All reflective optical delay line for real-time optical coherence tomography

One of the most interested aspects in the development of optical coherence tomography (OCT) is to construct a stable and easy fabricated optical delay line that can perform real-time imaging for clinical applications. There are many methods that have been used for fast scanning in OCT. However, most of the configurations are difficult to construct or variational intensity loss exists during the scanning because of the walk-off of different wavelength components and different tilted angle of the scanner. We proposed and constructed an optical delay line with all reflective components that is compact, easy to fabricate and can avoid the intensity loss during the scanning. The optical delay line was constructed of a retro-reflector fabricated with two right-angled prisms assembled on an aluminum jig, a reflection mirror and a galvoscanner. The size of the optical delay line is within 2 cm x 2 cm and the system can provide a scanning rate in the kilohertz range. The achieved imaging depth is 3.3 mm when the vibration angle of the scanning mirror is +/- 9 degrees. This system can perform a real-time scanning and thus is supposed suitable for clinical applications.