26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

Snapshot MWIR Polarimetric Imaging Enabled by a Metalens

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral ANZOS | Photonics and Optics (ANZCOP)

Description

Polarimetric thermal imaging provides information beyond conventional infrared intensity imaging, including surface orientation, material properties and polarisation signatures. Existing mid-wave infrared (MWIR) polarimetric imaging systems typically rely on rotating polarisers, beam splitters or detector-integrated micropolariser arrays, increasing system complexity and limiting compact implementation.

Here we present the design, optimisation and experimental demonstration of a snapshot MWIR polarimetric imaging system enabled by a polarisation-sensitive metalens. The metalens simultaneously forms multiple polarisation-resolved thermal images on a commercial bolometer-based infrared focal plane array (FPA), enabling linear polarisation information to be recovered from a single exposure without moving parts or additional polarisation optics. The optical design was optimised to improve imaging performance and polarisation discrimination while maintaining compatibility with a conventional thermal infrared camera.

The four simultaneously acquired linear-polarisation images, corresponding to analyser orientations of 0°, 45°, 90° and 135°, are processed to reconstruct the linear Stokes parameters (S0, S1 and S2). These parameters yield the total intensity, degree of linear polarisation (DoLP) and angle of linear polarisation (AoLP) of the observed scene. Experimental results demonstrate thermal polarimetric imaging of representative targets, revealing polarisation-dependent image contrast associated with surface geometry and material properties that is not apparent in conventional thermal images. Real-time measurements further demonstrate stable snapshot operation and continuous tracking of dynamic linear-polarisation changes.

The metalens provides a compact optical solution for infrared polarimetric imaging while remaining compatible with commercially available thermal cameras. This work highlights the potential of metasurface optics combined with computational polarimetric image reconstruction to realise compact and scalable MWIR polarimetric imaging systems for applications including autonomous sensing, machine vision, remote inspection and environmental monitoring.