Ultrahigh Speed Imaging with Swept Source Fourier Domain OCT

Abstract

Swept source / Fourier domain OCT is a complementary technique to spectral / Fourier domain OCT which uses frequency swept lasers instead of a spectrometer and line scan camera. Swept source OCT enables imaging at 1050 nm wavelengths which improve sensitivity through ocular opacity as well as improve visualization of the choroid and optic nerve head. An ultrahigh speed, swept source prototype OCT system is demonstrated at axial scan rates of 200 kHz to 400 kHz (compared with 25 to 50 kHz for standard OCT instruments). The technology enables both wide field and high magnification OCT retinal imaging. 3D-OCT data sets of 6x6 mm of the retina, consisting of 700x700 axial scans can be acquired in <3 seconds. These data sets contain ∼500,000 axial scans, or ∼0.5 Gigavoxels of data, ∼10x more data than the standard Zeiss Cirrus cube. Large field of view OCT covering 12x12 mm, can be acquired with longer scan times. Using high magnifications and smaller fields of view, individual photoreceptors can be visualized. Images from dense volumetric data sets can be averaged to improve contrast and reduce noise. Longer wavelengths enable deeper penetration into the choroid and optic nerve head. The ultrahigh imaging speeds provided by swept source OCT enable new imaging protocols which can cover large retinal areas with standard resolutions, or small retinal areas with high resolution. These advantages suggest that swept source OCT will be an important technology for the next generation of ophthalmic OCT instruments.

Acknowledgments

Supported in part by NIH R01-EY11289-24, R01-EY013178-10, R01-EY013516-06, AFOSR FA9550-07-1-0101 and FA9550-07-1-0014. 

Financial Disclosure. JGF and JSS receive royalties from intellectual property licensed by MIT to Carl Zeiss Meditec. JGF and DH have stock options in Optovue.