Total internal reflection based super-resolution imaging for sub-IR frequencies

TL;DR

This paper introduces a near-field imaging technique using total internal reflection and a spatial modulator to achieve sub-wavelength lateral resolution and sensitive optical thickness measurements at 140 GHz.

Contribution

The authors present a novel super-resolution imaging method combining total internal reflection with near-field modulation for rapid optical thickness mapping.

Findings

Achieved sub-wavelength lateral resolution at 140 GHz.

Enabled rapid computational reconstruction of optical thickness images.

Successfully mapped biological tissue variations.

Abstract

For measurements designed to accurately determine layer thickness, there is a natural trade-off between sensitivity to optical thickness and lateral resolution due to the angular ray distribution required for a focused beam. We demonstrate a near-field imaging approach that enables both sub-wavelength lateral resolution and optical thickness sensitivity. We illuminate a sample in a total internal reflection geometry, with a photo-activated spatial modulator in the near-field, which allows optical thickness images to be computationally reconstructed in a few seconds. We demonstrate our approach at 140 GHz (wavelength 2.15 mm), where images are normally severely limited in spatial resolution, and demonstrate mapping of optical thickness variation in inhomogeneous biological tissues.