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5 - Tunable Liquid Lenses
- from Part II - Devices and materials
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- By J. Andrew Yeh, National Tsing Hua University, Taiwan, Yen-Sheng Lu, National Tsing Hua University, Taiwan
- Edited by Hans Zappe, Albert-Ludwigs-Universität Freiburg, Germany, Claudia Duppé, Albert-Ludwigs-Universität Freiburg, Germany
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- Book:
- Tunable Micro-optics
- Published online:
- 05 December 2015
- Print publication:
- 17 December 2015, pp 123-155
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Summary
Introduction
Microlenses are used in many applications including optical coupling, light shaping, spatial light illumination modulation, and imaging (biomedical or monitoring). The basic function of a lens is to either diverge or converge the incident light beams. Solid lenses are the most widely used and have a fixed and nontunable focal length. In a solid lens module, voice coil motors (VCMs) are used to provide a back-and-forth track movement along the optical axis to achieve the required focal length change. However, the bulkiness and high power consumption of the lens module make it unsuitable for designing portable and energy saving products. The focal length of liquid lenses can be tuned by changing either the refractive index or the liquid lens geometry. As liquid lenses do not need any mechanical tracking devices such as VCMs for focal length tuning, the lenses provide the optimal solution for developing miniaturized lens modules with low power consumption in the mW range.
In the past two decades, liquid lenses have been widely investigated benefitting from the development of microfluidics (Berge & Peseux 2000, Chang et al. 2012, Chen et al. 2004). In microfluidics, the control or guidance of liquid/analyst droplets is very significant; especially for lab-on-a-chip (LOC) or micro-total analysis systems (μTAS). LOCs are devices that integrate one or several laboratory functions on a small chip of only few square millimeters to a few square centimeters in size, where the manipulation and the guidance of the tiny amounts of liquids or droplets becomes more and more significant. Certain liquid control mechanisms, such as external pressure pumping, electrowetting, and dielectrophoresis, have been developed and widely used for liquid manipulation (Agarwal et al. 2004, Berge & Peseux 2000, Cheng & Yeh 2007). The technique developed for the manipulation of liquids in microfluidics can be used to change the surface profile and the refractive indices of liquid lenses.
A liquid lens refracts the incident light beams based on the presence of the gradient index in liquids or the change in surface profiles formed from the solid (membrane)–liquid, liquid–liquid, and gas–liquid interfaces. The working liquids in the lens chamber must be transparent in the visible range and should be stable for a wide temperature range. To achieve these goals, liquid crystals, water, mixed alcohols, or silicone oil have been used and investigated.
Contributors
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- By Douglas L. Arnold, Laura J. Balcer, Amit Bar-Or, Sergio E. Baranzini, Frederik Barkhof, Robert A. Bermel, Francois A. Bethoux, Dennis N. Bourdette, Richard K. Burt, Peter A. Calabresi, Zografos Caramanos, Tanuja Chitnis, Stacey S. Cofield, Jeffrey A. Cohen, Nadine Cohen, Alasdair J. Coles, Devon Conway, Stuart D. Cook, Gary R. Cutter, Peter J. Darlington, Ann Dodds-Frerichs, Ranjan Dutta, Gilles Edan, Michelle Fabian, Franz Fazekas, Massimo Filippi, Elizabeth Fisher, Paulo Fontoura, Corey C. Ford, Robert J. Fox, Natasha Frost, Alex Z. Fu, Siegrid Fuchs, Kazuo Fujihara, Kristin M. Galetta, Jeroen J.G. Geurts, Gavin Giovannoni, Nada Gligorov, Ralf Gold, Andrew D. Goodman, Myla D. Goldman, Jenny Guerre, Stephen L. Hauser, Peter B. Imrey, Douglas R. Jeffery, Stephen E. Jones, Adam I. Kaplin, Michael W. Kattan, B. Mark Keegan, Kyle C. Kern, Zhaleh Khaleeli, Samia J. Khoury, Joep Killestein, Soo Hyun Kim, R. Philip Kinkel, Stephen C. Krieger, Lauren B. Krupp, Emmanuelle Le Page, David Leppert, Scott Litwiller, Fred D. Lublin, Henry F. McFarland, Joseph C. McGowan, Don Mahad, Jahangir Maleki, Ruth Ann Marrie, Paul M. Matthews, Francesca Milanetti, Aaron E. Miller, Deborah M. Miller, Xavier Montalban, Charity J. Morgan, Ichiro Nakashima, Sridar Narayanan, Avindra Nath, Paul W. O’Connor, Jorge R. Oksenberg, A. John Petkau, Michael D. Phillips, J. Theodore Phillips, Tammy Phinney, Sean J. Pittock, Sarah M. Planchon, Chris H. Polman, Alexander Rae-Grant, Stephen M. Rao, Stephen C. Reingold, Maria A. Rocca, Richard A. Rudick, Amber R. Salter, Paula Sandler, Jaume Sastre-Garriga, John R. Scagnelli, Dana J. Serafin, Lynne Shinto, Nancy L. Sicotte, Jack H. Simon, Per Soelberg Sørensen, Ryan E. Stagg, James M. Stankiewicz, Lael A. Stone, Amy Sullivan, Matthew Sutliff, Jessica Szpak, Alan J. Thompson, Bruce D. Trapp, Helen Tremlett, Maria Trojano, Orla Tuohy, Rhonda R. Voskuhl, Marc K. Walton, Mike P. Wattjes, Emmanuelle Waubant, Martin S. Weber, Howard L Weiner, Brian G. Weinshenker, Bianca Weinstock-Guttman, Jeffrey L. Winters, Jerry S. Wolinsky, Vijayshree Yadav, E. Ann Yeh, Scott S. Zamvil
- Edited by Jeffrey A. Cohen, Richard A. Rudick
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- Book:
- Multiple Sclerosis Therapeutics
- Published online:
- 05 December 2011
- Print publication:
- 20 October 2011, pp viii-xii
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Contributors
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- By Graeme J.M. Alexander, Heung Bae Kim, Michael Burch, Andrew J. Butler, Tanveer Butt, Roy Calne, Edward Cantu, Robert B. Colvin, Paul Corris, Charles Crawley, Hiroshi Date, Francis L. Delmonico, Bimalangshu R. Dey, Kate Drummond, John Dunning, John D. Firth, John Forsythe, Simon M. Gabe, Robert S. Gaston, William Gelson, Paul Gibbs, Alex Gimson, Leo C. Ginns, Samuel Goldfarb, Ryoichi Goto, Walter K. Graham, Simon J.F. Harper, Koji Hashimoto, David G. Healy, Hassan N. Ibrahim, David Ip, Fadi G. Issa, Neville V. Jamieson, David P. Jenkins, Dixon B. Kaufman, Kiran K. Khush, Heung Bae Kim, Andrew A. Klein, John Klinck, Camille Nelson Kotton, Vineeta Kumar, Yael B. Kushner, D. Frank. P. Larkin, Clive J. Lewis, Yvonne H. Luo, Richard S. Luskin, Ernest I. Mandel, James F. Markmann, Lorna Marson, Arthur J. Matas, Mandeep R. Mehra, Stephen J. Middleton, Giorgina Mieli-Vergani, Charles Miller, Sharon Mulroy, Faruk Özalp, Can Ozturk, Jayan Parameshwar, J.S. Parmar, Hari K. Parthasarathy, Nick Pritchard, Cristiano Quintini, Axel O. Rahmel, Chris J. Rudge, Stephan V.B. Schueler, Maria Siemionow, Jacob Simmonds, Peter Slinger, Thomas R. Spitzer, Stuart C. Sweet, Nina E. Tolkoff-Rubin, Steven S.L. Tsui, Khashayar Vakili, R.V. Venkateswaran, Hector Vilca-Melendez, Vladimir Vinarsky, Kathryn J. Wood, Heidi Yeh, David W. Zaas, Jonathan G. Zaroff
- Edited by Andrew A. Klein, Clive J. Lewis, Joren C. Madsen
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- Book:
- Organ Transplantation
- Published online:
- 07 September 2011
- Print publication:
- 11 August 2011, pp vii-x
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Contributors
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- By Gregory S. Aaen, Maria Pia Amato, Laura J. Balcer, Brenda Banwell, Amit Bar-Or, Khurram Bashir, Anita L. Belman, Susan Bennett, Dorothée Chabas, Tanuja Chitnis, Russell C. Dale, Angelo Ghezzi, Jin S. Hahn, Folker Hanefeld, Deborah Hertz, R. Q. Hintzen, Sunny Im-Wang, Laura J. Julian, Lauren B. Krupp, Nancy L. Kuntz, Grant T. Liu, Timothy Lotze, Andrew McKeon, Maria Milazzo, Ellen M. Mowry, Jayne Ness, Frank S. Pidcock, Immacolata Plasmati, Daniela Pohl, Christel Renoux, Moses Rodriguez, Martino Ruggieri, A. D. Sadovnick, Guillaume Sébire, Isabella Simone, Bruno P. Soares, Jonathan Strober, Esther Tantsis, Marc Tardieu, Silvia Tenembaum, Maria Trojano, Sunita Venkateswaran, Amy T. Waldman, Emmanuelle L. Waubant, Bianca Weinstock-Guttman, Max Wintermark, E. Ann Yeh
- Edited by Dorothée Chabas, University of California, San Francisco, Emmanuelle L. Waubant, University of California, San Francisco
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- Book:
- Demyelinating Disorders of the Central Nervous System in Childhood
- Published online:
- 11 April 2011
- Print publication:
- 17 March 2011, pp vii-ix
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Structural and magnetic properties of random mixture graphite intercalation compounds
- Masatsugu Suzuki, Louis J. Santodonato, Mildred Yeh, Samuel M. Sampere, Andrew V. Smith, Charles R. Burr
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- Journal:
- Journal of Materials Research / Volume 5 / Issue 2 / February 1990
- Published online by Cambridge University Press:
- 31 January 2011, pp. 422-434
- Print publication:
- February 1990
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The structural and magnetic properties of the stage 2 CocNi1−cCl2- and COcFe1−cCl2-graphite intercalation compounds (GICs) for 0 ≤ c ≤ 1 have been studied by x-ray scattering and dc magnetic susceptibility. The stage 2 CocNi1−cCl2-GICs approximate two-dimensional randomly-mixed ferromagnets with XY spin symmetry. The average effective magnetic moment Peff, the Curie-Weiss temperature θ, and the paramagnetic-to-ferromagnetic phase transition temperature Tc have been determined as continuously varying functions of Co concentration c. They indicate that the Co2+ and Ni2+ spins are randomly distributed on the triangular lattice sites of each intercalate layer. They also show that the intraplanar exchange interaction J(Co–Ni) between the Co2+ and Ni2+ spins is enhanced and is larger than the interaction J(Co–Co) between two Co2+ spins and J(Ni–Ni) between two Ni2+ spins. This enhanced interaction, J(Co–Ni), can be expressed as J(Co–Ni) = 1.28 [J(Co–Co) · J(Ni–Ni)]1/2. The stage 2 CocFc1−cCl2-GICs approximate two-dimensional randomly mixed ferromagnets with competing spin anisotropy. The dc magnetic susceptibility results suggest that Co2+, Fe3+ rather than Fe2+ are distributed in the intercalate layer. The repeat distance along the c-axis (d-spacing) versus Co concentration deviates from Vegard's law which states that the d-spacing is proportional to Co concentration. The broad peak of d-spacing observed at c = 0.75 is discussed in terms of the double layer model developed by Jin and Mahanti.