DIFFRACTION PHENOMENA IN THE FAR ZONE ON SMALL-DIAMETER CYLINDRICAL OBJECTS WITH ALLOWANCE FO THEIR REFLECTING PROPERTIES
Yu. V. Chugui1,2,3
1Technological Design Institute of Scientific Instrument Engineering, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
3Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: цилиндр, радиус, дифракция Фраунгофера, коэффициент отражения света, измерение диаметров, cylinder, radius, Fraunhofer diffraction, coefficient of light reflection, measurement of diameters
Abstract
Within the framework of the scalar diffraction light theory developed by Kirchhof and Fresnel, specific features of diffraction phenomena in the far zone on cylindrical (metal) objects of small diameters (0.01-0.5 mm) are investigated with allowance for their reflecting properties. A cylinder model in the form of a screen (of zero thickness) is used in the calculations. The reflected component of the field in the far zone is calculated by the stationary phase method. It is shown that the influence of the reflected light wave leads to a noticeable measurement error proportional to the amplitude coefficient of light reflection from the cylinder surface is standard algorithms are used for information processing (valid for objects of the screen type). To reduce this influence, an algorithm is proposed for determining the diameters of such objects with increased accuracy by means of the corresponding processing of the diffraction pattern in the range of angles θ << 3√ λ/R, where λ is the light wavelength and R is the cylinder radius. The results obtained can be used for the development of high-precision diffraction meters for thin cylindrical objects (wires, threads, and fibers).
|
