||High-speed optical delay line for optical coherence tomography
||Sanz, Laura Pastor (Fibers & Nonlinear Optics, COM, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
||Frosz, Michael Henoch (Fibers & Nonlinear Optics, COM•DTU Department of Communications, Optics & Materials, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Bjarklev, Anders Overgaard (management, COM•DTU Department of Communications, Optics & Materials, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
||Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark
||A review of the several methods used to build optical delay lines for optical coherence tomography has been done. Their advantages and disadvantages have been analyzed. The baseis and equations that define the operation of a fourier domain optical delay line (FD-OPL) based on a tilting mirror have been analyzed. This is the state of the art of the current technology. A high-speed FD-OPL with a galvo-scanner as a scanning element working at a central wavelength of 1550 nm with vertical geometry has been built as the reference arm of an optical coherence tomography (OCT) system. The vertical geometry mad a minimization of the DC level in the delay line as low as =10% possible. After achieving this, an interferogram has been obtained by placing a mirror in the sample arm. Its carrier frequency has been adjusted to 100 KHz and the dispersion has been compensated. Characterization of the delay line showed excellent linearity, scan velocity of 0.92 m/s and a total group delay of 4.6 mm. The dynamic range was 56 dB. The chirp, signal envelope and Fourier Transform (21 kHz bandwidth) were measured. Integration of the FD-OPL with an existing OCT mobile system, with digital processing at 100 KHz has been done. The 43.5 um achieved resolution was measured. The scan repetition rate, duty cycle and dynamic range were 125 A scans/s, 62.5% and 110 dB, respectively. Imaging of skin tissue has been done and compared with images acquired at 1300 nm. Som resolution measurements with a picosecond Photonic Crystal Fiber (PCF) source also have been done. The future lines with a resonant scanner for real time imaging and a special configuration for ultrabroadband sources based on all reflective elements have been described.
Creation date: 2006-06-22
Update date: 2007-02-24