Abstract:The image-based photoelectric encoder is a precision instrument that uses photoelectric conversion and image processing technology for displacement and angle measurement. It is widely applied in aerospace, industrial automation, robotics control, and other fields. Compared to traditional photoelectric encoders, image-based encoders integrate modern image sensors (such as CCD and CMOS) with digital signal processing technology, offering higher resolution and greater flexibility. This article reviews the development status of image-based photoelectric encoders both domestically and internationally, covering their basic principles, overseas technical achievements, and domestic research progress. International research focuses mainly on high-resolution absolute displacement encoders, multi-faceted optical axis angle encoders, and high-precision image processing encoders. In contrast, domestic research has improved encoder accuracy and reliability through advances in encoding methods and sensor design. Furthermore, the article also provides prospects for the improvement of complex signal processing capabilities, error correction and compensation technology, high-precision manufacturing and assembly technology of image-based optoelectronic encoders, hoping to provide useful references for related scientific research work.