Innovative light control technique improves miniature endoscopic imaging capabilities

Endoscopic optical coherence tomography is widely used to visualize tissue microstructures in real time, but current probes face clear limitations. Conventional designs struggle in narrow lumens, where space is limited and tissue damage must be avoided. More importantly, probe designers have long faced a physical trade-off: increasing image sharpness reduces imaging depth, while extending depth blurs fine details. These constraints restrict the clinical value of endoscopic imaging, especially for early diagnosis in confined organs. Manufacturing challenges further limit probe miniaturization and robustness. Based on these challenges, there is a strong need to develop new side-viewing probes that deliver deep, sharp imaging without increasing size or complexity.

Writing (DOI: 10.1038/s41378-025-01034-x) in Microsystems & Nanoengineering in 2025, a research team led by scientists at Beijing Institute of Technology presents a new side-viewing fiber probe for optical coherence tomography. The probe introduces a redesigned light-delivery strategy that dramatically extends imaging depth while preserving high lateral resolution. Tested using both linear and rotational scanning, the probe produced clear images in biological tissues and narrow-lumen samples. The results suggest a practical path toward safer, more informative endoscopic imaging in clinical and industrial settings.

At the core of the advance is how the probe controls light. Instead of focusing light into a single tight spot that quickly spreads, the new probe maintains a narrow beam over a long distance. This allows the system to capture clear images across a much larger depth range.

Experiments showed that the probe achieves an imaging depth of roughly 350 micrometers—more than ten times deeper than many conventional fiber probes—while keeping lateral resolution around 1.4 micrometers. In practical terms, this means fine structures remain visible even as the probe scans deeper into tissue.

Crucially, this performance comes in a probe with a diameter close to one millimeter, small enough for narrow anatomical passages. The researchers also demonstrated that imaging quality remains stable during rotational scanning, a key requirement for three-dimensional endoscopic imaging.

The probe successfully resolved internal features in layered materials, plant tissues, and animal tissues. These demonstrations show that extended depth and high resolution no longer need to be traded against each other. Instead, both can be achieved in a compact, fiber-based design suitable for real-world use.

"This work shows that we can rethink the limits of miniature endoscopic imaging," said the study's corresponding author. "By keeping the beam focused over a longer range, we can see deeper while preserving fine detail. Just as importantly, the probe is built using standard fiber-processing techniques, which makes it realistic to scale and deploy. We believe this approach can help bring more reliable, less invasive imaging tools into clinical practice."

The new fiber probe could broaden the use of endoscopic OCT in areas where imaging has been difficult or risky. In medicine, it may enable clearer visualization of airways, gastrointestinal tracts, and pediatric organs, supporting earlier diagnosis with less tissue disturbance. Beyond healthcare, the probe could be adapted for non-destructive inspection of industrial components, layered materials, or micro-scale defects. Because the design is compact, low-cost, and compatible with existing manufacturing methods, it offers a realistic route from laboratory research to practical devices. More broadly, the study highlights how smarter light control can redefine what miniature imaging systems can achieve.