| 摘要 |
PURPOSE:To exert no influence on the characteristic of an optical system for reading a reproduced image of an original picture, even if the image forming magnification of this image is varied, by making a focal distance variable in a state that an interval between an exit pupil of a projecting optical system and a Fresnel lens is kept constant, with regard to the projecting optical system for forming an image of the original picture. CONSTITUTION:In a projecting device 3 having projecting optical system 11, 12 for forming an image of an original picture 10, and a Fresnel lens 12 placed in an image field side of this projecting optical system, said projecting optical system is used as a variable magnification image forming optical system which can vary its focal distance, in a state that the interval between its exit pupil and said Fresnel lens 12 is kept constant.
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