Perspectives on Imaging with Diffractive Flat Optics

Flat optics have been applied successfully for focusing and imaging for many decades. Their recent resurgence is fueled by advances in computational electromagnetics and nanofabrication. In this brief perspective, we summarize the key connections of flat lenses to holograms, describe the current state of diffractive flat lenses, propose an effective metric to compare their performance (the generalized strehl ratio), and muse on potential areas for future research.