| 摘要 |
<P>PROBLEM TO BE SOLVED: To highly accurately correct displacement of the focusing position of an abnormal dispersion lens, resulting from a temperature change. <P>SOLUTION: The projection lens device 10 includes: a projection lens system 13 composed of first to third lens groups 16 to 18; a lens barrel 14 composed of first to third lens barrels 19 to 21; and a connection member 15. The third lens group 18 includes an abnormal dispersion lens 22 and is held by the third lens barrel 21. The connection member 15 is made of an Invar material with a small thermal expansion coefficient, extends along an optical axis L1 from the edge 12a of the mount 12 of a housing 11, and is screwed to the rear end of the third lens barrel 21. The axial dimension A of the connection member is set so that displacement of a focusing position, resulting from a temperature change of the abnormal dispersion lens 22, is offset by an amount of movement of the abnormal dispersion lens 22, resulting from a temperature change of the third lens barrel 21. <P>COPYRIGHT: (C)2011,JPO&INPIT |
