Algorithm for computing holographic optical tweezers at video rates

Author(s): Mario Montes-Usategui, Encarnación Pleguezuelos, Jordi Andilla, Estela Martín-Badosa, and Ignacio Juvells

Abstract:

“Digital holography enables the creation of multiple optical traps at arbitrary three-dimensional locations and spatial light modulators permit updating those holograms at video rates. However, the time required for computing the holograms makes interactive optical manipulation of several samples difficult to achieve. We introduce an algorithm for computing holographic optical tweezers that is both easy to implement and capable of speeds in excess of 10 Hz when running on a Pentium IV computer. A discussion of the pros and cons of the algorithm, a mathematical analysis of the efficiency of the resulting traps, as well as results of the three-dimensional manipulation of polystyrene micro spheres are included.”

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Publication: SPIE Digital Library
Issue/Year: Proceedings Volume 6326, Optical Trapping and Optical Micromanipulation III; 63262X (2006)
DOI: 10.1117/12.680504

Design of a low-cost interactive holographic optical tweezers system

Author(s): E. Pleguezuelos, J. Andilla, A. Carnicer, E. Martín-Badosa, S. Vallmitjana, and M. Montes-Usategui.

Abstract:

“The paper describes the design of an inexpensive holographic optical tweezers setup. The setup is accompanied by software that allows real-time manipulation of the sample and takes into account the experimental features of the setup, such as aberration correction and LCD modulation. The LCD, a HoloEye LCR-2500, is the physical support of the holograms, which are calculated using the fast random binary mask algorithm. The real-time software achieves 12 fps at full LCD resolution (including aberration correction and modulation) when run on a Pentium IV HT, 3.2 GHz computer.”

Link to Publications Page

Publication: SPIE Proceedings
Issue/Year: Proc. SPIE 6326, 63262Q (2006)
DOI: 10.1117/12.680593

Direct observation of Gouy phase shift in a propagating optical vortex

Author(s): Junichi Hamazaki, Yuriya Mineta, Kazuhiro Oka, and Ryuji Morita

Abstract:

“Direct observation of Gouy phase shift on an optical vortex was presented through investigating the intensity profiles of a modified LGpm beam with an asymmetric defect, around at the focal point. It was quantitatively found that the rotation profile of a modified LGpm beam manifests the Gouy phase effect where the rotation direction depends on only the sign of topological charge m. This profile measurement method by introducing an asymmetric defect is a simple and useful technique for obtaining the information of the Gouy phase shift, without need of a conventional interference method. In addition, the 3-dimernsional trajectory of the defect was found to describe a uniform straight line.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Vol. 14, Issue 18, pp. 8382-8392, 2006
DOI: 10.1364/OE.14.008382

An adaptive optics imaging system based on a high-resolution liquid crystal on silicon device

Author(s): Quanquan Mu, Zhaoliang Cao, Lifa Hu, Dayu Li, and Li Xuan

Abstract:

“An adaptive optics imaging system is introduced in this paper. A high resolution liquid crystal on silicon (LCOS) device was used as a phase only wave front corrector instead of a conversional deformable mirror. The wave front aberration was detected by a Shack-Hartmann (SH) wave front sensor, which has λ/100 rms wave front measurement accuracy. Under this construction 0.09λ (λ=0.6328µm) Peak to Valley correction precision was reached. Further more, some low frequency hot convection turbulence induced by an electric iron was compensated in real time at the same precision. The Modulation Transfer Function (MTF) of this system was also measured before and after wave front correction. Under the active correction of LCOS, the system reached the diffraction limited resolution approximately 65l p/mm on the horizontal direction. All of this showed the ability of using this device in high resolution, low temporal turbulence imaging system, such as retinal imaging, to improve the resolution performance.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Vol. 14, Issue 18, pp. 8013-8018, 2006
DOI: 10.1364/OE.14.008013