Abstract: In order to improve the precision of the incremental photoelectric encoder，reduce the complexity of the signal processing circuit and improve the stability of the servo control system，a high precision incremental encoder with a single loop output of 32 400 periodic square wave signals is developed． The encoder has an outer diameter of 90 mm，and the encoder has 3 240 lines． The data processing system completes 40 times accurate segmentation of Moiré fringe signals． Experiment result shows that the orthogonality deviation is less than 15% and the uniformity deviation is less than 20%，which greatly reduces the jitter of the servo system when the incremental encoder is applied．

Key words: accuracy, subdivision, moiré, incremental encoder, fringes