| 摘要 |
PURPOSE:To reduce a quantity of 'out of focus' of blade image by arranging plural pieces of blades for masking in a conjugate point with an original picture formed by a series of optical lenses and controlling a quantity of the movement of said blades based on a paraxial magnification with the image of the blade which is projected on the original picture. CONSTITUTION:The light of a mercury lamp 2 enters integrator lenses 3 by a means of mirror 1 and the secondary light source image is formed on a pupil 9 of a reduction lens by means of converging collimater lenses 4 and 7 and a relay lens 6. A position of a masking blade open-close mechanism 5 (blade 13) is conjugate with that of a plane of the original picture 8. The relay lens 6 forms an image of the blade 13 on the original picture 8. As the magnification obtained by the lenses 6 and 7 is y'1/y1not equal to y'2/y2, the moving process of the blade 13 is divided into a few sections according to the magnification and by controlling the moving quantity according to the magnification, a stop position 16 can approach to the proper position 17 and the reducing projection exposure in which the total quantity of 'out of focus' 18 is small can be attained. |
