[en] As the conventional optical defect inspection systems use a single or two lasers to form a measurement region, defects are inspected in a narrow measurement region. In this study, we fabricated a multidiode optical defect inspection system that used multiple laser diodes to expand the measurement region. An experiment was conducted to determine whether the proposed system had a similar performance with respect to the conventional systems. Specimens were fabricated by simulating the defects of the pressure piping, which could occur in a nuclear power plant or in industrial sites. Accordingly, the purpose of the experiment is to examine whether defects could be inspected during the operation of a piping circulation system. Our results show that using multiple laser diodes could reduce the cost and secure a wider measurement region, thereby achieving a cost-effective and high-efficiency defect detection