# Plan meta-objective for sub-micron quantitative phase imaging

## TL;DR

This paper introduces a compact quantitative phase imaging system using a plan meta-objective to achieve sub-micron resolution without mechanical parts.

## Contribution

A novel plan meta-objective design enables compact QPI with sub-micron resolution and no mechanical translations.

## Key findings

- The PMO design achieves a half-pitch lateral resolution of 488 nm.
- Phase accuracy of 0.06λ is demonstrated for high-quality QPI.
- The system supports imaging of unstained biospecimens with minimal aberrations.

## Abstract

Quantitative phase imaging (QPI) provides valuable objective insights for investigating transparent samples, yet miniaturizing QPI systems without compromising performance remains a critical challenge for applications requiring compactness and portability. Here, by introducing partially coherent illumination modulation, together with a plan meta-objective (PMO) design, we present a compact QPI system with sub-micron resolution. The PMO is a monolithically integrated doublet metalens with its dispersion enabling focal shifts at two wavelengths, obviating the need for mechanical translations during image acquisition for phase retrieval. The PMO is also optimized to correct for monochromatic aberrations, delivering an object-side field of view equivalent to ~90% of the lens aperture with minimal distortion and aberrations. The spatial coherence of the illumination is controlled to enhance imaging resolution. By co-designing illumination and imaging systems, we demonstrate QPI achieving a half-pitch lateral resolution of 488 nm with a phase accuracy of 0.06λ. Our approach enables high-quality QPI analysis of diverse phase objects, including unstained biospecimens, laying the foundation for the development of compact, stable, and practical QPI platforms.