"Multi-MHz retinal OCT"Thomas Klein, Wolfgang Wieser, Lukas Reznicek, Aljoscha Neubauer, Anselm Kampik, and Robert Huber
Biomedical Optics Express, Vol. 4, Issue 10, pp. 1890-1908 (2013)
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.
BMO authors (in alphabetic order):
Fourier Domain Mode Locking (FDML): Spectral mode locking in optics and applications
Optical Coherent Ranging and Optical Coherence Tomography (OCT): Imaging and profilometry with rapidly frequency swept laser sources