Broadband rotary joint for high-speed ultrahigh-resolution endoscopic OCT imaging at 800  nm

Abstract

We report the development of a broadband rotary joint for high-speed ultrahigh-resolution endoscopic optical coherence tomography (OCT) imaging in the 800 nm spectral range. This rotary joint features a pair of achromatic doublets in order to achieve broadband operation for a 3 dB bandwidth over 150 nm. The measured one-way throughput of the rotary joint is greater than 80%, while the fluctuation of the double-pass coupling efficiency during 360 deg rotation is less than ±5% at a near video-rate speed of 20 revolutions/s (rps). The rotary joint is used in conjunction with a diffractive-optics-based endoscope and 800 nm spectral domain OCT system and achieved an ultrahigh axial resolution of ∼2.4 μm in air. The imaging performance is demonstrated by 3D circumferential imaging of a mouse colon in vivo.

Theranostic OCT microneedle for fast ultrahigh-resolution deep-brain imaging and efficient laser ablation in vivo

“…A homemade broadband rotary joint was used to perform circumferential scan of the microneedle. The one-way throughput was greater than 80%, with a measured back reflection less than −60 dB and an optical coupling variation less than ±5% during continuous rotation (15).…”

“…Our microneedle adopted a monolithic fiber-optic design similar to the super-achromatic microprobe recently demonstrated for ultrahigh-resolution OCT imaging at 800 nm ( fig. S1A; see also Materials and Methods) (15). To incorporate a near-infrared (NIR) laser into the same needle for ablation, we modified the previous design by using a coating-striped single-mode fiber (HI780, Corning Inc.).…”

“…By using a homemade broadband rotary joint, 3D volumetric imaging was performed by pulling back the rotating microneedle within the stationary sheath with a computerized linear translation stage at the proximal end of the probe (15). The pullback speed was used to control the separation (i.e., pullback pitch) between two adjacent circumferential images, and 10 m was used in our studies.…”

“…The previously demonstrated super-achromatic monolithic fiber-optic ball lens design concept was adopted for the current 800-nm microneedle ( fig. S1A) (15). Specifically, it consists of a homemade fiberoptic ball lens of a 230-m-diameter and a 520-m-long coreless fiber spliced to a bare single-mode fiber.…”

“…Optical coherence tomography (OCT) is an appealing technology for real-time 3D visualization of tissue microanatomy in vivo with an imaging depth of 1 to 3 mm (13)(14)(15). To go beyond the depth limitation, an OCT needle was proposed and demonstrated to enable interstitial imaging of solid tissues/organs (11,(16)(17)(18)(19)(20)(21).…”