Wide-angle optical system for solid image pickup element

• US 6,995,928 B2
• Filed: 05/28/2003
• Issued: 02/07/2006
• Est. Priority Date: 05/29/2002
• Status: Expired due to Fees

• Current Assignee: Enplas Corporation
• Original Assignee: Enplas Corporation
• Inventors: Saito, Tomohiro
• Primary Examiner(s): Ben, Loha
• Assistant Examiner(s): MARTINEZ, JOSEPH P
• Application Number:
  US10/447,174
• Publication Number:
  US 20040017615A1
• Time in Patent Office: 986 Days
• Field of Search: 359/708, 359/712, 359717-720, 359749-753, 359738-739
• US Class Current: 359/718
• CPC Class Codes: G02B 13/0025 having one lens only
• CPC Class Codes: G02B 13/006 at least one element being a compound optical element, e.g. cemented elements
• CPC Class Codes: G02B 3/04 with continuous faces that are rotationally symmetrical but deviate from a true sphere , e.g. so called "aspheric" lenses
• CPC Class Codes: G02B 9/02 having one + component only simple lenses G02B3/00

Abstract

In a wide-angle optical system for a solid image pickup element, an image pickup lens 2 is a biconvex lens, and its surface closer to an image surface is being formed into such an aspherical shape that the positive refractive power is weaker at a location more spaced in a diametrical direction apart from an optical axis. Further, the image pickup lens 2 satisfies the following condition expression (1):
1.3≧|r₁/r₂|≧0.8  (1)
wherein r₁ is a radius of curvature of a surface of the image pickup lens closer to an object, and r₂ is a radius of curvature of the surface of the image pickup lens closer to the image surface. Thus, the distortion can be corrected appropriately.

Claims

1. A wide angle optical system for a solid image pickup element, comprising an image pickup lens, and a diaphragm disposed on a side of the image pickup lens closer to an object, wherein said image pickup lens is a biconvex lens, its surface on a side closer to an image surface being formed into such an aspherical shape that the positive refractive power is weaker at a location more spaced in a diametrical direction apart from an optical axis, and the image pickup lens satisfies the following condition expression (1):

1.3≧

|r₁/r₂|≧

0.8 

 

(1)

wherein r₁ is a radius of curvature of the surface of the image pickup lens closer to the object, and r₂ is a radius curvature of the surface of the image pickup lens closer to the image surface; and

wherein

said image pickup lens satisfies the following condition expression;

0.4≧

SH/fl≧

0.2 

 

(4)

wherein SH is a distance from a main point on a front side of the image pickup lens to the diaphragm.

2. A wide-angle optical system for a solid image pickup element according to claim 1, wherein said image pickup lens satiafies the following condition expression:

1.5≧

d/fl≧

0.7 

 

(2)

wherein d is a thickness of the image pickup lens at its center, and fl is a focal length of the image pickup lens.

3. A wide-angle optical system for a solid image pickup element according to claim 2, wherein said image pickup lens further satisfies the following condition expression (3):

1.5≧

|r₂/fl|≧

0.7 

 

(3).

4. The wide angle optical system for a solid stage image pickup element according to any one of claim 1 wherein said solid image pickup element is selected from the group consisting of a CCD and CMOS.