Adaptive-optics ultrahigh-resolution optical coherence tomography

TLDR

A compact 300 mm × 300 mm closed‑loop adaptive‑optics system using a 30 Hz Hartmann–Shack sensor and a 37‑actuator deformable mirror is integrated with a commercial UHR OCT instrument powered by a Ti:sapphire laser with 130‑nm bandwidth. The integrated AO‑UHR OCT achieves 3 µm axial and 5–10 µm transverse resolution, reduces residual wave‑front error to 0.1 µm, improves transverse resolution 2–3× over prior UHR OCT, and boosts signal‑to‑noise ratio by up to 9 dB.

Abstract

Merging of ultrahigh-resolution optical coherence tomography (UHR OCT) and adaptive optics (AO), resulting in high axial (3 µm) and improved transverse resolution (5–10 µm) is demonstrated for the first time to our knowledge in in vivo retinal imaging. A compact (300 mm×300 mm) closed-loop AO system, based on a real-time Hartmann–Shack wave-front sensor operating at 30 Hz and a 37-actuator membrane deformable mirror, is interfaced to an UHR OCT system, based on a commercial OCT instrument, employing a compact Ti:sapphire laser with 130-nm bandwidth. Closed-loop correction of both ocular and system aberrations results in a residual uncorrected wave-front rms of 0.1 µm for a 3.68-mm pupil diameter. When this level of correction is achieved, OCT images are obtained under a static mirror configuration. By use of AO, an improvement of the transverse resolution of two to three times, compared with UHR OCT systems used so far, is obtained. A significant signal-to-noise ratio improvement of up to 9 dB in corrected compared with uncorrected OCT tomograms is also achieved.