Wide angle fovea lens and a camera design using the lens are described. The lens has three lens groups and includes a single aspherical lens element. The lenses have higher magnification on the optical axis than at angles off the optical axis.
1. A wide angle fovea lens having an optical axis, an image plane, and an effective focal length, the wide angle fovea lens comprising:
a. three lens groups located along the optical axis, in order from object to the image plane: group 1, group 2 and group 3, and,
b. the group 1 having negative power and including no more than one lens element, said one lens element being an aspheric lens element, the group 1 having an effective focal length and the aspheric lens element having a center thickness and an on-axis effective focal length, and,
c. the group 2 having positive power and including only spherical lens elements, and,
d. an aperture stop between the group 2 and the group 3, and,
e. the group 3 having positive power and including only spherical lens elements, and,
f. the wide angle fovea lens satisfying the conditions:
IH (Θ)< F *sin(Θ), for Θ>0
Where IH(Θ) is an image height on the image plane of a chief ray at an angle Θ off-axis relative to the optical axis, and, F is the effective focal length of the fovea lens.
2. The wide angle fovea lens of claim 1 wherein at least one lens element in group 2 and group 3 is made of material having a negative do/dT value, where n is the index of refraction of the material at d-line, and, T is temperature.
3. The wide angle fovea lens of claim 1 further satisfying the following parametric equation:
0.4< IH 50/( F *Tan(50))<0.7 a.
where:
F is the effective focal length of the wide angle fovea lens, and,
IH50 is the image height at a half field angle +/−50 degrees.
4. The wide angle fovea lens of claim 1 further satisfying the following parametric equations:
0.4< Ta/F< 0.75 a.
0.08< Ta/TTL< 0.25 b.
1.2<| Fa|/F< 2.7 c.
1<| F 1|/ F< 1.6 d.
where:
F is the effective focal length of the wide angle fovea lens, and,
Fa the on-axis effective focal length of the aspheric element, and,
F1 is the effective focal length of group 1,
Ta is the center thickness of the aspheric element, and
TTL is an on-axis distance from the most object side surface of the wide angle fovea lens to an image plane.
5. A wide angle fovea lens having an optical axis, an image plane, and an effective focal length, the wide angle fovea lens consisting of:
a. three lens groups located along the optical axis in order from object to an image plane: group 1, group 2 and group 3, and,
b. the group 1 having negative power and consisting of one aspheric lens element, the group 1 having an effective focal length and the aspheric lens element having a center thickness and an on-axis effective focal length, and,
c. the group 2 having positive power and consisting of one spherical lens element, and,
d. an aperture stop between the group 2 and the group 3, and,
e. the group 3 having positive power and consisting of:
i. one spherical lens elements, and,
ii. one cemented doublet, both lens elements of the cemented doublet being spherical lens elements, and,
f. the wide angle fovea lens satisfying the conditions:
IH (Θ)< F *sin(Θ), for Θ>0
Where IH(Θ) is an image height on the image plane of a chief ray at an angle Θ off-axis relative to the optical axis, and, F is the effective focal length of the fovea lens.
6. The wide angle fovea lens of claim 5 wherein at least one lens element in group 2 and group 3 is made of material having a negative do/dT value, where n is the index of refraction of the material at d-line, and, T is temperature.
7. The wide angle fovea lens of claim 5 further satisfying the following parametric equation:
0.4< IH 50/( F *Tan(50))<0.7 a.
where:
F is the effective focal length of the wide angle fovea lens, and,
IH50 is the image height at a half field angle +/−50 degrees.
8. The wide angle fovea lens of claim 5 further satisfying the following parametric equations:
0.4< Ta/F< 0.75 a.
0.08< Ta/TTL< 0.25 b.
1.2<| Fa|/F< 2.7 c.
1<| F 1|/ F< 1.6 d.
where:
F is the effective focal length of the wide angle fovea lens, and,
Fa the on-axis effective focal length of the aspheric element, and,
F1 is the effective focal length of group 1,
Ta is the center thickness of the aspheric element, and
TTL is an on-axis distance from the most object side surface of the wide angle fovea lens to an image plane.
9. A wide angle fovea lens having an optical axis, an image plane, and an effective focal length, the wide angle fovea lens consisting of:
a. three lens groups located along the optical axis in order from object to an image plane: group 1, group 2 and group 3, and,
b. the group 1 having negative power and consisting of one spherical lens element and one aspheric lens element, the group 1 having an effective focal length and the aspheric lens element having a center thickness and an on-axis effective focal length, and,
c. the group 2 having positive power and consisting of two spherical lens elements, and,
d. an aperture stop between the group 2 and the group 3, and,
e. the group 3 having positive power and consisting of:
i. one cemented doublet, both lens elements of the cemented doublet being spherical lens elements, and,
f. the wide angle fovea lens satisfying the conditions:
IH (Θ)< F *sin(Θ), for Θ>0
Where IH(Θ) is an image height on the image plane of a chief ray at an angle Θ off-axis relative to the optical axis, and, F is the effective focal length of the fovea lens.
10. The wide angle fovea lens of claim 9 wherein at least one lens element in group 2 and group 3 is made of material having a negative do/dT value, where n is the index of refraction of the material at d-line, and, T is temperature.
11. The wide angle fovea lens of claim 9 further satisfying the following parametric equation:
0.4< IH 50/( F *Tan(50))<0.7 a.
where:
F is the effective focal length of the wide angle fovea lens, and,
IH50 is the image height at a half field angle +/−50 degrees.
12. The wide angle fovea lens of claim 9 further satisfying the following parametric equations:
0.4< Ta/F< 0.75 a.
0.08< Ta/TTL< 0.25 b.
1.2<| Fa|/F< 2.7 c.
1<| F 1|/ F< 1.6 d.
where:
F is the effective focal length of the wide angle fovea lens, and,
Fa the on-axis effective focal length of the aspheric element, and,
F1 is the effective focal length of group 1,
Ta is the center thickness of the aspheric element, and
TTL is an on-axis distance from the most object side surface of the wide angle fovea lens to an image plane.
13. A wide angle fovea lens having an optical axis, an image plane, and an effective focal length, the wide angle fovea lens consisting of:
a. three lens groups located along the optical axis in order from object to an image plane: group 1, group 2 and group 3, and,
b. the group 1 having negative power and consisting of one spherical lens element and one aspheric lens element, the group 1 having an effective focal length and the aspheric lens element having a center thickness and an on-axis effective focal length, and,
c. the group 2 having positive power and consisting of two spherical lens elements, and,
d. an aperture stop between the group 2 and the group 3, and,
e. the group 3 having positive power and consisting of:
i. one spherical lens element, and,
ii. one cemented doublet, both lens elements of the cemented doublet being spherical lens elements, and,
f. the wide angle fovea lens satisfying the conditions:
IH (Θ)< F *sin(Θ), for Θ>0
Where IH(Θ) is an image height on the image plane of a chief ray at an angle Θ off-axis relative to the optical axis, and, F is the effective focal length of the fovea lens.
14. The wide angle fovea lens of claim 13 wherein at least one lens element in group 2 and group 3 is made of material having a negative do/dT value, where n is the index of refraction of the material at d-line, and, T is temperature.
15. The wide angle fovea lens of claim 13 further satisfying the following parametric equation:
0.4< IH 50/( F *Tan(50))<0.7 a.
where:
F is the effective focal length of the wide angle fovea lens, and,
IH50 is the image height at a half field angle +/−50 degrees.
16. The wide angle fovea lens of claim 13 further satisfying the following parametric equations:
0.4< Ta/F< 0.75 a.
0.08< Ta/TTL< 0.25 b.
1.2<| Fa|/F< 2.7 c.
1<| F 1|/ F< 1.6 d.
where:
F is the effective focal length of the wide angle fovea lens, and,
Fa the on-axis effective focal length of the aspheric element, and,
F1 is the effective focal length of group 1,
Ta is the center thickness of the aspheric element, and
TTL is an on-axis distance from the most object side surface of the wide angle fovea lens to an image plane.
17. A wide angle fovea lens having an optical axis, an image plane, and an effective focal length, the wide angle fovea lens consisting of:
a. three lens groups located along the optical axis in order from object to an image plane: group 1, group 2 and group 3, and,
b. the group 1 having negative power and consisting of one spherical lens element and one aspheric lens element, the group 1 having an effective focal length and the aspheric lens element having a center thickness and an on-axis effective focal length, and,
c. the group 2 having positive power and consisting of two spherical lens elements, and,
d. an aperture stop between the group 2 and the group 3, and,
e. the group 3 having positive power and consisting of:
i. two spherical lens elements, and,
ii. one cemented triplet, all lens elements of the cemented triplet being spherical lens elements, and,
f. the wide angle fovea lens satisfying the conditions:
IH (Θ)< F *sin(Θ), for Θ>0
Where IH(Θ) is an image height on the image plane of a chief ray at an angle Θ off-axis relative to the optical axis, and, F is the effective focal length of the fovea lens.
18. The wide angle fovea lens of claim 17 wherein at least one lens element in group 2 and group 3 is made of material having a negative do/dT value, where n is the index of refraction of the material at d-line, and, T is temperature.
19. The wide angle fovea lens of claim 17 further satisfying the following parametric equation:
0.4< IH 50/( F *Tan(50))<0.7 a.
where:
F is the effective focal length of the wide angle fovea lens, and,
IH50 is the image height at a half field angle +/−50 degrees.
20. The wide angle fovea lens of claim 17 further satisfying the following parametric equations:
0.4< Ta/F< 0.75 a.
0.08< Ta/TTL< 0.25 b.
1.2<| Fa|/F< 2.7 c.
1<| F 1|/ F< 1.6 d.
where:
F is the effective focal length of the wide angle fovea lens, and,
Fa the on-axis effective focal length of the aspheric element, and,
F1 is the effective focal length of group 1,
Ta is the center thickness of the aspheric element, and
TTL is an on-axis distance from the most object side surface of the wide angle fovea lens to an image plane.
21. A wide angle fovea lens having an optical axis, an image plane, and an effective focal length, the wide angle fovea lens consisting of:
a. three lens groups located along the optical axis in order from object to an image plane: group 1, group 2 and group 3, and,
b. the group 1 having negative power and consisting of one spherical lens element and one aspheric lens element, the group 1 having an effective focal length and the aspheric lens element having a center thickness and an on-axis effective focal length, and,
c. the group 2 having positive power and consisting of one spherical lens element, and,
d. an aperture stop between the group 2 and the group 3, and,
e. the group 3 having positive power and consisting of:
i. one spherical lens elements, and,
ii. one cemented doublet, all lens elements of the cemented doublet being spherical lens elements, and,
f. the wide angle fovea lens satisfying the conditions:
IH (Θ)< F *sin(Θ), for Θ>0
Where IH(Θ) is an image height on the image plane of a chief ray at an angle Θ off-axis relative to the optical axis, and, F is the effective focal length of the fovea lens.
22. The wide angle fovea lens of claim 21 wherein at least one lens element in group 2 and group 3 is made of material having a negative do/dT value, where n is the index of refraction of the material at d-line, and, T is temperature.
23. The wide angle fovea lens of claim 21 further satisfying the following parametric equation:
0.4< IH 50/( F *Tan(50))<0.7 a.
where:
F is the effective focal length of the wide angle fovea lens, and,
IH50 is the image height at a half field angle +/−50 degrees.
24. The wide angle fovea lens of claim 21 further satisfying the following parametric equations:
0.4< Ta/F< 0.75 a.
0.08< Ta/TTL< 0.25 b.
1.2<| Fa|/F< 2.7 c.
1<| F 1|/ F< 1.6 d.
where:
F is the effective focal length of the wide angle fovea lens, and,
Fa the on-axis effective focal length of the aspheric element, and,
F1 is the effective focal length of group 1,
Ta is the center thickness of the aspheric element, and
TTL is an on-axis distance from the most object side surface of the wide angle fovea lens to an image plane.
25. A camera comprising:
a. a wide angle fovea lens made according to claim 1 , and,
b. an image sensor located at the image plane of the wide angle fovea lens, and,
c. a computing device,
d. wherein the computing device acquires image data from the image sensor.