# Ultra-stable speckle-based optical fiber sensing demonstrated on an uncrewed aerial vehicle platform

## TL;DR

A new ultra-stable optical fiber sensing system was tested on a drone, enabling real-time structural health monitoring in harsh aerospace conditions.

## Contribution

The study introduces an ultra-compact, stable speckle-based sensing architecture suitable for real-world aerospace applications.

## Key findings

- The system maintained measurement integrity at ±7 G sinusoidal acceleration.
- Real-time strain interrogation was validated in the −100–400 µε range with 1.63 µε standard deviation.
- The design suppresses environmental drift, enabling robust sensing in dynamic aerospace conditions.

## Abstract

Speckle-pattern interrogation offers a route to high-resolution spectral sensing, but its uptake has been constrained by poor temporal stability under real-world conditions. Here, we introduce an ultra-stable speckle-based architecture that overcomes these limitations and enables real-time structural health monitoring of uncrewed aerial vehicles. Unlike conventional approaches that rely on large-scale, free-space passive speckle decorrelation, our system utilizes an ultra-compact speckle pattern via laser-written scattering centers in a high aspect ratio flat fiber, encapsulated within a 3D-printed polylactide housing. This architecture suppresses environmental drift and enables robust, high-fidelity interrogation of fiber Bragg gratings in dynamic aerospace conditions. The system demonstrated exceptional stability under sustained mechanical excitation, maintaining measurement integrity at ±7 G sinusoidal acceleration along the axial direction. Furthermore, in-flight validation across uncrewed aerial vehicle flight tests confirmed real-time strain interrogation in the −100–400 µε range with a standard deviation in measurement of 1.63 µε. These results mark the demonstration of stable, real-time speckle-based interrogation in flight, establishing a path toward broader deployment of specklemeters in harsh environments.

Przemyslaw Falak and colleagues report optical speckle–based fiber sensing demonstrated outside the lab on a drone under vibration and environmental disturbance. The study shows specklemeter technology can support structural monitoring of real-world aerospace systems