MEMS-VCSEL swept-source optical coherence tomography for multi-MHz endoscopic structural and angiographic imaging

Abstract

Swept-source optical coherence tomography (SS-OCT) enables volumetric imaging of subsurface structure, but applications requiring wide fields of view, rapid imaging, and higher resolutions have been challenging because of the need for multi-MHz A-scan rates. Until now, achieving multi-MHz A-scan rates has been limited to Fourier-domain mode-locked lasers or stretched-pulse lasers. We describe a microelectromechanical-system, vertical-cavity surface-emitting laser (MEMS-VCSEL) for SS-OCT at A-scan rates of 2.4 and 3.0 MHz using a dual-channel acquisition system. Dual-channel operation enables simultaneous acquisition of Mach-Zehnder interferometer (MZI) fringes for sweep-to-sweep calibration and resampling, overcoming inherent optical clock limitations in state-of-the-art digitizers. We demonstrate structural OCT and OCT angiography (OCTA) imaging of the swine gastrointestinal tract using a suite of endoscopic devices, including a 3.2 mm diameter micromotor catheter, a 12 mm diameter tethered capsule, and a 12 mm diameter wide-field OCTA probe. MEMS-VCSELs promise to enable ultrahigh-speed SS-OCT with a scalable, low cost, and manufacturable technology, suitable for a diverse range of imaging applications.