Enhanced focusing and imaging with super high-order Hilbert zone plates

Abstract

Zone plates have emerged as a viable alternative to conventional refractive lenses due to their lightweight, compact design and ease of fabrication. However, achieving high-intensity single focus with enhanced imaging resolution remains a challenge. In this study, we proposed the super high-order Hilbert zone plates (HZPs) based on the space-filling Hilbert curve to address these limitations. Our comprehensive simulations and experimental validations demonstrated that the super high-order HZPs concentrate most of the incident light into a single focus, with a tiny focus spot, thus offering enhanced imaging resolution. Through a detailed comparison with the binarized geometric lenses, we illustrated the superior imaging capabilities of the super high-order HZPs. By redefining the traditional roles of zone plates, the super high-order HZPs emerge with the potential to replace binarized geometric lenses. The proposed super high-order HZPs hold significant promise for applications in integrated optical systems, optical imaging, medical imaging, photolithography, and precise scientific measurement.