Method and device for coding and measuring absolute position grid ruler based on pseudo random sequence

The invention relates to a method and device for coding and measuring an absolute position grid ruler based on pseudo random sequences. The method for coding and measuring the grid ruler comprises the following steps: using two basic coding units of a wide coding unit and a narrow coding unit to generate a single code channel absolute position coding grid ruler according to a pseudo random sequence value; acquiring grid ruler digital images with a plurality of codes through one step by an image sensor; and after pre-processing the images by a digital image processing unit, demodulating a phase difference of image carriers and reference carriers of the grid ruler and a rough measurement position of the digital image of the grid ruler, and further calculating the accurate absolute position of a grid ruler sensor relative to the grid ruler. The device consists of a grid ruler, a grid ruler image sensor and a digital image processor. The device is suitable for various linear and round grid rulers (encoders) and has s broad application prospect.