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1. (WO2013118471) OPTICAL SYSTEM FOR PROJECTION, AND PROJECTION-TYPE DISPLAY DEVICE

Pub. No.:    WO/2013/118471    International Application No.:    PCT/JP2013/000520
Publication Date: Fri Aug 16 01:59:59 CEST 2013 International Filing Date: Fri Feb 01 00:59:59 CET 2013
IPC: G02B 15/167
G02B 13/04
G02B 15/20
G03B 21/00
G03B 21/14
Applicants: FUJIFILM CORPORATION
富士フイルム株式会社
Inventors: NAGATOSHI, Yukiko
永利 由紀子
Title: OPTICAL SYSTEM FOR PROJECTION, AND PROJECTION-TYPE DISPLAY DEVICE
Abstract:
[Problem] To satisfactorily correct the displacement of the point of focus due to temperature variations in an optical system for projection, and to maintain the excellent optical properties of the system, even after correction, without requiring an increase in the size of the device. [Solution] An optical system which is for projection and in which the reduction side is telecentric, wherein a correction lens group (Gp) comprising a portion of the lens groups of the optical system for projection is configured so as to be mobile along the optical axis in order to correct the displacement of the point of focus due to temperature variations. The following conditional expressions (1) and (2) are satisfied. In the expressions: ΔBf represents the amount the point of focus on the reduction side is moved when the correction lens group is moved fw/100; fw represents the focal length of the entire system; ΔAt represents the amount the tangential component of the astigmatism of the maximum angle is varied when the correction lens group is moved fw/100; and Imφ represents the maximum effective image circle diameter on the reduction side. (1) 0.5<|ΔBf/(fw/100)|<5.0 (2) |(ΔAt×fw)/(ΔBf×Imφ)|<0.12