Transparent fabric transmission model, Coherent optical spectrum analyzer, Spatial spectrum


Background. The main element of optical information processing systems is a coherent optical spectrum analyzer (COSA). In the textile industry in the manufacture and use of thin transparent fabrics (gauze, bandages, etc.) there is a problem of controlling the shape and geometric dimensions of transparent cells. For this purpose, microscopes are used with the help of which the geometrical parameters of many transparent cells are measured. Such process is time consuming, requires a considerable amount of time for measurement. Using COSA allows you to directly measure the average cell size.

Objective. The purpose of the paper is development of an optical model of a transparent fabric, on the basis of which a laser method and an experimental stand for measuring the average geometric dimensions of transparent fabrics cells are proposed.

Methods. The proposed method of quality control of transparent fabrics is based on the use of COSA. If a transparent fabric is positioned in the front focal plane of a Fourier lens, then diffraction maximums are formed in the back focal plane, the position of which depends on the size of the transparent fabric cells.

Results. The geometric model of the structure of a transparent fabric, which describes the amplitude transmittance coefficient of the fabric depending on the period and the size of the transparent fabrics cells, is proposed. An analytical formula is obtained for calculating the spatial spectrum of the transmittance of such a model. The COSA laboratory stand was developed, which allows measuring the geometric dimensions of transparent fabric cells.

Conclusions. The research of the transmission model of transparent fabric showed that the fabric structure can be viewed as a two-dimensional diffraction grating, the period of which is determined by the thickness of the filament and the transparent part of the fabric cell. To measure the size of the cells of the transparent fabric, it is proposed to use the COSA, which allows you to directly measure the spatial frequencies of the diffraction peaks and calculate the average values of the fabric cell sizes. To validate the proposed method, an experimental stand of digital COSA has been developed.

Author Biography

Mykyta S. Kolobrodov, Igor Sikorsky Kyiv Polytechnic Institute

Микита Сергійович Колобродов


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