Mid-infrared quantum scanning microscopy via visible light beyond spatial correlations

TL;DR

This paper introduces a raster-scanning quantum imaging method that uses visible light to perform mid-infrared microscopy, overcoming previous limitations related to spatial correlations and enhancing resolution for chemical analysis.

Contribution

It presents a novel QIUL technique that is independent of spatial correlation strength, achieving higher spatial resolution in MIR microscopy.

Findings

Achieved MIR imaging resolution beyond spatial correlation limits.

Demonstrated effective chemical imaging using visible light detection.

Overcame detection challenges in MIR spectral range.

Abstract

The mid-infrared (MIR) region of the electromagnetic spectrum spans from 2- to 25-$\mu \mathrm{m}$, serving as a valuable tool for accessing rich chemical information. Functional groups, lipids, and other complex molecules can be analyzed by optical absorption measurements due to their vibrational modes in the MIR spectral region. Over the past few decades, this field has faced challenges due to difficulties in generating MIR light and the limited maturity of detection systems in this spectral range. Quantum imaging with undetected light (QIUL) provides a spectrally tuneable photon-pair source, in which the sample can be illuminated with MIR light while visible (VIS) light is employed for detection and image reconstruction, overcoming the detection limitations and benefiting from the rich chemical information of the MIR spectral region. All previous QIUL implementations are based on spatial correlations, which are never perfect and thus hindered the imaging performance. In this work, we implement a raster-scanning QIUL method that is independent of the strength of the spatial correlations and achieves a spatial resolution beyond the limitations of these correlations.