Elongated eye relief eyepiece lens

Abstract

The application provides a long eye relief eyepiece lens, the exit pupil diameter is 8mm, the exit pupil distance is 50mm, and the eyepiece lens is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged along an optical axis from an eye side to an image side; the first lens is a double convex lens; the second lens has positive refractive power, the eye side surface is a convex surface, and the image side surface is a concave surface; the third lens has positive refractive power, the eye side surface is a convex surface, and the image side surface is a concave surface; the fourth lens has negative refractive power, the eye side surface is a convex surface, and the image side surface is a concave surface; the fifth lens is a double convex lens; and the sixth lens has negative refractive power, the eye side surface is a concave surface, and the image side surface is a plane. Through the distribution of the refractive power of each lens and the interval between the lenses, the eyepiece lens has the advantages of small volume, light mass, short total optical length, long exit pupil distance, good imaging quality and stable performance, and is especially suitable for a 1.03-inch target surface and meets the application requirements of special fields.

Description

Technical Field

[0001] This application belongs to the field of optical lens technology, specifically relating to an eyepiece lens with an extended interpupillary distance. Background Technology

[0002] In the design of traditional eyepieces (such as microscope and conventional telescope eyepieces), the exit pupil distance is usually short, generally around 10mm to 20mm. Users need to bring their eyes very close to the last lens of the eyepiece to see the complete field of view. This design is feasible in most civilian applications, but it faces significant challenges in some specialized fields, particularly in military and special operations. However, increasing the exit pupil distance is not easy in optical design; it presents a complex and contradictory relationship with aberration correction. Simply lengthening the exit pupil distance often leads to severe off-axis aberrations (such as distortion, field curvature, and coma). Summary of the Invention

[0003] Therefore, it is necessary to provide a long exit pupil distance eyepiece lens with a long exit pupil distance and good imaging quality.

[0004] The technical solution proposed in this application is as follows: An eyepiece lens with an exit pupil diameter of 8mm and an exit pupil distance of 50mm is provided. The eyepiece lens is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged sequentially along the optical axis from the eye side to the image side. The first lens is a biconvex lens; the second lens has positive optical power, with the eye-side being convex and the image-side being concave; the third lens has positive optical power, with the eye-side being convex and the image-side being concave; the fourth lens has negative optical power, with the eye-side being convex and the image-side being concave; the fifth lens is a biconvex lens; and the sixth lens has negative optical power, with the eye-side being concave and the image-side being planar.

[0005] Furthermore, the air gap between the first lens and the second lens is 0.28 mm, the air gap between the second lens and the third lens is 0.286 mm, the air gap between the third lens and the fourth lens is 0.3 mm, the air gap between the fifth lens and the sixth lens is 2.606 mm, and the air gap between the sixth lens and the image plane is 8.192 mm.

[0006] Further, the first lens has a center thickness of 7.91 mm, an eye-side radius of curvature of 52.265 mm, and an image-side radius of curvature of -145.434 mm; the second lens has a center thickness of 7.8 mm, an eye-side radius of curvature of 34.382 mm, and an image-side radius of curvature of 127.646 mm; the third lens has a center thickness of 8 mm, an eye-side radius of curvature of 31.176 mm, and an image-side radius of curvature of 177.2 mm; the fourth lens has a center thickness of 3.89 mm, an eye-side radius of curvature of 126.502 mm, and an image-side radius of curvature of 18.523 mm; the fifth lens has a center thickness of 6.65 mm, an eye-side radius of curvature of 34.963 mm, and an image-side radius of curvature of -76.44 mm; and the sixth lens has a center thickness of 2 mm and an eye-side radius of curvature of -28.242 mm.

[0007] Furthermore, the refractive index Nd1 of the first lens satisfies: Nd1≥1.49, and the Abbe number Vd1 satisfies: Vd1≥81.6; The refractive index Nd2 of the second lens satisfies: Nd2≥1.49, and the Abbe number Vd2 satisfies: Vd2≥81.6; The refractive index Nd3 of the third lens satisfies: Nd3≥1.59, and the Abbe number Vd3 satisfies: Vd3≥68.3; The refractive index Nd4 of the fourth lens satisfies: Nd4≥1.75, and the Abbe number Vd4 satisfies: Vd4≥27.5; The refractive index Nd5 of the fifth lens satisfies: Nd5≥1.8, and the Abbe number Vd5 satisfies: Vd5≥46.5; The refractive index Nd6 of the sixth lens satisfies: Nd6≥1.8, and the Abbe number Vd6 satisfies: Vd6≥42.7.

[0008] Furthermore, the effective focal length f of the eyepiece lens is 39mm, and the focal lengths of the first lens to the sixth lens are f1, f2, f3, f4, f5, and f6, respectively, and the focal lengths of each lens satisfy the following: 1.9 <f1 / f<2.3,2.3<f2 / f<2.5,1.5<f3 / f<1.8,-0.8<f4 / f<-0.6,0.6<f5 / f<0.8,0.9<f6 / f<0.7。

[0009] Furthermore, all lenses are made of glass, and all lens surfaces are spherical.

[0010] Furthermore, the field of view of the eyepiece lens is 2 ≥37.8°, imaging circle diameter ≥26.2mm.

[0011] Furthermore, the total optical length of the eyepiece lens is 43.7 mm, and the back focal length is 8.19 mm.

[0012] The eyepiece lens provided in this application, through the allocation of the optical power of each lens and the spacing between each lens, has the advantages of small size, light weight, short total optical length, long exit pupil distance, good imaging quality and stable performance. It is especially suitable for 1.03-inch target surfaces and meets the application needs of special fields. Attached Figure Description

[0013] The accompanying drawings are provided to further understand this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof.

[0014] Figure 1 A schematic diagram of the optical path structure of an eyepiece lens with a long exit pupil distance provided in an embodiment of this application; Figure 2 for Figure 1 The MTF diagram of the eyepiece lens with extended interpupillary distance is shown. Figure 3 for Figure 1 The diagram shows the dot pattern of the eyepiece lens with a long interpupillary distance. Figure 4 for Figure 1 The diagram shows the field curvature distortion of the eyepiece lens with a long interpupillary distance.

[0015] Label Explanation: 11. Aperture stop; 12. First lens; 13. Second lens; 14. Third lens; 15. Fourth lens; 16. Fifth lens; 17. Sixth lens; 18. Image plane. Detailed Implementation

[0016] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0017] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0018] This application provides an eyepiece lens with a long exit pupil distance, an effective focal length of 39mm, an exit pupil diameter of 8mm, an exit pupil distance of 50mm, and a field of view of 2. ≥37.8°, imaging circle diameter ≥26.2mm. The large exit pupil distance ensures a safe distance between the observer's eye and the rear of the eyepiece, effectively mitigating the risk of eye injury caused by firearm recoil when used in firearm sight systems, thus improving safety.

[0019] like Figure 1 As shown, in one embodiment, the eyepiece lens comprises an aperture stop 11, a first lens 12, a second lens 13, a third lens 14, a fourth lens 15, a fifth lens 16, and a sixth lens 17 arranged sequentially along the optical axis from the eye side to the image side. Specifically, the first lens 12 is a biconvex lens; the second lens 13 has positive optical power, with a convex surface on the eye side and a concave surface on the image side; the third lens 14 has positive optical power, with a convex surface on the eye side and a concave surface on the image side; the fourth lens 15 has negative optical power, with a convex surface on the eye side and a concave surface on the image side; the fifth lens 16 is a biconvex lens; and the sixth lens 17 has negative optical power, with a concave surface on the eye side and a flat surface on the image side. The focal lengths of the first lens 12 to the sixth lens 17 are f1, f2, f3, f4, f5, and f6, respectively, and each lens focal length satisfies: 1.9 <f1 / f<2.3,2.3<f2 / f<2.5,1.5<f3 / f<1.8,-0.8<f4 / f<-0.6,0.6<f5 / f<0.8,0.9<f6 / f<0.7。

[0020] Furthermore, referring to Table 1, it can be seen that the air gap between the aperture stop 11 and the first lens 12 is 50 mm, the air gap between the first lens 12 and the second lens 13 is 0.28 mm, the air gap between the second lens 13 and the third lens 14 is 0.286 mm, the air gap between the third lens 14 and the fourth lens 15 is 0.3 mm, the air gap between the fifth lens 16 and the sixth lens 17 is 2.606 mm, and the air gap between the sixth lens 17 and the image plane 18 is 8.192 mm.

[0021] Furthermore, the center thickness of the first lens 12 is 7.91 mm, the radius of curvature of the eye-side is 52.265 mm, and the radius of curvature of the image-side is -145.434 mm; the center thickness of the second lens 13 is 7.8 mm, the radius of curvature of the eye-side is 34.382 mm, and the radius of curvature of the image-side is 127.646 mm; the center thickness of the third lens 14 is 8 mm, the radius of curvature of the eye-side is 31.176 mm, and the radius of curvature of the image-side is 177.2 mm; the center thickness of the fourth lens 15 is 3.89 mm, the radius of curvature of the eye-side is 126.502 mm, and the radius of curvature of the image-side is 18.523 mm; the center thickness of the fifth lens 16 is 6.65 mm, the radius of curvature of the eye-side is 34.963 mm, and the radius of curvature of the image-side is -76.44 mm; and the center thickness of the sixth lens 17 is 2 mm, and the radius of curvature of the eye-side is -28.242 mm.

[0022] Based on the above data, in this embodiment, the total optical length of the eyepiece lens is 43.7 mm, and the back focal length is 8.19. Furthermore, all lenses in this eyepiece lens are made of glass. Thus, this eyepiece lens has advantages such as small size and light weight, and is less prone to image quality degradation due to temperature variations.

[0023] In one embodiment, the refractive index Nd1 of the first lens 12 satisfies: Nd1≥1.49, and the Abbe number Vd1 satisfies: Vd1≥81.6; the refractive index Nd2 of the second lens 13 satisfies: Nd2≥1.49, and the Abbe number Vd2 satisfies: Vd2≥81.6; the refractive index Nd3 of the third lens 14 satisfies: Nd3≥1.59, and the Abbe number Vd3 satisfies: Vd3≥68.3; the refractive index Nd4 of the fourth lens 15 satisfies: Nd4≥1.75, and the Abbe number Vd4 satisfies: Vd4≥27.5; the refractive index Nd5 of the fifth lens 16 satisfies: Nd5≥1.8, and the Abbe number Vd5 satisfies: Vd5≥46.5; and the refractive index Nd6 of the sixth lens 17 satisfies: Nd6≥1.8, and the Abbe number Vd6 satisfies: Vd6≥42.7.

[0024] Table 1 Data for each lens Please see Figures 2 to 4 , Figure 2 This is the MTF plot of the eyepiece lens. Figure 3 This is a dot diagram of the eyepiece lens. Figure 4 This is a field curvature distortion diagram of the eyepiece lens. Figure 2 In this study, when the spatial cutoff frequency is 40 Hz, the MTF > 0.27, resulting in low energy loss, high contrast, and good imaging. Figure 3 In this study, the Airy disk size was <14.49 μm, resulting in low image diffusion, high resolution, and clear image quality. Figure 4 In this design, the small field curvature ensures minimal deviation between the sharp point and the ideal image point in each field of view. Imaging is clear near the ideal image plane in each field of view, preventing the simultaneous blurring of the center and edge points. Furthermore, distortion is less than 2% at the maximum field of view, and there is no significant bending at the edge of the field of view. Therefore, the eyepiece lens provided in this application, through the allocation of optical power and spacing between lenses, achieves advantages such as small size, light weight, short overall optical length, long exit pupil distance, good image quality, and stable performance. It is particularly suitable for 1.03-inch target surfaces, meeting the application requirements of specialized fields.

[0025] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An eyepiece lens with an extended interpupillary distance, characterized in that, The exit pupil diameter is 8mm and the exit pupil distance is 50mm. The eyepiece lens is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens arranged sequentially along the optical axis from the eye side to the image side. The first lens is a biconvex lens; the second lens has positive optical power, with the eye-side being convex and the image-side being concave; the third lens has positive optical power, with the eye-side being convex and the image-side being concave; the fourth lens has negative optical power, with the eye-side being convex and the image-side being concave; the fifth lens is a biconvex lens; and the sixth lens has negative optical power, with the eye-side being concave and the image-side being planar.

2. The eyepiece lens with extended exit pupil distance according to claim 1, characterized in that, The air gap between the first lens and the second lens is 0.28 mm, the air gap between the second lens and the third lens is 0.286 mm, the air gap between the third lens and the fourth lens is 0.3 mm, the air gap between the fifth lens and the sixth lens is 2.606 mm, and the air gap between the sixth lens and the image plane is 8.192 mm.

3. The eyepiece lens with extended exit pupil distance according to claim 1, characterized in that, The first lens has a center thickness of 7.91 mm, an eye-side radius of curvature of 52.265 mm, and an image-side radius of curvature of -145.434 mm; the second lens has a center thickness of 7.8 mm, an eye-side radius of curvature of 34.382 mm, and an image-side radius of curvature of 127.646 mm; the third lens has a center thickness of 8 mm, an eye-side radius of curvature of 31.176 mm, and an image-side radius of curvature of 177.2 mm; the fourth lens has a center thickness of 3.89 mm, an eye-side radius of curvature of 126.502 mm, and an image-side radius of curvature of 18.523 mm; the fifth lens has a center thickness of 6.65 mm, an eye-side radius of curvature of 34.963 mm, and an image-side radius of curvature of -76.44 mm; and the sixth lens has a center thickness of 2 mm and an eye-side radius of curvature of -28.242 mm.

4. The eyepiece lens with extended interpupillary distance according to claim 1, characterized in that: The refractive index Nd1 of the first lens satisfies: Nd1≥1.49, and the Abbe number Vd1 satisfies: Vd1≥81.6; The refractive index Nd2 of the second lens satisfies: Nd2≥1.49, and the Abbe number Vd2 satisfies: Vd2≥81.6; The refractive index Nd3 of the third lens satisfies: Nd3≥1.59, and the Abbe number Vd3 satisfies: Vd3≥68.3; The refractive index Nd4 of the fourth lens satisfies: Nd4≥1.75, and the Abbe number Vd4 satisfies: Vd4≥27.5; The refractive index Nd5 of the fifth lens satisfies: Nd5≥1.8, and the Abbe number Vd5 satisfies: Vd5≥46.5; The refractive index Nd6 of the sixth lens satisfies: Nd6≥1.8, and the Abbe number Vd6 satisfies: Vd6≥42.

7.

5. The eyepiece lens with extended exit pupil distance according to claim 1, characterized in that, The effective focal length f of the eyepiece lens is 39mm, and the focal lengths of the first lens to the sixth lens are f1, f2, f3, f4, f5, and f6, respectively. The focal lengths of each lens satisfy the following: 1.9 <f1 / f<2.3,2.3<f2 / f<2.5,1.5<f3 / f<1.8,-0.8<f4 / f<-0.6,0.6<f5 / f<0.8,0.9<f6 / f<0.7。 6. The eyepiece lens with extended exit pupil distance according to claim 1, characterized in that, All lenses are made of glass, and all lens surfaces are spherical.

7. The eyepiece lens with extended exit pupil distance according to claim 1, characterized in that, The eyepiece lens field of view 2 ≥37.8°, imaging circle diameter ≥26.2mm.

8. The eyepiece lens with extended exit pupil distance according to claim 1, characterized in that, The total optical length of the eyepiece lens is 43.7 mm, and the back focal length is 8.19 mm.

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