Source spectrum shaping method for low-coherence interferometry.

ABSTRACT

Low-coherence interferometry (LCI) suffers mainly from low signal-to-noise (S/N) ratio. By using the source spectrum shaping method (SSSM), the authors can enhance the visibility of the zero-order fringe (V) and S/N ratio in LCI. The presented approach was analyzed numerically for a set of theoretical Gaussian light sources, with different central wavelengths and different spectrum widths. The results have shown a significant improvement of the visibility V. Additionally, a set of commercially available light emitting diodes was analyzed to find the best possible setup. Results of numerical calculations were verified experimentally in an SSSM low coherence Twyman-Green interferometric setup equipped with three light sources.