Image pickup optical system

• US 7,551,373 B2
• Filed: 09/27/2006
• Issued: 06/23/2009
• Est. Priority Date: 10/05/2005
• Status: Active Grant

• Current Assignee: Konica Minolta OPTO Incorporated (Konica Minolta Inc.)
• Original Assignee: Konica Minolta OPTO Incorporated (Konica Minolta Inc.)
• Inventors: Hirose, Masatoshi
• Primary Examiner(s): Mack; Ricky L
• Assistant Examiner(s): Greece; James R
• Application Number:
  US11/527,889
• Publication Number:
  US 20070076308A1
• Time in Patent Office: 1,000 Days
• Field of Search: 359/753, 359/747, 359/734, 359714-715, 359/682, 359659-660, 359/781, 359/764, 359770-771
• US Class Current: 359/781
• CPC Class Codes: G02B 13/004 having four lenses
• CPC Class Codes: G02B 13/04 Reversed telephoto objectives
• CPC Class Codes: G02B 13/06 Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces
• 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 7/028 with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation
• CPC Class Codes: G02B 9/34 having four components only

Abstract

An image pickup optical system for forming a light flux from an object into an optical image on an image pickup element, is provided with, in order from an object side thereof: a first lens with a negative power in a meniscus shape including a convex surface facing the object side; a second lens in a bioconcave shape; a third lens with a positive power including a convex surface facing an image surface side; and a fourth lens with a positive power including a convex surface facing the image surface side. The first lens and the third lens are glass lenses and the second lens and the fourth lens are plastic lenses.

Claims

1. An image pickup optical system for forming a light flux from an object into an optical image on an image pickup element, the image pickup optical system consisting of, in order from an object side thereof:

a first lens with a negative power in a meniscus shape including a convex surface facing the object side;

a second lens in a biconcave shape;

a third lens with a positive power including a convex surface facing an image surface side; and

a fourth lens with a positive power including a convex surface facing the image surface side,

wherein the first lens and the third lens are glass lenses and the second lens and the fourth lens are plastic lenses.

2. The image pickup optical system as claimed in claim 1,

wherein the image pickup optical system fulfills a following conditional formula:

−

2<

f2/f4<

−

0.5,

where f2 is a focal length of the second lens and f4 is a focal length of the fourth lens.

3. The image pickup optical system as claimed in claim 1,

wherein the image pickup optical system fulfills a following conditional formula:

ν

d3<

50,

where ν

d3 is an Abbe'"'"'s constant of the third lens.

4. The image pickup optical system as claimed in claim 1, further comprising:

a stop arranged between the third lens and the fourth lens.