Image pickup apparatus and method for manufacturing the same

1. A image pickup apparatus, comprising:

an optical system;

an optical wavefront modulation element operable to modulate an optical transfer function;

an aperture stop located adjacent to the optical wavefront modulation element such that the following condition is satisfied:

φ× D< 2 mm 2 ,

where φ [mm] is an aperture diameter of the aperture stop, and D [mm] is a distance between the aperture stop and the optical wavefront modulation element; and

an image pickup device operable to pick up an object image that passes through the optical system and the optical wavefront modulation element,

wherein, a phase of the optical wavefront modulation element is based on the following relationship:

z

=

exp

⁢

{

ⅈ

×

(

∑

j

=

1

⁢

C

j

⁢

x

m

⁢

y

n

)

}

,

where z is the phase of the optical wavefront modulation element on an optical axis of the optical system and x and y are axes perpendicular to the optical axis and to each other, i is √{square root over (−1)}, C is a coefficient value, m and n are integers,

j

=

[

(

m

+

n

)

2

+

m

+

3

⁢

n

]

2

,



x



≤

1

,

and

⁢

⁢



y



≤

1.

2. The image pickup apparatus according to claim 1 , wherein a telecentricity of the aperture stop is maintained, and an outermost chief ray does not intersect an Fno ray in a space between the optical wavefront modulation element and the aperture stop.

3. The image pickup apparatus according to claim 2 , wherein, an image-side telecentricity is maintained and the following condition is satisfied:

0.5< S 1/ S 2<2.0,

where S 1 is a first area surrounded by a first section of a shading curve of the image pickup device, an upper ray incident angle, and a chief ray incident angle, and S 2 is a second area surrounded by a second section of the shading curve of the image pickup device, a lower ray incident angle, and the chief ray incident angle, wherein the shading curve comprises a relationship between a sensitivity of the image pickup device and a light ray incident angle.

4. The image pickup apparatus according to claim 1 , wherein, an image-side telecentricity is maintained and the following condition is satisfied:

0.5< S 1/ S 2<2.0,

where S 1 is a first area surrounded by a first section of a shading curve of the image pickup device, an upper ray incident angle, and a chief ray incident angle, and S 2 is a second area surrounded by a second section of the shading curve of the image pickup device, a lower ray incident angle, and the chief ray incident angle, wherein the shading curve comprises a relationship between a sensitivity of the image pickup device and a light ray incident angle.

5. The image pickup apparatus according to claim 4 , wherein a telecentricity of the aperture stop is maintained and the following condition is satisfied:

φ/ D< 1, and α<45°,

where α is an incident angle at which an outermost chief ray is incident on the aperture stop.

6. The image pickup apparatus according to claim 1 , wherein a telecentricity of the aperture stop is maintained and the following condition is satisfied:

φ/ D< 1, and α<45°,

where α is an incident angle at which an outermost chief ray is incident on the aperture stop.

7. The image pickup apparatus according to claim 1 , wherein the optical wavefront modulation element is formed as a part of optical lenses.

8. The image pickup apparatus according to claim 1 , further comprising means for generating an image signal with a smaller dispersion than that of a dispersed object-image signal that is obtained from the image pickup device.

9. A method of manufacturing an image pickup apparatus, the method comprising:

providing an optical wavefront modulation element;

providing an aperture stop; and

locating the optical wavefront modulation element near the aperture stop such that the following condition is satisfied:

φ× D< 2 mm 2 ,

where φ [mm] is an aperture diameter of the aperture stop, and D [mm] is a distance between the aperture stop and the optical wavefront modulation element;

providing an optical system;

wherein a phase of the optical wavefront modulation element is based on the following relationship:

z

=

exp

⁢

{

ⅈ

×

(

∑

j

=

1

⁢

C

j

⁢

x

m

⁢

y

n

)

}

,

where z is the phase of the optical wavefront modulation element on an optical axis of the optical system and x and y axes are axes perpendicular to the optical axis and to each other,

m and n are integers, i is √{square root over (−1)}, C is a coefficient value,

j

=

[

(

m

+

n

)

2

+

m

+

3

⁢

n

]

2

,



x



≤

1

,

and

⁢

⁢



y



≤

1.

10. The method according to claim 9 , further comprising providing an image pickup device.

11. The method according to claim 9 , wherein a telecentricity of the aperture stop is maintained, and an outermost chief ray does not intersect an Fno ray in a space between the optical wavefront modulation element and the aperture stop.

12. The method according to claim 9 , wherein an image-side telecentricity is maintained and the following condition is satisfied:

0.5< S 1/ S 2<2.0,

where S 1 is a first area surrounded by a first section of a shading curve of the image pickup device, an upper ray incident angle, and a chief ray incident angle, and S 2 is a second area surrounded by a second section of the shading curve of the image pickup device, a lower ray incident angle, and the chief ray incident angle, wherein the shading curve comprises a relationship between a sensitivity of the image pickup device and a light ray incident angle.

13. The method according to claim 9 , wherein a telecentricity of the aperture stop is maintained and the following condition is satisfied:

φ/ D< 1, and α<45°,

where α is an incident angle at which an outermost chief ray is incident on the aperture stop.

14. The method according to claim 9 , wherein the optical wavefront modulation element is formed as a part of the optical lenses.