Eyepiece lens with image located in space between first and second lens units
AssigneeCanon Kabushiki Kaisha
InventorSaburo Sugawara
Life of this patent
Estimating the term…
Abstract
An eyepiece lens is disclosed, in which the total number of constituent lenses is reduced but good optical performance is obtained by setting forth proper rules of design for optical parameters.
Claims6
An eyepiece lens comprising, in order from a light entrance side, a first lens unit composed of a positive meniscus lens convex toward a light exit side, a second lens unit of positive refractive power having a refractive power on the light exit side which is stronger than that of an opposite surface of said second lens unit, and a third lens unit of positive refractive power having a refractive power on the light entrance side which is stronger than that of an opposite surface of said third lens unit, said eyepiece lens satisfying the following conditions:
- -3<SF2<-0.3
- 0.1<SF3<3
- where
- SF2=(r2e+r2i)/(r2e-r2i)
- SF3=(r3e+r3i)/(r3e-r3i)
- where r2i and r2e are the radii of curvature of lens surfaces closest to the light entrance side and the light exit side of said second lens unit, respectively and r3i and r3e are the radii of curvature of lens surfaces closest to the light entrance side and the light exit side of said third lens unit, respectively.
An eyepiece lens comprising, in order from a light entrance side, a first lens unit composed of a meniscus lens convex toward a light exit side, a second lens unit of positive refractive power having a refractive power on the light exit side which is stronger than that of an opposite surface of said second lens unit, and a third lens unit of positive refractive power having a refractive power on the light entrance side which is stronger than that of an opposite surface of said third lens unit,
- wherein said first lens unit is a meniscus cemented lens of a negative lens and a positive lens cemented together, and said second and said third lens units each are a single lens, and satisfying the following conditions:
- 25<.nu.a-.nu.1p<60
- where .nu.a is the mean value of the Abbe numbers of said negative lens in said first lens unit and of said second and third lens units, and .nu.1p is the Abbe number of said positive lens in said first lens unit.
An eyepiece lens comprising, in order from a light entrance side, a first lens unit composed of a meniscus lens convex toward a light exit side, a second lens unit of positive refractive power having a refractive power on the light exit side which is stronger than that of an opposite surface of said second lens unit, and a third lens unit composed of a meniscus lens convex toward the light entrance side,
- wherein an image is located in a space between said first lens unit and said second lens unit.
An eyepiece lens comprising, in order from a light entrance side, a first lens unit composed of a meniscus lens convex toward a light exit side, a second lens unit of positive refractive power having a refractive power on the light exit side which is stronger than that of an opposite surface of said second lens unit, and a third lens unit composed of a cemented lens of a positive lens and a negative lens cemented together,
- wherein an image is located in a space between said first lens unit and said second lens unit.
Dependencies are inferred from the claim text.