Dynamic speckle illumination microscopy with wavelet prefiltering

Author(s): Cathie Ventalon, Rainer Heintzmann, and Jerome Mertz

Abstract:

“Dynamic speckle illumination (DSI) provides a simple and robust technique to obtain fluorescence depth sectioning with a widefield microscope. We report a significant improvement to DSI microscopy based on a statistical image-processing algorithm that incorporates spatial wavelet prefiltering. The resultant gain in sectioning strength leads to a fundamentally improved scaling law for the out-of-focus background rejection.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 32, Issue 11, pp. 1417-1419
DOI: 10.1364/OL.32.001417

Holographic and single beam optical manipulation of hyphal growth in filamentous fungi

Author(s): D. R. Burnham, G. D. Wright, N. D. Read and D. McGloin

Abstract:

“We report on the ability of holographic light fields to alter the normal growth patterns of filamentous fungi. The light fields are produced on a microscopic scale by borrowing methods from the field of optical tweezers, but without the aim of directly trapping or manipulating objects. Extended light fields are shown to redirect and constrict hyphal tip growth, and induce hyphal branching in a highly reproducible manner. The merits of using discrete and continuous light fields produced using a spatial light modulator are discussed and the use of three-dimensional ‘pseudowalls’ of light to control the growth patterns is reported. We also demonstrate the dependence of hyphal tip growth on the wavelength of light, finding that less power is needed at shorter wavelengths to effect changes in the growth dynamics of fungal hyphae.”

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Publication: Journal of Optics A: Pure and Applied Optics
Issue/Year: J. Opt. A: Pure Appl. Opt. 9 S172-S179 (2007)
DOI: 10.1088/1464-4258/9/8/S09

Holografisch generierte Doppelfallen für dreidimensionales Trapping

Author(s): Susanne Zwick, L. He, M. Warber, T. Haist, W. Osten

Abstract:

“In konventionellen optischen Pinzetten ist der axiale Einfang von mikroskopischen Partikeln nur durch starke Fokussierung des Laserstrahls mit einem hochaperturigen Mikroskopobjektiv möglich. Wir stellen ein Verfahren vor, mit dem der axiale Einfang in holografischen Pinzetten auch mit niederaperturigen Objektiven ermöglicht wird.”

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Publication: DGaO Proceedings
ISSN: 1614-8436

Angle multiplexed storage with object beam alone

Author(s): Hon-Fai Yau, Jung-Ping Liu

Abstract:

“Making use of the interference of incident light waves and the accompanying fanning waves in a photorefractive LiNbO3 crystal, the authors have recorded binary images as well as gray-tone images in a crystal with only an object beam. Angle multiplexing has also been demonstrated with this one beam recording method. Basing on a model that the recording is accomplished through the interference of the object light and its fanning light, the authors have estimated the minimal angular separation for achieving a cross-talk-free multiplexing.”

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Publication: Applied Physics Letters
Issue/Year: Appl. Phys. Lett. 90, 181916 (2007)
DOI: 10.1063/1.2733629

Wavefront correction of spatial light modulators using an optical vortex image

Author(s): A. Jesacher, A. Schwaighofer, S. Fürhapter, C. Maurer, S. Bernet, and M. Ritsch-Marte

Abstract:

“We present a fast and flexible non-interferometric method for the correction of small surface deviations on spatial light modulators, based on the Gerchberg-Saxton algorithm. The surface distortion information is extracted from the shape of a single optical vortex, which is created by the light modulator. The method can be implemented in optical tweezers systems for an optimization of trapping fields, or in an imaging system for an optimization of the point-spread-function of the entire image path.”

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Publication:Optics Express
Issue/Year: Optics Express, Vol. 15, Issue 9, pp. 5801-5808
DOI: 10.1364/OE.15.005801

Femtosecond pulse shaping using a two-dimensional liquid-crystal spatial light modulator

Author(s): E. Frumker and Y. Silberberg

Abstract:

“We introduce a programmable, high-rate scanning femtosecond pulse shaper based on a two-dimensional liquid crystal on a silicon spatial light modulator (SLM). While horizontal resolution of 1920 addressable pixels provides superior fidelity for generating complex waveforms, scanning across the vertical dimension (1080 pixels) has been used to facilitate at least 3 orders of magnitude speed increase as compared with typical liquid-crystal SLM-based pulse shapers. An update rate in excess of 100 kHz is demonstrated.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 32, Issue 11, pp. 1384-1386 (2007)
DOI: 10.1364/OL.32.001384

Digital spatially incoherent Fresnel holography

Author(s): Joseph Rosen and Gary Brooker

Abstract:

“We present a new method for recording digital holograms under incoherent illumination. Light is reflected from a 3D object, propagates through a diffractive optical element (DOE), and is recorded by a digital camera. Three holograms are recorded sequentially, each for a different phase factor of the DOE. The three holograms are superposed in the computer, such that the result is a complex-valued Fresnel hologram. When this hologram is reconstructed in the computer, the 3D properties of the object are revealed.”

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Publication:Optics Letters
Issue/Year: Optics Letters, Vol. 32, Issue 8, pp. 912-914
DOI: 10.1364/OL.32.000912

Holographic recording in Fe:Ce:Ti–LiNbO3 crystal

Author(s): Ravinder Kumar Banyal, B. Raghavendra Prasad

Abstract:

“High diffraction efficiency measurements in a triply doped Fe:Ce:Ti–LiNbO3 crystal are reported. The crystal shows an improved recording sensitivity, weak light-induced scattering and extremely slow readout erasure which makes it highly desirable for non-volatile data storage applications. The suitability of the crystal was demonstrated by high quality holographic recording and retrieval of several astronomical images using shift and rotational multiplexing scheme.”

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Publication: Optics Communications
Issue/Year:Optics Communications, Volume 274, Issue 2, 15 June 2007, Pages 300-306
DOI: 10.1016/j.optcom.2007.02.029

Fluorescence incoherent color holography

Author(s): Joseph Rosen and Gary Brooker

Abstract:

“We present a new imaging method to record multicolor digital holograms from objects emitting fluorescent light. The fluorescent light specific to the emission wavelength of various fluorescent dyes after excitation of three dimensional (3D) objects is recorded on a digital monochrome camera after reflection from a diffractive optical element (DOE). For each wavelength of fluorescent emission, the camera sequentially records three holograms reflected from the DOE, each with a different phase factor of the DOE’s function. The three holograms are superposed in a computer to create a complex valued Fresnel hologram of each fluorescent emission. The holograms for each fluorescent color are further combined in a computer to produce a multicolored fluorescence hologram and 3D color image.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 15, Issue 5, pp. 2244-2250
DOI: 10.1364/OE.15.002244

Binary diffractive beam splitters with arbitrary diffraction angles

Author(s): Andreas Hermerschmidt, Sven Krüger, and Günther Wernicke

Abstract:

“Diffractive optical beam splitters designed with iterative Fourier transform type algorithms can produce only certain diffraction angles given by the spatial frequencies used for the computations, which are multiples of a certain base spatial frequency. We have developed a design algorithm that overcomes this limitation and can be used to compute binary diffractive elements with arbitrary diffraction angles. The simulated and experimentally measured properties of optical elements producing beam arrays in circular arrangements are presented and discussed.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 32, Issue 5, pp. 448-450
DOI: 10.1364/OL.32.000448
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