧反应 plasma graphene CO3O4 Co3O4 oxygen vacancy electrocatalysis oxygen evolution reaction
