Abstract: From the perspective of technologies, the paper analyzed the hairiness testers of different detection principles, that is, photoelectric projection counting method, image method and diffuse reflection method, introducing their design ideas as well as merits and demerits, and analyzed the difference between the hairiness number indexes and hairiness H value. After analysis, it is believed that the hairiness tester using the photoelectric projection counting method will be more widely used.

Key words: hairiness; hairiness tester; image processing; diffuse reflection; projection