There is a lots of different papers reporting about the propagation of the different types of an optical beams in a uniaxial crystals are known by that time. This beams are: Lager-Gaussian and Bessel- Gaussian beams. It is common for all this types of beams, that if propagation axis and crystal axis coincides, and accident beam had a circular polarization, are can get type spiral type degenerated umbilici, which corresponds to the charge 2 optical vortex in the orthogonal polarized beam component, generated by crystal  (Fig 1). This generation accurse due to total angular momentum conservation law symmetry axis of the crystal. One to the changing of the spin momentum which is associated with the beam polarization, this leads to the orbital momentum changes that associated with topological charge of formed orthogonal circular component. Double charged optical vortex could be easily perturbed by tilting beam axis with respect to the crystal axis. If the tilt angles are small (<0.1°) central umbilici splits on two lemons and the surrounding ring umbilici splits on two pairs of monster-star. The further increasing of the tilt angle leads to the topological charge of circular components becomes, equal, and additional orbital moment correspond to the beam mass center displacement.
We have considered a new type of singular beams called as optical quarks. They have fractional topological charges being equal to half an integer and they possess rather unique properties. There are four types of optical quarks, even and odd ones, which reveal the opposite signs of topological charges. The sums or differences of the even and odd quarks form standard vortex or non-vortex beams with the topological charges of integer order. All the quarks in the same beam annihilate and the beam vanishes. We conducted an analysis of all possible combinations of even and odd optical quarks with different charges. What provided an opportunity to explore what interactions correspond to their "sum" and "difference."
Acoustic waves, generated in solids by irradiation of a surface with powerful laser pulses, are widely used to study mechanical, thermal and elastic properties of materials. Application of this technique to MEMS technology will open new insights into fabrication and characterization but will require understanding of acoustic wave generation in small-sized objects. To that end, acoustic wave generation was studied in thin (10-50 μm) metal and semiconductor foils (including Mo, Si, W, Ni, Ta, Au) back-side irradiated by nanosecond IR and UV laser pulses over a range of peak intensities. Both interferometric techniques and capacitance transducers were employed for detection of surface displacements in the foils. By varying the peak laser power over a wide range of intensities (1-500 MW/cm2) detection of the transition from a thermoelastic to a laser-plasma driven shock-wave mechanism for acoustic wave generation was possible. Measurements show that this transition is accompanied by a dramatic change in the waveform of the generated shock-wave and that this waveform differs for various materials and foil thicknesses. Since thin foils were studied, the longitudinal and shear waves were experimentally indistinguishable, making the observed waveform very complex. Moreover, at higher peak laser powers, mechanical vibrations at resonance frequencies of the thin foils can occur and further complicate the analysis. Nevertheless, the observed phenomena can be described in the framework of a simplified theoretical model and can be used for materials testing in different applications.