Ultrawide-field parallel spectral domain optical coherence tomography for nondestructive inspection of glass

Aiming at the requirements of real-time inspection in material industry, an ultrawide-field parallel SD-OCT system capable of visualizing cross-sectional image of internal structures by a single shot of a 2-D CMOS camera is developed. To achieve ultrawide-field parallel detection, one meniscus lens with negative dioptric is introduced as an additional relay lens and imaging optics including sample arm, relay lenses and spectrometer are optimized as a whole for desirable imaging quality. The developed system has an ultrawide-field of 35 mm and an axial range of 8 mm in air. The maximum on-axis sensitivity and the axial resolution are experimentally determined to be 65 dB and 17.7 μm, respectively. The on-axis lateral resolution is measured to be 44 μm in parallel direction and 22 μm in scanning direction. The system is applied to obtain 3-D volume images of a set of glass-samples covering an area of about 28 mm by 15 mm with thicknesses ranging between 2.1 mm and 4 mm, from which defects such as solid inclusion, micro-deformation and bubble are identified either on the surfaces or inside the samples.