Title:
TELECENTRIC FTHETA LENS
Document Type and Number:
Japanese Patent JPH0497211
Kind Code:
A
Abstract:
PURPOSE:To effectively correct various aberration by successively disposing the 1st to 5th groups in the direction from the object side to the image side and allowing this telecentric ftheta lens to satisfy specific conditions. CONSTITUTION:The 1st to 5th groups are successively disposed from the object side to the image side. The 1st group is a positive meniscus lens 10 turning its concave face to the object side, the 2nd group is a negative lens 12 turning its concave face to the object side, the 3rd group is a positive meniscus lens 14 turning its concave face to the object side, the 4th group is a positive meniscus lens 16 turning its concave face to the object side, and the 5th group is a positive lens 18 whose object side lens face is a convex face. When it is defined that the synthetic focal distance of the whole system is (f), the focal distance of the 4th group is f4, the radius of curvature of the lens face of the i-th lens counted from the object side is Ri (i = 1 to 10), the interval of optical axis upper faces between the i-th and (i+1)th lenses faces is Di (i = 1 to 9), and the refractive index of a material for the 2nd group lens is n2, conditions expressed by inequalities I to VI are satisfied. Consequently, the telecentric ftheta lens whose various aberration are effectively corrected can be obtained.
Inventors:
ONO KATSUAKI
Application Number:
JP21333290A
Publication Date:
March 30, 1992
Filing Date:
August 10, 1990
Export Citation:
Assignee:
RICOH KOGAKU KK
International Classes:
G02B13/00; G02B13/22; G02B13/24; (IPC1-7): G02B13/00
Attorney, Agent or Firm:
Toru Kabayama (1 person outside)
Next Patent: JPH0497212