Experimental demonstration of singular-optical colouring of regularly scattered white light

Experimental interference modelling of the effects of colouring of a beam traversing a light-scattering medium is presented. It is shown that the result of colouring of the beam at the output of the medium depends on the magnitudes of the phase delays of the singly forward scattered partial signals. The colouring mechanism has for the first time experimentally been illustrated for a forward propagating beam through a light-scattering medium. This is showed in video-fragments of the interferograms recorded within the zero interference fringe with a gradual change of the path difference of the interfering polychromatic wave trains. Spectral investigation of the effects of colouring has been carried out using a solution of liquid crystal in a polymer matrix. The amplitude ratio of the non-scattered and the singly forward scattered interfering components significantly affects the colour intensity. It has further been established that the spectral content of the illuminating beam strongly influences the colour of the resulting radiation

Biaxial crystal-based optical tweezers

We suggest an optical tweezer setup based on an optically biaxial crystal. To control movements of opaque particles, we use shifts. The results of experimental studies are reported which are concerned with this laser tweezer setup. We demonstrate a movement of microparticles of toner using a singular-optical trap, rotation of particles due to orbital angular momentum of the field, and converging or diverging of two different traps when changing transmission plane of polariser at the input of our polarisation interferometer

Jones-matrix images corresponding to networks of biological crystals for diagnostics and classification of their optical properties

Performed in this work is a complex statistical, correlation and fractal analysis of coordinate distributions for Jones-matrix elements describing birefringent networks observed in the main types of human amino acids. Determined are the values and ranges for changing the statistical, correlation and spectral moments of the 1-st to 4-th orders that characterize Jones-matrix images of these biological polycrystalline protein structures. We have ascertained objective criteria for classification and differentiation of optical properties inherent to polycrystalline networks of amino acids with different types of spatial symmetry – dendrite, spherolite and cluster ones

Orbital rotation without orbital angular momentum: mechanical action of the spin part of the internal energy flow in light beams

It is known that internal energy flow in a light beam can be divided into the orbital flow, associated with the macroscopic energy redistribution within the beam, and the spin flow originating from instantaneous rotation of the field vectors inherent in circular or elliptic polarization. In contrast to the orbital one, experimental observation of the spin flow constituent seemed problematic because (i) it does not manifest itself in the visible transformation of the beam profile and (ii) it converts into the orbital flow upon tight focusing of the beam, usually employed for the energy flow detection by the mechanical action on probe particles. We propose a two-beam interference technique that permits to obtain appreciable level of the spin flow in moderately focused beams and to detect the orbital motion of probe particles within a field where the transverse energy circulation is associated exclusively with the spin flow. This result can be treated as the first demonstration of mechanical action of the spin flow of a light field.Comment: 9 pages, 3 figures and 1 video cli