The linear scale is divided into open and close type.The open type is the high precision one, the production type is YJCT, and the output wave is sine wave. It is mainly used in digital reconstruction of precision apparatus, and its highest resolution ratio can reach 0.1μm.The close type is mainly used in the digital reconstruction of average machine and apparatus. The output wave is square wave. According to the outline, it can be divided into small-size type,standard-size and large-size type. The type is divided into YJCF, YJCE, YJCG. The large-size type can reach 3000mm,the resolution ratio is 1μm,5μm. Various type of assembly accessories is provided for the customer to facilitate the equipment of the system.