Optical system and imaging device

Abstract

To obtain an optical system that is compact and lightweight and has a high optical characteristic.SOLUTION: An optical system has one or more positive lenses Gp1 and one or more negative lenses Gn1. A positive lens disposed closest to an object side among the one or more positive lenses is a positive lens Gp1, and a negative lens disposed closer to an image side than the positive lens Gp1 and disposed closest to the object side among the one or more negative lenses is a negative lens Gn1. At least one of an object side surface and an image side surface of the positive lens Gp1 is an aspherical surface. A relation among the total lens length of the optical system, a focal distance of the optical system, and a distance on an optical axis from the image side surface of the positive lens Gp1 to an object side surface of the negative lens Gn1 is defined.SELECTED DRAWING: Figure 1

Claims

1. An optical system having one or more positive lenses and one or more negative lenses, Of the one or more positive lenses, the positive lens positioned closest to the object is defined as positive lens Gp1, and of the one or more negative lenses, the negative lens positioned closest to the object is defined as negative lens Gn1. At least one of the object-side surface and the image-side surface of the positive lens Gp1 is aspherical. When the total lens length of the optical system is LD, the focal length of the optical system is f, the distance along the optical axis from the image-side surface of the positive lens Gp1 to the object-side surface of the negative lens Gn1 is Dpn, the radius of curvature of the object-side surface of the positive lens Gp1 is rp1, the radius of curvature of the image-side surface of the positive lens Gp1 is rp2, the focal length of the positive lens Gp1 is f11, the refractive index of the material of the positive lens Gp1 with respect to the d line is Ndp1, and the Abbe number with respect to the d line is νdp1, 0.20<LD / f<1.00 0.382<Dpn / LD<0.800 0.10<(rp2+rp1) / (rp2-rp1)≦0.8958 0.20<f11 / f≦0.8906 1.493<Ndp1<1.700 55.0<νdp1<96.0 An optical system characterized by satisfying the following conditional equation.

2. When there are two or more positive lenses, and the second positive lens positioned from the object side is defined as positive lens Gp2, and the refractive index of the material of positive lens Gp2 with respect to the d line is Ndp2, and the Abbe number with respect to the d line is νdp2, 1.400<Ndp2<1.630 61.0<νdp2<96.0 The optical system according to claim 1, characterized in that it satisfies the following condition.

3. When there are three or more positive lenses, and the third positive lens from the object side is designated as positive lens Gp3, and the refractive index of the material of positive lens Gp3 with respect to the d line is Ndp3, and the Abbe number with respect to the d line is νdp3, 1.400<Ndp3<1.630 61.0<νdp3<96.0 The optical system according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

4. A system has four or more positive lenses, and the positive lens positioned closer to the image than the third positive lens Gp3 from the object side is defined as positive lens Gp4. When the refractive index of the material of positive lens Gp4 with respect to the d line is Ndp4, and the Abbe number with respect to the d line is νdp4, 1.400<Ndp4<1.630 50.0<νdp4<96.0 An optical system according to any one of claims 1 to 3, characterized in that it satisfies the following conditional expression.

5. When the refractive index of the material of the negative lens Gn1 with respect to the d line is Ndn1, and the Abbe number with respect to the d line is νdn1, 1.600<Ndn1<1.950 20.0<νdn1<50.0 An optical system according to any one of claims 1 to 4, characterized in that it satisfies the following conditional expression.

6. The optical system according to any one of claims 1 to 5, characterized in that it comprises a first lens group having a fixed positive refractive power during focusing, arranged in order from the object side to the image side, a second lens group having a positive or negative refractive power that moves during focusing, and a third lens group having a fixed positive or negative refractive power during focusing.

7. The optical system according to claim 6, wherein the third lens group has four or more positive lenses, and when the positive lens Gp4 is located on the image side of the third positive lens Gp3, counting from the object side, the third lens group has the positive lens Gp4 and a negative lens located on the image side of the positive lens Gp4.

8. The third lens group has a negative lens Gn2 positioned closer to the image than the positive lens Gp4, and when the refractive index of the material of the negative lens Gn2 with respect to the d line is Ndn2 and the Abbe number with respect to the d line is νdn2, 1.400<Ndn2<1.630 61.0<νdn2<96.0 The optical system according to claim 7, characterized in that it satisfies the following conditional equation.

9. The third lens group has a negative lens Gn3 positioned closer to the image than the positive lens Gp4, and when the refractive index of the material of the negative lens Gn3 with respect to the d line is Ndn3 and the Abbe number with respect to the d line is νdn3, 1.800<Ndn3<2.200 14.0<νdn3<24.0 The optical system according to claim 7 or 8, characterized in that it satisfies the following conditional expression.

10. When the focal length of the first lens group is f1, 0.10<f1 / f<1.20 The optical system according to any one of claims 6 to 9, characterized in that it satisfies the following conditional expression.

11. The second lens group has a positive refractive power, and the third lens group has a negative refractive power. The optical system according to any one of claims 6 to 10, characterized in that the second lens group moves toward the object when focusing from an object at infinity to the nearest object.

12. The second lens group has a negative refractive power, and the third lens group has a positive refractive power. The optical system according to any one of claims 6 to 10, characterized in that the second lens group moves toward the image when focusing from an object at infinity to the closest object.

13. The second lens group has negative refractive power, and the third lens group has negative refractive power. The optical system according to any one of claims 6 to 10, characterized in that the second lens group moves toward the image when focusing from an object at infinity to the closest object.

14. The optical system according to any one of claims 6 to 13, characterized in that the second lens group consists of three or fewer lenses.

15. When the aspherical amount at the 70% effective diameter position of the aspherical surface is DRGp1 and the F-number of the optical system is Fno, 0.00001<DRGp1×Fno / f<0.00500 An optical system according to any one of claims 1 to 14, characterized in that it satisfies the following conditional expression.

16. The optical system has two or more positive lenses, and the second positive lens from the object side among these two or more positive lenses is designated as positive lens Gp2. When the distance along the optical axis from the image-side surface to the object-side surface of positive lens Gp1 is d12 and the focal length of positive lens Gp1 is f11, 0.20<d12 / f11<0.60 The optical system according to any one of claims 1 to 15, characterized in that it satisfies the following conditional expression.

17. When the maximum height of the point of incidence of the on-axis ray on the aspherical surface when focusing on an object at infinity is YASPH (mm), 30<YASPH<100 An optical system according to any one of claims 1 to 16, characterized in that it satisfies the following conditional expression.

18. The optical system according to any one of claims 1 to 17, characterized in that it has the positive lens Gp1, positive lens Gp2, negative lens Gn1, and positive lens Gp3 arranged in a continuous sequence from the object side to the image side.

19. The optical system according to any one of claims 1 to 18, characterized in that the aspherical surface has a shape in which the negative refractive power increases from the vertex to the periphery.

20. An optical system comprising a first lens group having a fixed positive refractive power during focusing, arranged in order from the object side to the image side, a second lens group having a positive refractive power that moves toward the object side when focusing from an object at infinity to the closest object, and a third lens group having a fixed negative refractive power during focusing, The optical system has one or more positive lenses and one or more negative lenses. Of the one or more positive lenses, the positive lens positioned closest to the object is defined as positive lens Gp1, and of the one or more negative lenses, the negative lens positioned closest to the object is defined as negative lens Gn1. At least one of the object-side surface and the image-side surface of the positive lens Gp1 is aspherical. When the total length of the lens in the optical system is LD, the focal length of the optical system is f, the distance along the optical axis from the image-side surface of the positive lens Gp1 to the object-side surface of the negative lens Gn1 is Dpn, the radius of curvature of the object-side surface of the positive lens Gp1 is rp1, the radius of curvature of the image-side surface of the positive lens Gp1 is rp2, and the focal length of the positive lens Gp1 is f11, 0.20<LD / f<1.00 0.382<Dpn / LD<0.800 0.10<(rp2+rp1) / (rp2-rp1)≦0.8958 0.20<f11 / f≦0.8906 An optical system characterized by satisfying the following conditional equation.

21. An imaging device characterized by having an optical system according to any one of claims 1 to 20 and an image sensor that receives an image formed by the optical system.

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