Optical processing with vortex-producing lenses

Abstract

We discuss two types of optical processing using vortex-producing angular phase plates. In the most common spatial-filtering operation, an input object is Fourier transformed (either by Fraunhofer diffraction or with a lens system). The Fourier transform is then multiplied by an angular phase pattern, and the product is again Fourier transformed. The output is a space-invariant, edge-enhanced version of the input object. Alternatively we can directly image the object using a lens multiplied by the angular phase. The space-variant image is severely distorted along the optical axis of the system. We encode the phase plates onto a liquid-crystal display and present experimental results on both systems.

Programmable liquid crystal waveplate polarization gratings as elements for polarimetric and interference applications

“…As an example, we consider optical vortices, obtained by adding the helical phase characteristic of an optical vortex to the grating pattern. This phase varies azimuthally as exp(imT), where m is an integer number known as the topological charge, and T is the azimuthal angle [12]. Figure 6 shows the results for m=2, 3, and 4 where we again used a grating period of 64 pixels, as in Fig.…”

Experimental generation and characterization of Devil’s vortex-lenses

“…Vortex lenses produce wavefronts with helical structure and zero axial intensity [1]. These optical vortices are special optical traps having the ability to set the trapped particles into rotation due to the orbital angular momentum of light [2,3].…”

High power vortex generation with volume phase holograms and non-linear experiments in gases

“…Usually they consist of an amplitude mask [8], but alternative processing of CGHs has been reported [9]. Also, dynamic CGHs have been tested using liquid-crystal media [10]. In general, the CGH technique presents lower efficiencies than those obtained with the SPPs.…”

“…In addition, CGHs have been adapted to the femtosecond regime using 2f-2f set-ups, in order to compensate the spatial chirp [11,12]. The main limitations of CGHs to date are the low damage threshold of the materials used, preventing the generation of high-power OVs, and the very low efficiency (as an exception, CGHs consisting of bleached plates [9] and liquid crystals (LCs) [10] present higher efficiency, compared to the more common amplitude CGHs).…”