Single-track absolute grating ruler

The utility model discloses a single-track absolute grating ruler, comprising a light source, a reflector, incremental scaleplate grid lines, a glass substrate, a movable diaphragm, a photoelectric receiver and an indicating grating, wherein the light source and the reflector are assembled to form an illuminating light path, the glass substrate is engraved with the incremental scaleplate grid lines with equal width and equal distance, parallel and equidistant milestone marking positions are engraved below the incremental scaleplate grid lines on the glass substrate, the indicating grating is embedded in an opening on the left upper part of the movable diaphragm, an upper side CMOS sensor and a lower side CMOS sensor are respectively embedded in upper-lower symmetrical openings which are arranged on the right side of the movable diaphragm, the indicating grating is mounted by closely adhering to the glass substrate, the mounting position of the upper side CMOS sensor is aligned with the incremental scaleplate