title: Multi-MHz retinal OCT.
abstract: We analyze the benefits and problems of in vivo optical coherence tomography (OCT) imaging of the human retina at A-scan rates in excess of 1 MHz, using a 1050 nm Fourier-domain mode-locked (FDML) laser. Different scanning strategies enabled by MHz OCT line rates are investigated, and a simple multi-volume data processing approach is presented. In-vivo OCT of the human ocular fundus is performed at different axial scan rates of up to 6.7 MHz. High quality non-mydriatic retinal imaging over an ultra-wide field is achieved by a combination of several key improvements compared to previous setups. For the FDML laser, long coherence lengths and 72 nm wavelength tuning range are achieved using a chirped fiber Bragg grating in a laser cavity at 419.1 kHz fundamental tuning rate. Very large data sets can be acquired with sustained data transfer from the data acquisition card to host computer memory, enabling high-quality averaging of many frames and of multiple aligned data sets. Three imaging modes are investigated: Alignment and averaging of 24 data sets at 1.68 MHz axial line rate, ultra-dense transverse sampling at 3.35 MHz line rate, and dual-beam imaging with two laser spots on the retina at an effective line rate of 6.7 MHz.
authors.affiliation: Lehrstuhl für BioMolekulare Optik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Oettingenstr. 67, 80538 Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Klein
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wieser
authors.forename: Lukas
authors.initials: L
authors.lastname: Reznicek
authors.forename: Aljoscha
authors.initials: A
authors.lastname: Neubauer
authors.forename: Anselm
authors.initials: A
authors.lastname: Kampik
authors.forename: Robert
authors.initials: R
authors.lastname: Huber
keywords: (120.3890) Medical optics instrumentation; (140.3510) Lasers, fiber; (170.3880) Medical and biological imaging; (170.4460) Ophthalmic optics and devices; (170.4500) Optical coherence tomography