Optimization Design of Cylinder Grating Used for Non-Contact Speed Measurement

Abstract

In order to realize the detection of diffractive light after the image segmentation using cylinder grating, the parameters of a cylinder grating was optimized using the wave optics theory. By analyzing the relation of optical path length variation with the diffraction angle of single cylinder lens diffraction, and by Fraunhofer approximation, the analytical expressions of cylinder lens diffraction was given. By setting parameters to calculate and simulate, it was found that to increase the ratio of curvature radius and grating period could effectively reduce the spatial distribution of the diffraction light intensity. For the gratings that already exist, by reducing the ratio of refractive index of the gratings material and environment, the spatial light distribution of the grating could be reduced. If the cylinder grating period is too small, the overlap part of images segmentation light diffraction intensity will increase. But it occupies smaller proportion of the total light intensity. After the optimization design of cylinder grating, the results showed that it could be used for non-contact speed measurement in the range of some parameter.