Eyepiece and eyepiece optical system

Abstract

The embodiment of the invention provides an eyepiece and an eyepiece optical system. Wherein the eyepiece comprises a first lens group and a second lens group which are arranged along the same optical axis, the first lens group is located on the exit pupil side, and the second lens group is located on the focal plane side; the first lens group comprises a first lens, a second lens and a third lens; the second lens group comprises a fourth lens; a polarization reflection element is arranged on the side, away from the second lens, of the first lens, a light splitting element is arranged on the side, away from the second lens, of the third lens, and a phase retarder is arranged between the polarization reflection element and the light splitting element. The eyepiece satisfies the condition that [(1 / f)-(1 / F1)] / (1 / F2) is more than 0.065 and less than 0.07; wherein f is the total focal length of the eyepiece, F1 is the focal length of the first lens group, and F2 is the focal length of the second lens group.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical technology, and more specifically, to an eyepiece and an eyepiece optical system. Background Art

[0002] In the field of observation equipment, users have increasing demands for intelligence, portability and comfort. In order to meet these demands, observation and aiming equipment should have a larger exit pupil to ensure the comfort of observers. However, the exit pupil diameter of mainstream eyepieces is only between 4mm and 6mm, and users need to align precisely when observing or aiming, which undoubtedly increases the difficulty of use. In order to improve this situation, there is an urgent need for an observation and aiming lens that can enlarge the exit pupil size and increase the exit pupil distance. Summary of the invention

[0003] The purpose of this application is to provide a new technical solution for an eyepiece and an eyepiece optical system.

[0004] In a first aspect, the present application provides an eyepiece. The eyepiece includes a first lens group and a second lens group arranged along the same optical axis, the first lens group is located on the exit pupil side, and the second lens group is located on the focal plane side;

[0005] The first lens group includes a first lens, a second lens and a third lens;

[0006] The second lens group includes a fourth lens;

[0007] A polarizing reflection element is disposed on a side of the first lens away from the second lens, a beam splitter is disposed on a side of the third lens away from the second lens, and a phase retarder is disposed between the polarizing reflection element and the beam splitter;

[0008] The eyepiece satisfies 0.065<[(1 / f)-(1 / F 1 )] / (1 / F 2 )<0.07; wherein, f is the total focal length of the eyepiece, F 1 is the focal length of the first lens group, F 2 is the focal length of the second lens group.

[0009] Optionally, the eyepiece satisfies: 0.53<(EP×ED) / (f×h)<1.58; wherein EP is the exit pupil distance of the eyepiece, ED is the exit pupil diameter of the eyepiece, f is the total focal length of the eyepiece, and h is the image height of the eyepiece.

[0010] Optionally, the eyepiece satisfies: 0.53<EP / (NA×h)<1.58; wherein NA is the aperture of the eyepiece.

[0011] Optionally, the optical power of the first lens is positive, the optical power of the second lens is negative, and the optical power of the third lens is positive.

[0012] Optionally, the first lens group satisfies: 1.74<|[(1 / f 1 )+(1 / f 3 )] / (1 / f 2 )|<1.96; where f 1 is the focal length of the first lens, f 2 is the focal length of the second lens, f 3 is the focal length of the third lens.

[0013] Optionally, the optical power of the fourth lens is positive.

[0014] Optionally, the eyepiece satisfies: 1.12<D max / ED<1.24; where D max is the maximum effective aperture of the lens in the eyepiece, and ED is the exit pupil aperture of the eyepiece.

[0015] Optionally, the polarized reflection element and the phase retarder are arranged on a surface of the first lens close to the exit pupil side;

[0016] The beam splitter is disposed on a surface of the third lens away from the exit pupil.

[0017] Optionally, the first lens, the third lens and the fourth lens are plastic aspherical lenses;

[0018] The second lens is a glass spherical lens.

[0019] Optionally, the exit pupil distance EP of the eyepiece is 15 mm to 25 mm, the exit pupil diameter ED of the eyepiece is 20 mm to 25 mm, and the aperture NA of the eyepiece is 1.72 to 2.15.

[0020] Optionally, the image height h of the eyepiece is 9.2 mm to 13 mm.

[0021] Optionally, the FOV of the eyepiece is 12.2° to 17.4°.

[0022] Optionally, a polarizing element is provided on a surface of the fourth lens close to the exit pupil side.

[0023] In a second aspect, the present application provides an eyepiece optical system. The eyepiece optical system comprises:

[0024] An eyepiece as described in the first aspect.

[0025] The beneficial effects of this application are:

[0026] The eyepiece provided in the embodiment of the present application is a viewing and aiming lens with a large exit pupil and high definition. Through a new optical design, a larger exit pupil diameter and exit pupil distance are achieved, which improves the comfort of the observer; at the same time, the eyepiece of the present application has high definition, and this design ensures the superiority of imaging quality, making observation or aiming more accurate, which is based on the folded optical path design (pancake) adopted in the present application; in addition, the pancake design adopted in the present application can also make the optical architecture of the entire eyepiece more compact, which can reduce the volume and weight of the eyepiece. Since the eyepiece provided by the present application has the characteristics of large exit pupil, high definition and compact structure, it can be widely used in optical instruments such as telescopes and sights.

[0027] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0029] Figure 1 A schematic diagram of the structure of the eyepiece provided in an embodiment of the present application;

[0030] Figure 2 A dot array diagram of the eyepiece provided in an embodiment of the present application;

[0031] Figure 3 The MTF diagram of the eyepiece provided in the embodiment of the present application;

[0032] Figure 4 Distortion and field curvature diagram of the eyepiece provided in the embodiment of the present application;

[0033] Figure 5 This is a diagram of the vertical axis chromatic aberration of the eyepiece provided in an embodiment of the present application.

[0034] Description of reference numerals:

[0035] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Polarization reflection element; 6. Phase retarder; 7. Beam splitter; 8. Polarization element. DETAILED DESCRIPTION

[0036] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0037] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0038] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0039] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0040] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0041] The eyepiece and the eyepiece optical system provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0042] According to one embodiment of the present application, an eyepiece is provided, see Figure 1 The eyepiece includes a first lens group and a second lens group arranged along the same optical axis, the first lens group is located on the exit pupil side, and the second lens group is located on the focal plane side; the first lens group includes a first lens 1, a second lens 2 and a third lens 3; the second lens group includes a fourth lens 4; a polarizing reflection element 5 is provided on the side of the first lens 1 away from the second lens 2, a beam splitter 7 is provided on the side of the third lens 3 away from the second lens 2, and a phase retarder 6 is provided between the polarizing reflection element 5 and the beam splitter 7; the eyepiece satisfies: 0.065<[(1 / f)-(1 / F 1 )] / (1 / F 2 )<0.07; wherein, f is the total focal length of the eyepiece, F 1 is the focal length of the first lens group, F 2 is the focal length of the second lens group.

[0043] The eyepiece proposed in the embodiment of the present application is a viewing lens with a large exit pupil and high definition. Due to its unique optical structure design and superior optical performance, the eyepiece can have a wide range of applications. The following is a detailed description of its application range.

[0044] The eyepiece of the embodiment of the present application can be applied to various telescopes, especially telescopes that require high-definition observation and a wide exit pupil to meet the needs of long-term comfortable observation. The eyepiece of the present application can provide an excellent observation experience.

[0045] In sports such as shooting and archery, the accuracy and clarity of the scope are crucial. The eyepiece of the present application can be the choice of scope due to its high clarity and precise optical design. At the same time, its large exit pupil design can also make the shooter more comfortable when aiming and reduce eye fatigue.

[0046] The eyepiece of the present application is also applicable to photography and video equipment that require high resolution and clear imaging. It can be used as a supplement to a macro lens, a telephoto lens or a wide-angle lens to help capture more delicate and clear images.

[0047] The eyepiece provided in the embodiment of the present application is shown in FIG. Figure 1 The eyepiece includes two lens groups: a first lens group and a second lens group, and the two lens groups are arranged along the same optical axis. The first lens group is located on the exit pupil side, that is, the side close to the observer's eyes; and the second lens group is located on the focal plane side, that is, the side close to the observed object or the imaging plane.

[0048] Please continue to see Figure 1 The first lens group includes at least three lenses, such as a first lens 1, a second lens 2 and a third lens 3 arranged in sequence along the same optical axis. These lenses cooperate to achieve focusing and correction of light.

[0049] The second lens group includes at least one lens, such as a fourth lens 4. Although the second lens group includes only one lens, it also plays an important role in the focusing and imaging process of light.

[0050] The polarized reflection element 5 is disposed on a side of the first lens 1 away from the second lens 2. The polarized reflection element 5 has a specific polarization property and can reflect or transmit light in a specific direction, thereby achieving control of the light path.

[0051] The phase retarder 6 is disposed between the polarized reflection element 5 and the beam splitter 7. The phase retarder 6 can change the phase of the light, and further achieve fine control of the light path.

[0052] Wherein, the phase retarder 6 is a quarter wave plate.

[0053] The beam splitter element 7 is disposed on a side of the third lens 3 away from the second lens 2 . The beam splitter element 7 is, for example, a semi-transparent and semi-reflective film, which can transmit and reflect light at the same time.

[0054] It should be noted that the phase retarder 6 should be located between the beam splitter element 7 and the polarized reflection element 5 .

[0055] In the present application, a folded optical path design is achieved by arranging a polarized reflection element 5 on the side of the first lens 1 away from the second lens 2, and arranging a beam splitter 7 (semi-transmissive and semi-reflective film) on the side of the third lens 3 away from the second lens 2, and combining a phase retarder 6 (quarter wave plate) arranged between the two. This design not only makes the structure of the eyepiece more compact, but also reduces the length of the optical path, helps to reduce light loss, and improves imaging quality.

[0056] In the embodiment of the present application, the number of lenses in the first lens group and the second lens group can be flexibly adjusted according to actual needs to achieve a specific imaging effect. It is worth noting that Figure 1 The first lens group shown consists of three lenses, while the second lens group contains one lens. This configuration has been fully verified to meet high-quality imaging requirements.

[0057] The eyepiece provided in the embodiment of the present application also satisfies a specific focal length relationship, namely 0.065<

[0058] [(1 / f)-(1 / F 1 )] / (1 / F 2 )<0.07; where f is the total focal length of the entire eyepiece, F 1 is the focal length of the first lens group, F 2 This relation represents an important parameter in the eyepiece design of the present application, which is used to ensure the image clarity and large exit pupil of the eyepiece.

[0059] The optimization of the focal length in the embodiment of the present application enables the eyepiece to better correct aberrations, including spherical aberration, chromatic aberration, etc., thereby improving the clarity and accuracy of imaging.

[0060] The large exit pupil design makes it easier for the observer to align his eyes with the eyepiece, reducing eye fatigue during observation.

[0061] The eyepiece solution provided in the embodiment of the present application divides the eyepiece into a first lens group and a second lens group and adopts a folded optical path design, so that the structure of the entire eyepiece is more compact. This compact structural design not only reduces the volume and weight of the eyepiece, but also improves its portability, so that the eyepiece can be more widely used in various handheld or portable observation and aiming devices.

[0062] In summary, the eyepiece design described in the embodiment of the present application achieves technical effects such as improved imaging quality, observation comfort and portability through measures such as folded optical path, optimized focal length and compact structure. These technical effects make the eyepiece have a wide range of application prospects in the fields of observation and aiming.

[0063] In some examples of the present application, the eyepiece satisfies: 0.53<(EP×ED) / (f×h)<1.58; wherein EP is the exit pupil distance of the eyepiece, ED is the exit pupil diameter of the eyepiece, f is the total focal length of the eyepiece, and h is the image height of the eyepiece.

[0064] The exit pupil distance (EP) and the exit pupil diameter (ED) are key factors that determine the visual comfort and field of view of the eyepiece (or sighting lens) user. By adjusting the proportional relationship between these two parameters and the focal length (f) and image height (h), it is possible to ensure that the eyepiece provides a clear and comfortable visual experience in different usage scenarios.

[0065] The focal length (f) and image height (h) directly affect the clarity of the image and the size of the field of view. The relationship in this example of the present application helps to achieve high-resolution imaging while ensuring sufficient field of view by setting a reasonable ratio range, which is crucial for the high-definition requirements of the eyepiece.

[0066] When the value of (EP×ED) / (f×h) is less than 0.53, it means that the exit pupil distance (EP) or exit pupil diameter (ED) is too small relative to the focal length (f) and image height (h). This may lead to:

[0067] (1) Limited field of view: A small exit pupil diameter (ED) will limit the field of view of the lens, making it difficult for the observer to obtain sufficient information.

[0068] (2) Visual discomfort: A too small exit pupil distance (EP) may cause the observer's eyes to be too close to the lens when using it, causing visual fatigue or discomfort.

[0069] (3) Degraded image quality: An imbalance in the ratio between focal length (f) and image height (h) may affect image clarity, resulting in blurred or distorted images.

[0070] When the value of (EP×ED) / (f×h) is greater than 1.58, it means that the exit pupil distance (EP) or exit pupil diameter (ED) is too large relative to the focal length (f) and image height (h). This may cause the following problems:

[0071] (1) Increased eyepiece size and cost: In order to meet the requirements of a larger exit pupil distance (EP) and exit pupil diameter (ED), the number of lenses may need to be increased, which easily leads to an increase in the size and weight of the eyepiece, which is not conducive to the portability and lightweight design of the lens. Larger eyepiece size and more complex structural design often mean higher production costs.

[0072] (2) Decreased imaging performance: Although a larger exit pupil distance and diameter may improve the comfort and brightness of the field of view to a certain extent, excessive increase may also lead to a decline in imaging performance, such as increased aberrations and reduced resolution.

[0073] It can be seen that the range of 0.53 to 1.58 is the optimal range based on the balance between field of view, visual comfort, imaging quality, lens volume and cost. Within this range, the eyepiece can be ensured to have an appropriate exit pupil distance and diameter, while maintaining a reasonable ratio between focal length and image height, thereby achieving the best imaging effect and user experience.

[0074] In some examples of the present application, the eyepiece satisfies: 0.53<EP / (NA×h)<1.58; wherein NA is the aperture of the eyepiece.

[0075] On the basis that the eyepiece satisfies the condition of 0.53<(EP×ED) / (f×h)<1.58, the eyepiece should also satisfy the condition of 0.53<EP / (NA×h)<1.58. This can achieve the requirements of large exit pupil and high definition.

[0076] The exit pupil distance (EP) is an important parameter in the design of eyepieces. It determines the distance between the observer's eyes and the rear focus of the lens, which in turn affects the observation comfort and image quality. By adjusting the ratio of EP to NA and h, it is possible to ensure that sufficient light enters the eyepiece while ensuring that the observer can observe a clear, distortion-free image at a comfortable distance.

[0077] The reciprocal of the aperture value (NA) indicates the light transmission ability of the eyepiece, that is, the amount of light allowed to pass through the eyepiece. While keeping other parameters unchanged, increasing the NA (i.e. reducing its reciprocal) can improve the light transmission performance of the eyepiece, so that the eyepiece can capture enough details even in a low-light environment. However, an excessively large NA value will also cause problems such as aberrations, so it needs to be balanced through a reasonable proportional relationship.

[0078] Image height (h) refers to the size of the image on the eyepiece imaging surface. In different application scenarios, the observer's requirements for image height may vary. By adjusting the ratio of EP to NA and h, eyepieces suitable for different observation distances and image height requirements can be designed to meet a wider range of application scenarios.

[0079] The relationship in this example of the present application is proposed in the context of pursuing a high-definition large exit pupil design. By precisely controlling the proportional relationship between EP, NA and h, a larger exit pupil distance and a clear image effect can be achieved while ensuring imaging quality. This is especially important for sighting lenses that require long-term observation or are used in high-brightness environments.

[0080] When the value of EP / (NA×h) is less than 0.53, it means that the exit pupil distance (EP) is too small relative to the product of the aperture (NA) and the image height (h). This will lead to at least the following problems:

[0081] Limited field of view: A smaller exit pupil distance may limit the observer's field of view, making it difficult to obtain complete image information.

[0082] Eyestrain: Observers may need to move their eyes closer to see details when using it, which increases the risk of eyestrain.

[0083] Insufficient light: Although increasing the aperture (NA) can improve light transmittance, if the exit pupil distance is too small, the light may not be fully diffused into the observer's eyes, thus affecting the brightness and clarity of the image.

[0084] When the value of EP / (NA×h) is greater than 1.58, it means that the exit pupil distance (EP) is too large relative to the product of the aperture (NA) and the image height (h). This will lead to at least the following problems:

[0085] Increased size of the eyepiece: In order to meet a larger exit pupil distance, it may be necessary to increase the number of lenses in the eyepiece, which is not conducive to the portability and lightweight design of the lens.

[0086] Waste of light: Too large an exit pupil distance may cause excessive diffusion of light during propagation, thereby reducing light utilization and imaging contrast.

[0087] It can be seen that the range of 0.53 to 1.58 is the optimal range based on the balance between field of view, visual comfort, light utilization, lens volume and cost. Within this range, the eyepiece can be ensured to have an appropriate exit pupil distance while maintaining a reasonable ratio between aperture and image height, thereby achieving the best imaging effect and user experience.

[0088] In some examples of the present application, the optical power of the first lens 1 is positive, the optical power of the second lens 2 is negative, and the optical power of the third lens 3 is positive.

[0089] In this example of the present application, the eyepiece includes a first lens group located on the exit pupil side, and the first lens group is designed to include three lenses: a first lens 1, a second lens 2, and a third lens 3; wherein the first lens 1 has a positive focal power and is located on the exit pupil side, the third lens 3 has a positive focal power and is located on the side close to the second lens group, and the second lens 2 has a negative focal power and is located between the first lens 1 and the third lens 3. This positive-negative-positive lens focal power configuration has advantages in correcting aberrations and optimizing imaging quality.

[0090] The first lens 1 with positive focal power can initially focus the incident light, which helps to guide the light to the subsequent lens. The second lens 2 with negative focal power can produce divergent light, which helps to correct certain aberrations introduced by the first lens, especially spherical aberration and chromatic aberration. By properly selecting the material and surface shape of the second lens, the correction effect of these aberrations can be further optimized. The third lens 3 with positive focal power focuses the light again, and works together with the first lens 1 to ensure the clarity of the final image. It can also further fine-tune the aberrations introduced by the previous lens to achieve more optimized imaging quality.

[0091] The positive-negative-positive lens combination allows for finer control of light to optimize image quality. This configuration helps reduce aberrations and improves image contrast and sharpness.

[0092] In the eyepiece of the embodiment of the present application, the first lens group (including the first lens, the second lens and the third lens) is located on the exit pupil side. Since the first lens 1 has a positive optical power, it can attract and focus more light into the eyepiece, which helps to expand the exit pupil diameter. The expanded exit pupil diameter allows the observer to observe more comfortably, especially in a dark environment, which can reduce eye fatigue and improve the clarity of observation.

[0093] In some examples of the present application, the first lens group satisfies: 1.74<|[(1 / f 1 )+(1 / f 3 )] / (1 / f 2 )|<1.96; where f 1 is the focal length of the first lens 1, f 2 is the focal length of the second lens 2, f 3 is the focal length of the third lens 3.

[0094] In this example of the present application, the focal length ratio of the first lens group is designed to be 1.74<

[0095] |[(1 / f 1 )+(1 / f 3 )] / (1 / f 2 )|<1.96; where f 1 、f 2 and f 3 Respectively represent the focal lengths of the first lens 1, the second lens 2 and the third lens 3. This inequality condition is a precise control of the focal length relationship of the lens combination, aiming to achieve optimized imaging quality.

[0096] When the focal length ratio meets the above conditions, the first lens group can correct various aberrations more effectively. This is because, by adjusting the focal length relationship of each lens, the light can be more evenly focused on the image plane after passing through the lens combination, thereby reducing aberrations. At the same time, this focal length ratio condition also helps to improve the contrast and sharpness of the image, making the image quality clearer and more delicate.

[0097] When the above-mentioned focal length ratio conditions are met, the first lens group can better control the incident angle and diffusion range of light, thereby helping to expand the exit pupil diameter. This is crucial to improving the observer's field of view and comfort. The expanded exit pupil diameter enables the observer to clearly see the target object at a wider angle while reducing eye fatigue.

[0098] In addition, under the premise of meeting the above conditions, the arrangement and layout of the lenses can also be optimized to achieve a more compact optical system.

[0099] When the focal length ratio of the first lens group is less than 1.74, the aberration correction capability of the first lens group may be insufficient, which will reduce the image quality and cause blur and distortion. At the same time, a too small focal length ratio may also limit the expansion range of the exit pupil, thereby affecting the observer's field of view and comfort.

[0100] When the focal length ratio of the first lens group is greater than 1.96, some aberrations may be overcorrected, resulting in new aberration problems. For example, excessive spherical aberration or chromatic aberration may occur. In addition, an excessively large focal length ratio may also make the structure of the optical system complicated.

[0101] The focal length ratio condition of the first lens group in this example of the present application is 1.74<|[(1 / f 1 )+(1 / f 3 )] / (1 / f 2 )|<1.96, which is one of the important technical features for achieving high-definition large exit pupil observation lenses. It can optimize the image quality, expand the exit pupil diameter, and improve the stability and structural compactness of the eyepiece by precisely controlling the focal length relationship of the lens combination. At the same time, failure to meet this condition may lead to problems such as insufficient aberration correction ability, limited field of view, and system instability.

[0102] In some examples of the present application, the refractive power of the fourth lens 4 is positive.

[0103] In the eyepiece provided in the embodiment of the present application, the second lens group includes a fourth lens 4, and the fourth lens 4 is located on the focal plane side. The optical focal length of the fourth lens 4 is set to be positive, which can produce an effect that is beneficial to improving the imaging quality when combined with the first lens group.

[0104] The fourth lens 4 with positive refractive power can further focus and fine-tune the light passing through the front lens. This focusing effect helps to reduce the residual aberration that may be introduced by the front lens, ensuring the clarity and accuracy of the final image.

[0105] The fourth lens 4 with positive refractive power can enhance the contrast of the image. This is because when the light passes through the positive lens, it is more tightly focused on the image plane, thereby reducing the diffusion of the light. Higher contrast means clearer details in the image, which is crucial to improving the accuracy and reliability of observation.

[0106] The positive refractive power configuration of the fourth lens 4 helps to optimize the light transmission path of the entire eyepiece, which can indirectly enable the eyepiece to have a larger field of view while maintaining high imaging quality.

[0107] In some examples of the present application, the eyepiece satisfies: 1.12<D max / ED<1.24; where D max is the maximum effective aperture of the lens in the eyepiece, and ED is the exit pupil aperture of the eyepiece.

[0108] In this example of the present application, the design of the eyepiece satisfies a specific proportional relationship, namely, 1.12<D max / ED<1.24; where D max Represents the maximum effective aperture of the lens in the eyepiece, and ED represents the exit pupil diameter of the eyepiece. This ratio is set to optimize the image quality of the eyepiece.

[0109] Specifically, by max The ratio to ED is controlled between 1.12 and 1.24, which ensures that the eyepiece can effectively control aberration and distortion while maintaining sufficient light transmission. This balance makes the image clearer and more accurate, and is suitable for high-definition large exit pupil observation and other application scenarios.

[0110] Appropriate D max The / ED ratio helps optimize the light transmission path inside the eyepiece, reducing light loss and scattering. This can improve the utilization of light, allowing more light to reach the observer's eyes, thereby improving the brightness and contrast of observation.

[0111] Reasonable D max The / ED ratio also helps make observation more comfortable and natural, which is especially important for users who use spotting lenses for a long time.

[0112] If D maxWhen the ratio of / ED is less than 1.12, the effective aperture of the lens in the eyepiece is relatively small, while the exit pupil diameter is relatively large. In this case, although a sufficient exit pupil diameter can be ensured to accommodate users with different eye distances, a certain imaging quality and light utilization may be sacrificed. Specifically, it may lead to problems such as increased aberration, obvious distortion, and reduced observation brightness.

[0113] On the contrary, if D max If the ratio of / ED is greater than 1.24, it means that the effective aperture of the eyepiece lens is too large, while the exit pupil diameter is relatively small. In this case, although high image quality and light utilization can be ensured, the size of the exit pupil diameter may be limited, making it difficult for some users (especially those with a long eye distance) to obtain the best observation experience. In addition, an overly large lens aperture may also increase the weight and volume of the eyepiece, which is not conducive to portability and ease of use.

[0114] In some examples of this application, see Figure 1 The polarizing reflection element 5 and the phase retarder 6 are arranged on the surface of the first lens 1 close to the exit pupil side; the beam splitter 7 is arranged on the surface of the third lens 3 away from the exit pupil side.

[0115] In this example of the present application, the polarization reflection element 5 and the phase retarder 6 are arranged on the surface of the first lens 1 close to the exit pupil side, and the beam splitter element 7 is arranged on the surface of the third lens 3 away from the exit pupil side.

[0116] The polarized reflective element 5 and the phase retarder 6 can be designed to be stacked to form a composite film material, which brings convenience to the film lamination process. The phase retarder 6 is, for example, a quarter wave plate.

[0117] The combination of the polarization reflection element 5 and the phase retarder 6 can effectively manage the polarization state of light. By arranging them on the surface of the first lens 1 close to the exit pupil side, it can be ensured that the light has been optimized before entering the observer's eyes, thereby reducing adverse factors such as glare and ghosting, and improving the clarity and contrast of observation.

[0118] The light splitting element 7 is, for example, a semi-transparent and semi-reflective film, which can be disposed on the surface of the third lens 3 by coating or pasting.

[0119] The polarized reflection element 5, the phase retarder 6 and the beam splitter 7 are respectively arranged at specific positions of the first lens 1 and the third lens 3, which not only optimizes the optical effect, but also helps to improve the integration of the eyepiece. This configuration makes the entire sighting lens more compact and lightweight, which is conducive to improving the user's observation experience and portability.

[0120] In some examples of the present application, the first lens 1 , the third lens 3 , and the fourth lens 4 are plastic aspherical lenses; and the second lens 2 is a glass spherical lens.

[0121] The first lens 1, the third lens 3 and the fourth lens 4 in the eyepiece can all be plastic aspherical lenses, while the second lens 2 is a glass spherical lens. This combination design not only integrates the advantages of different materials, but also combines the characteristics of spherical and aspherical surfaces, aiming to achieve better optical performance and cost-effectiveness.

[0122] Specifically, the use of plastic aspherical lenses (such as the first lens 1, the third lens 3, and the fourth lens 4) significantly reduces aberrations and distortions because aspherical lenses can more accurately correct light and focus it more closely on the imaging surface. This design is particularly suitable for high-definition sighting lenses to ensure accurate restoration of image details.

[0123] Compared with glass aspherical lenses, plastic aspherical lenses have lower production costs while maintaining good optical performance. This helps reduce the manufacturing cost of eyepieces and improves the market competitiveness of products.

[0124] Plastic is lighter than glass, so the use of plastic aspherical lenses (first lens 1, third lens 3, fourth lens 4) helps to reduce the weight of the eyepiece, making it easier to carry and operate, which is particularly important in sighting equipment that needs to be held in the hand for a long time.

[0125] In this example of the present application, the second lens 2 has a negative optical power and adopts a glass spherical mirror. Glass materials have excellent refractive index and dispersion characteristics, which makes glass spherical mirrors have advantages in aberration correction. Compared with plastics, glass materials have lower thermal expansion coefficients and higher thermal stability. Therefore, the second lens 2 using a glass spherical mirror can maintain stable optical performance under various ambient temperatures and reduce aberration changes caused by temperature changes.

[0126] In the present application, the second lens with negative optical focal length is designed as a glass spherical mirror because the glass material has a lower thermal expansion coefficient. When the temperature changes, the negative lens of the glass spherical mirror can maintain a stable shape and optical performance, thereby reducing the aberration changes caused by temperature changes.

[0127] By combining a plastic aspherical lens with a glass spherical lens, the eyepiece design of the present application can find the best balance between cost control, light weight and optical performance. The selection of different lens materials and types helps to optimize the light transmission path of the eyepiece, reduce aberrations, and improve the contrast and clarity of the image.

[0128] Of course, in the eyepiece provided in the embodiment of the present application, the first lens 1 to the fourth lens 4 can all be made of plastic material or glass material. The first lens 1 to the fourth lens 4 can also all be aspherical.

[0129] In the present application, the first lens 1 is, for example, a plano-convex lens, and the optical film material can be arranged on its plane, the second lens 2 is a convex-concave lens, the third lens 3 is a biconvex lens, and the fourth lens 4 is a plano-convex lens. The concave-convex direction of the lens can be switched as needed.

[0130] In some examples of the present application, the exit pupil distance EP of the eyepiece is 15 mm to 25 mm, the exit pupil diameter ED of the eyepiece is 20 mm to 25 mm, and the aperture NA of the eyepiece is 1.72 to 2.15.

[0131] The pupil distance refers to the effective distance between the observer's eye and the lens exit pupil. In this example of the present application, the pupil distance of 15mm to 25mm ensures that the observer can observe the target at a comfortable distance without causing limited vision or visual fatigue due to too close distance.

[0132] The exit pupil diameter refers to the diameter of the lens exit pupil, which determines the amount of light that the observer's eyes can receive. In this example of the present application, the exit pupil diameter of 20mm to 25mm provides a sufficiently large light channel, allowing the eyepiece to capture more light, thereby improving the brightness and clarity of the image. In addition, a larger exit pupil diameter also helps to reduce the loss of light during propagation, thereby further improving the image quality.

[0133] Aperture is an important parameter of the lens, which determines the light transmittance and depth of field effect of the eyepiece. In this example of the present application, the aperture NA ranges from 1.72 to 2.15, which means that the eyepiece has a high light transmittance. A larger aperture can capture more light, allowing the eyepiece to present a clear image even in a low-light environment. At the same time, the size of the aperture will also affect the depth of field. A larger aperture can produce a shallower depth of field effect, making the target more prominent and the background more blurred.

[0134] The optical parameter design of the eyepiece in this example of the present application has the following technical effects: The exit pupil distance of 15mm to 25mm ensures that the observer can observe the target at a comfortable distance, reducing visual fatigue and limited field of view. The exit pupil diameter of 20mm to 25mm provides a sufficiently large light channel, allowing the lens to capture more light, improving the brightness and clarity of the image. The aperture range of 1.72 to 2.15 gives the lens a high light transmittance, which can present clear images in low-light environments.

[0135] In some examples of the present application, the image height h of the eyepiece is 9.2 mm to 13 mm.

[0136] Image height h refers to the height of the eyepiece image on the image plane, which determines the size of the target range that the eyepiece can clearly present. In this example of the present application, the image height range of 9.2mm to 13mm means that the eyepiece can provide a moderate and clear observation field of view. A moderate image height range helps reduce the user's visual fatigue.

[0137] When the viewing field is too large, users need to constantly move their eyes to capture the entire image, which can easily lead to visual fatigue; and when the viewing field is too small, users need to frequently adjust the lens or viewing position, which also increases the visual burden. Therefore, the image height range of 9.2mm to 13mm provides users with a comfortable and efficient viewing experience.

[0138] In some examples of the present application, the FOV of the eyepiece is 12.2° to 17.4°.

[0139] In the example of the present application, the FOV range of 12.2° to 17.4° means that the eyepiece can provide a moderate and clear observation field of view, which is neither too narrow to limit the observation range nor too wide to reduce the observation accuracy.

[0140] In VR (virtual reality) applications, a larger FOV is usually pursued to provide a more immersive experience. However, since VR devices usually have a smaller aperture (i.e., a smaller light channel), it is necessary to maximize the use of limited space and achieve a larger FOV through a folded optical path design.

[0141] In contrast, in sighting applications, higher precision and clarity are required, so the aperture is relatively large (i.e., the light channel is wider) to capture more light and improve imaging quality. However, since sighting usually requires observing smaller targets at a longer distance, the FOV is relatively small. In this application, the folded optical path is mainly used to optimize the lens layout, reduce volume and weight, while maintaining sufficient imaging quality and precision.

[0142] By folding the optical path, the eyepiece of the present application can optimize the lens layout, reduce the volume and weight while maintaining sufficient imaging quality and accuracy, which makes the eyepiece more suitable for application scenarios that require a compact design, such as aiming.

[0143] In some examples of the present application, a polarizing element 8 is disposed on a surface of the fourth lens 4 close to the exit pupil side.

[0144] Polarizing film is an optical film that can selectively transmit light vibrating in a certain direction and block light vibrating in other directions. This design is intended to further optimize the optical performance of the lens and enhance the user's viewing experience.

[0145] The polarizing element 8 of the present application can effectively reduce glare and reflection from strong reflective light sources such as sunlight, water surface, snow, etc. When the light from these light sources enters the eyepiece at a specific angle, they will cause glare and reflection, affecting the viewing effect. The polarizing film only allows light vibrating parallel to the film surface to pass through, while blocking the reflected light vibrating perpendicular to the film surface, thereby significantly reducing glare and reflection.

[0146] During long-term observation, interference factors such as glare and reflection can easily cause eye fatigue and discomfort. By providing the polarizing element 8, these interference factors can be significantly reduced, the viewing comfort can be improved, and the user can maintain a clear viewing state for a longer time.

[0147] Since the polarizing film can filter out some stray light, the light passing through the eyepiece is purer.

[0148] According to another embodiment of the present application, an eyepiece optical system is provided, which includes the eyepiece as described above.

[0149] The eyepiece of the present application is further described below through Example 1 and Example 2.

[0150] Example 1

[0151] The eyepiece provided in this embodiment 1 is shown in FIG. Figure 1 , comprising a first lens group and a second lens group arranged along the same optical axis, wherein the first lens group is located on the exit pupil side, and the second lens group is located on the focal plane side;

[0152] The first lens group includes a first lens 1, a second lens 2 and a third lens 3, the second lens group includes a fourth lens 4, the first lens 1 has a positive focal power, the second lens 2 has a negative focal power, the third lens 3 has a positive focal power, and the fourth lens 4 has a positive focal power; the first lens 1, the third lens 3 and the fourth lens 4 are plastic aspherical lenses, and the second lens 2 is a glass spherical lens;

[0153] A polarizing reflection element 5 and a phase retarder 6 are provided on a surface of the first lens 1 facing away from the second lens 2, a beam splitter 7 is provided on a surface of the third lens 3 facing away from the second lens 2, and a polarizing element 8 is provided on a surface of the fourth lens 4 close to the exit pupil side;

[0154] Wherein, the focal length of the first lens group is F 1 is 43.59 mm, and the focal length of the second lens group is F2 is 219.4 mm, the total focal length f of the eyepiece is 43 mm, and the total system length of the eyepiece is 30.7 mm;

[0155] The eyepiece has an exit pupil distance EP of 15 mm to 25 mm, and an exit pupil diameter ED of 20 mm to 25 mm;

[0156] The aperture NA of the eyepiece is 1.72-2.15;

[0157] The image height h of the eyepiece is 9.2 mm to 13 mm;

[0158] The FOV of the eyepiece is 12.2° to 17.4°.

[0159] Table 1 shows the optical parameters of each lens in the eyepiece, which are as follows.

[0160] Table 1

[0161]

[0162] Example 2

[0163] The eyepiece provided in this embodiment 2 has the same optical structure as that of the above-mentioned embodiment 1, which can be seen in Figure 1 The differences are:

[0164] Wherein, the focal length of the first lens group is F 1 The focal length of the second lens group is 44.1 mm. 2 is 118.8 mm, the total focal length f of the eyepiece is 43 mm, and the total system length of the eyepiece is 31.2 mm;

[0165] The eyepiece has an exit pupil distance EP of 15 mm to 25 mm, and an exit pupil diameter ED of 20 mm to 25 mm;

[0166] The aperture NA of the eyepiece is 1.72-2.15;

[0167] The image height h of the eyepiece is 9.2 mm to 13 mm;

[0168] The FOV of the eyepiece is 12.2° to 17.3°.

[0169] The optical parameters of each lens in the eyepiece are shown in Table 2.

[0170] Table 2

[0171]

[0172] The eyepieces provided in Example 1 and Example 2 have optical properties such as Figures 2 to 5 As shown: Figure 2is a schematic diagram of the point diagram. Figure 3 is the MTF curve graph, Figure 4 is the field curvature distortion diagram, Figure 5 This is the vertical axis chromatic aberration diagram.

[0173] See also Figure 2 In the eyepieces provided in Example 1 and Example 2, the maximum value of the image point in the point array diagram is less than 8 μm.

[0174] See also Figure 3 , the eyepieces provided in Example 1 and Example 2 have an MTF of >0.1 at 80lp / mm.

[0175] See also Figure 4 For the eyepieces provided in Example 1 and Example 2, the maximum distortion occurs in 1 field of view, and the absolute value is less than 8%, and the distortion is very small.

[0176] See also Figure 5 The eyepieces provided in Example 1 and Example 2 have a maximum chromatic aberration value of less than 30 μm.

[0177] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0178] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. An eyepiece, characterized in that: It comprises a first lens group and a second lens group arranged along the same optical axis, wherein the first lens group is located on the exit pupil side, and the second lens group is located on the focal plane side; The first lens group comprises a first lens (1), a second lens (2) and a third lens (3); The second lens group comprises a fourth lens (4); A polarizing reflection element (5) is provided on the side of the first lens (1) facing away from the second lens (2), a beam splitting element (7) is provided on the side of the third lens (3) facing away from the second lens (2), and a phase retarder (6) is provided between the polarizing reflection element (5) and the beam splitting element (7); The eyepiece satisfies 0.065<[(1 / f)-(1 / F1)] / (1 / F2)<0.07; wherein f is the total focal length of the eyepiece, F1 is the focal length of the first lens group, and F2 is the focal length of the second lens group.

2. The eyepiece according to claim 1, characterized in that The eyepiece satisfies: 0.53<(EP×ED) / (f×h)<1.58; wherein EP is the exit pupil distance of the eyepiece, ED is the exit pupil diameter of the eyepiece, f is the total focal length of the eyepiece, and h is the image height of the eyepiece.

3. The eyepiece according to claim 2, characterized in that The eyepiece satisfies: 0.53<EP / (NA×h)<1.58; wherein NA is the aperture of the eyepiece.

4. The eyepiece according to claim 1, characterized in that The optical focal power of the first lens (1) is positive, the optical focal power of the second lens (2) is negative, and the optical focal power of the third lens (3) is positive.

5. The eyepiece according to claim 4, characterized in that The first lens group satisfies: 1.74<|[(1 / f1)+(1 / f3)] / (1 / f2)|<1.96; wherein f1 is the focal length of the first lens (1), f2 is the focal length of the second lens (2), and f3 is the focal length of the third lens (3).

6. The eyepiece according to claim 4, characterized in that The optical power of the fourth lens (4) is positive.

7. The eyepiece according to claim 1, characterized in that The eyepiece satisfies: 1.12<D max / ED<1.24; where D max is the maximum effective aperture of the lens in the eyepiece, and ED is the exit pupil aperture of the eyepiece.

8. The eyepiece according to claim 1, characterized in that The polarized reflection element (5) and the phase retarder (6) are arranged on a surface of the first lens (1) close to the exit pupil side; The light splitting element (7) is arranged on a surface of the third lens (3) that is away from the exit pupil.

9. The eyepiece according to claim 1, characterized in that The first lens (1), the third lens (3) and the fourth lens (4) are plastic aspherical lenses; The second lens (2) is a glass spherical lens.

10. The eyepiece according to claim 3, characterized in that The exit pupil distance EP of the eyepiece is 15 mm to 25 mm, the exit pupil diameter ED of the eyepiece is 20 mm to 25 mm, and the aperture NA of the eyepiece is 1.72 to 2.

15.

11. The eyepiece according to claim 10, characterized in that The image height h of the eyepiece is 9.2 mm to 13 mm.

12. The eyepiece according to any one of claims 1 to 11, characterized in that The FOV of the eyepiece is 12.2° to 17.4°.

13. The eyepiece according to claim 8, characterized in that A polarizing element (8) is provided on a surface of the fourth lens (4) on a side close to the exit pupil side.

14. An eyepiece optical system, characterized in that: include: An eyepiece as claimed in any one of claims 1 to 13.

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