| 摘要 |
PURPOSE:To prevent a filter from being damaged even under high heat without using a powerful device, and to absorb infrared rays of a light source, by subdividing at least one direction of the vertical direction and the horizontal direction of the filter, and pressing the intercepts against each other. CONSTITUTION:An exposure illuminating device for radiating a light beam to an original 7 and projecting a reflected light from the original 7, onto a photosensitive body is provided with a light source (halogen lamp), a reflecting mirror 3 for covering a part of the light source 1 and forming a reflecting surface on the inner wall surface, and a filter 4 which is positioned between the light source 1 and the original 7, subdivides at least one direction of the vertical direction and the horizontal direction, and obstructs passing of infrared rays formed vby pressing the intercepts against each other. That is, since the intensity distribution in the vertical direction and/or the horizontal direction of a light beam by the filter is subdivided, the thermal expansion in one direction or both the directions is decreased, and the filter 4 comes to be scarcely damaged. In such a way, filter structure being free from damage due to heat is obtained without necessitating the powerful cooling device.
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