Purpose
Real time volumetric OCT imaging would enable novel applications including efficient field triage ophthalmic exams and surgical guidance. We demonstrate a prototype ultrafast SSOCT system capable of acquiring, processing, and rendering 275 MVoxel 3D interactive images of the anterior segment up to 10 volumes/sec.
Methods
The novel SSOCT system employed a 100kHz repetition rate wavelength-swept laser source (1040 +/- 50 nm) buffered to 200kHz using a 1km optical fiber delay line and fast optical switch. The SSOCT interferometer employed a Mach-Zender topology with a transmissive reference arm and dual balanced detection (Fig. 1). System control and signal processing was performed using C++/CUDA software on a high performance graphical processing unit (Nvidia GTX TITAN). Three concurrent software threads operated to 1) perform data input using an Alazar 9360FIFO PCIe card sampling in 12 bits at 800 MS/s, 2) control OCT scanning and interact with the operator through a graphical user interface, and 3) render rotatable ray-cast volumetric data, live B-scans, and live summed-volume projections in real time. The sample arm design provided near diffraction-limited telecentric imaging over a 20mm square field of view. Images were obtained in human subjects under an IRB approved protocol.
Results
The ultrafast SSOCT system achieved an SNR of 98 dB at 200kHz A-scan rate, an axial resolution of 10.8 μm, and a 6 dB image fall-off range of 3.4 mm. For voxel dimensions of 1376x336x60, the system acquired, processed, and displayed 9.92 volumes per second. High quality real time volume renderings of the anterior segment of the naturally blinking eye of a human subject are shown in Fig. 2.
Conclusions
An ultrafast SSOCT system capable of acquiring, processing, and rendering 275 MVoxel 3D interactive images of the anterior segment up to 10 volumes/sec was demonstrated with potential novel applications in interactive ophthalmic imaging.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)