Gaas Cathode Components Pinhole Flaw Detection Technology

Gallium arsenide is one of the most important and most widely used semiconductor materials. GaAs photocathode's preparation process is extremely complicated, and has a high desire of the preparation technique and the condition.This dissertation mainly researches the auto-detection of the pinhole and other blemish on the surface of the gallium arsenide substrate. An apparatus is designed for last detection of the cathode components before the next working procedure, and eliminate the unqualified production. It can also store the data of the detection, which can use to compare the different technique and materials, and research to develop the technique.This dissertation expatiate the method of collection the micrograph of the cathode components using the image acquisition card, discuss the basic theory and method of the image segmentation, and proposes a method of detecting the blemish on the cathode components' surface by deal with the micrograph, and programs to verify its feasibility.The microscope's field of view is small and it can only get a small part of the cathode component's surface. In order to overcome this disadvantage, this dissertation designs a flow of scanning the surface of cathode components. By controlling and coordinating the two-dimensional mover and auto-focus device, it can scan the cathode components automatically, and gain all the valuable surface details.This dissertation introduces the concept of the database and the characteristics of relational database. According to the characteristics of the data involved in the cathode components' surface detection, a database is designed to store the data permanently, and to search and maintain the data conveniently.Finally, the whole work is summarized and some problems remaining to be solved are pointed out.