DIFFRACTION GRATING EXPOSING DEVICE

PURPOSE:To make possible the exposure of a diffraction grating with good accuracy by taking out a laser beam for exposing by a reflection means and reading the diffraction angle of the diffracted light by the diffraction grating attached to a checking stage so that the result thereof can be utilized for correcting the set angle of an exposing mirror in the exposing stage. CONSTITUTION:A checking means 7 for confirming the diffraction grating period formed on a substrate 10 is provided to an exposing device. The means 7 is movably disposed with a sliding mirror 75 in the optical path between the 2nd mirror 13 and the 1st beam expander 16 of an exposing optical system 2. The mirror 75 is retreated so as not to hinder the exposure by the laser beam L from a laser oscillator 1 for exposing in the exposing stage but is moved to the advance position and is disposed into the optical path to reflect the beam L toward the checking stage 76 in the checking stage. The stage 76 has a diffraction grating mounting part 77, which part 77 is freely rotatably supported by a turntable 78. The rotating angle thereof is measured and is displayed on a display part 79.