O financiamento foi fornecido pela Universidade de Utah. Gostaríamos de agradecer ao Dr. J. Xu (UC Merced) e Dr. BJN Reddy (UC Irvine) para discussões úteis.

1. Instalação de 980 nm de comprimento de onda Armadilha Único Optical <ol><li> Captura óptica a 980 nm de comprimento de onda é muitas vezes ideal para experimentos biofísica e diodos laser de baixo custo estão disponíveis com potência tão alta quanto 300 mW. É preferível que um laser de diodo ser pigtailed com polarização preserva fibra monomodo com um diâmetro de campo do modo conhecido. A fibra deve ser suficientemente longo para actuar como um filtro de modo e é normalmente terminado com um ou FC / PC ou FC / APC conector. Destes, o FC / APC é preferível para minimizar a reflexão da luz e instabilidades de feedback potencial. </li><li> Fixe o laser de diodo 980 nm em uma montagem que permite a potência e controle de temperatura. É melhor para corrigir a montagem de uma mesa óptica diretamente para maximizar dissipação de calor passivo e, assim, minimizar o risco de fracasso diodo devido a uma avaria do controlador de temperatura. </li><li> Monte o conector de fibra PC / APC para as lentes de colimação do feixe. Écrítico para assegurar que o feixe colimado tem divergência mínimo para portas de fibra ajustáveis ​​são mais úteis. Certifique-se de que a porta de fibra escolhido coincide com o diâmetro da fibra pigtail diodo campo de modo. Se o feixe é para ser rastered utilizando os deflectores acusto-óptica (AOD) ou deflectores electro-ópticos (EOD), então o feixe de laser colimado cintura também deve ser um pouco menor do que o tamanho da abertura do deflector. </li><li> Fixar a placa de colimação para a mesa óptico a uma distância suficiente para permitir que o microscópio para o feixe de encaminhamento, a expansão, e colocação de outros componentes desejados. Ajustar a porta de fibra para assegurar cintura do feixe coerente sobre distâncias comparáveis ​​às caminho global feixe ao microscópio. </li><li> Instalar espelhos indicados na Figura 1. Remover o objectivo do microscópio e utilizar os espelhos de percurso do feixe através da abertura em fase de montagem na objectiva. Se preferido, o posicionamento do espelho dicróico DM1 e DM3 pode ser omitido atémais tarde. DM2 e DM3 são ambos shortpass e transmitir luz visível, enquanto refletindo próximo IR e acima. </li><li> É útil para montar temporariamente um ponteiro laser vermelho no lugar do objectivo, alinhados no eixo óptico do microscópio. Um adaptador mecânico personalizado é necessário para garantir a centralização do ponteiro laser. Feixe visível a partir do ponteiro laser pode então ser encaminhada de volta para o centro da abertura da porta de fibra e podem, então, ser usadas para instalar as lentes (ver abaixo). </li><li> Instale a 980 nm expansor de feixe (L8 e L9) a uma distância adequada do porto de fibra para permitir a inserção futura de componentes de direção (AOD ou EOD), se necessário 1. O feixe expandido deve encha um pouco a abertura focal de trás do objetivo. (Aqui, as lentes com distâncias focais de 125 milímetros e 60 milímetros estão em um arranjo de Kepler para aproximadamente o dobro da cintura do feixe). Use visível feixe de laser pointer (ver secção 1.6) para assegurar a colocação de lente adequada e alinhamento áspera. </li><li> Instalarl os 980 nm lentes de direção (L2 e L3) em um arranjo telescópio como indicado (neste caso, ambos têm 60 mm de distância focal) 1. L3 é montado em um conjugado de avião para o avião de volta-focal da objetiva. Montagem L3 numa fase de posicionamento XYZ precisão para permitir a direcção do feixe. É útil para a fase XYZ dispor de indicadores digitais para as suas micrómetros, o que permite um posicionamento repetitivo e reposicionamento da armadilha. A &quot;faixa de deslocamento de 0,5 é geralmente suficiente, porém mais viajar para o posicionamento L3 ao longo do eixo óptico pode ser útil. Use visível feixe de laser pointer (ver secção 1.6) para assegurar a colocação de lente adequada e alinhamento áspera. </li></ol> 2. Instalação de Detector Laser <ol><li> Instalar o DM3 espelho dicróico acima do condensador, como mostrado na Figura 1. Uma montagem personalizada é normalmente necessária. Fixe a foto diodo quad (QPD) ou um detector sensível à posição (PSD) 8 ao lado do conjunto do condensador e ensure que a 980 nm raio laser refletido pela DM3 é batê-lo mais ou menos sobre o centro. Ao utilizar QPD, assegurar que é montado sobre uma plataforma XY pequenos para permitir a centragem exacta do sensor sobre o feixe de laser. </li><li> Instalar L1 (tipicamente uma lente de 30 mm) entre DM3 e o sensor. Posição L1 de modo a focar o feixe para um único ponto sobre o sensor. </li><li> Instale o filtro notch pouco antes L1 para bloquear o feixe de 1064 nm, bem como quaisquer reflexos de luz visíveis desviar-se do iluminador microscópio e iluminação ambiente. </li></ol> 3. Instalação de 1.064 nm de comprimento de onda holográfica Armadilha <ol><li> A parte holográfica da instalação é construído em torno de um pacote de hardware / software disponível comercialmente Os espelhos holográficos usados ​​neste pacote são classificados para uma potência máxima incidente de 5 ou 10 W / cm 2. Monomodo TEM00 vigas nesta faixa de potência pode ser facilmente obtida a partir de um laser DPSS em 1064 nm de comprimento de onda. </li><li> Monte o laser de 1.064 nm em um elevadoplataforma para corresponder aproximadamente a altura do trajecto do feixe para a linha 980 (ver ponto 1). </li><li> Se não diretamente controlável, potência do laser pode ser ajustado manualmente através da instalação de uma placa de meia onda (HWP) e um polarizador (PBS) logo após a abertura da saída do laser. É útil para montar o polarizador numa fase rotativo para ser capaz de combinar requisito espelho holográfica para a polarização do feixe. </li><li> Instale a 1064 nm expansor de feixe (L6 e L7). A cintura do feixe de laser deve ser expandido para corresponder ao tamanho diagonal do espelho holográfico. Para taxas de expansão grandes (acima de 10X), pode ser uma preocupação de manter o tamanho do expansor pequena. Assim, pode ser desejável a utilização de lentes com invulgarmente pequeno comprimento focal (aqui: 16 mm e 175 mm). </li><li> Instale os outros espelhos conforme indicado para dirigir o feixe de 1064 nm através da objectiva. <ol><li> Seguro DM1 dicróica (45 ° de ângulo de incidência) em uma montagem cinemática e coloque o conjunto no caminho do feixe de 980 nm a fim de que ele permite undiminishea transmissão d desse feixe. </li><li> Ative luz ponteiro laser. O espelho DM1 deve reflectir uma quantidade suficiente de luz visível, para posicionar adequadamente o modulador de luz espacial (SLM) no caminho desse feixe. O SLM também precisa ser inclinado para que os feixes de laser de entrada e saída são tão próximas quanto possível da incidência normal. No entanto, o ângulo de incidência deve ser suficientemente grande para assegurar que o feixe de laser não é recortado por montagens de lente e outros elementos ópticos. Um ângulo de 5 ° deve ser facilmente alcançável e é suficientemente pequena. Finalmente, a distância entre a DM1 SLM devem ser medidos com precisão de modo que a inserção de lentes de L4 e L5 (ver 3.6) pode conjugar o plano do espelho SLM e o plano de back-focal da objectiva. </li><li> Instale um espelho para direcionar a luz a partir de 1064 nm expansor de feixe para o SLM. Certifique-se de que a luz ponteiro laser atinge o expansor de abertura do feixe de centro. </li></ol></li><li> Instale lentes L4 e L5 (aqui: lentes com 125 milímetros e 200 milímetros, respectivamente). Este par telescópio conjuga o plano do espelho SLM para o plano focal da objetiva e também reduz a cintura do feixe, apenas encha um pouco a abertura de trás do objetivo. Nós escolhemos lentes com distâncias focais longas para o espaço o SLM longe de DM1. Isto não só sala limpa para a segunda linha de laser, mas também tende a tornar mais fácil o alinhamento. </li><li> Remover o ponteiro laser. Deixe o adaptador de montagem para servir como abertura alinhamento grosseiro. </li></ol> 4. Instalação e Alinhamento Notas do sistema <ol><li> Lente L3 e SLM deve ser posicionada de modo a ser opticamente conjugados com o plano focal posterior do objectivo. O ponto focal comum de L4 e L5 é opticamente conjugados com o plano da amostra, se os feixes de armadilhagem ópticos são injectados no espaço infinito do microscópio. </li><li> cantar IR espectador cartão alinhar o feixe de 980 nm para ir ao longo do eixo central da abertura do adaptador ponteiro laser. </li><li> Use IR placa to assegurar que o feixe atinge 1.064 nm no mesmo lugar que o feixe de 980 nm em DM1, L2 e L3 e que o feixe de 1064 nm, passa ao longo do eixo do centro da abertura na placa de ponteiro laser. </li><li> Substitua o adaptador de montagem ponteiro laser com um objetivo. Alta do petróleo ou água objetivo abertura numérica é típico. </li><li> Alinhar a armadilha 980 nm tal como descrito em 9, de &quot;walking&quot; do feixe de laser até um padrão de interferência radial simétrico é visto na câmara. </li><li> Com o off espelho holográfico (ou seja, agindo como um espelho passivo) usar SLM e DM1 a &quot;andar&quot; a undiffracted 1064 feixe nm para alinhar o nm armadilha 1064. </li><li> A SLM produz um feixe undiffracted significativa que resulta numa forte armadilha de laser inamovível no campo de visão. Isto é útil para alinhamento, mas podem ser indesejáveis ​​para fins experimentais. Para bloquear esta armadilha pode-se inserir um pequeno objecto opaco no caminho da luz undiffracted no conjugado de localização para o plano da amostra (por exemplo, poe ponto focal comum de L4 e L5). O tamanho desse bloqueador ponto central tem de ser um pouco maior do que o diâmetro do disco de Airy para a luz focalizada (um bloqueador com 100-300 um de diâmetro para que o sistema descrito). </li><li> djust 1064 nm polarização do feixe usando o polarizador para coincidir com a orientação SLM. Girar a placa de meia onda para ajustar a potência do feixe de saída, como desejado. </li><li> Se desejar, inserir AOD ou EOD elementos de orientação do feixe para a linha de laser 980 nm. Assegurar a correcta conjugação desses elementos para o plano de back-focal da objetiva e re-alinhar a armadilha. É útil para montar os elementos de direção em um palco goniométrico. </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>

Os autores não têm nada a revelar.

Nós construímos um instrumento que combina duas armadilhas ópticas de tipos diferentes (Figura 1) para proporcionar facilidades de armadilhagem separadas para manipulação de objectos e de medição. A armadilha óptica &quot;convencional&quot; é construído em torno de 980 nm diodo laser. Este feixe é expandido, dirigidos e, em seguida, injectado no nosso microscópio invertido (&quot;luz vermelha&quot; feixe na Figura 1). A armadilha óptica holográfica é construído em torno ...

A armadilha óptica é uma das principais técnicas na biofísica 6. Um avanço importante na captura óptica tem sido o desenvolvimento de armadilhas holográficas que permitem a criação de padrões de armadilhagem tridimensionais, em vez de pontos de armadilhas convencionais 7. Tais armadilhas holográficos possuem a vantagem de versatilidade no posicionamento de objetos de refração. No entanto armadilhas convencionais podem ser facilmente alinhadas para ser mais simétrico do holográficas kits disponíveis comercialmente. Eles também permitem um controle preciso rápido dos objetos presos. Aqui, nós descrevemos um sistema (Figura 1), que combina as duas abordagens de armadilhagem num instrumento e permite que o utilizador para explorar os benefícios de ambos, conforme apropriado. As considerações gerais de construção de armadilhas ópticas (baseado em feixes de laser simples ou múltiplas) são discutidos em detalhe noutro local 8-10. Aqui, destacamos as considerações específicas para o nosso setup e fornecer detalhes do nosso processo de alinhamento. Por exemplo, os sistemas com dois feixes de armadilhagem ópticas foram descritos antes (por exemplo, ref. 11), tipicamente utilizando um feixe de laser para capturar um objecto de refracção e usando a outra (intencionalmente baixo feixe de energia) para a leitura dissociada da posição do objecto preso . Aqui, no entanto, ambos os feixes de laser precisa ser de alta potência (300 mW ou superior), pois ambos são para ser usado para captura. Para as medições dos sistemas biológicos, os lasers utilizados para aprisionamento optimamente deve cair dentro de uma janela de comprimento de onda NIR específico de luz para minimizar a degradação da proteína induzida por 1. Aqui, optou-se por usar diodo 980 nm e 1064 nm lasers DPSS por causa de seu custo, alta disponibilidade e facilidade de operação baixa. Também optou por usar um modulador de luz espacial (SLM) para criar e manipular várias armadilhas simultaneamente em tempo real, 4,5. Estes dispositivos estão disponíveis comercialmenteno entanto a sua integração numa configuração completa apresenta desafios únicos. Aqui nós descrevemos uma abordagem prática, que aborda estas dificuldades potenciais e fornece um instrumento muito versátil. Fornecemos uma lista explícita para a configuração específica descrita, que pode ser usado como um guia para modelos modificados.

<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

Sistemas de microscópio de alta resolução com armadilhas ópticas para permitir uma manipulação precisa de vários objectos de refracção, tal como esferas de dieléctricos um ou organelas celulares 2,3, bem como para a leitura de alta da sua posição em relação ao centro do colector de resolução espacial e temporal. O sistema aqui descrito tem uma tal &quot;tradicional&quot; armadilha operando a 980 nm. Ele proporciona adicionalmente um segundo sistema de captação óptica que utiliza um pacote holográfico disponível comercialmente para criar e manipular simultaneamente padrões de armadilhagem complexas no campo de visão do microscópio de 4,5 a um comprimento de onda de 1064 nm. A combinação dos dois sistemas permite a manipulação de múltiplos objectos de refracção, ao mesmo tempo, ao mesmo tempo realizando medições de alta velocidade e de movimento de alta resolução e de produção de força em escala nanométrica e piconewton.

A configuração de montagem permite que o operador para prender múltiplos objectos de refracção em tempo real e posicioná-los em todas as três dimensões dentro do campo de visão. Nós ilustramos os recursos holográficos do instrumento, prendendo 11 microesferas (Figura 2). A armadilha confinando cada objeto é manualmente reposicionada sobre armadilhas para que o acordo final mostra o logotipo da Universidade de Utah, onde este experimento foi realizado. Uma função combinada de armadilha holo...

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

O sistema aqui descrito emprega uma armadilha óptica tradicional, bem como uma linha de captura óptica holográfica independente, capaz de criar e manipular múltiplas armadilhas. Isso permite a criação de disposições geométricas complexas de partículas de refração e ao mesmo tempo permitindo medições simultâneas de alta velocidade, de alta resolução da atividade de enzimas biológicas.

Construção de um microscópio de alta resolução com recursos de captura óptica convencional e holográfico

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

construction-high-resolution-microscope-with-conventional-holographic

Research

JoVE Journal

Engineering

12.0K visualizações.  University of Utah. O sistema aqui descrito emprega uma armadilha óptica tradicional, bem como uma linha de captura óptica holográfica independente, capaz de criar e manipular múltiplas armadilhas. Isso permite a criação de disposições geométricas complexas de partículas de refração e ao mesmo tempo permitindo medições simultâneas de alta velocidade, de alta resolução da atividade de enzimas biológicas.

Vídeo: 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.

Silício policristalino de película fina de células solares com plasmonic avançada Luz-caça com armadilhas

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

Engenharia

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.

Construção e Teste de Pilhas da moeda de baterias de lítio

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.

Captura óptica de nanopartículas

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.

De alta resolução, de alta velocidade, de imagens de vídeo tridimensional com Franja Digital Técnicas de Projeção

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

Convergent Polishing: A Simple, Rapid, Full Aperture Polishing Process of High Quality Optical Flats &amp; Spheres

Convergent Polishing is a novel polishing system and method for finishing flat and spherical glass optics in which a workpiece, independent of its initial shape (i.e., surface figure), will converge to final surface figure with excellent surface quality under a fixed, unchanging set of polishing parameters in a single polishing iteration. In contrast, conventional full aperture polishing methods require multiple, often long, iterative cycles involving polishing, metrology and process changes to achieve the desired surface figure. The Convergent Polishing process is based on the concept of workpiece-lap height mismatch resulting in pressure differential that decreases with removal and results in the workpiece converging to the shape of the lap. The successful implementation of the Convergent Polishing process is a result of the combination of a number of technologies to remove all sources of non-uniform spatial material removal (except for workpiece-lap mismatch) for surface figure convergence and to reduce the number of rogue particles in the system for low scratch densities and low roughness. The Convergent Polishing process has been demonstrated for the fabrication of both flats and spheres of various shapes, sizes, and aspect ratios on various glass materials. The practical impact is that high quality optical components can be fabricated more rapidly, more repeatedly, with less metrology, and with less labor, resulting in lower unit costs. In this study, the Convergent Polishing protocol is specifically described for fabricating 26.5 cm square fused silica flats from a fine ground surface to a polished ~&#955;/2 surface figure after polishing 4 hr per surface on a 81 cm diameter polisher.

A novel optical polishing process, called &#8220;Convergent Polishing&#8221;, which enables faster, lower cost polishing, is described. Unlike conventional polishing processes, Convergent Polishing allows a glass workpiece to be polished in a single iteration and with high surface quality to its final surface figure without requiring changes to polishing parameters.

Convergente Polimento: Um simples, rápido, de abertura total Polimento Processo de alta qualidade ótica Flats &amp; Spheres

Convergent Polishing is a novel polishing system and method for finishing flat and spherical glass optics in which a workpiece, independent of its initial ...

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 Lens-less Digital Holographic Microscope de Inspeção MEMS e Caracterização

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

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.

Plasmonic captura e liberação de nanopartículas em um ambiente de Monitoramento

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.

Demonstração de um microscópio integrado Hyperlens e super resolução imagem

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.

Método para gravação de banda larga de alta resolução espectros de emissão de laboratório arcos relâmpago

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

Single-Digit Nanometer Electron-Beam Lithography with an Aberration-Corrected Scanning Transmission Electron Microscope

We demonstrate extension of electron-beam lithography using conventional resists and pattern transfer processes to single-digit nanometer dimensions by employing an aberration-corrected scanning transmission electron microscope as the exposure tool. Here, we present results of single-digit nanometer patterning of two widely used electron-beam resists: poly (methyl methacrylate) and hydrogen silsesquioxane. The method achieves sub-5 nanometer features in poly (methyl methacrylate) and sub-10 nanometer resolution in hydrogen silsesquioxane. High-fidelity transfer of these patterns into target materials of choice can be performed using metal lift-off, plasma etch, and resist infiltration with organometallics.

We use an aberration-corrected scanning transmission electron microscope to define single-digit nanometer patterns in two widely-used electron-beam resists: poly (methyl methacrylate) and hydrogen silsesquioxane. Resist patterns can be replicated in target materials of choice with single-digit nanometer fidelity using liftoff, plasma etching, and resist infiltration by organometallics.

Litografia de feixe de elétrons do nanômetro do dígito com uma aberração corrigida digitalização microscópio eletrônico de transmissão

We demonstrate extension of electron-beam lithography using conventional resists and pattern transfer processes to single-digit nanometer dimensions by ...