EXPOSURE DEVICE FOR DIFFRACTION GRATING

PURPOSE:To improve the precision of exposure by obtaining a plurality of observed values of grating periods by a verification means, correcting a set value to values corresponding to the observed values by a control unit on the basis of the observed values and compensating the quantity of control of an exposure mirror. CONSTITUTION:A substrate 10 is irradiated by laser beams L, and a diffraction- grating forming surface is adjusted by an adjusting mechanism 93 so as to be shaped at right angles with a surface-plate surface 8 and laser beams L. A reference surface 10a is positioned by projecting laser beams L and regulating the revolution of a mounting section 77. A rotating carriage 78 is turned to irradiate a grating surface by laser beams, and the rotating carriage 78 is adjusted so that reflected beams reflected by a diffraction grating G coincide with incident beams. A control unit 90 varies and regulates the pitches of interference fringes by controlling the angles of exposure mirrors 3, 4 and controls a grating period while adjusting the movement of the stroke of a sample base 5 in response to the grating period, positions the reference of the substrate 10 by regulating the revolution of the sample base 5, and controls the exposure time by the open-close operation of a shutter 25 for exposure.