scholarly journals Optical Assembling of Micro-Particles at a Glass–Water Interface with Diffraction Patterns Caused by the Limited Aperture of Objective

2018 ◽  
Vol 8 (9) ◽  
pp. 1522 ◽  
Author(s):  
Min-Cheng Zhong ◽  
Ai-Yin Liu ◽  
Rong Zhu
Keyword(s):  
Optical Tweezers ◽  
Bottom Surface ◽  
Microfluidic Channels ◽  
Compact Structure ◽  
Particle Distributions ◽  
Micro Particles ◽  
Polarized Beam ◽  
Linearly Polarized ◽  
Ring Structures ◽  
Diffraction Patterns

Optical tweezers can manipulate micro-particles, which have been widely used in various applications. Here, we experimentally demonstrate that optical tweezers can assemble the micro-particles to form stable structures at the glass–solution interface in this paper. Firstly, the particles are driven by the optical forces originated from the diffraction fringes, which of the trapping beam passing through an objective with limited aperture. The particles form stable ring structures when the trapping beam is a linearly polarized beam. The particle distributions in the transverse plane are affected by the particle size and concentration. Secondly, the particles form an incompact structure as two fan-shaped after the azimuthally polarized beam passing through a linear polarizer. Furthermore, the particles form a compact structure when a radially polarized beam is used for trapping. Thirdly, the particle patterns can be printed steady at the glass surface in the salt solution. At last, the disadvantage of diffraction traps is discussed in application of optical tweezers. The aggregation of particles at the interfaces seriously affects the flowing of particles in microfluidic channels, and a total reflector as the bottom surface of sample cell can avoid the optical tweezers induced particle patterns at the interface. The optical trapping study utilizing the diffraction gives an interesting method for binding and assembling microparticles, which is helpful to understand the principle of optical tweezers.

ROTATIONAL PROPERTIES OF MICRO-SLABS DRIVEN BY LINEARLY-POLARIZED LIGHT

2005 ◽  
Vol 14 (03) ◽  
pp. 375-382 ◽  
Author(s):  
CHIH-LANG LIN ◽  
IRÈNE WANG ◽  
MARC PIERRE ◽  
ISABELLE COLOMBIER ◽  
CHANTAL ANDRAUD ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Polarized Light ◽  
Polarization Plane ◽  
Light Polarization ◽  
Good Prediction ◽  
Polarization Anisotropy ◽  
Two Photon ◽  
Flat Slabs ◽  
Linearly Polarized ◽  
Optical Torque

We study the rotational motion of objects trapped in a focused laser beam (optical tweezers). Micrometer-sized flat slabs are fabricated using two-photon photopolymerization. These objects, trapped by linearly-polarized light, tend to align parallel to the polarization plane. This alignment effect is attributed to the polarization anisotropy resulting from the object shape and we present a simple electromagnetic approach to estimate the resulting optical torque. Micro-rotors of different sizes are studied experimentally. We characterize the behavior of micro-objects when the light polarization is rotated at constant speed. Our theoretical approach gives a good prediction of how the size of micro-objects affects their rotation efficiency.

scholarly journals Research and Development of a Novel TIG Welding Torch for Joining Thin Sheets

2019 ◽  
Vol 9 (23) ◽  
pp. 5260 ◽  
Author(s):  
Ngo Huu Manh ◽  
Nguyen Van Anh ◽  
Nguyen Van Tuan ◽  
Bin Xu ◽  
Murata Akihisa
Keyword(s):  
Welding Current ◽  
Optical Microscope ◽  
Electron Back Scatter Diffraction ◽  
Weld Bead ◽  
Tig Welding ◽  
Bottom Surface ◽  
Thin Sheets ◽  
Tungsten Electrode ◽  
Welding Torch ◽  
Diffraction Patterns

This paper aims to develop a novel tungsten inner gas (TIG) welding torch in order to join thin sheets efficiently. Using a narrowing nozzle (constricted nozzle) inside a conventional TIG torch can critically improve the position accuracy of the tungsten electrode and also the arc plasma characteristics and heat input density. In order to evaluate the efficiency of this new torch, weld bead appearance and cross-section images were examined by an optical microscope, scanning electron microscope (SEM), and electron back scatter diffraction patterns (EBSD). The results showed that in all cases, the weld bead profile was stable without undercut and burn-through. Full penetration weld was seen. The width of weld bead on the bottom surface was increased much in comparison to conventional TIG welding. However, the results from SEM and EBSD images indicated that in the case of low welding current, the blowholes were found out on the side of the thinner material (SS400). The penetration of SUS430 material to SS400 material was not good. It seems that no fusion of SUS430 material to SS400 at the bottom surface can be seen. Meanwhile, no blowholes were seen in the case of high welding current. The penetration was better, and the fusion was reached on the bottom surface.

Detection of Directivity of Fluorescence From a Mixed Specimen Which Consists of Micro Particles Attached Different Fluorescent Substances Using a Light Waveguide Incorporated Optical TAS

2018 ◽  
Author(s):  
Toshifumi Ohkubo ◽  
Nobuyuki Terada ◽  
Yoshikazu Yoshida
Keyword(s):  
Microfluidic Channel ◽  
Laser Source ◽  
Microfluidic Channels ◽  
Fluorescent Substance ◽  
Total Analysis System ◽  
Micro Particles ◽  
Total Analysis ◽  
Light Waveguide ◽  
Analysis System ◽  
Near Future

A resin-based optical total analysis system (O-TAS) which consists both of microfluidic channels and light waveguides [1] is thought to be one of the most promising components in developing a “ubiquitous human healthcare system” in the near future. Along with this technology trend, we have already developed a transparent epoxy-resin-based optical TAS chip which has a specially prepared light waveguide structure of radially arranged configuration at an intersection portion with a microfluidic channel, in order to detect directivity of fluorescence from fluorescent substance attached micro particles [2],[3]. Schematic diagram of the optical TAS is shown in Figure 1. In the latest research, utilizing an AC modulated laser source and time-series averaging function on detected signal waveforms, we could have successfully obtained directivities of fluorescence from 5-μm-diameter particles with higher signal to noise (S/N) ratio [3].

scholarly journals Multipoint viscosity measurements in microfluidic channels using optical tweezers

Lab on a Chip ◽  
2009 ◽  
Vol 9 (14) ◽  
pp. 2059 ◽  
Author(s):  
Stephen Keen ◽  
Alison Yao ◽  
Jonathan Leach ◽  
Roberto Di Leonardo ◽  
Chris Saunter ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Microfluidic Channels ◽  
Viscosity Measurements

Optical Manipulation of Inorganic and Organic Objects in Soft Microfluidic Devices

2000 ◽  
Vol 657 ◽  
Author(s):  
Cengiz S. Ozkan ◽  
Erhan Ata ◽  
Mihrimah Ozkan ◽  
Sadik C. Esener
Keyword(s):  
Optical Tweezers ◽  
Cell Sorting ◽  
Cell Biology ◽  
Microfluidic Devices ◽  
Optical Manipulation ◽  
Microfluidic Channels ◽  
Negative Photoresist ◽  
Pdms Elastomer ◽  
Biology Research ◽  
Inorganic And Organic

ABSTRACTWe describe a technique for trapping and manipulation of inorganic and organic objects in microfluidic channels, based on photonic momentum transfer using an optical tweezers arrangement. Microfluidic devices have been fabricated by polydimethylsiloxane (PDMS) elastomer molding of patterns lithographically defined on a thick negative photoresist. Polystyrene microspheres dispersed in water were transferred into the fluidic channels using a syringe pump. Microspheres and live biological cells are trapped and redirected by optical manipulation within the fluidic channels. Optical trapping and patterning will have applications in creation of active cellular arrays for cell biology research, tissue engineering, cell sorting and drug discovery.

Measurement of Trap Stiffness of Holographic Optical Tweezers with Power Spectrum Method

2013 ◽  
Vol 787 ◽  
pp. 423-426
Author(s):  
Kai Xu ◽  
Jing Li ◽  
Gang Du ◽  
Chun Li Zhu ◽  
Peng Fei Li ◽  
...  
Keyword(s):  
Brownian Motion ◽  
Power Spectrum ◽  
Optical Tweezers ◽  
Laser Power ◽  
Optical Trap ◽  
Bottom Surface ◽  
Sample Cell ◽  
Spectrum Method ◽  
Holographic Optical Tweezers ◽  
Power Spectrum Method

A microsphere trapped by optical tweezers moves according to the Brownian motion law, which can be described by the Langevin equation. Based on it, a quadrant photodiode (QD) is used to track the displacement of the microsphere with a diameter of 2.5um trapped by holographic optical tweezers, and power spectrum method is adopted to obtain radial trap stiffness. Experiments show that the trap stiffness increases with the increase of the laser power, and decreases as the distance between the optical trap and the inside bottom surface of the sample cell increases.

scholarly journals A Triple Band Bow Tie Array Antenna Using Both-sided MIC Technology

2018 ◽  
Vol 8 (5) ◽  
pp. 3038
Author(s):  
Akimun Jannat Alvina ◽  
Samia Sabrin ◽  
Mohammad Istiaque Reja ◽  
Jobaida Akhtar
Keyword(s):  
Impedance Matching ◽  
Axial Ratio ◽  
Array Antenna ◽  
Matching Problem ◽  
Compact Structure ◽  
Antenna Performance ◽  
Linearly Polarized ◽  
Feed Network ◽  
Feed Networks ◽  
Bow Tie

<span>A single-fed linearly polarized 2x2 microstrip bow tie array antenna is proposed. The feed network has microstrip line and slot line where microstrip-slot branch circuit is connected in parallel. The feed network of the array is designed using both-sided MIC Technology to overcome the impedance matching problem of conventional feed networks. The 2x2 half bow tie array antenna is also truncated with spur lines for optimization of antenna performance. The array antenna unit can be realized in very simple and compact structure, as all the antenna elements and the feeding circuit is arranged on a Teflon glass fiber substrate without requiring any external network. The design frequency of the proposed antenna is 5 to 8 GHz (CBand) and the obtained peak gain is 12.41 dBi. The resultant axial ratio indicates that linear polarization is achieved. </span>

scholarly journals Trapping and rotation of microparticles using a metasurface exciting by linearly polarized beam

2021 ◽  
Vol 11 ◽  
pp. 184798042110151
Author(s):  
Yi Yang ◽  
Siyuan Huang
Keyword(s):  
Angular Momentum ◽  
Surface Plasmon ◽  
Orbital Angular Momentum ◽  
Surface Plasmon Polariton ◽  
Polarized Beams ◽  
Archimedes Spiral ◽  
Clockwise Direction ◽  
Polarized Beam ◽  
Linearly Polarized ◽  
Plasmon Polariton

We numerically demonstrate trapping and rotation of particles using a metasurface formed by arranging nanocavities as a right-handed Archimedes’ spiral. Excited by a 90° linearly polarized beam, a focused surface plasmon polariton (SPP) field is formed at the center of the spiral, and the particle can be trapped by the field. While excited by −45° linearly polarized beams, a vortex SPP field carrying orbital angular momentum is formed, and the particles can be trapped and rotated in the clockwise direction at the vortex field.

scholarly journals An online diagnosis technique for simultaneous measurement of the fundamental, second and third harmonics in one snapshot

2019 ◽  
Vol 7 ◽  
Author(s):  
Xue Dong ◽  
Xingchen Pan ◽  
Cheng Liu ◽  
Jianqiang Zhu
Keyword(s):  
Random Phase ◽  
High Accuracy ◽  
Measurement Methods ◽  
Laser Beams ◽  
Phase Plate ◽  
Diffraction Intensity ◽  
Compact Structure ◽  
Laser Driver ◽  
Diffraction Patterns ◽  
Diagnosis Technique

A three-wavelength coherent-modulation-imaging (CMI) technique is proposed to simultaneously measure the fundamental, second and third harmonics of a laser driver in one snapshot. Laser beams at three wavelengths (1053 nm, 526.5 nm and 351 nm) were simultaneously incident on a random phase plate to generate hybrid diffraction patterns, and a modified CMI algorithm was adopted to reconstruct the complex amplitude of each wavelength from one diffraction intensity frame. The validity of this proposed technique was verified using both numerical simulation and experimental analyses. Compared to commonly used measurement methods, this proposed method has several advantages, including a compact structure, convenient operation and high accuracy.

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