| 摘要 |
PROBLEM TO BE SOLVED: To provide a projection optical system which has zoom configuration by a small number of lenses while maintaining high optical performance. SOLUTION: The projection optical system has the zoom configuration by a first negative group (Gr1), a second positive group (Gr2), a third group (Gr3), and a fourth positive group (Gr4) in order from its enlargement side; and the third group (Gr3) is composed of one negative lens and one positive lens, i.e. two lenses and the fourth group (Gr4) is composed of one positive lens. Further, the first group (Gr1) and third group (Gr3) each include one or more aspherical surfaces and the power is varied by moving at least the second group (Gr2) and third group (Gr3). COPYRIGHT: (C)2004,JPO
|
