Single focus telescopic lens
View Patent ↗A single focus telescopic lens includes, in order from the object side: a diaphragm stop; and first and second lens components, each lens component being of positive refractive power and each having a convex surface on the object side near the optical axis. Each of the two lens components has two aspheric surfaces, may be a lens element, and preferably is made of plastic. The single focus telescopic lens may include no other lens elements and the diaphragm stop may be on the object side of the single focus telescopic lens. A specified on-axis condition is satisfied in order to reduce aberrations and to make the single focus telescopic lens compact. Additionally, satisfying a condition related to the maximum angle of incidence of among all the image forming principal rays helps achieve the desired telescopic properties with the desired optical performance.
1. A single focus telescopic lens for forming a real image comprising, arranged along an optical axis in order from the object side:
a stop on the object side of the single focus telescopic lens;
a first lens component of positive refractive power, having a meniscus shape, having both surfaces of aspheric shape, and having a convex object-side surface;
a second lens component of positive refractive power, having a meniscus shape, having both surfaces of aspheric shape, and having a convex object-side surface near the optical axis, wherein
the following conditions are satisfied:
0.12 <R 1 /f< 0.40
tan θ<0.45
where
R1 is the radius of curvature on the optical axis of the object-side surface of the first lens component,
f is the focal length of the entire single focus telescopic lens on the optical axis, and
θ is the maximum angle of incidence among all the image forming principal rays on the object-side surface of the first lens component.
2. The single focus telescopic lens of claim 1 , wherein the first lens component is a lens element.
3. The single focus telescopic lens of claim 2 , wherein the second lens component is a lens element.
4. The single focus telescopic lens of claim 3 , wherein each of the first lens component and the second lens component is made of plastic.
5. The single focus telescopic lens of claim 1 , wherein the stop, the first lens component, and the second lens component are arranged in that order along the optical axis from the object side without any intervening lens element.
6. The single focus telescopic lens of claim 5 , wherein each of the first and second lens components consists of a lens element.
7. The single focus telescopic lens of claim 1 , wherein the single focus telescopic lens is formed of only two lens components.
8. The single focus telescopic lens of claim 7 , wherein the first lens component is a lens element.
9. The single focus telescopic lens of claim 8 , wherein the second lens component is a lens element.
10. The single focus telescopic lens of claim 1 , wherein each of the first lens component and the second lens component is made of plastic.
11. The single focus telescopic lens of claim 1 , wherein the following condition is satisfied:
0.70 <ΔZF/ΔZR< 1.50
where
ΔZF is the object-side shape displacement at the maximum height at which an image forming light ray passes through the object-side surface of the first lens component, and
ΔZR is the image-side shape displacement at the maximum height at which an image forming light ray passes through the image-side surface of the first lens component.
12. The single focus telescopic lens of claim 11 , wherein the first lens component is a lens element.
13. The single focus telescopic lens of claim 12 , wherein the second lens component is a lens element.
14. The single focus telescopic lens of claim 13 , wherein each of the first lens component and the second lens component is made of plastic.
15. The single focus telescopic lens of claim 11 , wherein the stop, the first lens component, and the second lens component are arranged in that order along the optical axis from the object side without any intervening lens element.
16. The single focus telescopic lens of claim 15 , wherein each of the first and second lens components consists of a lens element.
17. The single focus telescopic lens of claim 11 , wherein the single focus telescopic lens is formed of only two lens components.
18. The single focus telescopic lens of claim 17 , wherein the first lens component is a lens element.
19. The single focus telescopic lens of claim 18 , wherein the second lens component is a lens element.
20. The single focus telescopic lens of claim 19 , wherein each of the first and second lens components is made of plastic.