Laser acceleration of absorbing particles

Mitra, Tirtha; Brown, Andrew; Bernot, David; DeFrances, Sage; Talghader, Joseph J.

doi:10.1364/oe.26.006639

Cited by 13 publications

(6 citation statements)

References 29 publications

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“…To calculate the heat flux from the particle into the film via contact conductance, the temperature of the particle must be known in addition to that of the film. The evaporating particle is assumed to stabilize at its sublimation temperature of 4000 K 19 , as previous studies with evaporating contaminants have shown the temperature gradient across such a particle to be minimal 20 . Modeling heat flux between the particle and surface was done using MATLAB’s partial differential equation toolbox.…”

Section: Resultsmentioning

confidence: 99%

Physical Origin of Early Failure for Contaminated Optics

Brown

Bernot

Ogloza

et al. 2019

Sci Rep

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Laser-Induced optical breakdown often occurs unexpectedly at optical intensities far lower than those predicted by ultra-short pulse laser experiments, and is usually attributed to contamination. To determine the physical mechanism, optical coatings were contaminated with carbon and steel microparticles and stressed using a 17 kW continuous-wave laser. Breakdown occurred at intensity levels many orders of magnitude lower than expected in clean, pristine materials. Damage thresholds were found to strongly follow the bandgap energy of the film. A thermal model incorporating the particle absorption, interface heat transfer, and free carrier absorption was developed, and it explains the observed data, indicating that surface contamination heated by the laser thermally generates free carriers in the films. The observed bandgap dependence is in direct contrast to the behavior observed for clean samples under continuous wave and long-pulse illumination, and, unexpectedly, has similarities to ultra-short pulse breakdown for clean samples, albeit with a substantially different physical mechanism.

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Section: Resultsmentioning

confidence: 99%

Physical Origin of Early Failure for Contaminated Optics

Brown

Bernot

Ogloza

et al. 2019

Sci Rep

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“…In summary, we have demonstrated how breaking the symmetry of the well-known counter-propagating optical trapping system can modify the overall optical forces leading to increased trapping stability and allowing for long-range particle trapping and manipulation in liquid media. While there are numerous reports on long-range particle manipulation via optical tweezers, most of them are performed in gas or vacuum media and mainly rely on thermophoretic forces [29,44,45]. Here we trap and manipulate a broad range of particles with different sizes and shapes, including microorganisms, with the use of radiation pressure forces and without creating standing waves [22] or thermal effects.…”

Section: Discussionmentioning

confidence: 99%

Optical Trapping of Sub-millimeter Sized Particles and Microorganisms

Lialys

Salandrino

et al. 2023

Preprint

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While Optical Tweezers (OT) are mostly used for confining smaller size particles, the counter-propagating (CP) dual-beam traps have been a versatile method for confining both small and larger size particles including biological specimen. However, CP traps are complex sensitive systems, requiring tedious alignment to achieve perfect symmetry with rather low trapping stiffness values compared to OT. Moreover, due to their relatively weak forces, CP traps are limited in the size of particles they can confine which is about 100µm. In this paper, a new class of counter-propagating optical tweezers with a broken symmetry is discussed and experimentally demonstrated to trap and manipulate larger than 100µm particles inside liquid media. Our technique exploits a single Gaussian beam folding back on itself in an asymmetrical fashion forming a CP trap capable of confining small and significantly larger particles (up to 250µm in diameter) based on optical forces only. Such optical trapping of large-size specimen to the best of our knowledge has not been demonstrated before. The broken symmetry of the trap combined with the retro-reflection of the beam has not only significantly simplified the alignment of the system, but also made it robust to slight misalignments and enhances the trapping stiffness as shown later. Moreover, our proposed trapping method is quite versatile as it allows for trapping and translating of a wide variety of particle sizes and shapes, ranging from one micron up to a few hundred of microns including microorganisms, using very low laser powers and numerical aperture optics. This in turn, permits the integration of a wide range of spectroscopy techniques for imaging and studying the optically trapped specimen. As an example, we will demonstrate how this novel technique enables simultaneous 3D trapping and light-sheet microscopy of C. elegans worms with up to 450µm length.

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“…For metal particles, the forces exerted by the diffraction fringes repel them to leave the traps. For the absorbing particles, the laser heating of particles results in a strong thermal gradient that drives the particles to leave the diffraction fringes [35][36][37]. Plasmonic tweezers may be a suitable method to assemble the metal or absorbing particles [38][39][40][41].…”

Section: Forming Steady Patterns Of Particles In a Salt Solutionmentioning

confidence: 99%

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

2018

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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.

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Laser acceleration of absorbing particles

Cited by 13 publications

References 29 publications

Physical Origin of Early Failure for Contaminated Optics

Physical Origin of Early Failure for Contaminated Optics

Optical Trapping of Sub-millimeter Sized Particles and Microorganisms

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

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