Vortex knots in light

Author(s): J. Leach, M. R. Dennis, J. Courtial and M. J. Padgett

Abstract:

“Optical vortices generically arise when optical beams are combined. Recently, we reported how several laser beams containing optical vortices could be combined to form optical vortex loops, links and knots embedded in a light beam (Leach et al 2004 Nature 432 165). Here, we describe in detail the experiments in which vortex loops form these structures. The experimental construction follows a theoretical model originally proposed by Berry and Dennis, and the beams are synthesized using a programmable spatial light modulator and imaged using a CCD camera.”

Link to Publications Page

Publication:New Journal of Physics
Issue/Year:New J. Phys. 7, 55 (2005)
DOI: 10.1088/1367-2630/7/1/055

Spiral phase contrast imaging in microscopy

Author(s): Severin Fürhapter, Alexander Jesacher, Stefan Bernet, and Monika Ritsch-Marte

Abstract:

“We demonstrate an optical method for edge contrast enhancement in light microscopy. The method is based on holographic Fourier plane filtering of the microscopic image with a spiral phase element (also called vortex phase or helical phase filter) displayed as an off-axis hologram at a computer controlled high resolution spatial light modulator (SLM) in the optical imaging pathway. The phase hologram imprints a helical phase term of the form exp(i ??) on the diffracted light field in its Fourier plane. In the image plane, this results in a strong and isotropic edge contrast enhancement for both amplitude and phase objects.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Vol. 13, Issue 3, pp. 689-694, 2005
DOI: 10.1364/OPEX.13.000689