Abstract—Using the Angular Spectrum (AS) method, we have calculated the spatial distribution of the light intensity ring at the observation plane for a Vortex Micro-lens (VML). By comprehensive investigation of the variations in the ring characteristics, including the radius and width of the ring, the maximum intensity and the radius of the null spot versus the observation plane distance and VML topological charge, we have found a zone of maximum power level behind the VML in the Fresnel region. The zone is located at the between its double peaks. We call this zone the Maximum Power Zone (MPZ) and Also, we have shown that the location of the MPZ is independent of the refractive index and topological charge of VML while is dependent on frees-pace wavelength (λ₀) and diameter of VML (D) and there is an absolute peak of power level in the MPZ at the distance of D²/3λ₀. The result can easily use to design a VML with a specified ring characterization.

Index Terms—DOE, vortex micro-lens, angular spectrum and design

Cite: Seyyed Hossein Kazemi and Ali Jebelli, "Angular Spectrum of Vortex Micro-lens," Journal of Image and Graphics, Vol. 7, No. 4, pp. 145-148, December 2019. doi: 10.18178/joig.7.4.145-148