Multifocal Fresnel lenses with adjustable focal points recorded in photopolymers

We present the recording of multifocal lenses based on a linear Fresnel zone combination in a photopolymer medium based on polyvinyl-alcohol acrylamide (PVA/AA). A 4F system with a spatial light modulator (SLM) is used to compare experimental results with numerical simulations, achieving a ×2/3 magnification that enhances resolution in lens profile measurements. On the other hand, a genetic algorithm is proposed to optimize energy allocation at each focal point, maximizing the Fresnel-Kirchhoff integral in multifocal lens configurations. This work examines the performance and phase design of these lenses, highlighting the crucial role of an optimal design in controlling energy distribution among focal points for visible wavelengths. Such control enables compensation for energy losses at shorter focal lengths (around 70 mm), which arise due to the low-pass filtering effect of the 4F system during the recording process. Furthermore, the proposed setup facilitates the mass production of these diffractive lenses with 3 to 5 mm radius sizes, ensuring efficient fabrication while maintaining high diffraction efficiency.