Eyepiece lens

Abstract

The embodiment of the invention discloses an eyepiece lens. The eyepiece lens comprises a diaphragm, a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged from an observation side to a display side along an optical axis, the first lens is a glass spherical lens with positive focal power, the second lens is a glass spherical lens with positive focal power, the third lens is a glass spherical lens with negative focal power, the fourth lens is a glass spherical lens with negative focal power, and the fifth lens is a glass spherical lens with positive focal power. According to the embodiment of the invention, an all-glass 5G structure is designed and adopted, through matching of lens materials and reasonable distribution of focal power, the eyepiece lens with long exit pupil distance, small distortion, small aberration and low cost is realized, the exit pupil distance reaches 48mm, and the distortion is less than 1.5%.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of optical lenses, and in particular to an eyepiece lens. Background Art

[0002] The eyepiece is a visual optical device used to observe the image formed by the optical system in front. It is a component of visual optical instruments such as telescopes and microscopes. Its main function is to magnify the real image obtained by the objective lens again, so as to form a clear virtual image at the clear vision distance. Therefore, its quality will ultimately affect the quality of the object image. This requires the eyepiece to achieve higher resolution, less distortion, and higher magnification. Moreover, if used in handheld observation equipment, the eyepiece is also required to have a long exit pupil distance and a long back intercept.

[0003] The current eyepieces generally have various problems such as small pupil distance, generally less than 22mm, large distortion, severe chromatic aberration, etc. Therefore, it is particularly important to develop eyepieces with long pupil distance, small distortion and good image quality. In addition, the existing eyepieces with small aberration mostly use aspherical lenses, which increases the difficulty of processing and production and also increases the manufacturing cost. Summary of the invention

[0004] The invention provides an eyepiece lens to realize a full-glass spherical eyepiece lens with long exit pupil distance, small distortion, small aberration and low cost.

[0005] An embodiment of the present invention provides an eyepiece lens, comprising a stop, a first lens, a second lens, a third lens, a fourth lens and a fifth lens arranged in sequence from an observation side to a display side along an optical axis;

[0006] The first lens is a glass spherical lens with positive optical power, the second lens is a glass spherical lens with positive optical power, the third lens is a glass spherical lens with negative optical power, the fourth lens is a glass spherical lens with negative optical power, and the fifth lens is a glass spherical lens with positive optical power.

[0007] Optionally, the eyepiece lens satisfies the following conditions: 1.47≤EX / f≤1.62;

[0008] Wherein, EX is the on-axis distance from the aperture to the observation side surface of the first lens, and f is the effective focal length of the eyepiece lens.

[0009] Optionally, the eyepiece lens satisfies the following conditions: 0.9≤f5 / f≤1.2;

[0010] Among them, f5 is the focal length of the fifth lens, and f is the effective focal length of the eyepiece lens.

[0011] Optionally, the eyepiece lens satisfies the following condition: 0.8≤f2 / f5≤1.42;

[0012] Wherein, f2 is the focal length of the second lens, and f5 is the focal length of the fifth lens.

[0013] Optionally, the eyepiece lens satisfies the following conditions: -2.41≤f1 / f3≤-1.81;

[0014] Wherein, f1 is the focal length of the first lens, and f3 is the focal length of the third lens.

[0015] Optionally, the eyepiece lens satisfies the following conditions: -2.5≤R1 / R2≤-1.18;

[0016] Wherein, R1 is the curvature radius of the observation side surface of the first lens, and R2 is the curvature radius of the display side surface of the first lens.

[0017] Optionally, the eyepiece lens satisfies the following conditions: 1.21≤R7 / R8≤1.38;

[0018] Among them, R7 is the curvature radius of the observation side surface of the fourth lens, and R8 is the curvature radius of the display side surface of the fourth lens.

[0019] Optionally, the eyepiece lens satisfies the following conditions: 0.36≤BF / f≤0.44;

[0020] Among them, BF is the back focal length of the eyepiece lens, and f is the effective focal length of the eyepiece lens.

[0021] Optionally, the eyepiece lens satisfies the following conditions: 2.84≤TTL / f≤2.93;

[0022] Wherein, TTL is the distance from the observation side surface of the first lens to the center of the image plane of the eyepiece lens, and f is the effective focal length of the eyepiece lens.

[0023] Optionally, the eyepiece lens satisfies the following condition: |vd4-vd5|≤23.55;

[0024] Wherein, vd4 is the Abbe number of the fourth lens, and vd5 is the Abbe number of the fifth lens.

[0025] In the embodiment of the present invention, the first lens, the second lens and the fifth lens are set to have positive optical power, while the third lens and the fourth lens are set to have negative optical power. In essence, through the positive-positive-negative-negative-positive optical power distribution, the light can pass through the optical system more smoothly, balance the distribution of aberrations, and achieve better aberration correction as a whole, reduce distortion, and ensure sufficiently clear image quality. In addition, by using glass spherical lenses for all five lenses, the characteristics of glass materials can be used to reduce the sensitivity of the imaging process of the optical system to temperature, reduce the degree of deformation of the lens at different temperatures, and ensure that clear imaging can still be achieved in high and low temperature environments. Therefore, the embodiment of the present invention can ultimately achieve an eyepiece lens with a long exit pupil distance, small distortion, small aberration, and low cost by designing an all-glass 5G structure, matching lens materials and reasonably distributing optical power. The exit pupil distance reaches 48mm and the distortion is less than 1.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic structural diagram of an eyepiece lens provided in Embodiment 1 of the present invention;

[0027] Figure 2 for Figure 1 Field curvature distortion curve of the eyepiece lens shown;

[0028] Figure 3 for Figure 1 Light fan diagram of the eyepiece lens shown;

[0029] Figure 4 for Figure 1 Through-focus MTF diagram of the eyepiece lens shown;

[0030] Figure 5 is a structural schematic diagram of an eyepiece lens provided in Embodiment 2 of the present invention;

[0031] Figure 6 for Figure 5 Field curvature distortion curve of the eyepiece lens shown;

[0032] Figure 7 for Figure 5 Light fan diagram of the eyepiece lens shown;

[0033] Figure 8 for Figure 5 Through-focus MTF diagram of the eyepiece lens shown;

[0034] Fig. 9 is a structural schematic diagram of an eyepiece lens provided in Embodiment 3 of the present invention;

[0035] Fig.10 for Fig. 9 Field curvature distortion curve of the eyepiece lens shown;

[0036] Fig.11 for Fig. 9 Light fan diagram of the eyepiece lens shown;

[0037] Fig.12 for Fig. 9 Through-focus MTF plot of the eyepiece lens shown. DETAILED DESCRIPTION

[0038] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0039] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. It should be noted that the directional words such as "upper", "lower", "left", "right" and the like described in the embodiments of the present invention are described at the angles shown in the accompanying drawings and should not be understood as limitations on the embodiments of the present invention. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is formed "on" or "under" another element, it can not only be directly formed "on" or "under" another element, but also indirectly formed "on" or "under" another element through an intermediate element. The terms "first", "second", etc. are only used for descriptive purposes and do not represent any order, quantity or importance, but are only used to distinguish different components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] The term “including” and its variations used in the present invention are open inclusions, that is, “including but not limited to.” The term “based on” means “based at least in part on.” The term “one embodiment” means “at least one embodiment.”

[0041] It should be noted that the concepts such as "first" and "second" mentioned in the present invention are only used to distinguish the corresponding contents, and are not used to limit the order or interdependence.

[0042] It should be noted that the modifications of "one" and "plurality" mentioned in the present invention are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0043] Figure 1 is a schematic diagram of the structure of an eyepiece lens provided in Embodiment 1 of the present invention, with reference to Figure 1The eyepiece lens includes an aperture STO, a first lens 10, a second lens 20, a third lens 30, a fourth lens 40 and a fifth lens 50 arranged in sequence along the optical axis from the observation side to the display side; wherein the observation side is the side that the observer uses the eyepiece lens to observe, and the display side is the side where the observed object is located.

[0044] The first lens 10 is a glass spherical lens with positive power, the second lens 20 is a glass spherical lens with positive power, the third lens 30 is a glass spherical lens with negative power, the fourth lens 40 is a glass spherical lens with negative power, and the fifth lens 50 is a glass spherical lens with positive power.

[0045] First of all, for optical lenses, the focal length is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam, which characterizes the ability of the optical system to deflect light. The larger the absolute value of the focal length, the stronger the ability to bend light, and the smaller the absolute value of the focal length, the weaker the ability to bend light. When the focal length is a positive number, the refraction of light is convergent; when the focal length is a negative number, the refraction of light is divergent. The focal length can be used to characterize a refractive surface of a lens (i.e., a surface of a lens), can be used to characterize a lens, and can also be used to characterize a system formed by multiple lenses (i.e., a lens group).

[0046] In the eyepiece lens provided in this embodiment, each lens can be fixed to a lens barrel ( Figure 1 (not shown) in the Figure 1 As shown, in the embodiment of the present invention, the first lens 10, the second lens 20 and the fifth lens 50 are set to have positive optical power, while the third lens 30 and the fourth lens 40 are set to have negative optical power. In essence, through the positive-positive-negative-negative-positive optical power distribution, the light can pass through the optical system more smoothly, balance the distribution of aberrations, and thus achieve better aberration correction as a whole, reduce distortion, and ensure sufficiently clear image quality. In addition, in the embodiment of the present invention, all five lenses are glass spherical lenses, and the characteristics of glass materials can be used to reduce the sensitivity of the imaging process of the optical system to temperature, reduce the degree of deformation of the lens at different temperatures, and ensure that clear imaging can still be achieved in high and low temperature environments. Therefore, the embodiment of the present invention can ultimately achieve an eyepiece lens with a long exit pupil distance, small distortion, small aberration, and low cost by designing a 5G structure using all-glass, matching lens materials and reasonably distributing optical power. The exit pupil distance reaches 48mm and the distortion is less than 1.5%.

[0047] In an optional embodiment, the eyepiece lens satisfies the following condition: 1.47≤EX / f≤1.62; wherein EX is the on-axis distance from the aperture STO to the observation side surface of the first lens 10, and f is the effective focal length of the eyepiece lens.

[0048] Specifically, since the magnification of the eyepiece is the ratio of the human eye's visual distance to the effective focal length of the eyepiece, the smaller the effective focal length of the eyepiece, the greater the magnification. The smaller the effective focal length of the eyepiece, the larger the field of view of the eyepiece, and the greater the off-axis aberration of the lens, which is not conducive to achieving the image quality requirements; if the effective focal length of the eyepiece is larger, the chromatic aberration produced by the lens will also be larger, and large chromatic aberration is not conducive to achieving the image quality of the lens. Within the above constraints, the requirements of large exit pupil distance and large magnification can be better met.

[0049] In an optional embodiment, the eyepiece lens satisfies the following condition: 0.9≤f5 / f≤1.2; wherein f5 is the focal length of the fifth lens 50, and f is the effective focal length of the eyepiece lens.

[0050] In an optional embodiment, the eyepiece lens satisfies the following condition: 0.8≤f2 / f5≤1.42; wherein f2 is the focal length of the second lens 20 , and f5 is the focal length of the fifth lens 50 .

[0051] In an optional embodiment, the eyepiece lens satisfies the following condition: -2.41≤f1 / f3≤-1.81; wherein f1 is the focal length of the first lens 10 , and f3 is the focal length of the third lens 30 .

[0052] Specifically, by constraining the focal length variation range of the lens, reasonably allocating the relative relationship between the focal lengths of the lenses and the ratio of the focal length of a single lens to the focal length of the optical system, light can pass through the optical system more smoothly, maximally balancing the distribution of aberrations, reducing the overall aberration of the optical system, and lowering the sensitivity of tolerances, making the lens have good processability.

[0053] In an optional embodiment, the eyepiece lens satisfies the following condition: -2.5≤R1 / R2≤-1.18; wherein R1 is the curvature radius of the observation side surface of the first lens 10 , and R2 is the curvature radius of the display side surface of the first lens 10 .

[0054] In an optional embodiment, the eyepiece lens satisfies the following condition: 1.21≤R7 / R8≤1.38; wherein R7 is the curvature radius of the observation side surface of the fourth lens 40 , and R8 is the curvature radius of the display side surface of the fourth lens 40 .

[0055] Specifically, by controlling the surface curvature radius of the corresponding lens, the shape of the lens is actually limited, thereby constraining the lens's ability to bend light and reducing the generation of large light bending angles, which has a favorable effect on the control of eyepiece lens aberrations and is beneficial to improving the image quality of the optical system.

[0056] In an optional embodiment, the eyepiece lens satisfies the following condition: 0.36≤BF / f≤0.44; wherein BF is the back focal length of the eyepiece lens, and f is the effective focal length of the eyepiece lens.

[0057] Specifically, if the upper limit of this limit range is exceeded, the focal length of the eyepiece lens will become shorter, the off-axis aberration of the system will become larger, which is not conducive to the improvement of image quality; and if the lower limit of this limit range is exceeded, the back focus of the optical system will become too short, which is not conducive to the installation and replacement of components. Through the constraints of the above conditions, sufficient back focus space can be reserved on the basis of ensuring image quality to avoid mechanism interference.

[0058] In an optional embodiment, the eyepiece lens satisfies the following condition: 2.84≤TTL / f≤2.93; wherein TTL is the center distance from the observation side surface of the first lens 10 to the image plane of the eyepiece lens, and f is the effective focal length of the eyepiece lens.

[0059] Specifically, the above conditions are essentially restrictions on the total optical length of the eyepiece lens, thereby ensuring that the eyepiece lens has a relatively small total optical length, making the lens more compact and helping to achieve miniaturization.

[0060] In an optional embodiment, the eyepiece lens satisfies the following condition: |vd4-vd5|≤23.55; wherein vd4 is the Abbe number of the fourth lens 40 , and vd5 is the Abbe number of the fifth lens 50 .

[0061] Specifically, the Abbe constant represents the dispersion ability of an optical medium. The above conditions essentially limit the Abbe constants of the last two lenses of the lens to be similar, thereby better controlling the chromatic aberration of the lens and ensuring higher imaging quality.

[0062] Continue to refer Figure 1 In the embodiment of the present invention, the eyepiece lens may further be provided with a flat glass 60; the flat glass 60 is located on the side of the fifth lens 50 away from the fourth lens 40. The flat glass 60 may be a protective glass or a filter having a filtering effect.

[0063] Based on the same inventive concept above, the present invention provides three different specific embodiments, whose optical power relationships and related physical optical parameter design ranges are shown in Table 1:

[0064] Table 1 Relationship between the focal powers of the lenses and the design values ​​of the relevant physical optical parameters in the three embodiments

[0065] Scope of protection Example 1 Example 2 Example 3 Lower limit Upper limit EX / f 1.5419 1.5389 1.5519 1.47 1.62 f5 / f 1.0925 0.9817 1.0824 0.9 1.2 f2 / f5 0.9456 1.3795 1.3336 0.8 1.42 f1 / f3 -2.2966 -2.0009 -1.888 -2.41 -1.81 R1 / R2 -1.2598 -1.7624 -2.4255 -2.5 -1.18 R7 / R8 1.2641 1.2826 1.3374 1.21 1.38 BF / f 0.4038 0.3892 0.4279 0.36 0.44 TTL / f 2.8946 2.8737 2.9059 2.84 2.93 |vd4-vd5| 12.8 14.3 15.1 23.55

[0066] like Figure 1 The parameter design values ​​of each lens in the eyepiece lens of the first embodiment are shown in Table 2:

[0067] Table 2 Design values ​​of each lens of the eyepiece lens in Example 1

[0068]

[0069] The surface numbers in Table 2 are numbered according to the order of the surfaces of each lens; "Object" represents the object surface of the eyepiece lens; "STO" represents the aperture of the eyepiece lens; "IMAGE" represents the image surface of the eyepiece lens; the radius of curvature represents the curvature of the lens surface, a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the ability of the material between the current surface and the next surface to deflect light, and a blank space represents that the current position is air, and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to light.

[0070] Figure 2 for Figure 1 The field curvature distortion curve of the eyepiece lens is shown in the figure. In the left coordinate system, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, without unit; T represents the meridian, S represents the sagittal; Figure 2 It can be seen that the field curvature of the eyepiece lens provided in this embodiment is effectively controlled, that is, when imaging, the difference between the image quality at the center and the image quality at the periphery is small; in the coordinate system on the right, the horizontal coordinate represents the magnitude of the distortion, in units of %; the vertical coordinate represents the normalized image height, in units of %. Figure 2 It can be seen that the distortion of the lens provided in this embodiment is well corrected, and the imaging distortion is small.

[0071] Figure 3 for Figure 1 The light fan diagram of the eyepiece lens is shown in the figure. The horizontal axis is the beam diameter and the vertical axis is the vertical axis aberration. Figure 2 It can be seen that the eyepiece lens is close to the horizontal axis in each band under each field of view, indicating that the vertical axis aberration of each wavelength of the system is well corrected. At the same time, there is no obvious dispersion in each band, indicating that the system chromatic aberration is also well corrected, thus ensuring that the eyepiece lens can achieve high-resolution imaging requirements.

[0072] Figure 4 for Figure 1 The defocus MTF diagram of the eyepiece lens is shown in the figure, where the horizontal axis is the defocus amount before and after the image plane, and the vertical axis is the modulus of the optical transfer function. Different curves represent the change trend of the optical transfer function of the image at different field positions (image heights are 0, 2mm, 4mm, 6mm and 8.64mm respectively) as the defocus amount increases. Figure 4 It can be seen that the optical transfer function of the system is relatively high when each field of view is imaged at 50lp / mm, indicating that the optical system can achieve high-resolution imaging requirements.

[0073] Figure 5is a schematic diagram of the structure of an eyepiece lens provided in Embodiment 2 of the present invention, with reference to Figure 5 The parameter design values ​​of each lens in the eyepiece lens of the second embodiment are shown in Table 3:

[0074] Table 3 A design value of each lens of the eyepiece lens in Example 2

[0075]

[0076] The surface numbers in Table 3 are numbered according to the order of the surfaces of each lens; "Object" represents the object surface of the eyepiece lens; "STO" represents the aperture of the eyepiece lens; "IMAGE" represents the image surface of the eyepiece lens; the radius of curvature represents the curvature of the lens surface, a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the ability of the material between the current surface and the next surface to deflect light, and a blank space represents that the current position is air, and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to light.

[0077] Figure 6 for Figure 5 The field curvature distortion curve of the eyepiece lens is shown in the figure. In the left coordinate system, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, without unit; T represents the meridian, S represents the sagittal; Figure 5 It can be seen that the field curvature of the eyepiece lens provided in this embodiment is effectively controlled, that is, when imaging, the difference between the image quality at the center and the image quality at the periphery is small; in the coordinate system on the right, the horizontal coordinate represents the magnitude of the distortion, in units of %; the vertical coordinate represents the normalized image height, in units of %. Figure 5 It can be seen that the distortion of the lens provided in this embodiment is well corrected, and the imaging distortion is small.

[0078] Figure 7 for Figure 5 The light fan diagram of the eyepiece lens is shown in the figure. The horizontal axis is the beam diameter and the vertical axis is the vertical axis aberration. Figure 7 It can be seen that the eyepiece lens is close to the horizontal axis in each band under each field of view, indicating that the vertical axis aberration of each wavelength of the system is well corrected. At the same time, there is no obvious dispersion in each band, indicating that the system chromatic aberration is also well corrected, thus ensuring that the eyepiece lens can achieve high-resolution imaging requirements.

[0079] Figure 8 for Figure 5The defocus MTF diagram of the eyepiece lens is shown in the figure, where the horizontal axis is the defocus amount before and after the image plane, and the vertical axis is the modulus of the optical transfer function. Different curves represent the change trend of the optical transfer function of the image at different field positions (image heights are 0, 2mm, 4mm, 6mm and 8.64mm respectively) as the defocus amount increases. Figure 8 It can be seen that the optical transfer function of the system is relatively high when each field of view is imaged at 50lp / mm, indicating that the optical system can achieve high-resolution imaging requirements.

[0080] Fig. 9 is a schematic diagram of the structure of an eyepiece lens provided in Embodiment 3 of the present invention, with reference to Fig. 9 The parameter design values ​​of each lens in the eyepiece lens of the third embodiment are shown in Table 4:

[0081] Table 4: Design values ​​of each lens of the eyepiece lens in Example 3

[0082]

[0083] The surface numbers in Table 4 are numbered according to the order of the surfaces of each lens; "Object" represents the object surface of the eyepiece lens; "STO" represents the aperture of the eyepiece lens; "IMAGE" represents the image surface of the eyepiece lens; the radius of curvature represents the curvature of the lens surface, a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side; the thickness represents the central axial distance from the current surface to the next surface, the refractive index represents the ability of the material between the current surface and the next surface to deflect light, and a blank space represents that the current position is air, and the refractive index is 1; the Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to light.

[0084] Fig.10 for Fig. 9 The field curvature distortion curve of the eyepiece lens is shown in the figure. In the left coordinate system, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, without unit; T represents the meridian, S represents the sagittal; Fig.10 It can be seen that the field curvature of the eyepiece lens provided in this embodiment is effectively controlled, that is, when imaging, the difference between the image quality at the center and the image quality at the periphery is small; in the coordinate system on the right, the horizontal coordinate represents the magnitude of the distortion, in units of %; the vertical coordinate represents the normalized image height, in units of %. Fig.10 It can be seen that the distortion of the lens provided in this embodiment is well corrected, and the imaging distortion is small.

[0085] Fig.11 for Fig. 9 The light fan diagram of the eyepiece lens is shown in the figure. The horizontal axis is the beam diameter and the vertical axis is the vertical axis aberration. Fig.11It can be seen that the eyepiece lens is close to the horizontal axis in each band under each field of view, indicating that the vertical axis aberration of each wavelength of the system is well corrected. At the same time, there is no obvious dispersion in each band, indicating that the system chromatic aberration is also well corrected, thus ensuring that the eyepiece lens can achieve high-resolution imaging requirements.

[0086] Fig.12 for Fig. 9 The defocus MTF diagram of the eyepiece lens is shown in the figure, where the horizontal axis is the defocus amount before and after the image plane, and the vertical axis is the modulus of the optical transfer function. Different curves represent the change trend of the optical transfer function of the image at different field positions (image heights are 0, 2mm, 4mm, 6mm and 8.64mm respectively) as the defocus amount increases. Fig.12 It can be seen that the optical transfer function of the system is relatively high when each field of view is imaged at 50lp / mm, indicating that the optical system can achieve high-resolution imaging requirements.

[0087] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. An eyepiece lens, characterized in that: It includes an aperture, a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are arranged in sequence from the observation side to the display side along the optical axis; The first lens is a glass spherical lens with positive optical power, the second lens is a glass spherical lens with positive optical power, the third lens is a glass spherical lens with negative optical power, the fourth lens is a glass spherical lens with negative optical power, and the fifth lens is a glass spherical lens with positive optical power.

2. The eyepiece lens according to claim 1, characterized in that: The eyepiece lens meets the following conditions: 1.47≤EX / f≤1.62; Wherein, EX is the on-axis distance from the aperture to the observation side surface of the first lens, and f is the effective focal length of the eyepiece lens.

3. The eyepiece lens according to claim 1, characterized in that: The eyepiece lens meets the following conditions: 0.9≤f5 / f≤1.2; Among them, f5 is the focal length of the fifth lens, and f is the effective focal length of the eyepiece lens.

4. The eyepiece lens according to claim 1, characterized in that: The eyepiece lens meets the following conditions: 0.8≤f2 / f5≤1.42; Wherein, f2 is the focal length of the second lens, and f5 is the focal length of the fifth lens.

5. The eyepiece lens according to claim 1, characterized in that: The eyepiece lens satisfies the following conditions: -2.41≤f1 / f3≤-1.81; Wherein, f1 is the focal length of the first lens, and f3 is the focal length of the third lens.

6. The eyepiece lens according to claim 1, characterized in that: The eyepiece lens meets the following conditions: -2.5≤R1 / R2≤-1.18; Wherein, R1 is the curvature radius of the observation side surface of the first lens, and R2 is the curvature radius of the display side surface of the first lens.

7. The eyepiece lens according to claim 1, characterized in that: The eyepiece lens meets the following conditions: 1.21≤R7 / R8≤1.38; Among them, R7 is the curvature radius of the observation side surface of the fourth lens, and R8 is the curvature radius of the display side surface of the fourth lens.

8. The eyepiece lens according to claim 1, characterized in that: The eyepiece lens meets the following conditions: 0.36≤BF / f≤0.44; Among them, BF is the back focal length of the eyepiece lens, and f is the effective focal length of the eyepiece lens.

9. The eyepiece lens according to claim 1, characterized in that: The eyepiece lens meets the following conditions: 2.84≤TTL / f≤2.93; Wherein, TTL is the distance from the observation side surface of the first lens to the center of the image plane of the eyepiece lens, and f is the effective focal length of the eyepiece lens.

10. The eyepiece lens according to claim 1, characterized in that: The eyepiece lens meets the following conditions: |vd4-vd5|≤23.55; Wherein, vd4 is the Abbe number of the fourth lens, and vd5 is the Abbe number of the fifth lens.

Images