Fiber-based high resolution OCT system with halogen light source

Fiber-based high resolution OCT system was achieved using a white-light source with a halogen lamp, which has advantages of wide spectrum, compact size and low cost. The axial resolution measured without using objective lens in the sample arm was about 2.5 mum. The thickness of a thin film (about 7 gm thick) was measured to evaluate the high resolution performance. The measured interferogram showed two well-distinguished peaks corresponding to two interfaces of the thin film. The implemented OCT system was composed of fiber-optic Michelson interferometer instead of that of conventional bulk optics. To adapt a white-light source to the fiber based OCT system and providing high resolution, a wideband single mode fiber with a large mode field diameter for high coupling efficiency, a wideband fiber coupler with flat coupling response, a cascaded detector scheme for broadband detection and dispersion control are required. Dispersion mismatch due to introducing an objective lens in the sample arm can be controlled effectively by employing a proper optical component in the reference arm. After dispersion control, resolution of about 3.5 mum was enhanced to about 2.5 mum, which is similar to the objective lens-free resolution, and wide sidelobes was also well suppressed.