Collimator lens and optical scanning apparatus using the same
AssigneeFuji Photo Optical Co., Ltd.
InventorRyoko Otomo
Life of this patent
Estimating the term…
Abstract
A collimator lens comprises, successively from a parallel luminous flux side, a first lens having a positive refracting power, second and third lenses having a negative composite refracting power, a fourth lens having a positive refracting power, and a fifth lens having a positive refracting power. The second and third lenses are cemented together. One of the second and third lenses has a negative refracting power, whereas the other has a positive refracting power. The collimator lens further satisfies Bƒ/ƒ>0.6, where Bf is the back focus of the whole lens system, and f is the focal length of the whole lens system.
Claims11
A collimator lens comprising, successively from a parallel luminous flux side, a first lens having a positive refracting power, second and third lenses having a negative composite refracting power, a fourth lens having a positive refracting power, and a fifth lens having a positive refracting power, said second and third lenses being cemented together, one of said second and third lenses having a negative refracting power, the other having a positive refracting power;
- said collimator lens satisfying the following conditional expression (1):
- Bƒ/ƒ>0.6 (1)
- where
- Bf is the back focus of the whole lens system;
- and
- f is the focal length of the whole lens system.
Dependencies are inferred from the claim text.