Holographic Optical Tweezers
Holograms for Micromanipulation

Optical tweezers enable us to confine a microscopic object of nano- or micrometers and move it precisely. Many applications, however, require the ability to control more than one object simultaneously. Holographic optical tweezers elegantly extend the basic principle of optical tweezers towards the optical control of a multitude of particles. For this purpose we modulate the phase-front of a laser light field spatially by means of computer generated holograms in order to create several single tweezers in the microscopic sample at the same time.



Each individually calculated hologram can, for example, yield hundreds of copies of the incident light wave, which can be fully tailored with respect to their three-dimensional position information. The holograms are calculated in real-time and displayed on a suitable liquid crystal display in rapid sequence. By this means each individual trap can be positioned arbitrarily inside the sample and the position can be changed dynamically. Furthermore, we are engaged in the optimization of the hologram calculation in order to eliminate undesirable effects as ghost trap formation. Many application scenarios are only possible with holographic optical tweezers and cannot be realized with single optical tweezers. One obvious application is the parallel execution of many single experiments. As another example, in order to measure the binding force of two microscopic objects it might be necessary to hold both objects and then separate them in a defined way. With non-spherical objects it is furthermore possible to use multiple traps – tailored to the object shape – in order to rotate the object into a defined orientation and align it arbitrarily.

Optically Induced Organization
Highly topical subjects in biology and molecular medical sciences envisage the question how biological, chemical, or physical processes in complex systems can be understood and controlled. The important role of self organization and self structuring is more and more revealed in the recent years. With this development attends a strong need for control and defined intervention in these processes. Here, holographic optical tweezers are of outstanding importance. For example, only the simultaneous control of position and orientation of several particles makes it feasible to arrange and structure particular nanocontainers. These nanocontainers can host various chemical loadings and with suitable internal structuring, as e.g. zeolites possess, supramolecular organization of the guest molecules can be achieved. We have achieved to organize these containers themselves solely by optical means. Thus a system emerges that is highly ordered on different length scales – from the single molecules up to the micrometer scale – and thereby can exhibit novel, exciting properties.


Organization of zeolite nanocontainers in
holographic optical tweezers


Contact person:  Christina Alpmann

References:

• Advanced optical trapping by complex beam shaping
  M. Woerdemann, C. Alpmann, M, Esseling, C. Denz
  accepted for publication, published first online as Laser & Photon. Rev., 2013, 1-16 PDF
• Creating Functional Microstructures with an Optical-Tweezers Assembly-Line
  M. Woerdemann, M. Veiga-Gutiérrez, L. De Cola, C. Denz
  OPN 23, 2012, 47 PDF
• Optical-Tweezers Assembly-Line for the Construction of Complex Functional Zeolite L Structures
  M. Veiga-Gutiérrez, M. Woerdemann, E. Prasetyanto, C. Denz, L. De Cola
  Adv. Mater. 24, 2012, 5199–5204 PDF
• Three-dimensional Particle Control by Holographic Optical Tweezers
  M. Woerdemann, C. Alpmann, C. Denz
  in "Optical Imaging and Metrology - Advanced Technologies" (2012)
  Eds. W. Osten, N. Reingand
  Wiley Verlag, ISBN-10: 3-527-41064-3
• Controlling ghost traps in holographic optical tweezers
  C. Hesseling, M. Woerdemann, A. Hermerschmidt, C. Denz
  Opt. Lett. Vol. 36, 2011, 3657 -3659 PDF
  also published in Virtual Journal for Biomedical Optics 6, 2011, Iss. 10
• Dynamic multiple-beam counter-propagating optical traps using optical phase-conjugation
  M. Woerdemann, K. Berghoff, C. Denz
  Optics Express 18, 2010, 22348-22357 PDF
• Managing hierarchical supramolecular organization with holographic optical tweezers OPN
  Woerdemann, M.; Devaux, A.; De Cola, L. & Denz, C.
  Optics in 2010, 2010, 21, 40 PDF
• Optical control and dynamic patterning of zeolites
  Mike Wördemann, Christina Alpmann, Florian Hörner, André Devaux, Luisa De Cola, and Cornelia Denz
  Proc. SPIE Vol. 7762, 2010, 77622E PDF
• Dynamic and reversible organization of zeolite L crystals induced by holographic optical tweezers
  M. Woerdemann, S. Gläsener, F. Hörner, A. Devaux, L. De Cola, C. Denz
  Advanced Materials Vol. 22, 2010, 4176-4179 PDF