Optical system and image pickup apparatus
An optical system includes, in order from an object side to an image side, a first unit, a second unit, and a third unit. The first unit includes a first substrate, and a first lens having a negative refractive power and disposed on the image side of the first substrate. The second unit includes a second substrate, and a second lens having a positive refractive power and disposed on the object side of the second substrate. The third unit includes a third substrate, and a third lens having a positive refractive power and disposed on the object side of the third substrate.
1. An optical system comprising, in order from an object side to an image side, a first unit, a second unit, and a third unit,
wherein the first unit includes a first substrate, and a first lens having a negative refractive power and disposed on the image side of the first substrate,
wherein the second unit includes a second substrate, and a second lens having a positive refractive power and disposed on the object side of the second substrate,
wherein the third unit includes a third substrate, and a third lens having a positive refractive power and disposed on the object side of the third substrate,
wherein the third unit includes no other lenses than the third lens.
2. The optical system according to claim 1 , wherein the second unit further includes a diaphragm.
3. The optical system according to claim 2 , wherein the diaphragm is disposed on the second substrate.
4. The optical system according to claim 2 , wherein the following inequality is satisfied:
0.10< d/f< 0.50
where d is a distance from the diaphragm to the third lens on an optical axis, and f is a focal length of the optical system.
5. The optical system according to claim 2 , wherein the following inequality is satisfied:
0.07< d/f< 0.65
where d is a distance from the diaphragm to the third lens on an optical axis, and f is a focal length of the optical system.
6. The optical system according to claim 2 , wherein the following inequality is satisfied:
0.03< d/f 3<0.40
where d is a distance from the diaphragm to the third lens on an optical axis, and f3 is a focal length of the third lens.
7. The optical system according to claim 1 , wherein the following inequality is satisfied:
1.00< f 2/ f< 1.50
where f2 is a focal length of the second lens, and f is a focal length of the optical system.
8. The optical system according to claim 1 , wherein the following inequality is satisfied:
0.60< f 2/ f< 1.60
where f2 is a focal length of the second lens, and f is a focal length of the optical system.
9. The optical system according to claim 1 , wherein the following inequality is satisfied:
−2.50< f 3/ f 1<−1.80
where f1 is a focal length of the first lens, and f3 is a focal length of the third lens.
10. The optical system according to claim 1 , wherein the following inequality is satisfied:
−3.50< f 3/ f 1<−1.50
where f1 is a focal length of the first lens, and f3 is a focal length of the third lens.
11. The optical system according to claim 1 , wherein the following inequality is satisfied:
1.20< L/f< 2.40
where L is a distance from the third lens to the image plane, and f is a focal length of the optical system.
12. The optical system according to claim 1 , wherein the following inequality is satisfied:
1.00< L/f< 2.40
where L is a distance from the third lens to the image plane, and f is a focal length of the optical system.
13. The optical system according to claim 1 , wherein the following inequality is satisfied:
0.30<( f 2− f 1)/ f 3<1.60
where f1 is a focal length of the first lens, f2 is a focal length of the second lens, and f3 is a focal length of the third lens.
14. The optical system according to claim 1 , wherein the following inequality is satisfied:
1.50< f 3/ f< 3.00
where f3 is a focal length of the third lens, and f is a focal length of the optical system.
15. The optical system according to claim 1 , wherein the following inequality is satisfied:
0.60< Lar /( d 1+ d 2)<2.00
wherein d1 is a thickness of the first substrate, d2 is a thickness of the second substrate, and Lar is a distance from a surface on the image side of the first lens to a surface on the object side of the second substrate.
16. The optical system according to claim 1 , wherein the first substrate and the first lens have refractive indexes different from each other.
17. The optical system according to claim 1 , wherein the second substrate and the second lens have refractive indexes different from each other.
18. The optical system according to claim 1 , wherein the third substrate and the third lens have refractive indexes different from each other.
19. An image pickup apparatus comprising:
the optical system according to claim 1 ; and
an image sensor configured to receive an image formed by the optical system.
20. The optical system according to claim 1 , wherein the third unit includes a fourth substrate disposed on the image side of the third substrate.