# FACE-ing the future of single-pixel complex-field microscopy beyond the visible spectrum

## TL;DR

A new imaging technique called FACE improves speed and performance for single-pixel imaging in non-visible light, enabling real-time applications.

## Contribution

FACE introduces a novel method for single-pixel complex-field imaging with high speed and throughput in non-visible spectral regions.

## Key findings

- FACE achieves a high space-bandwidth-time product for real-time imaging.
- FACE-SPCM is demonstrated for phase imaging in microfluidic devices.
- FACE enables real-time imaging of chemical reactions and fluid mixing.

## Abstract

Single-pixel imaging (SPI) has long been recognized for its potential in spectral regions where conventional imaging sensors fall short, such as the near-infrared spectrum. Yet, despite its sensitivity, SPI and its complex-field variants have faced critical bottlenecks in speed and throughput, hindering their adoption for real-time applications. A recently proposed approach—frequency-comb acousto-optic coherent encoding (FACE)—places an important step in overcoming these barriers, delivering an unprecedented space-bandwidth-time product. By showcasing its versatility through several compelling proof-of-concept demonstrations in real-time complex-field microscopy, this advance paves the way for transformative progress in optical imaging beyond the visible spectrum. We discuss here advantages, challenges and potential future directions for scaling up this technology.

Examples on the utility of single-pixel complex-field microscopy with frequency-comb acousto-optic coherent encoding (FACE-SPCM) as demonstrated by Wu et al., by phase imaging inside a microfluidic device. Left: Droplet formation with water and oil as dispersed and carrier medium, respectively. Center: Chemical reaction between acetic acid and baking soda. Right: non-reactive liquid mixing of ethanol and pure water. FACE-SPCM images adapted from Wu et al.1