In the production process of OLED products, process cutting, transportation collision and so on may lead to cracks on the edge of the product, and the organic light-emitting materials inside will be oxidized and eroded by water vapor due to the direct contact between cracks and air, resulting in serious poor functional display. And this process is progressive. At the initial stage, the defects are very subtle, which can not be identified by naked eyes and ordinary equipment. It is difficult to check and intercept, which has become the difficulty of the whole industry.