Imaging apparatus having a curved image surface

Patent metadata

Field	Value
Publication number	US-9453986-B2
Application number	US-201514791625-A
Country	US
Kind code	B2
Filing date	Jul 6, 2015
Priority date	Mar 30, 2012
Publication date	Sep 27, 2016
Grant date	Sep 27, 2016

Abstract

Provided is an imaging apparatus, including: an imaging optical system including a plurality of lenses; and an image plane which is disposed on an image side of the imaging optical system and is curved so that a concave surface thereof faces an object side of the imaging optical system. The imaging optical system includes an aperture stop. In the imaging optical system, a lens closer to the object side than the aperture stop and a lens closer to the image side than the aperture stop have different positive powers. A focal length of the imaging optical system is substantially equal to a distance from an exit pupil of the imaging optical system to the image plane. A radius of curvature of the image plane is substantially equal to the focal length of the imaging optical system.

First claim

What is claimed is:

1. An imaging apparatus comprising:
an imaging optical system including (a) an aperture stop, (b) a first optical system disposed on an object side of the aperture stop, and (c) a second optical system disposed on an image side of the aperture stop; and
a light-receiving surface which is disposed on an image side of the imaging optical system and is a concave surface facing the imaging optical system,
wherein the first optical system and the second optical system have different positive power,
wherein the first optical system includes a first lens closest to the object side and a second lens adjacent to the first lens,
wherein the second optical system includes a third lens closest to the image side and a fourth lens adjacent to the third lens,
wherein a difference between an Abbe number of the third lens and an Abbe number of the fourth lens is larger than a difference between an Abbe number of the first lens and an Abbe number of the second lens, and
wherein the following conditional expressions are satisfied:
0.8≦| R img |/f sys ≦1.5, and

0.8≦| R img |/d pup ≦1.5

where f sys represents a focal length of the imaging optical system, d pup represents a distance from an exit pupil of the imaging optical system to the light-receiving surface, and R img represents a radius of curvature of the light-receiving surface.

2. The image pickup apparatus according to claim 1 , further comprising an image sensor including the light-receiving surface.

3. The image pickup apparatus according to claim 1 , further comprising an optical transmission unit including the light-receiving surface.

4. The image pickup apparatus according to claim 1 , wherein the following expression is satisfied:
1.850000≦Nd≦2.300000,

where Nd represents a refractive index of at least one of the first lens and the third lens.

Assignees

• Canon Kk

Inventors

• Ishihara Keiichiro

Classifications

• G02B13/18

  with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)} · CPC title

• G02B9/04

  having two components only · CPC title

• H04N5/2254

  Electricity · mapped topic

• G02B3/00

  Simple or compound lenses · CPC title

• G02B13/0015 Primary

  characterised by the lens design · CPC title