Name: high-speed optical diagnostics of a supersonic ping-pong cannon
Uploaded: 2023-03-24T13:10:00
Description: Watch this Scientific Journal Video about High-Speed Optical Diagnostics of a Supersonic Ping-Pong Cannon at JoVE.com

Ce travail est soutenu par la NSF Division of Undergraduate Education (prix # 2021157) dans le cadre du programme IUSE: EHR

1. Construction et montage du canon de ping-pong (PPC)
<ol><li>Assemblez tous les composants du PPC conformément à la figure 1.</li>
	<li>Insérez deux fenêtres en acrylique haute clarté sur les côtés du canon pour permettre un sondage optique à l’intérieur du canon.<ol><li>Percez deux 1/2 trous dans les côtés opposés du PVC près de la sortie du canon.</li>
		<li>Préparez deux fenêtres en acrylique épaisses 1/8 à l’aide d’un graveur laser. Télécharg...

<ol>
	<li>Peterson, R. W., Pulford, B. N., Stein, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+ping-pong+cannon:+A+closer+look.">The ping-pong cannon: A closer look.</a> The Physics Teacher. 43 (1), 22-25 (2005).</li><li>Olson, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+shock+waves+in+expansion+tube+accelerators.">The role of shock waves in expansion tube accelerators.</a> American Journal of Physics. 74 (12), 1071-1076 (2006).</li><li>Cockman, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+vacuum+bazooka.">Improved vacuum bazooka.</a> The Physics Teacher. 41 (4), 246-247 (2003).</li><li>Ayars, E., Buchholtz, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+the+vacuum+cannon.">Analysis of the vacuum cannon.</a> American Journal of Physics. 72 (7), 961-963 (2004).</li><li>Thuecks, D. J., Demas, H. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modeling+the+effect+of+air-intake+aperture+size+in+the+ping-pong+ball+cannon.">Modeling the effect of air-intake aperture size in the ping-pong ball cannon.</a> American Journal of Physics. 87 (2), 136-140 (2019).</li><li>Liepmann, H. W., Roshko, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Elements of gas dynamics. , (1957).</li><li>Settles, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Schlieren and shadowgraph techniques. , (2001).</li><li>Geisert, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+single+mirror+schlieren+optical+system.">A single mirror schlieren optical system.</a> American Journal of Physics. 52 (5), 467 (1984).</li><li>French, R. M., Gorrepati, V., Alcorta, E., Jackson, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+mechanics+of+a+ping-pong+ball+gun.">The mechanics of a ping-pong ball gun.</a> Experimental Techniques. 32 (1), 24-30 (2008).</li><li>French, M., Zehrung, C., Stratton, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+supersonic+ping-pong+gun.">A supersonic ping-pong gun.</a> arXiv. , (2013).</li><li>French, F., Choudhuri, R., Stratton, J., Zehrung, C., Huston, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+modular+supersonic+ping-pong+gun.">A modular supersonic ping-pong gun.</a> arXiv. , (2018).</li><li>Fredrick, C. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complementary+studies+on+supersonic+nozzle+flow:+heterodyne+interferometry,+high-speed+video+shadowgraphy,+and+numerical+simulation.">Complementary studies on supersonic nozzle flow: heterodyne interferometry, high-speed video shadowgraphy, and numerical simulation.</a> WIT Transactions on Modelling and Simulation. 59, 223-234 (2015).</li></ol>

Nous avons présenté une méthode pour la construction d’un PPC et d’un SSPPC ainsi que des diagnostics optiques pour la mesure des vitesses de la bille et pour la caractérisation de la propagation des chocs près de la sortie du canon. Le PPC standard est construit avec une section de 2 m de 1,5 dans le tuyau en PVC de l’annexe 80. Le tuyau est équipé de brides à chaque extrémité, de raccords à vide à connexion rapide et de fenêtres en acrylique près de la sortie pour le diagnostic laser. Un schéma dé...

Le PPC est une démonstration de physique populaire utilisée pour montrer l’immense pression atmosphérique à laquelle les gens sont continuellement exposés 1,2,3,4,5. La démonstration implique le placement d’une balle de ping-pong dans une section de tuyau dont le diamètre intérieur est approximativement égal au diamètre de la balle. Le tuyau est scellé à chaque extrémité avec du ruban adhésif et évacué à une pression interne inférieure à 2 Torr. Le ruban à une extrémité du tuyau est perforé, ce qui permet à l’air d’entrer dans le canon et provoque des accélérations maximales d’environ 5 000 g à la balle. La balle, qui est accélérée par la seule pression atmosphérique, sort du canon à une vitesse d’environ 300 m/s après avoir parcouru 2 m.
Bien que le PPC soit généralement utilisé comme une simple démonstration de la pression atmosphérique, c’est aussi un appareil qui présente une physique complexe de l’écoulement compressible, ce qui a donné lieu à de nombreux projets étudiants ouverts. La dynamique de la balle est influencée par des facteurs secondaires tels que le frottement de la paroi, la fuite d’air autour de la balle et la formation d’ondes de choc par la balle accélérante. L’accélération substantielle de la balle introduit une onde de compression de grande amplitude qui se déplace le long du tube devant la balle. Ces compressions se déplacent plus rapidement que la vitesse du son local, ce qui entraîne une pentification de l’onde de compression et la formation éventuelle d’une onde de choc6. Des travaux antérieurs ont étudié l’accumulation rapide de pression à la sortie du tube due aux réflexions de l’onde de choc entre la bille et la sortie scotchée du tube et au détachement du ruban qui en résulte avant la sortie de la bille2. La vidéo à grande vitesse utilisant une technique d’imagerie schlieren à miroir unique a révélé la réponse de la bande aux ondes de choc réfléchissantes et le détachement éventuel de la bande à la sortie du PPC 7,8 (vidéo 1). Ainsi, le PPC sert à la fois de simple démonstration de la pression atmosphérique qui intrigue les publics de tous âges et de dispositif présentant une physique des fluides complexe, qui peut être étudiée en détail dans un laboratoire.
Avec le PPC standard, les vitesses de balle de ping-pong sont limitées par la vitesse du son. Cette version de base du PPC est couverte dans le cadre de cet article, ainsi qu’un canon modifié utilisé pour propulser la balle à des vitesses supersoniques. Dans des travaux antérieurs de French et al., les vitesses de balle de ping-pong supersoniques ont été obtenues en utilisant un écoulement entraîné par la pression à travers une buse convergente-divergente 9,10,11. Le SSPPC présenté ici utilise un tuyau pressurisé (conducteur) pour fournir une différence de pression plus grande sur la balle de ping-pong que celle fournie par la pression atmosphérique seule. Un mince diaphragme en polyester est utilisé pour séparer le tuyau conducteur du tuyau sous vide (entraîné) contenant la bille. Ce diaphragme se rompt sous une pression de jauge suffisante (généralement 5-70 psi, selon l’épaisseur du diaphragme), accélérant ainsi la balle de ping-pong à des vitesses allant jusqu’à Mach 1,4. La balle de ping-pong supersonique produit une onde de choc stationnaire, comme on peut le voir en utilisant des techniques d’imagerie shadowgraph à grande vitesse 7,12 (vidéo 2).
Un laser HeNe de faible puissance (classe II) est utilisé pour effectuer des études de diagnostic optique sur les performances du canon. Le faisceau laser HeNe est divisé en deux chemins, l’un traversant un ensemble de fenêtres en acrylique près de la sortie du canon et le second chemin passant juste après la sortie du canon. Chaque chemin se termine sur un photorécepteur et le signal est affiché sur un oscilloscope à deux canaux. La trace de l’oscilloscope enregistrée lors du tir du canon révèle des informations à la fois sur la vitesse de la balle de ping-pong accélérée et sur le flux compressible et les ondes de choc qui précèdent la sortie de la balle du canon. La vitesse de la balle de ping-pong de 40 mm de diamètre à chaque emplacement de poutre est directement liée au temps pendant lequel la balle bloque la poutre. Une configuration sensible de détection de choc « couteau » est obtenue en recouvrant la moitié du détecteur avec un morceau de ruban électrique noir et en positionnant le bord de la bande au centre du faisceau2. Avec cette configuration, de légères déviations du faisceau laser He-Ne, produites par l’indice de gradients de réfraction induit par le flux compressible, sont clairement visibles sous forme de pics de tension sur la trace de l’oscilloscope. Les ondes de choc se déplaçant vers la sortie du canon et les ondes de choc réfléchies dévient le faisceau dans des directions opposées et sont donc identifiées par un pic de tension positif ou négatif.
Ici, nous fournissons des instructions pour la construction et l’utilisation d’un PPC et d’un SSPPC optimisés, ainsi que des techniques de diagnostic optique (Figure 1, Figure 2 et Figure 3). Les techniques et les mesures de diagnostic optique ont été développées au cours des années précédentes d’étude 1,2.

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high-speed optical diagnostics of a supersonic ping-pong cannon

Le canon de ping-pong traditionnel (PPC) est un appareil éducatif qui lance une balle de ping-pong dans un tuyau évacué à des vitesses presque soniques en utilisant uniquement la pression atmosphérique. Le SSPPC, une version augmentée du PPC, atteint des vitesses supersoniques en accélérant la balle avec une pression supérieure à la pression atmosphérique. Nous fournissons des instructions pour la construction et l’utilisation d’un PPC et d’un SSPPC optimisés.
Les diagnostics optiques sont mis en œuvre dans le but d’étudier la dynamique des canons. Un laser HeNe qui est envoyé à travers deux fenêtres en acrylique près de la sortie du tuyau est terminé sur un capteur photorécepteur. Un microprocesseur mesure le temps pendant lequel le faisceau est obstrué par la balle de ping-pong pour calculer automatiquement la vitesse de la balle. Les résultats sont immédiatement présentés sur un écran LCD. 
Une configuration optique à bord de couteau fournit un moyen très sensible de détecter les ondes de choc en coupant une fraction du faisceau HeNe au niveau du capteur. Les ondes de choc provoquent des déviations induites par la réfraction du faisceau, qui sont observées sous forme de petits pics de tension dans le signal électrique du photorécepteur. 
Les méthodes présentées sont hautement reproductibles et offrent la possibilité d’approfondir les recherches en laboratoire.

Ici, nous fournissons des instructions pour la construction et l’utilisation d’un PPC et d’un SSPPC, ainsi que la mise en œuvre du diagnostic optique pour la caractérisation des chocs et les mesures de vitesse. Des résultats expérimentaux représentatifs sont également fournis. Les systèmes complets du PPC et du SSPPC, ainsi que les accessoires nécessaires, sont illustrés à la figure 1 et à la figure 2. Le SSPPC est une version augmentée du PPC,...

Watch this Scientific Journal Video about High-Speed Optical Diagnostics of a Supersonic Ping-Pong Cannon at JoVE.com

High-Speed Optical Diagnostics of a Supersonic Ping-Pong Cannon

Nous décrivons une méthode pour la construction d’un canon de ping-pong supersonique (SSPPC) ainsi que des techniques de diagnostic optique pour la mesure de la vitesse de la balle et la caractérisation de la propagation des ondes de choc pendant le tir du canon.

Diagnostic optique à grande vitesse d’un canon de ping-pong supersonique

The traditional ping-pong cannon (PPC) is an educational apparatus that launches a ping-pong ball down an evacuated pipe to nearly sonic speeds using ...

Nous fournissons des instructions pour construire et utiliser un canon de ping-pong supersonique ainsi que des techniques de diagnostic optique pour mesurer la vitesse des balles et détecter les ondes de choc. La configuration optique du bord du couteau est très sensible aux petites déviations transversales d’un faisceau laser et fournit un moyen de détecter les ondes de choc associées au canon. Pour commencer, alimentez les récepteurs photo et le module laser en les connectant à une alimentation limitée à courant de 15 volts et à une alimentation laser.Ensuite, fixez les récepteurs photo aux deux canaux de l’oscilloscope à l’aide de câbles BNC. Pour la configuration du diagnostic optique, placez le laser perpendiculairement au canon fabriqué avec le premier faisceau traversant les fenêtres en acrylique à l’intérieur du tuyau et le second juste à l’extérieur de la sortie du canon. Placez du ruban électrique noir sur la moitié du capteur du récepteur photo, créant ainsi une configuration de détection des chocs sur le tranchant du couteau.Pour éviter l’écrêtage, réglez la position du faisceau sur le bord du couteau de sorte que la tension de base soit d’environ 50 % du maximum. Ensuite, ajustez les paramètres de l’oscilloscope pour collecter 20 millions de points de données. Utilisez le bouton de la balance horizontale pour régler le taux d’acquisition des données à 500 mégahertz.Tournez le bouton de déclenchement pour qu’il se déclenche à une tension légèrement inférieure à la ligne de base définie acquise à partir du récepteur photo. Avant de tirer le PPC, portez une protection des oreilles et des yeux. Insérez une balle de ping-pong dans la sortie du canon et soufflez légèrement dans l’extrémité du canon jusqu’à ce qu’elle atteigne le raccord d’aspiration près de l’entrée du tuyau.Scellez la bride de sortie et le capuchon en acrylique du canon à l’aide de deux morceaux de ruban adhésif carré. Assurez-vous que le faisceau laser est centré sur le bord du couteau, que la gâchette est correctement positionnée et que le récipient de capture est sécurisé. Allumez la pompe à vide pour évacuer le tuyau à une pression absolue réduite inférieure à deux Torr.Une fois qu’un vide suffisant est atteint, utilisez une pointe à tête large pour percer le ruban à l’entrée. Après la cuisson, éteignez la pompe à vide et retirez tout ruban restant de la bride de sortie et du capuchon en acrylique. Pour tirer le PPC supersonique, fermez la vanne reliant le tuyau de commande au compresseur d’air et remplissez le réservoir du compresseur d’air.Soufflez la balle, comme démontré précédemment. Après avoir scellé la bride de sortie PPC supersonique, insérez un mince diaphragme en polyester prédécoupé entre deux joints en caoutchouc et placez-les entre le pilote du canon et les sections entraînées. Connectez les deux sections à l’aide de quatre colliers de serrage.Une fois la pression réduite dans le tuyau, relâchez la pression du compresseur d’air dans le tuyau du conducteur, ce qui permet d’augmenter la pression jusqu’à ce que le diaphragme se rompe et que l’air comprimé dans le tuyau d’entraînement rempli le tuyau entraîné sous vide. Après la mise à feu supersonique du PPC, éteignez le compresseur d’air et la pompe à vide. Retirez le diaphragme en polyester rompu et le ruban adhésif du canon.L’onde de choc qui se propageait, réfléchie tout au long du processus de tir du canon, était représentée par un changement de tension par rapport au temps. Un pic positif ou négatif montre la direction de l’onde de choc dans le signal, et la vitesse a été calculée à travers la largeur d’impulsion carrée, produite par la bille coupant le faisceau. Un microprocesseur a été utilisé pour traiter le signal du faisceau traversant l’intérieur du tuyau afin de calculer et d’afficher automatiquement la vitesse de la bille près de la sortie du canon.Les traces de l’oscilloscope ont démontré le tir à double canal du PPC supersonique. La trace supérieure représente la poutre traversant l’intérieur du canon, près de la sortie. Alors que la trace inférieure correspond à la poutre traversant la trajectoire de la balle de ping-pong après être sortie du canon.Un signal de coupure indiquait que la balle passait et obstruait chaque faisceau. Le graphique de la différence de pression en fonction du nombre de Mach a révélé que les diaphragmes de 0,001 et 0,002 pouce d’épaisseur se rompent à une différence de pression suffisante pour accélérer la balle de ping-pong à une vitesse supersonique. La vitesse de la bille était constamment supérieure à Mach 1,3 avec un diaphragme de 0,002 pouce d’épaisseur.Le canon de ping-pong supersonique présenté et le diagnostic optique amélioreront la valeur du canon, à la fois comme dispositif de démonstration et comme appareil pour des expériences de laboratoire de suivi.

high-speed-optical-diagnostics-of-a-supersonic-ping-pong-cannon

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Unit 1

Kinematics of a Particle

SCIENTISTS IN ACTION

Construction and Testing of Coin Cells of Lithium Ion Batteries

Rechargeable lithium ion batteries have wide applications in electronics, where customers always demand more capacity and longer lifetime. Lithium ion batteries have also been considered to be used in electric and hybrid vehicles1 or even electrical grid stabilization systems2. All these applications simulate a dramatic increase in the research and development of battery materials3-7, including new materials3,8, doping9, nanostructuring10-13, coatings or surface modifications14-17 and novel binders18. Consequently, an increasing number of physicists, chemists and materials scientists have recently ventured into this area. Coin cells are widely used in research laboratories to test new battery materials; even for the research and development that target large-scale and high-power applications, small coin cells are often used to test the capacities and rate capabilities of new materials in the initial stage. 
 In 2010, we started a National Science Foundation (NSF) sponsored research project to investigate the surface adsorption and disordering in battery materials (grant no. DMR-1006515). In the initial stage of this project, we have struggled to learn the techniques of assembling and testing coin cells, which cannot be achieved without numerous help of other researchers in other universities (through frequent calls, email exchanges and two site visits). Thus, we feel that it is beneficial to document, by both text and video, a protocol of assembling and testing a coin cell, which will help other new researchers in this field. This effort represents the "Broader Impact" activities of our NSF project, and it will also help to educate and inspire students.
In this video article, we document a protocol to assemble a CR2032 coin cell with a LiCoO2 working electrode, a Li counter electrode, and (the mostly commonly used) polyvinylidene fluoride (PVDF) binder. To ensure new learners to readily repeat the protocol, we keep the protocol as specific and explicit as we can. However, it is important to note that in specific research and development work, many parameters adopted here can be varied. First, one can make coin cells of different sizes and test the working electrode against a counter electrode other than Li. Second, the amounts of C black and binder added into the working electrodes are often varied to suit the particular purpose of research; for example, large amounts of C black or even inert powder were added to the working electrode to test the "intrinsic" performance of cathode materials14. Third, better binders (other than PVDF) have also developed and used18. Finally, other types of electrolytes (instead of LiPF6) can also be used; in fact, certain high-voltage electrode materials will require the uses of special electrolytes7.

A protocol to construct and test coin cells of lithium ion batteries is described. The specific procedures of making a working electrode, preparing a counter electrode, assembling a cell inside a glovebox and testing the cell are presented.

Construction et d&#39;essai des Piles de batteries lithium-ion

Rechargeable lithium ion batteries have wide applications in electronics, where customers always demand more capacity and longer lifetime.  Lithium ion ...

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Ingénierie

Fabricating Metamaterials Using the Fiber Drawing Method

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe their electromagnetic properties to the structure of their constituents, instead of the atoms that compose them. For example, sub-wavelength metal wires can be arranged to possess an effective electric permittivity that is either positive or negative at a given frequency, in contrast to the metals themselves 2. This unprecedented control over the behaviour of light can potentially lead to a number of novel devices, such as invisibility cloaks 3, negative refractive index materials 4, and lenses that resolve objects below the diffraction limit 5. However, metamaterials operating at optical, mid-infrared and terahertz frequencies are conventionally made using nano- and micro-fabrication techniques that are expensive and produce samples that are at most a few centimetres in size 6-7. Here we present a fabrication method to produce hundreds of meters of metal wire metamaterials in fiber form, which exhibit a terahertz plasmonic response 8. We combine the stack-and-draw technique used to produce microstructured polymer optical fiber 9 with the Taylor-wire process 10, using indium wires inside polymethylmethacrylate (PMMA) tubes. PMMA is chosen because it is an easy to handle, drawable dielectric with suitable optical properties in the terahertz region; indium because it has a melting temperature of 156.6 &deg;C which is appropriate for codrawing with PMMA. We include an indium wire of 1 mm diameter and 99.99% purity in a PMMA tube with 1 mm inner diameter (ID) and 12 mm outside diameter (OD) which is sealed at one end. The tube is evacuated and drawn down to an outer diameter of 1.2 mm. The resulting fiber is then cut into smaller pieces, and stacked into a larger PMMA tube. This stack is sealed at one end and fed into a furnace while being rapidly drawn, reducing the diameter of the structure by a factor of 10, and increasing the length by a factor of 100. Such fibers possess features on the micro- and nano- scale, are inherently flexible, mass-producible, and can be woven to exhibit electromagnetic properties that are not found in nature. They represent a promising platform for a number of novel devices from terahertz to optical frequencies, such as invisible fibers, woven negative refractive index cloths, and super-resolving lenses.

Metamaterials at terahertz frequencies offer unique opportunities, but are challenging to fabricate in bulk. We adapt the fabrication procedure for microstructured polymer optical fibers to inexpensively fabricate metamaterials potentially on an industrial scale. We produce polymethylmethacrylate fibers containing ~10 &mu;m diameter indium wires separated by ~100 &mu;m, which exhibit a terahertz plasmonic response.

Les métamatériaux Fabricating aide de la méthode de tirage de fibre

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe ...

Optical Trapping of Nanoparticles

Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping and manipulating small biological particles. Ashkin and co-workers first demonstrated optical tweezers using a single focused beam1. The single beam trap can be described accurately using the perturbative gradient force formulation in the case of small Rayleigh regime particles1. In the perturbative regime, the optical power required for trapping a particle scales as the inverse fourth power of the particle size. High optical powers can damage dielectric particles and cause heating. For instance, trapped latex spheres of 109 nm in diameter were destroyed by a 15 mW beam in 25 sec1, which has serious implications for biological matter2,3.
A self-induced back-action (SIBA) optical trapping was proposed to trap 50 nm polystyrene spheres in the non-perturbative regime4. In a non-perturbative regime, even a small particle with little permittivity contrast to the background can influence significantly the ambient electromagnetic field and induce a large optical force. As a particle enters an illuminated aperture, light transmission increases dramatically because of dielectric loading. If the particle attempts to leave the aperture, decreased transmission causes a change in momentum outwards from the hole and, by Newton's Third Law, results in a force on the particle inwards into the hole, trapping the particle. The light transmission can be monitored; hence, the trap can become a sensor. The SIBA trapping technique can be further improved by using a double-nanohole structure.
The double-nanohole structure has been shown to give a strong local field enhancement5,6. Between the two sharp tips of the double-nanohole, a small particle can cause a large change in optical transmission, thereby inducing a large optical force. As a result, smaller nanoparticles can be trapped, such as 12 nm silicate spheres7 and 3.4 nm hydrodynamic radius bovine serum albumin proteins8. In this work, the experimental configuration used for nanoparticle trapping is outlined. First, we detail the assembly of the trapping setup which is based on a Thorlabs Optical Tweezer Kit. Next, we explain the nanofabrication procedure of the double-nanohole in a metal film, the fabrication of the microfluidic chamber and the sample preparation. Finally, we detail the data acquisition procedure and provide typical results for trapping 20 nm polystyrene nanospheres.

The following setup approach details low power optical trapping of dielectric nanoparticles using a double-nanohole in metal film.

Le piégeage optique de nanoparticules

Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping ...

High-resolution, High-speed, Three-dimensional Video Imaging with Digital Fringe Projection Techniques

Digital fringe projection (DFP) techniques provide dense 3D measurements of dynamically changing surfaces.&#160;Like the human eyes and brain, DFP uses triangulation between matching points in two views of the same scene at different angles to compute depth.&#160;However, unlike a stereo-based method, DFP uses a digital video projector to replace one of the cameras1. The projector rapidly projects a known sinusoidal pattern onto the subject, and the surface of the subject distorts these patterns in the camera&#8217;s field of view. Three distorted patterns (fringe images) from the camera can be used to compute the depth using triangulation.
Unlike other 3D measurement methods, DFP techniques lead to systems that tend to be faster, lower in equipment cost, more flexible, and easier to develop.&#160;DFP systems can also achieve the same measurement resolution as the camera.&#160;For this reason, DFP and other digital structured light techniques have recently been the focus of intense research (as summarized in1-5). Taking advantage of DFP, the graphics processing unit, and optimized algorithms, we have developed a system capable of 30&#160;Hz 3D video data acquisition, reconstruction, and display for over 300,000 measurement points per frame6,7.&#160;Binary defocusing DFP methods can achieve even greater speeds8.
Diverse applications can benefit from DFP techniques. Our collaborators have used our systems for facial function analysis9, facial animation10, cardiac mechanics studies11, and fluid surface measurements, but many other potential applications exist.&#160;This video will teach the fundamentals of DFP techniques and illustrate the design and operation of a binary defocusing DFP system.

This video describes the fundamentals of digital fringe projection techniques, which provide dense 3D measurements of dynamically changing surfaces.&#160;It also demonstrates the design and operation of a high-speed binary defocusing system based on these techniques.

Digital fringe projection (DFP) techniques provide dense 3D measurements of dynamically changing surfaces.&#160;Like the human eyes and brain, DFP uses ...

Construction of a High Resolution Microscope with Conventional and Holographic Optical Trapping Capabilities

High resolution microscope systems with optical traps allow for precise manipulation of various refractive objects, such as dielectric beads 1 or cellular organelles 2,3, as well as for high spatial and temporal resolution readout of their position relative to the center of the trap. The system described herein has one such "traditional" trap operating at 980 nm. It additionally provides a second optical trapping system that uses a commercially available holographic package to simultaneously create and manipulate complex trapping patterns in the field of view of the microscope 4,5 at a wavelength of 1,064 nm. The combination of the two systems allows for the manipulation of multiple refractive objects at the same time while simultaneously conducting high speed and high resolution measurements of motion and force production at nanometer and piconewton scale.

The system described herein employs a traditional optical trap as well as an independent holographic optical trapping line, capable of creating and manipulating multiple traps. This allows for the creation of complex geometric arrangements of refractive particles while also permitting simultaneous high-speed, high-resolution measurements of the activity of biological enzymes.

Construction d&#39;un microscope à haute résolution avec des capacités de piégeage optique classique et holographique

High resolution microscope systems with optical traps allow for precise manipulation of various refractive objects, such as dielectric beads 1 or cellular ...

High-speed Particle Image Velocimetry Near Surfaces

Multi-dimensional and transient flows play a key role in many areas of science, engineering, and health sciences but are often not well understood. The complex nature of these flows may be studied using particle image velocimetry (PIV), a laser-based imaging technique for optically accessible flows. Though many forms of PIV exist that extend the technique beyond the original planar two-component velocity measurement capabilities, the basic PIV system consists of a light source (laser), a camera, tracer particles, and analysis algorithms. The imaging and recording parameters, the light source, and the algorithms are adjusted to optimize the recording for the flow of interest and obtain valid velocity data. 
Common PIV investigations measure two-component velocities in a plane at a few frames per second. However, recent developments in instrumentation have facilitated high-frame rate (&gt; 1 kHz) measurements capable of resolving transient flows with high temporal resolution. Therefore, high-frame rate measurements have enabled investigations on the evolution of the structure and dynamics of highly transient flows. These investigations play a critical role in understanding the fundamental physics of complex flows.
A detailed description for performing high-resolution, high-speed planar PIV to study a transient flow near the surface of a flat plate is presented here. Details for adjusting the parameter constraints such as image and recording properties, the laser sheet properties, and processing algorithms to adapt PIV for any flow of interest are included.

A procedure for studying transient flows near boundaries using high-resolution, high-speed particle image velocimetry (PIV) is described here. PIV is a non-intrusive measurement technique applicable to any optically accessible flow by optimizing several parameter constraints such as the image and recording properties, the laser sheet properties, and analysis algorithms.

Particules à haute vitesse vélocimétrie par image de près de surfaces

Multi-dimensional and transient flows play a key role in many areas of science, engineering, and health sciences but are often not well understood. The ...

Visualization of High Speed Liquid Jet Impaction on a Moving Surface

Two apparatuses for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device (for examining surface speeds between 0 and 25 m/sec) and a spinning disk device (for examining surface speeds between 15 and 100 m/sec). The air cannon linear traverse is a pneumatic energy-powered system that is designed to accelerate a metal rail surface mounted on top of a wooden projectile. A pressurized cylinder fitted with a solenoid valve rapidly releases pressurized air into the barrel, forcing the projectile down the cannon barrel. The projectile travels beneath a spray nozzle, which impinges a liquid jet onto its metal upper surface, and the projectile then hits a stopping mechanism. A camera records the jet impingement, and a pressure transducer records the spray nozzle backpressure. The spinning disk set-up consists of a steel disk that reaches speeds of 500 to 3,000 rpm via a variable frequency drive (VFD) motor. A spray system similar to that of the air cannon generates a liquid jet that impinges onto the spinning disc, and cameras placed at several optical access points record the jet impingement. Video recordings of jet impingement processes are recorded and examined to determine whether the outcome of impingement is splash, splatter, or deposition. The apparatuses are the first that involve the high speed impingement of low-Reynolds-number liquid jets on high speed moving surfaces. In addition to its rail industry applications, the described technique may be used for technical and industrial purposes such as steelmaking and may be relevant to high-speed 3D printing.

Two experimental devices for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device and a spinning disk device. The apparatuses are used to determine optimal approaches to the application of liquid friction modifier (LFM) onto rail tracks for top-of-rail friction control.

Visualisation de High Speed ​​Liquid Jet impaction sur une surface en mouvement

Two apparatuses for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device (for examining surface speeds ...

Fabrication and Operation of a Nano-Optical Conveyor Belt

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological and physical sciences over the past few decades. The progress made in this field invites further study of even smaller systems and at a larger scale, with tools that could be distributed more easily and made more widely available. Unfortunately, the fundamental laws of diffraction limit the minimum size of the focal spot of a laser beam, which makes particles smaller than a half-wavelength in diameter hard to trap and generally prevents an operator from discriminating between particles which are closer together than one half-wavelength. This precludes the optical manipulation of many closely-spaced nanoparticles and&#160;limits the&#160;resolution of optical-mechanical systems. Furthermore, manipulation using focused beams requires beam-forming or steering optics, which can be very bulky and expensive. To address these limitations in the system scalability of conventional optical trapping our lab has devised an alternative technique which utilizes near-field optics to move particles across a chip. Instead of focusing laser beams in the far-field, the optical near field of plasmonic resonators produces the necessary local optical intensity enhancement to overcome the restrictions of diffraction and manipulate particles at higher resolution. Closely-spaced resonators produce strong optical traps which can be addressed to mediate the hand-off of particles from one to the next in a conveyor-belt-like fashion. Here, we describe how to design and produce a conveyor belt using a gold surface patterned with plasmonic C-shaped resonators and how to operate it with polarized laser light to achieve super-resolution nanoparticle manipulation and transport. The nano-optical conveyor belt chip can be produced using lithography techniques and easily packaged and distributed.

The scalability and resolution of conventional optical manipulation techniques are limited by diffraction. We circumvent the diffraction limit and describe a method of optically transporting nanoparticles across a chip using a gold surface patterned with a path of closely spaced C-shaped plasmonic resonators.

Fabrication et fonctionnement d&#39;un Convoyeur Nano-optique

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological ...

Writing Bragg Gratings in Multicore Fibers

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong suppression at a single wavelength requires that all cores have matching transmission profiles. These gratings cannot be inscribed using the same method as for single-core fibers because the curved surface of the cladding acts as a lens, focusing the incoming UV laser beam and causing variations in exposure between cores. Therefore we use an additional optical element to ensure that the beam shape does not change while passing through the cross-section of the multicore fiber. This consists of a glass capillary tube which has been polished flat on one side, which is then placed over the section of the fiber to be inscribed. The laser beam enters the fiber through the flat surface of the capillary tube and hence maintains its original dimensions. This paper demonstrates the improvements in core-to-core uniformity for a 7-core fiber using this method. The technique can be generalized to larger multicore fibers.

We describe a technique for inscribing identical fiber Bragg gratings into each core of a multicore fiber. This is achieved by introducing an additional surface into the optical path to mitigate lensing by the curved surface of the fiber cladding.

Rédaction de Bragg dans les fibres multipaires

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong ...

Compact Lens-less Digital Holographic Microscope for MEMS Inspection and Characterization

A micro-electro-mechanical-system (MEMS) is a widely used component in many industries, including energy, biotechnology, medical, communications, and automotive. However, effective inspection and characterization metrology systems are needed to ensure the functional reliability of MEMS. This study presents a system based on digital holography as a tool for MEMS metrology. Digital holography has gained increasing attention in the past 20 years. With the fast development and decreasing cost of sensor arrays, resolution of such systems has increased broadening potential applications. Thus, it has attracted attention from both research and industry sides as a potential reliable tool for industrial metrology. Indeed, by recording the interference pattern between an object beam (which contains sample height information) and a reference beam on a CCD camera, one can retrieve the quantitative phase information of an object. However, most of digital holographic systems are bulky and thus not easy to implement on industry production lines. The novelty of the system presented is that it is lens-less and thus very compact. In this study, it is shown that the Compact Digital Holographic Microscope (CDHM) can be used to evaluate several characteristics typically consider as criteria in MEMS inspections. The surface profiles of MEMS in both static and dynamic conditions are presented. Comparison with AFM is investigated to validate the accuracy of the CDHM.

We present a compact reflection digital holographic system (CDHM) for inspection and characterization of MEMS devices. A lens-less design using a diverging input wave providing natural geometrical magnification is demonstrated. Both static and dynamic studies are presented.

Compact numérique Holographic Microscope pour les MEMS Inspection et caractérisation de Lens-moins

A micro-electro-mechanical-system (MEMS) is a widely used component in many industries, including energy, biotechnology, medical, communications, and ...