Title:
f・θレンズ
Document Type and Number:
Japanese Patent JP4488263
Kind Code:
B2
Abstract:
An ftheta lens comprises, successively from the luminous flux entrance side, a first lens made of a negative lens having a flat surface on one side, a positive second lens having a surface with a stronger curvature directed onto the image side, and a third lens made of a negative meniscus lens cemented to the second lens; and satisfies the following conditional expressions (1) to (3):where f is the composite focal length of the whole lens system, f1 is the focal length of first lens, f2 is the focal length of second lens, N3 is the refractive index of third lens at d-line, and ν3 is the Abbe number of third lens at d-line.
Inventors:
Yoko Nakai
Application Number:
JP2000090803A
Publication Date:
June 23, 2010
Filing Date:
March 29, 2000
Export Citation:
Assignee:
Fujinon Co., Ltd.
International Classes:
G02B13/00; G02B9/12
Domestic Patent References:
| JP7191261A |
Attorney, Agent or Firm:
Hiroshi Kawano