A grating ruler is a device for measuring length or position, which utilizes optical principles and digital technology. Grating scales usually consist of a long transparent base and a read head that moves along the base. The base has a series of parallel grating lines that have been etched into the transparent base at very precise intervals. A photoelectric sensor is built into the readhead that detects reflected light on the grating lines to determine the position and direction of movement of the readhead. The readhead also includes a digital display that shows the position of the readhead relative to the base.

Grating scales are widely used in machining, precision measurement, semiconductor manufacturing and other fields, and are popular for their high precision, high reliability, and ease of use. The accuracy of the grating ruler can usually reach the sub-micron level, and it can be connected with computers, controllers and other equipment through various interfaces (such as digital, analog, and communication interfaces) to realize automatic measurement and control.