A laser beam from the light source part 311 is made incident on a modulation part 314 being the array of the diffraction grating type modulation elements, and only zero-order diffracted light from the modulation part 314 is guided to sensitive material 9 by using a filtering optical system. 光源部311からのレーザー光を回折格子型の変調素子の配列である変調部314へと入射させ、変調部314からの0次回折光のみをフィルタリング光学系を用いて感材9へと導く。 - 特許庁