Absolute grating encoder with high-precision and large measurement range

In order to solve the problem of the mutual limitations of large measurement range and high precision of absolute grating encoders, this paper employs absolute codes to individually number each spliced grating section on the substrate, leveraging the asymmetric code arrangement. With the light splitting ability of beam splitter, the light source is divided into dual beams and inputted into the encoder to form a dual beam reading head. At least one beam of light can always generate a stable signal within the travel range, and then the serial number of this grating area is determined through absolute codes. The signals generated by gratings with different numbers can be calibrated using calibration parameters. With the help of the data splicing principle and the structure of dual-beam, a nanoscale positioning accuracy scheme with a meter-level measurement range is proposed.