Jan Masajada

Optical vortex generation by three plane wave interference

In this paper the generation of optical vortices by three plane waves interference is studied. The necessary conditions for such process are derived and the net structure of optical vortices generated in this way is analyzed. The results are verified experimentally.

Half-plane diffraction in the case of Gaussian beams containing an optical vortex

In this paper the half-plane diffraction of the Gaussian light beam containing an optical vortex is examined. The analysis is performed analytically (scalar theory in the near field approximation). The stability and dynamics of the optical vortex within the diffracted wavefront is investigated. Some examples of diffraction by single slit are also presented.

Micro-step localization using double charge optical vortex interferometer

We investigate the diffraction effects of focused Gaussian beams yielding a double optical vortex by a nano-step structure fabricated in a transparent media. When approaching such a step the double vortex splits into single ones which move in a characteristic way. By observing this movement we can determine the position of the step with high resolution. Our theoretical predictions were verified experimentally.

The interferometric system using optical vortices as phase markers

In this paper the idea of the interferometer which use the optical vortices generated in the reference field is presented. The two simple measurements and analysis schemes are briefly described. The characteristic problem for such kind of interferometry, i.e. optical vortices localization is treated in more details. The advantages, disadvantages, and future development are shortly discussed.

Deep microstructure topography characterization with optical vortex interferometer

We report on a new method of inspecting deep microstructures manufactured in transparent media. Although their lateral dimension (tens of microns) do not exceed the diffraction limit for optical microscopy resolution, their deepness makes the nondestructive measurements practically impossible with presently available methods. We show that the optical vortex interferometer with a vortex generator can be used to differentiate between the samples of good and poor quality. The measurement system is simple and the interpretation of the results is straightforward.

New scanning technique for the optical vortex microscope

In the optical vortex microscopy the focused Gaussian beam with optical vortex scans a sample. An optical vortex can be introduced into a laser beam with the use of a special optical element--a vortex lens. When moving the vortex lens, the optical vortex changes its position inside the spot formed by a focused laser beam. This effect can be used as a new precise scanning technique. In this paper, we study the optical vortex behavior at the sample plane. We also estimate if the new scanning technique results in observable effects that could be used for a phase object detection.

Creation of vortex lattices by a wavefront division.

The Youngs double-slit experiment is one of the most popular stories in the history of physics. This paper, like many others, has emerged from the Youngs idea. It investigates the diffraction of the plane or spherical wave produced by three or four small holes in an opaque screen. It was noticed that the interference field contained a lattice of optical vortices which were equivalent to those produced in optical vortex interferometer. The vortex lattice generated by the three holes possessed some unique properties from which the analytical formulae for vortex points position were derived. We also pointed out the differences between our case and the double-slit experiment. Finally, some remarks on possible applications of our arrangement are discussed briefly. These theoretical considerations are illustrated with the use of experimental results.

Optical vortex scanning inside the Gaussian beam

We discussed a new scanning method for optical vortex-based scanning microscopy. The optical vortex is introduced into the incident Gaussian beam by a vortex lens. Then the beam with the optical vortex is focused by an objective and illuminates the sample. By changing the position of the vortex lens we can shift the optical vortex position at the sample plane. By adjusting system parameters we can get 30 times smaller shift at the sample plane compared to the vortex lens shift. Moreover, if the range of vortex shifts is smaller than 3% of the beam radius in the sample plane the amplitude and phase distribution around the phase dislocation remains practically unchanged. Thus we can scan the sample topography precisely with an optical vortex.

Cluster formation in ferrofluids induced by holographic optical tweezers

Holographic optical tweezers were used to show the interaction between a strongly focused laser beam and magnetic nanoparticles in ferrofluid. When the light intensity was high enough, magnetic nanoparticles were removed from the beam center and formed a dark ring. The same behavior was observed when focusing vortex or Bessel beams. The interactions between two or more separated rings of magnetic nanoparticles created by independent optical traps were also observed.

Optical vortex dynamics induced by vortex lens shift—optical system error analysis

Optical vortices can be used in scanning microscopy. A sample can be scanned just by moving a vortex lens, introducing an optical vortex into a Gaussian beam. This technique seems to be cheap, precise and stable. In this paper the influence of various factors on this scanning technique has been investigated numerically, experimentally and analytically (when possible). Our results show that vortex scanning can be affected by Gaussian beam astigmatism. Other factors (such as optical vortex asymmetry) play a negligible role.