Quantitative Phase Imaging for Meta‐Lenses by Phase Retrieval

Abstract Meta‐lenses have advanced focusing and imaging capabilities. Traditional methods for assessing meta‐lenses performance, such as focusing light field scanning, are time‐consuming and cannot obtain phase information. Meta‐lenses require accurate and fast phase information measurements for industrial‐level applications. Here, a novel approach is introduced for meta‐lenses phase recovery from defocused images. The precise phase can be obtained by optimizing the complex amplitude of the meta‐lens from the experimentally collected defocused images through complex gradient descent. This method doesn't need complicated experimental setups like traditional off‐axis interferometry. This method is robust and applicable to meta‐lenses with diverse phase modulations. The investigation is extended to measure the phase information of the Pancharatnam‐Berry phase‐based meta‐lens and the achromatic meta‐lens in different incident wavelengths. These results demonstrate that this technique accurately recovers phase information. The 3D intensity profile can be retrieved at arbitrary distances, which is faster and more accurate, enabling the prediction of optical properties such as focal length. This advancement enhances the understanding of meta‐lense behavior in practical scenarios. It provides a foundation for future optimizations in meta‐lenses design, potentially leading to more efficient and versatile optical systems.