Real-time defect inspection of periodic patterns using self-pumped barium titanate crystal

Results are presented on the observation of 5 μm×5 μm defects in a similar size periodic structure using self-pumping in a 5 mm×6 mm×5 mm barium titanate crystal and optics of NA ≈ 0.1 Signal-to-noise ratios in excess of 10 have been obtained, indicating that smaller sizes can be detected using a larger crystal and optics with higher NA without the need to magnify the object mask. The self-pumping geometry is useful in simplifying the experimental setup. © 1990.