Feature Of The Week 01/11/15: Indiana University Demonstrates Adaptive Optics Optical Coherence Tomography at 1 MHz
Since its first report in 1991, OCT has undergone tremendous advances in almost all aspects of its underlying technologies and methods. For ophthalmic imaging, one of the most impactful advances has been the substantial improvement in image acquisition speed. Increased speed has enabled larger fields of view (FOV) of the retina to be imaged faster and with finer spatial and temporal sampling than ever before. These have greatly expanded the scientific and clinical utility of OCT and have opened new directions into imaging both structure and function of the retina.
In this paper, we demonstrate a novel quad-spectrometer adaptive optics (AO-)OCT system for ophthalmologic use that operates at 1,000,000 A-lines/s (MHz) at a wavelength of 790 nm with 2.4 x 2.4 x 5.3 μm^3 3D resolution in retinal tissue. Central to the spectral-domain design is a novel detection channel based on four high-speed spectrometers that receive light sequentially from a 1 × 4 optical switch assembly. Absence of moving parts enables ultra-fast (50ns) and precise switching with low insertion loss (−0.18 dB per channel). This manner of control makes use of all available light in the detection channel and avoids camera dead-time, both critical for imaging at high speeds. Additional benefit in signal-to-noise accrues from the larger numerical aperture afforded by the use of AO and yields retinal images of comparable dynamic range to that of clinical OCT. We validated system performance by a series of experiments that included imaging in both model and human eyes. We demonstrated the performance of Indiana MHz AO-OCT system to capture detailed images of the microscopic retina. To date, this is the fastest ophthalmic OCT system based on spectral-domain technology in the 700 to 915 nm spectral band.
For more information see recent Article. Courtesy of Omer Kocaoglu from Indiana University.