| 摘要 |
PURPOSE: Catadioptric reduction lens is provided to prevent damage the reflective coatings that are normally applied to the surfaces of mirror blanks and also prevent slightest flaws on any of their reflective surfaces adversely affect the qualities of images projected onto their image plane. CONSTITUTION: Light from an illumination system enters a projection lens from that side of the object plane(2) opposite to the image plane and initially passes through a mask arranged in the object plane. Light transmitted by the mask then transits a collecting lens(11) with a convex entrance surface, where the collecting lens is arranged between the object plane(2) and the beam-deflecting device(7), and then is deflected toward a mirror group(12) that contains both the concave mirror(6) and a pair of negative lenses(13,14) situated immediately in front of same, each of which has its surfaces curved towards the front surface of the concave mirror(6), by the folding mirror(9) of the beam-deflecting device(7), where the folding mirror(9) is inclined at an angle with respect to the optical axis(15) of the preceding section differing from 45£deg.| that has been chosen such that it deflects light incident on it through an angle greater than 90£deg.|, e.g., through 100£deg.|. Light reflected by the concave mirror(6) that has passed through the pair of negative lenses(13,14) twice and been reflected back to the beam-deflecting device(7) is reflected toward the dioptric second section(8) by the second folding mirror(10) of the beam-deflecting device(7). The optical axis(16) of the second section is parallel to the optical axis(15) of the entrance section and thus allows a mutually parallel orientation of the object plane(2) and the image plane(3), which simplifies the operation of a scanner.
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