Motivation:
Endoscopy is a critical tool in modern medicine, enabling minimally invasive diagnosis and surgery for conditions ranging from colorectal cancer to gastrointestinal disorders. However, standard endoscopes are limited to capturing 2D intensity images (RGB), which often miss subtle tissue anomalies. Polarization information is a crucial missing modality; light polarization reveals properties of tissue microstructure—such as surface texture, collagen alignment, and early-stage lesions—that remain invisible to standard color cameras and the human eye. Adding polarization capabilities to endoscopy could significantly improve diagnostic accuracy and early detection rates.
Challenge:
a. The primary obstacle to integrating polarization imaging into clinical practice is physical size. Conventional polarization cameras rely on bulky optical assemblies, moving parts, or complex division-of-focal-plane sensors that sacrifice resolution. These solutions simply cannot fit into the constrained tip of a medical endoscope. To address this, our project turned to lensless imaging. By removing the bulky lens and replacing it with a simple, ultra-thin optical element (such as a diffuser or coded mask), the imaging system can be miniaturized to a scale suitable for insertion into the human body. This approach offers a potential path to the "Holy Grail" of a compact, disposable, and informative endoscopic sensor.
b. While lensless imaging solves the size constraint, it introduces a significant performance challenge. Lensless polarization reconstruction is an ill-posed computational problem; without a lens to focus light, the resulting images often suffer from low spatial resolution, noise, and a lack of high-frequency detail. On its own, a lensless polarization camera is "not good enough" to provide the reliable, high-fidelity imagery required for medical diagnosis.
Goal:
The core objective of this project was to overcome this quality barrier without sacrificing miniaturization. We observed that standard miniature RGB cameras are already mature, widely available, and easily integrated into endoscopes.
Consequently, we designed and built a prototype that combines a lensless polarization camera with a standard RGB camera. Our breakthrough lies in utilizing the high-quality structural information from the standard RGB image to "guide" the reconstruction of the polarization data. By fusing the detailed spatial data from the standard camera with the raw polarization signals from the lensless sensor, we can computationally recover high-fidelity polarization images.
Impact:
This approach allows us to generate a next-generation endoscope that provides rich polarization information alongside standard RGB video, with negligible impact on the device's size or cost. The successful development of this Guided Lensless Polarization Imaging system (validated in our CVPR 2026 acceptance) paves the way for advanced medical devices that can detect pathologies earlier and more accurately than ever before.
