Miniaturized endoscopic probe for optical coherence tomography with magnet driving device

This paper proposes an endoscopic probe for optical coherence tomography (OCT) applying on side-imaging of internal organs. The probe consists of single-mode fiber, a gradient-index (GRIN) lens, and a mirror of cylindrical wedge shape attaching to a magnetized metal piece by epoxy with a short steel wire. For OCT scanning, we use magnetic field generated by a larger magnet externally to drive the rotation of the magnetized metal. Compare with other probes, our probe design has two distinct advantages: 1) The exit beam will be unobstructed during 360 degree circumference scanning because there are no connecting wires in the scanning part. 2) In principle, the probe can be made very tiny because of the simple structure consisting only the single-mode fiber, GRIN lens, reflection mirror and the magnetized metal piece. We used a spectrometer-based Fourier-domain OCT system and the system sensitivity with our prototype probe was measured to be 91 dB. The axial and lateral resolutions of the system are 6.5 μm and 8.1 μm, respectively.