Development of a small-diameter and high-resolution industrial endoscope with CMOS image sensor

In the industrial field, an endoscope is typically employed for the observation and inspection of internal defect and corrosion of an engine and chemical plant. Current industrial optical endoscopes normally use CMOS sensor which offers best performance as an image pickup device. Here we report experimental demonstration of an industrial endoscope modality consisting of a 5 mm diameter rigid tube and 1280 × 960 pixels CMOS camera, which enables accurate diagnosis of small-scale industrial components with hollow shape. As a proof of concept, we successfully perform arc-surface imaging at a resolution of 57 lp/mm and ± 30° field of view. Finally, potentially applying the wave-front coding method to extend the depth of field of endoscopic system is comprehensively discussed.