Laser box, plane grating measuring system and photoetching machine

The utility model provides a laser box, a plane grating measuring system and a photoetching machine, and relates to the technical field of semiconductor manufacturing equipment. The laser box can be arranged on a workpiece table and comprises a box body, a single-frequency laser and a photoelectric conversion module, the single-frequency laser is used for generating and emitting laser, and the photoelectric conversion module is used for receiving and processing measurement optical signals passing through a sensor. In the laser box, the single-frequency laser performs homodyne measurement, so that the non-linear error of a measurement result is small, a frequency shift module and the like are not included, the structure is simple, the laser box is convenient to miniaturize, the laser box is convenient to arrange on a workpiece table, and the space outside the workpiece table can be saved so as to arrange other parts; in addition, the laser box is compact in structural arrangement, the distance of the laser emi