SPIE Proceedings [SPIE International Symposium on Photoelectronic Detection and Imaging: Technology and Applications 2007 - Beijing, China (Sunday 9 September 2007)] International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing - Analysis on the interferogram of a low coherence interferometric system for measuring the dispersion of chirped fiber grating through Fourier spectrometry method