经费是由美国犹他州大学。我们要感谢徐坚博士（加州大学默塞德）和的BJN雷迪博士（加州大学欧文分校）有用的讨论。

1。安装980 nm波长单光阱<ol><li>在980纳米波长的光学俘获往往是最佳的生物物理学实验和廉价的激光二极管输出功率高达300毫瓦都是现成的。这是优选的公知的模场直径的单模光纤，其与保偏尾纤的二极管激光器。需要足够长，以作为模式过滤器的纤维，通常是与任何一个FC / PC或FC / APC连接终止。其中，FC / APC是可取的，以尽量减少反射光不稳定和潜在的反馈。 </li><li> 980 nm激光二极管固定在山上，它允许电力和温控。这是最好的修复直接安装到光学平台，以最大限度地提高被动散热，从而减少二极管失灵的危险，由于温度控制器故障。 </li><li> PC / APC光纤连接器安装的光束准直光学。这是关键，以保证准直光束有最小的发散，所以是最有用的可调光纤端口。确保所选择的光纤端口匹配二极管尾纤光纤的模场直径。如果光束是使用声光偏转器（AOD）或电光偏转器的光栅（EOD）的准直激光束腰身也必须是略小于偏转器孔径的大小。 </li><li>以足够的距离，从显微镜的准直适配器固定在光学平台上，以允许束路由，扩展和其他所需的组件的位置。调整纤维港口整体束路径显微镜相媲美的距离，以确保一致的束腰。 </li><li>安装在图1中所示的反射镜。从显微镜中取出目标，并用反射镜将光束通过客观安装阶段中的孔中。如果优选，分色镜DM1和DM3的放置可以被省略，直到后来。 DM2和DM3而都shortpass透过可见光，同时反射近红外及以上。 </li><li>是有帮助的暂时安装，对准显微镜的光轴上的红色激光指针代替的客观。一个自定义的的机械适配器是必要的，以确保中心定位的激光指针。从激光指示器的可见光束，然后可以回路由光纤端口的光圈的中心，然后，可以使用安装的透镜（见下文）。 </li><li>安装980 nm的扩束（L8和L9）在适当的距离的光纤端口，允许未来插入转向组件（AOD或EOD）为必要1。扩束必须稍微装得过满后焦距光圈的客观。 （在这里，125毫米和60毫米焦距的透镜是在约两倍的光束束腰的开普勒安排）。可见激光指针梁（参见1.6节），以确保适当的镜头的位置和粗调。 </li><li>安装l为980纳米转向镜头（L2和L3）望远镜安排在（这里都有60毫米焦距）1。 L3被安装在一个平面上的共轭物镜的后焦平面。贴装，L3上的一个精确的XYZ定位阶段，以允许光束转向。它是有帮助的XYZ阶段有其微米的数字指标，允许重复定位和重新定位的陷阱。 0.5"范围内的旅行通常是足够的，但是更长的旅行沿光轴L3定位可能会有所帮助。使用可见的激光笔光束（参见1.6节），以确保适当的镜头的位置和粗调。 </li></ol> 2。激光探测器的安装<ol><li>安装DM3，冷凝器的二向色反射镜，如在图1中示出。通常需要一个自定义安装。四光电二极管（QPD）或位置敏感探测器（PSD）8固定侧的冷凝器组件和ENSURE 980 nm激光束反射的DM3击中它大致的中心。当使用QPD，确保它被安装在一个小的XY载物台以允许上的激光束的传感器的精确的定心。 </li><li>安装L1（通常是30毫米镜头）DM3和传感器之间。位置L1，以将光束聚焦到一个点上的传感器。 </li><li>安装之前L1阻止的1064 nm的光束以及从显微镜任何杂散的可见光反射照明器和环境照明的陷波滤波器。 </li></ol> 3。安装的1,064 nm波长全息陷阱<ol><li>全息设置的一部分是围绕市售硬件/软件包，这个软件包中使用的全息反射镜被评为5或10瓦/厘米2的最大入射功率。单模式TEM00光束在这个功率范围内，可以很容易地来源于一个1,064 nm波长的DPSS激光器。 </li><li>在高架安装1,064 nm激光平台，以大致为980线（参见第1）的光束路径的高度相匹配。 </li><li>如果不是直接控制，可手动调整激光功率，通过安装一个半波片（HWP）和偏振器（PBS）后激光输出孔。是有帮助的偏振器安装在一个旋转的阶段，能够匹配光束偏振全息镜要求。 </li><li>安装1,064 nm的扩束（L6和L7）。必须扩大相匹配的对角尺寸的全息镜的激光光束束腰。对于较大的膨胀比（大于10倍），它可能是一个关注的保持膨胀​​机的大小小。因此，它可能是可取的，与异常小的焦距（这里使用镜头:16毫米和175毫米）。 </li><li>安装其他镜像1,064纳米束直接通过目标。 <ol><li>安全的DM1分色（45°的入射角）运动的安装和装配在980纳米光束路径，以便，它允许undiminishe的ð传输，光束。 </li><li>启动雷射光束。 DM1镜应反映可见光的足够量的，适当地定位该光束的路径中的空间光调制器（SLM）。在SLM也需要的角度，​​从而使输入和输出的激光束的正常发生率尽可能接近。然而，入射角必须足够大，以确保激光束由透镜轴承，及其他光学部件不剪切。 5°的角度应该是容易实现的，足够小。最后的距离DM1到SLM必须进行精确测量，从而使插入的透镜L4和L5（见下文3.6）共轭的的SLM反射镜平面和物镜的后焦平面。 </li><li>安装镜子直接从1,064 nm的扩束光的SLM。确保雷射光束扩束击中孔径中心。 </li></ol></li><li>安装镜头L4和L5（这里:12镜头5毫米和200毫米）。此望远镜对共轭物的SLM反射镜平面的物镜的后焦平面，也减少了只是稍微过满的目标回光圈的光束束腰。我们选择了长焦距的镜头空间的SLM远离DM1。这不仅清除第二激光线的空间，但也往往使取向变得更容易。 </li><li>拆下激光指针。离开安装适配器作为粗对准光圈。 </li></ol> 4。系统安装和校准附注<ol><li>透镜L3和SLM必须定位成光学共轭的后焦面的客观。 L4和L5的共同焦点的样品平面光学共轭的，如果的光俘获束显微镜的无限空间注入。 </li><li>唱IR卡浏览器在980 nm的光束对准一起去激光指针适配器中的孔的中心轴线。 </li><li>使用红外感应卡考勤确保1064 nm的光束击中DM1，L2和L3和1064 nm的光束沿着激光指针适配器中的孔的中心轴线的相同点为980 nm的光束。 </li><li>更换一个客观的激光指针安装适配器。高数值孔径的油或水的目标，是典型的。 </li><li> 9中所描述的"行走"的径向对称的干涉图案的激光束，直到在相机上看到的980 nm的陷阱对齐。 </li><li>随着全息镜像关闭（ 即作为一个被动的镜子）使用SLM和DM1"走"未衍射1,064 nm的光束对准1064nm的陷阱。 </li><li>在SLM产生了显着的未衍射光束产生一个强有力的不可移动的激光陷阱中的视场。对应的，这是非常有用的，但可能是不理想的实验。为了阻止这个陷阱，一个可以插入一个小的不透明的对象未衍射的光的路径中，在样品平面共轭的位置（ 例如，第É共同的焦点，L4和L5）。此中央点阻滞剂的大小需要是稍微大于艾里斑的直径为聚焦光（100-300微米直径的所描述的系统中的阻断剂）。 </li><li> djust 1,064纳米束使用偏光镜的偏振，到SLM方向相匹配。旋转的半波片，然后随意设定光束的输出功率。 </li><li>如果需要，插入到980 nm激光线AOD或排爆光束转向元素。确保适当结合这些元素的后焦平面的目标，并重新调整的陷阱。安装在方向盘测角舞台上的元素是很有帮助的。 </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>

什么都没有透露。

我们已经构建了一个仪器，结合了两种不同类型的光学陷阱（ 图1），以提供独立的诱捕设施为对象的操作和测量。 980纳米激光二极管围绕"常规"光陷阱。被扩展时，该光束转向，然后注射到我们的倒置显微镜（"浅红色"束在图1中）。是围绕一个1,064 nm的DPSS激光全息光学陷阱。束被扩展以适应大小的空间光调制器（SLM）的SLM，减少在低入射角稍微过满的后焦光圈的目标，?...

光学俘获生物物理学6中的关键技术之一。一个关键的进步一直在光学诱捕的发展全息陷阱允许创建三维俘获模式，而不是传统的点陷阱7。这种全息陷阱具有定位屈光对象的通用性的优点。然而，传统的陷阱，可以很容易地对准更对称比市售全息套件。他们还允许被困物体的快速精确跟踪。这里，我们描述的系统（ 图1）相结合的两个捕集方法在一台仪器中，并允许用户利用的好处，同时以适当的。 建设光陷阱（基于单个或多个激光束）的一般考虑别处8-10详细讨论。在这里，我们勾勒出具体考虑我们的Setup并提供细节，我们的校准程序。比如，已经描述了两束光俘获系统之前（ 例如，参考文献11），用于捕集的折射率的对象去耦读出捕获的对象的位置和使用的其他（故意低功率波束），通常使用一个激光束。然而，在这里，两个激光束的高功率（300 mW或更高），因为两者都是用于俘获。对于生物系统的测量，激光器用于诱捕最佳应该属于一个特定的波长的近红外窗口，以尽量减少光诱导蛋白降解1。在这里，我们选择了使用980 nm的二极管和1,064 nm的DPSS激光器，因为其低成本，高可用性和易于操作。 我们也选择了使用空间光调制器（SLM）创建和操纵多个陷阱，同时在实时4,5。这些设备是市售的但是他们整合成一个完整的设置提出了独特的挑战。在这里，我们描述了一个切实可行的办法，解决这些潜在的困难，并提供了一​​个高度灵活的工具。我们提供了一个明确的例子具体描述的设置，可以用来作为一个指南的修改设计。

<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

光阱的高清晰度显微镜系统允许精确地操纵各种折射对象，如电介质有孔玻璃珠1或细胞器2,3，以及对高时空分辨率读出他们的相对位置的陷阱中心。本文描述的系统有一个这样的"传统的"陷阱在980 nm处的作业。另外还提供了一个第二光学捕获系统，采用市售的全息包，同时在图4,5在波长为1064 nm的显微镜领域的创建和操作复杂的俘获模式。这两个系统的组合允许在同一时间的多个折射对象的操纵的同时进行高速和高分辨率的测量，运动和力的生产纳米和微微牛顿规模。

组设置，使操作员可以实时捕获多个折射对象，并将其放置在所有三个维度中，在视场之内。我们说明了仪器的性能后的全息，捕集微球11（ 图2）。限制每个对象的陷阱手动重新定位时捕获最后的安排，犹他州立大学的这个实验进行描绘的标志。合的功能的全息和常规陷阱如图3所示。传统的陷阱中央珠移动速度越来越快（1.3，10和82微米/秒的速度陷阱），而全息定义的?...

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

本文介绍的系统采用传统的光陷阱，以及一个独立的全息光阱线，能够创建和操作多个陷阱。这使得创建复杂的几何安排的折光颗粒，同时还允许同时高速，高分辨率测量生物酶的活性。

高分辨率显微镜与常规和全息光学捕获能力建设

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

12.1K 次观看.  University of Utah. 本文介绍的系统采用传统的光陷阱，以及一个独立的全息光阱线，能够创建和操作多个陷阱。这使得创建复杂的几何安排的折光颗粒，同时还允许同时高速，高分辨率测量生物酶的活性。

视频: 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.

多晶硅薄膜太阳能电池电浆增强光捕获

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

科研

工程学

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.

钮扣电池锂离子电池的建设和测试

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.

纳米粒子的光学捕获

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.

紧凑的镜头少数字全息显微镜的MEMS检测与表征

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.

高分辨率声子辅助准共振荧光光谱仪

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

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.

电浆捕获和纳米粒子的释放在监控环境

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.

Hyperlens 综合显微镜和超分辨率成像的演示

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.

记录实验室闪电弧宽带高分辨率发射光谱的方法

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.

用畸变校正扫描透射电镜进行单数字纳米电子束光刻

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