Researches of spectra of spatial frequencies to the problem of a focusing solving

Experimental measurements of a distance from a surface of an object up to a focal plane of the objective are theoretically justified on the base of the analysis of distribution of the upper spatial frequencies intensities of a spectrum of an image. As a rule, one or several resonant spatial frequencies exist for a surface of any object. It is connected to a method of a roughness formation. On the grounds of stochastic and random oscillations theory it is possible to assert that all actual rough surfaces are not absolute random in a sense of a theory of probabilities. Therefore, the optical fields generated by these objects are not random too and comprise the information on that degree of ordering, which characterized an object. In this case the image is a result of a field and screen interaction. Such submission has allowed us to use correlation dimensionality of the optical field spatial chaos as an optical field characteristic. This parameter is determined by the quantity of incommensurable spatial-frequency components of the radiation, which has taken part in a field formation. Pakkard-Takens computing procedure was used for an evaluation of the correlation dimensionality in an optical field. The correlation dimensionality of a field obtained as a result of diffraction of radiation on a surface linearly depends on a number of diffraction gratings, which superposition was approximated by the given surface. For example, the polishing and filing results in formation on the surface of the superposition of a series of linear diffraction gratings. If the surface is precisely in an objective focal plane, resonant frequencies will have maximum intensity and their quantity will correspond to the correlation dimensionality of spatial chaos of an optical field. The conducted researches have allowed us to combine the process of technological laser precision pointing on a focal point with obtaining the sharp image of a treated surface.