Optimisation of light focusing by mesowave Fresnel phase plates with tilted zone profiles

We present the results of numerical simulation of optical radiation focusing by a phase Fresnel zone plate (ZP) of mesowave size with zones having an inclined profile. In order to reveal the features of the formation of the spatial structure of the focus, the optical field is calculated in the case of monochromatic optical wave diffraction by a single ZP and by an array of identical plates. It is shown that the parameters of the focal region (intensity, longitudinal and transverse dimensions, focal distance) are sensitive to the angle of inclination of the annular zones of the ZP. By changing the slope of the faces, it is possible to optimise the focusing and achieve a significant increase in the focal intensity (up to 40 %) with respect to the binary ZP.