Dispersion and compensation of optical coherence tomography using double-path rapid scanning optical delay line

Optical coherence tomography (OCT) with advantages of high resolution and high sensitivity is an emerging optical imaging technology that performs cross-sectional tomographic imaging of microstructure in biological system. In spite of the improvement of the longitudinal resolution by using low coherence light source, the dispersion effect aggravates with the increase of spectral bandwidth, which result in serious image blur and loss of image features. We demonstrate a double-path rapid scanning optical delay line (D-RSOD) structure in reference arm that produce the additional phase delay and group delay independent in OCT. The phase delay determined by grating defocus offset (GDO) of D-RSOD is controllable and the system dispersion is compensated by accurate adjustment of GDO in experiment. The full width at half maximum (FWHM) of the interference peak was measured to be 23.2 mu m and 15.2 mu m respectively before and after compensation. The experimental results indicate that the interference signal envelops shrink and the tomographic image clarify after dispersion compensation, D-RSOD is an effective means of dispersion compensation in OCT as well.