| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that the utilization efficiency of light from a light source part is bad in the case of exposing a printing plate by using 1st- order diffracted light from a diffraction grating type modulation element. SOLUTION: 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. At such a time, the light source part 311 and an illumination optical system are designed to satisfy a specified conditional expression, whereby the zero-order diffracted light and±1st-order diffracted light are not superposed each other. Thus, the zero-order diffracted light is utilized as signal light for exposure, and the exposing and recording device good at the utilization efficiency of the light is constituted. The numerical aperture of an image-formation optical system is restrained to be small, and the design of the image-formation optical system is facilitated.
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