Image pickup apparatus

• US 6,545,714 B1
• Filed: 02/25/1999
• Issued: 04/08/2003
• Est. Priority Date: 02/22/1999
• Status: Expired due to Term

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Takada, Katsuhiro
• Primary Examiner(s): Christensen, Andrew
• Assistant Examiner(s): Harris, Tia M.
• Application Number:
  US09/257,270
• Time in Patent Office: 1,503 Days
• Field of Search: 348/340
• US Class Current: 348/340
• CPC Class Codes: G02B 13/04 Reversed telephoto objectives
• CPC Class Codes: G02B 13/18 with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration G02B13/002 takes precedence
• CPC Class Codes: G02B 15/144 having four groups only

Abstract

The present invention relates to a compact and low-cost image pickup apparatus that is capable of photographing a high-quality image comparable to silver halide photographs even when the image is enlarged to 8×10″ size or larger and that enables the depth of field to be controlled with an aperture number exceeding F4. In the image pickup apparatus, an image of an object produced by an optical system (10) is formed on an electronic image pickup device (20), thereby obtaining image information concerning the object. The optical system (10) has a structure capable of obtaining an aperture number equal to or larger than F4 by reducing the beam diameter. Performance required for the optical system (10) is such that the size of the diameter of 90% encircled energy of the point spread function by amplitude is allowed to be up to about 8 times larger than the pixel pitch corresponding to the resolvable pixel unit. The pixel pitch of the image pickup device (20) is not larger than about 5 micrometers. The number of pixels is not less than about 2.5 million, which meets the resolvable pixel unit.

Claims

1. An image pickup apparatus wherein an image of an object produced by an optical system is formed on an electronic image pickup device, thereby obtaining image information concerning the object, said optical system having a structure capable of obtaining an aperture number equal to or larger than F4 by reducing a beam diameter, said image pickup apparatus satisfying the following conditions:

2. An image pickup apparatus according to claim 1, which satisfies the following condition at all focus positions that may be used:

3. An image pickup apparatus according to claim 1 or 2, which satisfies the following condition:

4. An image pickup apparatus according to claim 1 or 2, which satisfies the following condition:

5. An image pickup apparatus according to claim 4, which satisfies the following condition:

6. An image pickup apparatus according to claim 1 or 2, which does not use an optical low-pass filter.

7. An image pickup apparatus according to claim 1 or 2, which is a color image pickup apparatus.