Finanziamento è stato fornito dalla University of Utah. Vorremmo ringraziare il Dott. J. Xu (UC Merced) e il Dr. Reddy BJN (UC Irvine) per le discussioni utili.

1. Installazione di 980 nm Lunghezza d&#39;onda singola trappola ottica <ol><li> Intrappolamento ottico a 980 nm di lunghezza d&#39;onda è spesso ottimale sono facilmente disponibili con potenza di uscita alto come 300 mW esperimenti di biofisica e diodi laser poco costoso. È preferibile per un laser a diodi ad essere Pigtailed con polarizzazione-preserving fibra monomodale con un diametro del campo modalità noto. La fibra deve essere sufficientemente lungo per agire come filtro modalità e tipicamente è terminato sia con FC / PC o connettore FC / APC. Di questi, FC / APC è preferibile per minimizzare riflessione posteriore di instabilità di feedback chiari e potenziali. </li><li> Fissare il 980 nm diodo laser in un supporto che permette di potere e di controllo della temperatura. E &#39;meglio per risolvere il mount di un tavolo ottico direttamente a massimizzare passiva affondamento di calore e quindi ridurre al minimo il pericolo di fallimento diodo a causa di un malfunzionamento del regolatore di temperatura. </li><li> Montare il connettore in fibra PC / APC per le ottiche collimanti fascio. Èfondamentale per assicurare che il fascio collimato è minimo di divergenza così porte in fibra regolabili sono più utili. Assicurarsi che la porta a fibre ottiche scelto corrisponde al diametro del campo modalità della fibra codino diodo. Se il fascio deve essere rastered utilizzando deflettori acusto-ottica (AOD) o deflettori elettro-ottici (EOD) allora la vita di fascio laser collimato deve essere leggermente inferiore alla dimensione dell&#39;apertura deflettore. </li><li> Fissare l&#39;adattatore di collimazione al tavolo ottico ad una distanza sufficiente dal microscopio per consentire la trave di routing, l&#39;espansione e il posizionamento di altri componenti desiderati. Regolare la porta in fibra di assicurare coerenza vita trave su distanze paragonabili al percorso complessivo del fascio al microscopio. </li><li> Installare specchi indicate in Figura 1. Rimuovere l&#39;obiettivo dal microscopio e utilizzare gli specchi per indirizzare il fascio attraverso l&#39;apertura nella fase di montaggio obiettivo. Se preferito, il posizionamento degli specchi dicroici DM1 e DM3 può essere omesso finosuccessivamente. DM2 e DM3 sono entrambi shortpass e trasmissione della luce visibile, mentre riflettendo vicino IR e sopra. </li><li> È utile temporaneamente montare un puntatore laser rosso al posto dell&#39;obiettivo, allineato sull&#39;asse ottico del microscopio. Un adattatore meccanico personalizzato è necessario per assicurare la centratura del puntatore laser. Raggio visibile dal puntatore laser può quindi essere instradato indietro al centro dell&#39;apertura della porta fibra e può quindi essere utilizzato per installare le lenti (vedi sotto). </li><li> Installare il 980 nm beam expander (L8 e L9) a debita distanza dal porto di fibra per consentire futuro inserimento dei componenti dello sterzo (AOD o EOD), se necessario 1. Il raggio estesa deve leggermente riempire troppo il diaframma focale posteriore dell&#39;obiettivo. (Qui, obiettivi con lunghezze focali di 125 mm e 60 mm sono in una disposizione kepleriano di raddoppiare circa la vita del fascio). Utilizzare visibile fascio laser pointer (vedi sezione 1.6) per garantire il posizionamento della lente corretta e l&#39;allineamento approssimativo. </li><li> Install le lenti dello sterzo 980 nm (L2 e L3) in una disposizione telescopio come indicato (qui entrambi hanno 60 mm di focale) 1. L3 è montato in un piano coniugato al piano di back-focale dell&#39;obiettivo. Monte L3 su un palco di posizionamento di precisione XYZ per consentire orientamento del fascio. E &#39;utile per la fase di XYZ disporre di indicatori digitali per le sue micrometri, permettendo il posizionamento ripetibile e riposizionamento della trappola. La &quot;gamma di viaggi 0.5 è in genere sufficiente, tuttavia più viaggi per il posizionamento L3 lungo l&#39;asse ottico può essere utile. Usa puntatore laser visibile (vedi sezione 1.6) per garantire il posizionamento della lente corretta e l&#39;allineamento approssimativo. </li></ol> 2. Installazione del rivelatore del laser <ol><li> Installare il specchio dicroico DM3 sopra del condensatore, come mostrato in Figura 1. Un supporto personalizzato è in genere necessaria. Fissare il fotodiodo quad (QPD) o un rivelatore sensibile alla posizione (PSD) 8 al lato del gruppo condensatore e ensure che la 980 nm raggio laser riflesso da DM3 sta colpendo è all&#39;incirca sul centro. Quando si utilizza QPD, assicurarsi che sia montato su un piccolo palco XY per consentire un corretto centraggio del sensore sul raggio laser. </li><li> Installare L1 (tipicamente una lente 30 mm) tra DM3 e il sensore. Posizione L1 in modo da concentrare il fascio di una sola macchia sul sensore. </li><li> Installare il filtro notch poco prima di L1 per bloccare il fascio di 1.064 nm, nonché degli eventuali randagi riflessi di luce visibile dal illuminatore microscopio e illuminazione ambientale. </li></ol> 3. Installazione di 1.064 nm Holographic Trappola <ol><li> La parte olografica del setup è costruito intorno a un pacchetto hardware / software disponibile in commercio Gli specchi olografici usati in questo pacchetto sono tarati ad una potenza massima di incidente di 5 o 10 W / cm 2. Monomodali TEM00 travi di questa gamma di potenza possono essere facilmente acquistati da un laser DPSS a 1.064 nm di lunghezza d&#39;onda. </li><li> Montare il laser 1064 nm su un elevatopiattaforma che corrisponda approssimativamente l&#39;altezza del percorso del fascio per la linea 980 (vedere sezione 1). </li><li> Se non direttamente controllabile, potenza del laser può essere regolata manualmente mediante l&#39;installazione di una piastra semi onda (HWP) e un polarizzatore (PBS) a destra dopo diaframma uscita laser. È utile per montare il polarizzatore in una fase rotante per poter abbinare requisito specchio olografico per la polarizzazione del fascio. </li><li> Installare il 1.064 nm beam expander (L6 e L7). La vita di fascio laser deve essere ampliato in base alle dimensioni diagonale dello specchio olografico. Per grandi rapporti di espansione (sopra 10X) può essere una preoccupazione di mantenere la dimensione dell&#39;espansore piccola. Così può essere desiderabile utilizzare lenti con insolitamente piccola lunghezza focale (qui: 16 mm e 175 mm). </li><li> Installare gli altri mirror, come indicato di dirigere il fascio di 1.064 nm attraverso l&#39;obiettivo. <ol><li> Sicuro DM1 dicroico (45 ° angolo di incidenza) in un supporto cinematico e posizionare il gruppo nel percorso del raggio 980 nm in modo che permette di undiminished trasmissione di tale trave. </li><li> Attiva luce puntatore laser. Lo specchio DM1 dovrebbe riflettere sufficiente quantità di luce visibile per posizionare correttamente il modulatore spaziale di luce (SLM) nel percorso di questa trave. L&#39;SLM deve anche essere inclinate in modo che i raggi laser in entrata e in uscita sono il più vicino possibile incidenza normale. Tuttavia l&#39;angolo di incidenza, deve essere sufficientemente grande da garantire che il raggio laser non è troncato da monta lente e altri componenti ottici. Un angolo di 5 ° deve essere facilmente raggiungibile ed è sufficientemente piccolo. La distanza tra DM1 alla SLM deve essere accuratamente misurata in modo che l&#39;inserimento di lenti L4 e L5 (vedi 3.6) può coniugare piano di riflessione SLM e il piano focale posteriore dell&#39;obiettivo. </li><li> Installare uno specchio per dirigere la luce da 1.064 nm beam expander al SLM. Assicurarsi che la luce puntatore laser colpisce l&#39;espansore apertura del fascio sul centro. </li></ol></li><li> Installare lenti L4 e L5 (qui: lenti con 125 millimetri e 200 mm rispettivamente). Questa coppia telescopio coniuga il piano di riflessione SLM al piano focale posteriore dell&#39;obiettivo e riduce anche il punto vita trave a solo leggermente riempire eccessivamente l&#39;apertura posteriore dell&#39;obiettivo. Abbiamo scelto obiettivi con lunghezze focali lunghe per lo spazio della SLM lontano da DM1. Questo cancella non solo spazio per la seconda linea di laser, ma tende anche a rendere più facile l&#39;allineamento. </li><li> Rimuovere il puntatore laser. Lasciare l&#39;adattatore di montaggio per servire come apertura allineamento grossolano. </li></ol> 4. Sistema di installazione e allineamento Note <ol><li> Lente L3 e SLM devono essere posizionati in modo da essere otticamente coniugata al piano focale posteriore dell&#39;obiettivo. Il punto focale comune di L4 e L5 è otticamente coniugata al piano campione se i fasci ottici di cattura sono iniettati nello spazio infinito del microscopio. </li><li> cantare scheda visore IR allineare il fascio 980 nm per andare lungo l&#39;asse centrale del diaframma nell&#39;adattatore puntatore laser. </li><li> Utilizzare carta di IR to Assicurarsi che il fascio 1.064 nm colpisce lo stesso punto come il raggio 980 nm su DM1, L2 e L3 e che il fascio 1.064 nm va lungo l&#39;asse centro dell&#39;apertura nell&#39;adattatore puntatore laser. </li><li> Sostituire l&#39;adattatore di montaggio puntatore laser con un obiettivo. Obiettivo olio o acqua ad alta apertura numerica è tipica. </li><li> Allineare la trappola nm 980, come descritto in 9 per &quot;camminare&quot; il raggio laser fino a quando una figura di interferenza radiale simmetrico è visto sulla fotocamera. </li><li> Con l&#39;olografico specchio off (cioè agisce come uno specchio passivo) utilizzare SLM e DM1 a &quot;camminare&quot; il undiffracted 1.064 fascio nm per allineare la trappola nm 1.064. </li><li> Il SLM produce un significativo fascio undiffracted che si traduce in un forte trappola laser inamovibile nel campo di vista. Questo è utile per allineamento ma può essere indesiderabile per esperimenti. Bloccare questa trappola si può inserire un oggetto opaco piccola nel percorso della luce undiffracted nella posizione coniugato al piano del campione (ad es the punto focale comune di L4 e L5). La dimensione di questa macchia bloccante centrale deve essere in qualche modo più grande del diametro del disco di Airy per la luce concentrata (un bloccante con 100-300 micron di diametro per il sistema descritto). </li><li> egolare 1.064 nm polarizzazione del fascio utilizzando il polarizzatore per abbinare l&#39;orientamento SLM. Ruotare la piastra semionda per impostare la potenza del fascio di uscita come desiderato. </li><li> Se lo si desidera, inserire EOD fascio elementi sterzanti AOD o nella linea di laser a 980 nm. Garantire la corretta coniugazione di questi elementi al piano di back-focale dell&#39;obiettivo e riallineare la trappola. E &#39;utile per montare gli organi di sterzo su un palcoscenico goniometrica. </li></ol>

<ol>
	<li>Svoboda, K., Block, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biological+applications+of+optical+forces.">Biological applications of optical forces.</a> Annu. Rev. Biophys. Biomol. Struct. 23, 247-285 (1994).</li><li>Ashkin, A., Schutze, K., Dziedzic, J. M., Euteneuer, U., Schliwa, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Force+generation+of+organelle+transport+measured+in+vivo+by+an+infrared+laser+trap.">Force generation of organelle transport measured in vivo by an infrared laser trap.</a> Nature. 348, 346-348 (1990).</li><li>Shubeita, G. T., Tran, S. L., 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=Consequences+of+motor+copy+number+on+the+intracellular+transport+of+kinesin-1-driven+lipid+droplets.">Consequences of motor copy number on the intracellular transport of kinesin-1-driven lipid droplets.</a> Cell. 135, 1098-1107 (2008).</li><li>Polin, M., Ladavac, K., Lee, S. H., Roichman, Y., Grier, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimized+holographic+optical+traps.">Optimized holographic optical traps.</a> Opt Express. 13, 5831-5845 (2005).</li><li>Sun, B., Roichman, Y., Grier, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Theory+of+holographic+optical+trapping.">Theory of holographic optical trapping.</a> Opt. Express. 16, 15765-15776 (2008).</li><li>Moffitt, J. R., Chemla, Y. R., Smith, S. B., Bustamante, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+in+optical+tweezers.">Recent advances in optical tweezers.</a> Annu. Rev. Biochem. 77, 205-228 (2008).</li><li>Grier, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+revolution+in+optical+manipulation.">A revolution in optical manipulation.</a> Nature. 424, 810-816 (2003).</li><li>Neuman, K. C., Block, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+trapping.">Optical trapping.</a> Rev. Sci. Instrum. 75, 2787-2809 (2004).</li><li>Sheetz, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+tweezers+in+cell+biology.">Laser tweezers in cell biology.</a> Introduction. Methods Cell Biol. 55, xi-xii (1998).</li><li>Spudich, J. A., Rice, S. E., Rock, R. S., Purcell, T. J., Warrick, H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+traps+to+study+properties+of+molecular+motors.">Optical traps to study properties of molecular motors.</a> Cold Spring Harb. Protoc. 2011, 1305-1318 (2011).</li><li>Visscher, K., Gross, S. P., Block, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Construction+of+multiple-beam+optical+traps+with+nanometer-resolution+position+sensing.+Selected+Topics+in+Quantum+Electronics.">Construction of multiple-beam optical traps with nanometer-resolution position sensing. Selected Topics in Quantum Electronics.</a> IEEE Journal of. 2, 1066-1076 (1996).</li><li>Valentine, M. T., Guydosh, N. R., 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=Precision+steering+of+an+optical+trap+by+electro-optic+deflection.">Precision steering of an optical trap by electro-optic deflection.</a> Opt Lett. 33, 599-601 (2008).</li></ol>

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Abbiamo costruito uno strumento che combina due trappole ottiche di tipo diverso (Figura 1) per fornire strutture trapping separate per manipolazione di oggetti e misura. La trappola ottica &quot;convenzionale&quot; è costruito intorno a un laser a diodo 980 nm. Questo fascio viene espanso, guidato e poi iniettato nel nostro microscopio invertito (&quot;luce rossa&quot; trave in Figura 1). La trappola ottica olografica è costruito intorno a un nm DPSS laser a 1.064. Il fascio viene es...

Intrappolamento ottico è una delle tecniche chiave in biofisica 6. Un avanzamento cruciale intrappolamento ottico è stato lo sviluppo di trappole olografici che consentono la creazione di modelli di intrappolamento tridimensionali anziché trappole point convenzionali 7. Queste trappole olografiche possiedono il vantaggio di versatilità nel posizionamento di oggetti rifrazione. Tuttavia trappole convenzionali possono essere facilmente allineate per essere più simmetrica rispetto commercialmente disponibili kit olografiche. Permettono anche per un veloce monitoraggio preciso degli oggetti intrappolati. Qui si descrive un sistema (Figura 1) che combina i due approcci di cattura in un apparecchio e permette all&#39;utente di sfruttare i vantaggi di entrambi come appropriato. Le considerazioni generali di costruzione di trappole ottiche (sulla base di fasci laser singole o multiple) sono discussi in dettaglio altrove 8-10. Qui, delineare le considerazioni specifiche per il nostro setup e fornire i dettagli della nostra procedura di allineamento. Per esempio, i sistemi con due fasci intrappolamento ottico sono state descritte in precedenza (es. rif. 11), tipicamente utilizzando un raggio laser per intrappolare un oggetto di rifrazione e utilizzando l&#39;altro (fascio potenza volutamente basso) per la lettura disaccoppiato della posizione dell&#39;oggetto intrappolato . Qui tuttavia, entrambi i fasci laser devono essere ad alta potenza (300 mW o superiore) perché entrambi sono da utilizzare per la cattura. Per misurazioni di sistemi biologici, i laser utilizzati per intrappolare dovrebbero rientrare in modo ottimale all&#39;interno di una specifica finestra NIR di lunghezza d&#39;onda per ridurre al minimo la degradazione proteica indotta luce 1. Qui abbiamo scelto di usare 980 nm diodo e 1064 nm laser DPSS a causa del loro basso costo, alta disponibilità e facilità di funzionamento. Abbiamo anche scelto di utilizzare un modulatore spaziale di luce (SLM) per creare e manipolare più trappole contemporaneamente in tempo reale 4,5. Questi dispositivi sono disponibili in commerciotuttavia la loro integrazione in un setup completo rappresenta una sfida unica. Qui si descrive un approccio pratico che affronta queste potenziali difficoltà e fornisce uno strumento estremamente versatile. Forniamo un esempio esplicito per il setup specifico descritto che può essere utilizzato come guida per i disegni modificati.

<table border="1">
	<tbody>
		<tr>
			<td>Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Optical table</td>
			<td>Newport corporation</td>
			<td>ST-UT2-56-8</td>
			<td>Irvine, CA</td>
		</tr>
		<tr>
			<td>Microscope, Inverted, Eclipse Ti</td>
			<td>Nikon USA</td>
			<td>MEA53220</td>
			<td>Melville, NY</td>
		</tr>
		<tr>
			<td>Plan apo 100X oil objective (1.4 NA)</td>
			<td>Nikon USA</td>
			<td>MRD01901</td>
			<td>Melville, NY</td>
		</tr>
		<tr>
			<td>Oil condenser Lens 1.4 NA</td>
			<td>Nikon USA</td>
			<td>MEL41410</td>
			<td>Melville, NY</td>
		</tr>
		<tr>
			<td>EMCCD camera</td>
			<td>Andor technology USA</td>
			<td>Ixon DU897</td>
			<td>South Windsor, CT</td>
		</tr>
		<tr>
			<td>1/3" CCD IEEE1394 camera</td>
			<td>NET USA Inc</td>
			<td>Foculus FO124SC</td>
			<td>Highland IN</td>
		</tr>
		<tr>
			<td>Laser, TEM00, SLM, 1,064 nm wavelength</td>
			<td>Klastech Laser Technologies</td>
			<td>Senza-1064-1000</td>
			<td>Dortmund; Germany</td>
		</tr>
		<tr>
			<td>laser diode, TEM00, SLM, 980 nm</td>
			<td>Axcel Photonics</td>
			<td>BF-979-0300-P5A</td>
			<td>Marlborough, MA</td>
		</tr>
		<tr>
			<td>laser diode mount</td>
			<td>ILX Lightwave</td>
			<td>LDX-3545, LDT-5525, and LDM-4984</td>
			<td>Bozeman, MT</td>
		</tr>
		<tr>
			<td>adjustable fiber ports</td>
			<td>Thorlabs</td>
			<td>PAF-X-11-B</td>
			<td>Newton, NJ</td>
		</tr>
		<tr>
			<td>holographic system</td>
			<td>Arryx</td>
			<td>HOTKIT-ADV-1064</td>
			<td>Chicago, IL</td>
		</tr>
		<tr>
			<td>holographic mirror</td>
			<td>Boulder Non-linear Systems</td>
			<td>this is a part of HOTKIT-ADV-1064</td>
			<td>Lafayette, CO</td>
		</tr>
		<tr>
			<td>Calcite polarizer</td>
			<td>Thorlabs</td>
			<td>GL10-B</td>
			<td>Newton, NJ</td>
		</tr>
		<tr>
			<td>half-wave plate</td>
			<td>Thorlabs</td>
			<td>WPH05M-1064</td>
			<td>Newton, NJ</td>
		</tr>
		<tr>
			<td>Polarizer rotation mount</td>
			<td>Thorlabs</td>
			<td>PRM1</td>
			<td>Newton, NJ</td>
		</tr>
		<tr>
			<td>half-wave plate rotation mount</td>
			<td>Thorlabs</td>
			<td>RSP1</td>
			<td>Newton, NJ</td>
		</tr>
		<tr>
			<td>Shutter</td>
			<td>Thorlabs</td>
			<td>SH05</td>
			<td>Newton, NJ</td>
		</tr>
		<tr>
			<td>dichroic mirrors (DM2 &amp; DM3); 45&deg; AOI</td>
			<td>Chroma Technology</td>
			<td>t750spxrxt</td>
			<td>Bellows Falls, VT</td>
		</tr>
		<tr>
			<td>dichroic mirror (DM1); 45&deg; AOI</td>
			<td>Thorlabs</td>
			<td>DMSP1000R</td>
			<td>Newton, NJ</td>
		</tr>
		<tr>
			<td>custom mechanical adapter</td>
			<td>Thorlabs</td>
			<td>SM1A11 and AD12F with enlarged inner bore</td>
			<td>Newton, NJ</td>
		</tr>
		<tr>
			<td>notch filter</td>
			<td>Semrock</td>
			<td>FF01-850/310-25</td>
			<td>Rochester, NY</td>
		</tr>
		<tr>
			<td>Acousto-Optic deflector (2-axis)</td>
			<td>intraAction</td>
			<td>DTD-584CA28</td>
			<td>Bellwood, IL</td>
		</tr>
		<tr>
			<td>goniometric stage</td>
			<td>New Focus</td>
			<td>9081</td>
			<td>Santa Clara, CA</td>
		</tr>
		<tr>
			<td>60 mm steering lenses</td>
			<td>Thorlabs</td>
			<td>LA1134-B</td>
			<td>Newton, NJ</td>
		</tr>
		<tr>
			<td>16 mm aspherical expander lens</td>
			<td>Thorlabs</td>
			<td>AC080-016-C</td>
			<td>Newton, NJ</td>
		</tr>
		<tr>
			<td>175 mm expander lens</td>
			<td>Thorlabs</td>
			<td>LA1229-C</td>
			<td>Newton, NJ</td>
		</tr>
		<tr>
			<td>Spot blocker (cabron-steel sphere)</td>
			<td>Bal-Tec</td>
			<td>0.0100" diameter</td>
			<td>Los Angeles, CA</td>
		</tr>
		<tr>
			<td>Microspheres (Carboxyl-polystyrene)</td>
			<td>Spherotech</td>
			<td>CP-45-10</td>
			<td>Lake Forest, IL</td>
		</tr>
	</tbody>
</table>

construction of a high resolution microscope with conventional and holographic optical trapping capabilities

Sistemi microscopio ad alta risoluzione con trappole ottiche consentono di intervenire precisa di vari oggetti rifrazione, come dielettrici perline uno o organelli cellulari 2,3, nonché per lettura ad alta risoluzione spaziale e temporale della loro posizione rispetto al centro della trappola. Il sistema qui descritto presenta uno di tali &quot;tradizionale&quot; trappola operante a 980 nm. Esso fornisce inoltre un secondo sistema intrappolamento ottico che utilizza un pacchetto olografico disponibile in commercio per creare e manipolare simultaneamente schemi di cattura complessi nel campo visivo del microscopio a 4,5 ad una lunghezza d&#39;onda di 1064 nm. La combinazione dei due sistemi permette la manipolazione di oggetti multipli refrattivi allo stesso tempo mentre condurre simultaneamente misure ad alta risoluzione di moto e di produzione di forza a scala nanometrica e piconewton alta velocità e.

La configurazione assemblata permette all&#39;operatore di intrappolare più oggetti rifrazione in tempo reale e posizionarli in tre dimensioni all&#39;interno del campo di vista. Illustriamo le capacità olografiche dello strumento intrappolando 11 microsfere (Figura 2). La trappola confinare ogni oggetto è ricreare manualmente posizionato su di intrappolare in modo che la disposizione finale raffigura il logo della University of Utah, dove è stato eseguito questo esperimento. Una funzione combinata ...

Watch this Scientific Journal Video about Construction of a High Resolution Microscope with Conventional and Holographic Optical Trapping Capabilities at JoVE.com

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

Il sistema qui descritto impiega una trappola ottica tradizionale e una linea intrappolamento ottico olografico indipendente, capace di creare e manipolazione di più trappole. Questo consente la creazione di complessi arrangiamenti geometrici di particelle di rifrazione e che permetta ad alta velocità misurazioni simultanee, ad alta risoluzione della attività degli enzimi biologici.

Costruzione di un microscopio ad alta risoluzione con convenzionali e Holographic Capabilities intrappolamento ottico

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

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12.1K Views.  University of Utah. Il sistema qui descritto impiega una trappola ottica tradizionale e una linea intrappolamento ottico olografico indipendente, capace di creare e manipolazione di più trappole. Questo consente la creazione di complessi arrangiamenti geometrici di particelle di rifrazione e che permetta ad alta velocità misurazioni simultanee, ad alta risoluzione della attività degli enzimi biologici.

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

Polycrystalline Silicon Thin-film Solar cells with Plasmonic-enhanced Light-trapping

One of major approaches to cheaper solar cells is reducing the amount of semiconductor material used for their fabrication and making cells thinner. To compensate for lower light absorption such physically thin devices have to incorporate light-trapping which increases their optical thickness. Light scattering by textured surfaces is a common technique but it cannot be universally applied to all solar cell technologies. Some cells, for example those made of evaporated silicon, are planar as produced and they require an alternative light-trapping means suitable for planar devices. Metal nanoparticles formed on planar silicon cell surface and capable of light scattering due to surface plasmon resonance is an effective approach.
The paper presents a fabrication procedure of evaporated polycrystalline silicon solar cells with plasmonic light-trapping and demonstrates how the cell quantum efficiency improves due to presence of metal nanoparticles.
To fabricate the cells a film consisting of alternative boron and phosphorous doped silicon layers is deposited on glass substrate by electron beam evaporation. An Initially amorphous film is crystallised and electronic defects are mitigated by annealing and hydrogen passivation. Metal grid contacts are applied to the layers of opposite polarity to extract electricity generated by the cell. Typically, such a ~2 &mu;m thick cell has a short-circuit current density (Jsc) of 14-16 mA/cm2, which can be increased up to 17-18 mA/cm2 (~25% higher) after application of a simple diffuse back reflector made of a white paint.
To implement plasmonic light-trapping a silver nanoparticle array is formed on the metallised cell silicon surface. A precursor silver film is deposited on the cell by thermal evaporation and annealed at 23&deg;C to form silver nanoparticles. Nanoparticle size and coverage, which affect plasmonic light-scattering, can be tuned for enhanced cell performance by varying the precursor film thickness and its annealing conditions. An optimised nanoparticle array alone results in cell Jsc enhancement of about 28%, similar to the effect of the diffuse reflector. The photocurrent can be further increased by coating the nanoparticles by a low refractive index dielectric, like MgF2, and applying the diffused reflector. The complete plasmonic cell structure comprises the polycrystalline silicon film, a silver nanoparticle array, a layer of MgF2, and a diffuse reflector. The Jsc for such cell is 21-23 mA/cm2, up to 45% higher than Jsc of the original cell without light-trapping or ~25% higher than Jsc for the cell with the diffuse reflector only.
Introduction
Light-trapping in silicon solar cells is commonly achieved via light scattering at textured interfaces. Scattered light travels through a cell at oblique angles for a longer distance and when such angles exceed the critical angle at the cell interfaces the light is permanently trapped in the cell by total internal reflection (Animation 1: Light-trapping). Although this scheme works well for most solar cells, there are developing technologies where ultra-thin Si layers are produced planar (e.g. layer-transfer technologies and epitaxial c-Si layers) 1 and or when such layers are not compatible with textures substrates (e.g. evaporated silicon) 2. For such originally planar Si layer alternative light trapping approaches, such as diffuse white paint reflector 3, silicon plasma texturing 4 or high refractive index nanoparticle reflector 5 have been suggested.
Metal nanoparticles can effectively scatter incident light into a higher refractive index material, like silicon, due to the surface plasmon resonance effect 6. They also can be easily formed on the planar silicon cell surface thus offering a light-trapping approach alternative to texturing. For a nanoparticle located at the air-silicon interface the scattered light fraction coupled into silicon exceeds 95% and a large faction of that light is scattered at angles above critical providing nearly ideal light-trapping condition (Animation 2: Plasmons on NP). The resonance can be tuned to the wavelength region, which is most important for a particular cell material and design, by varying the nanoparticle average size, surface coverage and local dielectric environment 6,7. Theoretical design principles of plasmonic nanoparticle solar cells have been suggested 8. In practice, Ag nanoparticle array is an ideal light-trapping partner for poly-Si thin-film solar cells because most of these design principle are naturally met. The simplest way of forming nanoparticles by thermal annealing of a thin precursor Ag film results in a random array with a relatively wide size and shape distribution, which is particularly suitable for light-trapping because such an array has a wide resonance peak, covering the wavelength range of 700-900 nm, important for poly-Si solar cell performance. The nanoparticle array can only be located on the rear poly-Si cell surface thus avoiding destructive interference between incident and scattered light which occurs for front-located nanoparticles 9. Moreover, poly-Si thin-film cells do not requires a passivating layer and the flat base-shaped nanoparticles (that naturally result from thermal annealing of a metal film) can be directly placed on silicon further increases plasmonic scattering efficiency due to surface plasmon-polariton resonance 10.
The cell with the plasmonic nanoparticle array as described above can have a photocurrent about 28% higher than the original cell. However, the array still transmits a significant amount of light which escapes through the rear of the cell and does not contribute into the current. This loss can be mitigated by adding a rear reflector to allow catching transmitted light and re-directing it back to the cell. Providing sufficient distance between the reflector and the nanoparticles (a few hundred nanometers) the reflected light will then experience one more plasmonic scattering event while passing through the nanoparticle array on re-entering the cell and the reflector itself can be made diffuse - both effects further facilitating light scattering and hence light-trapping. Importantly, the Ag nanoparticles have to be encapsulated with an inert and low refractive index dielectric, like MgF2 or SiO2, from the rear reflector to avoid mechanical and chemical damage 7. Low refractive index for this cladding layer is required to maintain a high coupling fraction into silicon and larger scattering angles, which are ensured by the high optical contrast between the media on both sides of the nanoparticle, silicon and dielectric 6. The photocurrent of the plasmonic cell with the diffuse rear reflector can be up to 45% higher than the current of the original cell or up to 25% higher than the current of an equivalent cell with the diffuse reflector only.

Polycrystalline silicon thin-film solar cells on glass are fabricated by deposition of boron and phosphorous doped silicon layers followed by crystallisation, defect passivation and metallisation. Plasmonic light-trapping is introduced by forming Ag nanoparticles on the silicon cell surface capped with a diffused reflector resulting in ~45% photocurrent enhancement.

Celle in silicio policristallino solari a film sottile con plasmoniche-enhanced Light-trapping

One of major approaches to cheaper solar cells is reducing the amount of semiconductor material used for their fabrication and making cells thinner. To ...

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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.

Costruzione e collaudo di Pile Batterie agli ioni di litio

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

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.

Trapping ottica di nanoparticelle

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 ...

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.

Lens-meno compatta digitale olografico microscopio per MEMS di ispezione e caratterizzazione

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

High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy

High resolution optical spectroscopy methods are demanding in terms of either technology, equipment, complexity, time or a combination of these. Here we demonstrate an optical spectroscopy method that is capable of resolving spectral features beyond that of the spin fine structure and homogeneous linewidth of single quantum dots (QDs) using a standard, easy-to-use spectrometer setup. This method incorporates both laser and photoluminescence spectroscopy, combining the advantage of laser line-width limited resolution with multi-channel photoluminescence detection. Such a scheme allows for considerable improvement of resolution over that of a common single-stage spectrometer. The method uses phonons to assist in the measurement of the photoluminescence of a single quantum dot after resonant excitation of its ground state transition. The phonon&#39;s energy difference allows one to separate and filter out the laser light exciting the quantum dot. An advantageous feature of this method is its straight forward integration into standard spectroscopy setups, which are accessible to most researchers.

The manuscript describes a method of phonon-assisted quasi-resonant fluorescence spectroscopy that incorporates both laser-limited resolution and photoluminescence (PL) spectroscopy. This method utilizes optical phonons to provide linewidth-limited resolution spectra of atom-like semiconductor structures in the energy domain. The method is also easily realized with a single spectrometer optical spectroscopy setup.

Alta Risoluzione Phonon-assisted Quasi-risonanza spettroscopia di fluorescenza

High resolution optical spectroscopy methods are demanding in terms of either technology, equipment, complexity, time or a combination of these. Here we ...

Hand Controlled Manipulation of Single Molecules via a Scanning Probe Microscope with a 3D Virtual Reality Interface

Considering organic molecules as the functional building blocks of future nanoscale technology, the question of how to arrange and assemble such building blocks in a bottom-up approach is still open. The scanning probe microscope (SPM) could be a tool of choice; however, SPM-based manipulation was until recently limited to two dimensions (2D). Binding the SPM tip to a molecule at a well-defined position opens an opportunity of controlled manipulation in 3D space. Unfortunately, 3D manipulation is largely incompatible with the typical 2D-paradigm of viewing and generating SPM data on a computer. For intuitive and efficient manipulation we therefore couple a low-temperature non-contact atomic force/scanning tunneling microscope (LT NC-AFM/STM) to a motion capture system and fully immersive virtual reality goggles. This setup permits &#34;hand controlled manipulation&#34; (HCM), in which the SPM tip is moved according to the motion of the experimenter&#39;s hand, while the tip trajectories as well as the response of the SPM junction are visualized in 3D. HCM paves the way to the development of complex manipulation protocols, potentially leading to a better fundamental understanding of nanoscale interactions acting between molecules on surfaces. Here we describe the setup and the steps needed to achieve successful hand-controlled molecular manipulation within the virtual reality environment.

We demonstrate the precise manipulation of individual organic molecules on a metal surface with the tip of a scanning probe microscope driven in 3D by the experimenter's hand using a motion capture system and fully immersive virtual reality goggles.

A mano controllata manipolazione di singole molecole attraverso un microscopio a scansione di sonda con una realtà virtuale 3D

Considering organic molecules as the functional building blocks of future nanoscale technology, the question of how to arrange and assemble such building ...

Plasmonic Trapping and Release of Nanoparticles in a Monitoring Environment

Plasmonic tweezers use surface plasmon polaritons to confine polarizable nanoscale objects. Among the various designs of plasmonic tweezers, only a few can observe immobilized particles. Moreover, a limited number of studies have experimentally measured the exertable forces on the particles. The designs can be classified as the protruding nanodisk type or the suppressed nanohole type. For the latter, microscopic observation is extremely challenging. In this paper, a new plasmonic tweezer system is introduced to monitor particles, both in directions parallel and orthogonal to the symmetric axis of a plasmonic nanohole structure. This feature enables us to observe the movement of each particle near the rim of the nanohole. Furthermore, we can quantitatively estimate the maximal trapping forces using a new fluidic channel.

A microchip fabrication process that incorporates plasmonic tweezers is presented here. The microchip enables the imaging of a trapped particle to measure maximal trapping forces.

Plasmonico cattura e rilascio di nanoparticelle in un ambiente di monitoraggio

Plasmonic tweezers use surface plasmon polaritons to confine polarizable nanoscale objects. Among the various designs of plasmonic tweezers, only a few ...

Demonstration of a Hyperlens-integrated Microscope and Super-resolution Imaging

The use of super-resolution imaging to overcome the diffraction limit of conventional microscopy has attracted the interest of researchers in biology and nanotechnology. Although near-field scanning microscopy and superlenses have improved the resolution in the near-field region, far-field imaging in real-time remains a significant challenge. Recently, the hyperlens, which magnifies and converts evanescent waves into propagating waves, has emerged as a novel approach to far-field imaging. Here, we report the fabrication of a spherical hyperlens composed of alternating silver (Ag) and titanium oxide (TiO2) thin layers. Unlike a conventional cylindrical hyperlens, the spherical hyperlens allows for two-dimensional magnification. Thus, incorporation into conventional microscopy is straightforward. A new optical system integrated with the hyperlens is proposed, allowing for a sub-wavelength image to be obtained in the far-field region in real time. In this study, the fabrication and imaging setup methods are explained in detail. This work also describes the accessibility and possibility of the hyperlens, as well as practical applications of real-time imaging in living cells, which can lead to a revolution in biology and nanotechnology.

The use of a hyperlens has been regarded as a novel super-resolution imaging technique due to its advantages in real-time imaging and its simple implementation with conventional optics. Here, we present a protocol describing the fabrication and imaging applications of a spherical hyperlens.

Dimostrazione di un microscopio Hyperlens-integrato e super-resolution Imaging

The use of super-resolution imaging to overcome the diffraction limit of conventional microscopy has attracted the interest of researchers in biology and ...

Method for Recording Broadband High Resolution Emission Spectra of Laboratory Lightning Arcs

Lightning is one of the most common and destructive forces in nature and has long been studied using spectroscopic techniques, first with traditional camera film methods and then digital camera technology, from which several important characteristics have been derived. However, such work has always been limited due to the inherently random and non-repeatable nature of natural lightning events in the field. Recent developments in lightning test facilities now allow the reproducible generation of lightning arcs within controlled laboratory environments, providing a test bed for the development of new sensors and diagnostic techniques to understand lightning mechanisms better. One such technique is a spectroscopic system using digital camera technology capable of identifying the chemical elements with which the lightning arc interacts, with these data then being used to derive further characteristics. In this paper, the spectroscopic system is used to obtain the emission spectrum from a 100 kA peak, 100 &#181;s duration lightning arc generated across a pair of hemispherical tungsten electrodes separated by a small air gap. To maintain a spectral resolution of less than 1 nm, several individual spectra were recorded across discrete wavelength ranges, averaged, stitched, and corrected to produce a final composite spectrum in the 450 nm (blue light) to 890 nm (near infrared light) range. Characteristic peaks within the data were then compared to an established publicly available database to identify the chemical element interactions. This method is readily applicable to a variety of other light emitting events, such as fast electrical discharges, partial discharges, and sparking in electrical equipment, apparatus, and systems.

Emission spectroscopy techniques have traditionally been used to analyze inherently random lightning arcs occurring in nature. In this paper, a method developed to obtain the emission spectroscopy from reproducible lightning arcs generated within a laboratory environment is described.

Metodo per la registrazione dei spettri ad alta risoluzione a banda larga degli arci fulmini di laboratorio

Lightning is one of the most common and destructive forces in nature and has long been studied using spectroscopic techniques, first with traditional ...