The annual shipment of semiconductor detectors of the coaxis Transistor Outline（TO） packaging type is as high as tens of millions. Therefore

the quality control and testing are very important. Traditional manual visual inspection with microscope has a high rate of false detection and missed detection because of the influence of subjective judgment and visual fatigue. To solve this problem

this paper proposes an Automatic Optical Inspection（AOI） scheme for the appearance of coaxial semiconductor detectors. The visual inspection is used to automatically identify and classify qualified products and non-conforming products. The depth of field synthesis technique is used for the height detection of wire arcs. The test results of the prototype show that the proposed scheme has good detection adaptability and low false detection rate

which is suitable for batch inspection task of production line and can replace manual visual inspection.