"Real time en face Fourier-domain optical coherence tomography with direct hardware frequency demodulation"Benjamin R. Biedermann, Wolfgang Wieser, Christoph M. Eigenwillig, Gesa Palte, Desmond C. Adler, Vivek J. Srinivasan, James G. Fujimoto, Robert Huber
Optics Letters 33, 2556-2558 (2008)
We demonstrate en face swept source optical coherence tomography (ss-OCT) without requiring a Fourier transformation step. The electronic optical coherence tomography (OCT) interference signal from a k-space linear Fourier domain mode-locked laser is mixed with an adjustable local oscillator, yielding the analytic reflectance signal from one image depth for each frequency sweep of the laser. Furthermore, a method for arbitrarily shaping the spectral intensity profile of the laser is presented, without requiring the step of numerical apodization. In combination, these two techniques enable sampling of the in-phase and quadrature signal with a slow analog-to-digital converter and allow for real-time display of en face projections even for highest axial scan rates. Image data generated with this technique is compared to en face images extracted from a three-dimensional OCT data set. This technique can allow for real-time visualization of arbitrarily oriented en face planes for the purpose of alignment, registration, or operator-guided survey scans while simultaneously maintaining the full capability of high-speed volumetric ss-OCT functionality.
BMO authors (in alphabetic order):
Optical Coherent Ranging and Optical Coherence Tomography (OCT): Imaging and profilometry with rapidly frequency swept laser sources
Fourier Domain Mode Locking (FDML): Spectral mode locking in optics and applications