The detailed theoretical and experimental investigations of the self-reconstruction of the structure of Bessel beams in various scattering media, including biological tissue, have been carried out. Also the self- reconstruction of Bessel beam after shadowing with single obstacle is studied. Using conical beams, the peculiarities of speckle contrast imaging of subsurface targets embedded into highly scattering media have been investigated.
We propose a method of rotation of higher-order Bessel light beams based on controlling phase difference between the interfering Bessel beam and a super-Gaussian or annular beam coaxial with it. TO realize the optically-controlled rotation of light field, a phase modulator based on quadratic or cubic nonlinearities can be used.
In this paper properties of the generation of difference frequency of Bessel light beams at the quasi-synchronous interaction in periodically poled nonlinear crystals are investigated. The angular width of the synchronism for collinear and vectorial interactions under condition of first-order quasi-synchronism is defined. It is shown that in periodically poled nonlinear KTP crystals where the maximum nonlinear coefficient (sigma) <SUB>33</SUB> is used, an effective generation of difference frequency of Bessel light beams takes place, which is in contrast with homogeneous media.