Planar Cassegrain-type Schwarzschild Objective with Optical Metasurfaces

TL;DR

This paper introduces a planar Cassegrain-type Schwarzschild objective using optical metasurfaces, enabling compact, integratable, and broadband reflective imaging systems with experimentally verified focusing and imaging capabilities.

Contribution

It presents a novel planar reflective Schwarzschild objective replacing curved mirrors with metasurfaces, simplifying design and broadening application potential.

Findings

Achieved a functional planar Cassegrain-type Schwarzschild objective.

Experimentally verified focusing and imaging functionalities.

Demonstrated potential for compact broadband imaging systems.

Abstract

Curved reflective mirrors play an indispensable role in widely-employed Cassegrain-type optics, which consequently are inevitably bulky, and thus neither integratable nor well extendable. Through substituting geometric phase based reflective metasurfaces for curved mirrors, here a planar Cassegrain-type Schwarzschild objective is obtained, with both the focusing and imaging functionalities experimentally verified. The planar reflective objective achieved is intrinsically free of residual light and thus imposes less stringent restrictions on illuminating light and nanofabrications compared to its refractive counterpart. Our planar Cassegrain-type designs can potentially reshape and simplify the core components of the microscope and telescope systems working at a broadband spectral range, and thus opens new avenues for designing compact imaging systems.