High-speed Cone Beam Scanning for Thin Endoscopic Three-dimensional Measurement

Summary

Recent years have seen increasing demand for technologies that can measure the three-dimensional geometry of narrow tubular structures in medical and industrial fields. In particular, for biological tissues such as the trachea, it is desirable to observe rapid shape changes associated with respiration. However, achieving both miniaturization and high-speed operation is difficult when using endoscopes with diameters of only a few millimeters. Furthermore, approaches that incorporate actuators or optical components at the distal tip of the endoscope raise challenges in terms of safety and miniaturization.

In this study, we propose a high-speed cone beam scanning system that combines a cone beam generated by a multimode optical fiber with a high-speed rotating mirror and an ellipsoidal mirror (Fig. 1). The proposed optical system rapidly controls the incident angle of light entering the optical fiber, enabling high-speed scanning of the cone-beam emission angle at the tip of the endoscope (Fig. 2). Compared with conventional approaches based on a rotation stage, the proposed system enables substantially faster scanning performance (Fig. 3). We also demonstrate three-dimensional shape measurement of cylindrical and prismatic inner surfaces using a thin probe with a diameter of only a few millimeters (Fig. 4). This research provides a fundamental technology toward faster three-dimensional measurement with thin endoscopes and is expected to contribute to applications such as medical diagnosis and robotic inspection in confined spaces.

Fig. 1 Proposed concept.	Fig. 2 Optical designs; a) conventional, b) proposed.
Fig. 3 Cone beam scanning speeds; a) conventional, b) proposed.	Fig. 4 Three-dimensional endoscopic measurement.

Reference

1. Tomohiro Sueishi, Makoto Komura, and Masatoshi Ishikawa: High-speed Scanning Design of Fiber-optic Cone Beam for Fast Three-dimensional Endoscopic Measurement, SICE Festival 2026 with Annual Conference (SICE FES 2026) (Yokohama, 2026.9.17)/Proceedings, pp.1209-1216