| 发明名称 |
F theta lens |
| 摘要 |
An f theta lens includes first and second lens groups arranged in this order from the entrance pupil side. The first lens group consists of a first lens having a negative or positive refracting power. The second lens group consists of a second lens having a positive refracting power and a third lens having a negative refracting power with the second and third lenses being cemented together. The second lens group has a positive refracting power as a whole. The following formulae (1) to (4) are satisfied. 12</= nu d2- nu d3 (1) -0.035</= SIGMA ( phi i/ nu di)</=0.005 (2) 0.7</= phi 23</=2.0 (3) 0.03</=d12</=0.20 (4) wherein phi i represents the power of i-th lens as numbered from the entrance pupil side standardized on the basis of the power of the whole system, phi 23 represents the power of the second lens group standardized on the basis of the power of the whole system, nu di represents the Abbe's number for the sodium d-line of i-th lens as numbered from the entrance pupil side and d12 represents the surface separation between the first and second lens groups standardized on the basis of the focal length of the whole system.
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| 申请公布号 |
US5694251(A) |
申请公布日期 |
1997.12.02 |
| 申请号 |
US19940202263 |
申请日期 |
1994.02.25 |
| 申请人 |
FUJI PHOTO FILM CO., LTD. |
发明人 |
SHIMADA, KATSUMI;TSUJITA, KAZUHIRO;NOGUCHI, MASARU |
| 分类号 |
G02B13/00;(IPC1-7):G02B3/00;G02B26/08;G02B9/00 |
主分类号 |
G02B13/00 |
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