Isotropic Bessel–Hilbert Visualization of Phase Optical Density Fields

The method and possibility of implementation of isotropic Bessel–Hilbert diagnostics of phase optical density fields of gaseous, condensed, and reactive media are discussed. The probing field in such systems is formed as a mono- or polychromatic configuration of Bessel beams the spatial-frequency Fourier spectrum of which is optically conjugate with the concentric phase structure of an isotropic Hilbert filter, and the color structure corresponds to spectral sensitivity of the photomatrix of the video camera connected to a computer which analyzes the frame-by-frame sequence of the obtained images. The structure of such a probing field is resistant to diffraction perturbations induced by the medium under study and their influence on isotropy of the Hilbert visualization of the phase optical density. The areas of possible applications are experimental fluid and gas dynamics, thermophysics, oceanology, and the corresponding industrial technologies.