Eyepiece optical system for sighting telescope

Abstract

The utility model provides an eyepiece optical system for a sighting telescope. From an object space to an image space along an optical axis, the eyepiece optical system sequentially comprises a first biconvex spherical lens, a second biconvex spherical lens, a third biconvex spherical lens and a fourth biconvex spherical lens, the object space side of the second meniscus spherical lens is a convex surface, and the image space side of the second meniscus spherical lens is a concave surface; a third meniscus spherical lens with positive focal power; the object side of the fourth meniscus spherical lens is a convex surface, and the image side of the fourth meniscus spherical lens is a concave surface; the object space side of the fifth meniscus spherical lens is a concave surface, and the image space side of the fifth meniscus spherical lens is a convex surface; and the object space side of the sixth meniscus spherical lens is a convex surface, and the image space side of the sixth meniscus spherical lens is a concave surface. Through the elaborately-designed lens combination, accurate control and correction of incident light are achieved, and the imaging quality and observation comfort of the system are remarkably improved. Due to the design of the large exit pupil diameter and the long exit pupil distance, eye fatigue is reduced, and the use comfort and safety are improved.

Description

Technical field

[0002] The utility model relates to the technical field of optical observation, in particular to an eyepiece optical system for a sighting tool. [Background Technology]

[0004] As the optical system near the eye, the eyepiece plays a crucial role in optical observation equipment. It is typically used in conjunction with the objective lens at the front end to magnify the image formed by the objective lens. It is widely used in various devices such as telescopes and microscopes. Eyepieces play an irreplaceable role in industries such as military, industrial instrumentation, security, and medicine. Especially in individual combat, eyepieces are often used in conjunction with low-light-level or long-wave infrared objective lenses as rifle scopes to improve combat efficiency and accuracy.

[0005] However, the current eyepiece optical systems for sights on the market have many shortcomings. First, traditional eyepiece optical systems often have multiple aberration problems, such as spherical aberration, chromatic aberration, and distortion, which can seriously affect the accuracy and comfort of observation.

[0006] Secondly, the exit pupil distance of the eyepiece optical system of the current sights on the market is mostly around 50mm, and the exit pupil diameter is only about 5mm. With such a design, the observation comfort is low and the human eye is easily fatigued. In addition, due to the short exit pupil distance, the safety of use is relatively low, especially in gun sights, which are prone to accidental injuries due to the recoil of the gun. [Utility Model Content]

[0008] The purpose of the present utility model is to provide an eyepiece optical system for a sight, aiming to solve at least one of the above-mentioned problems existing in the eyepiece optical system for a sight in the prior art.

[0009] The utility model is realized by the following technical solutions:

[0010] An eyepiece optical system for a sighting device, comprising, in order from the object side to the image side along the optical axis:

[0011] a first biconvex spherical lens having positive optical power;

[0012] a second meniscus spherical lens having negative optical power, the object side of which is convex and the image side of which is concave;

[0013] a third meniscus spherical lens with positive optical power;

[0014] A fourth meniscus spherical lens with positive optical power, whose object side is convex and image side is concave;

[0015] A fifth meniscus spherical lens with negative optical power, whose object side is concave and image side is convex;

[0016] A sixth meniscus spherical lens with positive optical power, whose object side is convex and image side is concave.

[0017] In the above-mentioned eyepiece optical system for a sight, the object side of the third meniscus spherical lens is convex, and the image side is concave.

[0018] In the above-mentioned eyepiece optical system for a sight, the object side of the third meniscus spherical lens is a convex surface, and the image side is a flat surface.

[0019] In the above-described eyepiece optical system for a sight, the total focal length of the eyepiece optical system is f, and the focal lengths of the first biconvex spherical lens to the sixth meniscus spherical lens are f1, f2, f3, f4, f5, and f6, respectively. The relationship between the focal lengths of the lenses satisfies the following conditions:

[0020] 2 <f1 / f<2.5;

[0021] 3 <f2 / f<3.9;

[0022] 2 <f3 / f<2.5;

[0023] 1.2 <f4 / f<1.5;

[0024] -2 <f5 / f<-1.3;

[0025] -1.5 <f6 / f<-1.1。

[0026] As described above, the eyepiece optical system for a sight has an exit pupil diameter φ of 15 mm and an exit pupil distance H of 95 mm.

[0027] In the eyepiece optical system for a sight as described above, a stop for limiting the light beam to improve imaging quality is provided on the object side of the first biconvex spherical lens.

[0028] In the above-mentioned eyepiece optical system for a sight, the image side of the first biconvex spherical lens and the object side of the second meniscus spherical lens are cemented together to form a cemented lens.

[0029] The eyepiece optical system for a sight as described above has a ratio of lens length to lens focal length less than 1.5, and a total lens weight less than 36 g.

[0030] In the above-mentioned eyepiece optical system for a sight, the first biconvex spherical lens to the sixth meniscus spherical lens are all made of spherical glass lenses.

[0031] An eyepiece optical system for a sight as described above, wherein the total focal length EFFL of the eyepiece optical system is 39.97 mm, the field of view angle 2w is ≥17.5°, the imaging circle diameter is greater than 10.5 mm, the total optical length TTL is ≤50.5 mm, the optical back focus is ≥7.6 mm, and the F-Tan (Theta) distortion is ≤2%.

[0032] Compared with the prior art, the utility model has the following advantages:

[0033] 1. Through a carefully designed lens arrangement and configuration, the synergistic effect of each lens not only achieves precise control and correction of incident light, but also significantly improves the imaging quality and viewing comfort of the eyepiece optical system. Specifically, it effectively reduces aberrations such as spherical aberration, chromatic aberration, and distortion, ensuring high image clarity and contrast at all viewing positions. Furthermore, the system's compact design allows for easy integration into various sights while maintaining high performance, meeting the needs of diverse scenarios. By optimizing lens shape and power distribution, the lens size and aperture are reduced, contributing to cost and weight reductions.

[0034] 2. The present invention provides a large exit pupil diameter and a long exit pupil distance, which enables the observer to maintain a clear observation effect even when the scope is shaken or offset. In addition, in a gun sight system, the probability of accidental injury to the user due to the recoil generated by the firearm during use can be greatly reduced.

[0035] 3. All lenses are made of spherical glass lenses, which have good lens stability and low product cost. Compared with other similar products using plastic lenses, they have higher stability and can meet military standards.

Brief Description of the Drawings

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the utility model, the following briefly introduces the drawings required for describing the embodiments.

[0038] Figure 1 This is a schematic structural diagram of an embodiment of the present utility model;

[0039] Figure 2 This is a schematic diagram of the optical layout of an embodiment of the present utility model;

[0040] Figure 3 This is a normal temperature MTF curve diagram of an embodiment of the present utility model;

[0041] Figure 4 This is a curve diagram of the center field curvature distortion of the exit pupil diameter at room temperature according to an embodiment of the present invention. [Specific implementation method]

[0043] In order to make the technical problems, technical solutions and beneficial effects solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0044] See Figures 1 to 4 This embodiment provides an eyepiece optical system for a sight, which includes, along the optical axis from the object side to the image side, the following components:

[0045] a first biconvex spherical lens L1 having positive optical power;

[0046] a second meniscus spherical lens L2 having negative optical power, the object side of which is convex and the image side of which is concave;

[0047] a third meniscus spherical lens L3 having positive optical power;

[0048] a fourth meniscus spherical lens L4 having positive optical power, with a convex object-side surface and a concave image-side surface;

[0049] A fifth meniscus spherical lens L5 with negative optical power, whose object side is concave and image side is convex;

[0050] The sixth meniscus spherical lens L6 has positive refractive power and has a convex object-side surface and a concave image-side surface.

[0051] In this embodiment, the first biconvex spherical lens L1 has positive focal power and a flat shape. This compresses the angle of incident light, achieving a smooth transition and allowing divergent light to enter the rear lens smoothly, thus reducing the rear lens aperture. Its image-side convex surface helps reduce the angle of incident light and the overall size of the lens. Made of high-refractive-index, low-dispersion optical glass, it is designed to initially converge incident light, improving the system's light transmittance and image clarity.

[0052] The second meniscus spherical lens L2 has negative optical power, with a convex surface on the object side and a concave surface on the image side. This design helps to smooth the wide-angle light collected by the first biconvex spherical lens L1 and helps to reduce aberrations in the eyepiece optical system.

[0053] The third meniscus spherical lens L3 has positive power, with a convex surface on the object side and a concave or flat surface on the image side. Positioned at the highest point of the system's light rays, it can adopt either a convex-flat or convex-concave configuration, facilitating a reduction in lens aperture, reducing wide-angle light, and reducing the angle of incidence on the rear lens group, further facilitating correction of rear-group aberrations.

[0054] The fourth spherical meniscus lens L4 has positive power, with a convex surface on the object side and a concave surface on the image side. This convex-concave configuration helps reduce the angle of wide-angle light, reducing the angle of incidence on the rear lens group and further correcting residual aberrations, particularly field curvature and astigmatism.

[0055] The fifth meniscus lens L5 has negative power, with a concave surface on the object side and a convex surface on the image side. This convex-concave shape provides the primary negative power of the eyepiece optical system, helping to compensate for spherical aberration introduced by the preceding lens element and further correcting aberrations generated by the preceding lens group. This maximizes the penetration of wide-angle light into the system, enhancing wide-angle performance and contributing to increased illumination.

[0056] The sixth meniscus spherical lens L6 has positive power, with a convex object-side surface and a concave image-side surface. This convex-concave, gently sloping shape helps reduce the lens's aperture, allowing light to converge effectively and smoothly towards the imaging surface. It also collects more light entering the image plane, increasing luminous flux and ensuring accurate focus on the viewer's retina, resulting in a clear, distortion-free image.

[0057] The eyepiece optical system for sights provided in this embodiment, through a carefully designed combination of six lenses, not only achieves precise control and correction of incident light, but also significantly improves the system's imaging quality and observation comfort. Specifically, through the synergistic effect of each lens, the system can effectively reduce various aberrations such as spherical aberration, chromatic aberration, and distortion, ensuring that the image maintains high clarity and high contrast at all field of view positions. In addition, the system's compact design makes it easy to integrate into various sights while maintaining high performance, meeting the needs of use in different scenarios. In particular, by optimizing the lens shape and optical power distribution, the system further reduces the lens size and lens diameter, which is conducive to reducing costs and weight. Therefore, this eyepiece optical system not only improves the aiming accuracy of the sight, but also enhances the user's observation experience and operational convenience, and has broad application prospects.

[0058] Furthermore, as a preferred embodiment of the present invention but not a limitation, the object side of the third meniscus spherical lens L3 is convex, and the image side can be concave, which is conducive to further converging light and can effectively correct aberrations, especially reduce distortion and improve image plane flatness.

[0059] Optionally, in some other embodiments, the object side of the third meniscus spherical lens L3 is convex, and the image side can be a plane. When the image side is a plane, the lens can maintain the parallelism of the light while converging the light, which helps to reduce the incident angle of the light on the rear group of lenses, thereby being more conducive to the correction of the aberrations of the rear group.

[0060] It should be noted that the basic parameters of the eyepiece system used in the sight in this embodiment are shown in Table 1, where the units of curvature radius and thickness are both millimeters (mm).

[0061] Table 1

[0062]

[0063] Specifically, in order to enable the spherical lenses to cooperate with each other to achieve the effects of optimizing light control, reducing aberrations, and improving system compactness, the total focal length of the eyepiece optical system is f, and the focal lengths of the first biconvex spherical lens L1 to the sixth meniscus spherical lens L6 are f1, f2, f3, f4, f5, and f6, respectively, and the relationship between the focal lengths of the lenses satisfies the following conditions:

[0064] 2 <f1 / f<2.5;

[0065] 3 <f2 / f<3.9;

[0066] 2 <f3 / f<2.5;

[0067] 1.2 <f4 / f<1.5;

[0068] -2 <f5 / f<-1.3;

[0069] -1.5 <f6 / f<-1.1。

[0070] Furthermore, as a preferred embodiment of this solution but not a limitation, the exit pupil diameter φ of the eyepiece optical system is 15 mm, and the exit pupil distance H is 95 mm.

[0071] In this embodiment, the exit pupil diameter φ is set to 15 mm, ensuring clear observation at the center of the exit pupil for the observer's eyes (an adult's eye diameter is typically approximately 5 mm). It is particularly noteworthy that this large 15 mm exit pupil diameter allows the observer to maintain clear observation even when the observer is moving up, down, or left, or right. This feature allows this product to serve as a universal alternative to other products with smaller exit pupil diameters, greatly improving ease of use and comfort. Furthermore, similar eyepiece lenses typically have a shorter exit pupil distance of approximately 50 mm. However, in military scope systems, particularly those used with firearms, this design can easily cause the recoil generated during shooting to cause accidental injury to the firearm user. In this embodiment, the exit pupil distance is increased to 95 mm. This improvement can largely avoid this problem and improve safety. Therefore, the eyepiece optical system proposed in this embodiment can be widely used in various devices such as telescopes and microscopes, and performs particularly well in firearm scopes.

[0072] Furthermore, as a preferred embodiment of the present invention but not a limitation, a stop A for limiting the light beam to improve the imaging quality is provided on the object side of the first biconvex spherical lens L1, thereby further improving the imaging quality of the eyepiece optical system for the sight, expanding the light entering the eyepiece optical system, reducing the front port diameter of the eyepiece optical system, and reducing the assembly sensitivity of the system.

[0073] Furthermore, as a preferred embodiment of the present invention but not a limitation, the image side of the first biconvex spherical lens L1 and the object side of the second meniscus spherical lens L2 are glued together to form a glued lens. The two lenses are glued together by an optical glue to form an integral optical element, which can not only reduce the air gap between the lenses and reduce the loss and interference of light during propagation, but also improve the stability and durability of the system. In this embodiment, the gluing of the first biconvex spherical lens L1 and the second meniscus spherical lens L2 makes the transition of light between the two smoother, which is conducive to correcting chromatic aberration and achieving better tolerance sensitivity. The first biconvex spherical lens L1 has positive optical power and a flat lens shape, which can compress the angle of the incident light to achieve a smooth transition of light, so that the divergent light can smoothly enter the rear, further making the light transition smooth, which is conducive to reducing the rear end lens aperture to obtain a higher quality imaging effect.

[0074] Furthermore, as a preferred embodiment of the present invention but not a limitation, the ratio of the lens length to the lens focal length of the eyepiece optical system is less than 1.5, and the total weight of the lens is less than 36g, so that the eyepiece optical system can ensure sufficient focal length while also having a compact and lightweight appearance, which is easy to carry and use. It is suitable for various occasions requiring high-precision observation, especially in the military, industrial, security and other fields where there are restrictions on weight and volume.

[0075] Furthermore, as a preferred embodiment of the present invention but not a limitation, the first biconvex spherical lens L1 to the sixth meniscus spherical lens L6 all use spherical glass lenses, which have good lens stability and low product cost. Compared with other products that use plastic lenses, they have high stability and can meet military standards.

[0076] Furthermore, as a preferred embodiment of this solution but not a limitation, the total focal length EFFL of the eyepiece optical system is 39.97 mm, the field of view angle 2w is ≥ 17.5°, the imaging circle diameter is greater than 10.5 mm, the total optical length TTL is ≤ 50.5 mm, the optical back focus is ≥ 7.6 mm, and the F-Tan (Theta) distortion is ≤ 2%.

[0077] It should be noted that the optical performance of this embodiment is as follows Figures 3 and 4 As shown, Figure 3This is the MTF diagram of the center of the exit pupil diameter of this embodiment at room temperature. It can be seen from the figure that the MTF is ≥ 0.3 within the 0.8 field of view at 40lp, and the imaging quality is high. Figure 4 This is a distortion diagram of the embodiment facing the center of the exit pupil diameter at room temperature. It can be seen that the distortion is less than 2%, which is very small. The human eye can observe the image without distortion and it is more comfortable.

[0078] Working principle of this utility model:

[0079] The eyepiece optical system for a scope proposed in this utility model comprises six lenses arranged sequentially along the optical axis from the object side to the image side, each lens having a specific optical power and shape design. First, the first biconvex spherical lens serves as the entrance to the eyepiece optical system. Its flat shape and positive optical power compress the angle of the incident light, allowing the diverging light to enter the rear smoothly. This helps reduce the rear lens aperture and improves the system's light transmittance and image clarity.

[0080] The second meniscus spherical lens L2 has negative optical power, and its design is conducive to smoothing the large-angle light collected by the first lens, while reducing the aberration of the eyepiece optical system.

[0081] The third meniscus spherical lens L3 is located at the highest position of the system light. Its shape design is conducive to reducing the lens aperture, making the large-angle light smaller, reducing the incident angle of the light on the rear lens group, and facilitating the correction of the rear lens aberration.

[0082] The fourth meniscus spherical lens L4 and the fifth meniscus spherical lens L5 have positive and negative optical power respectively. Their design is conducive to further correcting residual aberrations, especially field curvature and astigmatism, and compensating for the spherical aberration introduced by the previous lens, thereby improving wide-angle performance and illumination.

[0083] Finally, the sixth meniscus spherical lens L6 has positive optical power, and its flat shape helps to reduce the aperture, so that the light can be effectively and smoothly converged at the end, ensuring that the light is accurately focused on the observer's retina to form a clear, distortion-free image.

[0084] Furthermore, by optimizing lens shape and focal power distribution, this eyepiece optical system reduces lens size and aperture, reducing cost and weight. Furthermore, the specific exit pupil diameter and distance design enhance ease, comfort, and safety of use. The aperture setting further enhances image quality, while the cemented lens design reduces light loss and interference during propagation.

[0085] In summary, the eyepiece optical system of the sight achieves precise control and correction of the incident light through a carefully designed combination of six lenses, significantly improving the system's imaging quality, observation comfort, and safety of use, and has broad application prospects.

[0086] The above are implementation methods provided in conjunction with specific content, and the specific implementation of this application is not limited to these descriptions. Any method structure that is similar to the method structure of this application, or any technical deduction or replacement based on the concept of this application, should be considered as the scope of protection of this application.

Claims

1. An eyepiece optical system for a sight, characterized in that: Along the optical axis from object to image, it includes: a first biconvex spherical lens (L1) having positive optical power; a second meniscus spherical lens (L2) having negative optical power, the object side of which is convex and the image side of which is concave; a third meniscus spherical lens (L3) with positive optical power; a fourth meniscus spherical lens (L4) with positive optical power, the object side of which is convex and the image side is concave; a fifth meniscus spherical lens (L5) with negative optical power, the object side of which is concave and the image side is convex; A sixth meniscus spherical lens (L6) with positive optical power has a convex object side and a concave image side.

2. The eyepiece optical system for a sight according to claim 1, characterized in that: The object side of the third meniscus spherical lens (L3) is convex, and the image side is concave.

3. The eyepiece optical system for a sight according to claim 1, characterized in that: The object side of the third meniscus spherical lens (L3) is a convex surface, and the image side is a flat surface.

4. The eyepiece optical system for a sight according to any one of claims 1 to 3, characterized in that: The total focal length of the eyepiece optical system is f, and the focal lengths of the first biconvex spherical lens (L1) to the sixth meniscus spherical lens (L6) are f1, f2, f3, f4, f5, and f6, respectively. The relationship between the focal lengths of the lenses satisfies the following conditions: 2 < f1 / f < 2.5; 3 < f2 / f < 3.9; 2 < f3 / f < 2.5; 1.2 < f4 / f < 1.5; -2 < f5 / f < -1.3; -1.5 < f6 / f < -1.

1.

5. The eyepiece optical system for a sight according to any one of claims 1 to 3, characterized in that: The eyepiece optical system has an exit pupil diameter φ of 15 mm and an exit pupil distance H of 95 mm.

6. The eyepiece optical system for a sight according to any one of claims 1 to 3, characterized in that: The object side of the first biconvex spherical lens (L1) is provided with a stop (A) for limiting the light beam to improve imaging quality.

7. The eyepiece optical system for a sight according to any one of claims 1 to 3, characterized in that: The image side of the first biconvex spherical lens (L1) and the object side of the second meniscus spherical lens (L2) are cemented together to form a cemented lens.

8. The eyepiece optical system for a sight according to any one of claims 1 to 3, characterized in that: The ratio of the lens length to the lens focal length of the eyepiece optical system is less than 1.5, and the total weight of the lens is less than 36g.

9. The eyepiece optical system for a sight according to any one of claims 1 to 3, characterized in that: The first biconvex spherical lens (L1) to the sixth meniscus spherical lens (L6) all adopt spherical glass lenses.

10. The eyepiece optical system for a sight according to any one of claims 1 to 3, characterized in that: The eyepiece optical system has a total focal length EFFL=39.97 mm, a field of view angle 2w≥17.5°, an imaging circle diameter greater than 10.5 mm, a total optical length TTL≤50.5 mm, an optical back focus≥7.6 mm, and an F-Tan (Theta) distortion≤2%.

Images