| 摘要 |
A high performance, large aperture, long focal length visible waveband ob- jective lens system (60) comprises a telephoto objective lens group (48) spaced from a focusing lens group (49) and an auxiliary lens group (54), all supported in a support assembly (43) of fixed length. The lens groups are aligned on a common optical axis (40). The telephoto objective lens group (48) is stationary and comprises a positively powered lens element (A) and a negatively powered lens sub-group (50) containing a quintuplet lens group (51) with lens elements (B, C, D, E, F) and a lens element (G). The quintuplet lens group includes two lens elements (C and E) of liquid materials which exhibit highly abnormal partial dispersions and one solid glass lens element (F) which exhibits slightly abnormal partial dispersion. In addition, the liquid materials of lens elements (C) and (E) exhibit very large changes in refractive index with temperature and the material of lens element (F) exhibits a compensa- ting large change in refractive index with temperature. The remaining lens ele- ments of the system are common optical glass and exhibit substantially normal par- tial dispersions. The focusing lens group (49) contains a positively powered first lens group (52) and a negatively powered second lens group (53) which are inde- pendently movable along the optical axis (40) to provide continuous focusing for object to image magnifications from infinity to less than 3:1. The configuration and material selection of the lens system (60) results in a high performance, compact, low in weight, relatively inexpensive, well corrected for chromatic aberration and substantially passively athermal objective lens system. <IMAGE> |
