Eyepiece lens

Abstract

The invention discloses an eyepiece lens, and the eyepiece lens sequentially comprises a first lens with positive focal power from a first side to a second side along an optical axis, a first side surface paraxial region of the first lens is a convex surface, and a second side surface paraxial region of the first lens is a plane or a convex surface or a concave surface; a reflective polarizing element; a quarter-wave plate; a paraxial region of the first side surface of the second lens is a concave surface, and a paraxial region of the second side surface of the second lens is a convex surface; a partially reflective element; a paraxial region of the first side surface of the third lens is a convex surface, and a paraxial region of the second side surface of the third lens is a concave surface; the number of the lenses with focal power of the eyepiece lens is three.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical elements, and more particularly, to an eyepiece lens. BACKGROUND

[0002] An eyepiece is a lens used to expand the field of view and viewing distance of the human eye, and is a key device in visual optical instruments. With the development of society and the progress of science and technology, the eyepiece is not only widely used in optical instruments such as telescopes and microscopes, but also plays an important role in the fields of medical treatment, military affairs, aerospace, and consumer electronics. With the increasing demand for eyepieces, people's requirements for the optical performance of eyepieces are also becoming higher and higher.

[0003] However, the current eyepiece still has the following problems:

[0004] 1. The exit pupil diameter of the existing eyepiece lens is small;

[0005] 2. The existing eyepiece lens is large in size and cannot meet the requirements of miniaturization;

[0006] 3. The existing eyepiece lens has a large weight and cannot meet the requirements of lightweight;

[0007] 4. The existing eyepiece lens has large distortion and cannot meet the requirements of high-precision aiming and measuring.

[0008] Therefore, it has become a market development trend to design an eyepiece lens that at least meets one of the characteristics of large exit pupil diameter, low cost, light weight, small size, and low distortion. SUMMARY

[0009] The present application provides an eyepiece lens, which comprises, in order along an optical axis from a first side to a second side: a first lens having a positive refractive power; a reflective polarizing element; a quarter-wave plate; a second lens having a negative refractive power; a partially reflective element; a third lens having a positive refractive power; and the number of lenses having refractive power of the eyepiece lens is 3.

[0010] According to an example embodiment of the present application, the first side surface paraxial region of the first lens is convex, and the second side surface paraxial region is planar or convex or concave; the first side surface paraxial region of the second lens is concave, and the second side surface paraxial region is convex; and the first side surface paraxial region of the third lens is convex, and the second side surface paraxial region is concave.

[0011] According to an example embodiment of the present application, the eyepiece lens satisfies the condition formula: 0.38≤ENPD / F≤0.77, wherein ENPD is the exit pupil diameter of the eyepiece lens, and F is the effective focal length of the eyepiece lens.

[0012] According to an example embodiment of the present application, the eyepiece lens satisfies at least one of the following conditional expressions: 0.43≤TTL / F≤0.81, 0.14≤BFL / TTL≤0.27, where TTL is a center distance from the first side surface of the first lens to the image plane of the eyepiece lens, F is an effective focal length of the eyepiece lens, and BFL is a center distance from the second side surface of the third lens to the image plane of the eyepiece lens.

[0013] According to an example embodiment of the present application, the eyepiece lens satisfies the conditional expression: 0.30≤D / F≤0.62, where D is an exit pupil distance of the eyepiece lens, and F is an effective focal length of the eyepiece lens.

[0014] According to an example embodiment of the present application, the eyepiece lens satisfies the conditional expression: 3.03≤F / H≤6.08, where F is an effective focal length of the eyepiece lens, and H is a maximum image plane of the eyepiece lens.

[0015] According to an example embodiment of the present application, the eyepiece lens satisfies at least one of the following conditional expressions: 0.53≤F1 / F≤2.25, -6.20≤F2 / F≤-0.54, 0.21≤F3 / F≤1.11, -6.46≤F2 / F3≤-2.25,

[0016] where F1 is an effective focal length of the first lens, F2 is an effective focal length of the second lens, F3 is an effective focal length of the third lens, and F is an effective focal length of the eyepiece lens.

[0017] According to an example embodiment of the present application, the eyepiece lens satisfies at least one of the following conditional expressions: 0.24≤d1 / d12≤0.36, 0.06≤d2 / d12≤0.26, where d1 is a center distance from the first side surface of the first lens to the second side surface of the quarter wave plate, d12 is a center distance from the second side surface of the quarter wave plate to the first side surface of the second lens, and d2 is a center thickness of the second lens.

[0018] According to an example embodiment of the present application, the eyepiece lens satisfies the conditional expression: 0.28≤BFL / d12≤0.6, where BFL is a center distance from the second side surface of the third lens to the image plane of the eyepiece lens, and d12 is a center distance from the second side surface of the quarter wave plate to the first side surface of the second lens.

[0019] According to one example embodiment of the present application, the eyepiece lens satisfies at least one of the following conditional expressions: 0.42 ≤ ENPD / F ≤ 0.70, 0.48 ≤ TTL / F ≤ 0.73, 0.16 ≤ BFL / TTL ≤ 0.25, 0.34 ≤ D / F ≤ 0.56, 3.36 ≤ F / H ≤ 5.52, 0.59 ≤ F1 / F ≤ 2.04, -5.64 ≤ F2 / F ≤ -0.60, 0.24 ≤ F3 / F ≤ 1.01, -5.87 ≤ F2 / F3 ≤ -2.51, 0.27 ≤ d1 / d12 ≤ 0.33, 0.07 ≤ d2 / d12 ≤ 0.24, 0.31 ≤ BFL / d12 ≤ 0.55, wherein ENPD is an exit pupil diameter of the eyepiece lens, F is an effective focal length of the eyepiece lens, TTL is a center distance from a first side surface of the first lens to an image surface of the eyepiece lens, BFL is a center distance from a second side surface of the third lens to the image surface of the eyepiece lens, D is an exit pupil distance of the eyepiece lens, H is a maximum image surface of the eyepiece lens, F1 is an effective focal length of the first lens, F2 is an effective focal length of the second lens, F3 is an effective focal length of the third lens, d1 is a center distance from the first side surface of the first lens to a second side surface of the quarter wave plate, d12 is a center distance from the second side surface of the quarter wave plate to the first side surface of the second lens, and d2 is a center thickness of the second lens. BRIEF DESCRIPTION OF DRAWINGS

[0020] Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments thereof as taken in conjunction with the accompanying drawings. In the drawings:

[0021] Figure 1 A structural schematic diagram of an eyepiece lens according to Embodiment 1 of the present application is shown;

[0022] Figure 2 A field curvature curve and a distortion curve of the eyepiece lens according to Embodiment 1 of the present application are shown;

[0023] Figure 3 An MTF (Modulation Transfer Function) curve of the eyepiece lens according to Embodiment 1 of the present application is shown;

[0024] Figure 4 A structural schematic diagram of an eyepiece lens according to Embodiment 2 of the present application is shown;

[0025] Figure 5 A field curvature curve and a distortion curve of the eyepiece lens according to Embodiment 2 of the present application are shown;

[0026] Figure 6 An MTF (Modulation Transfer Function) curve of the eyepiece lens according to Embodiment 2 of the present application is shown;

[0027] Figure 7A structural diagram of an eyepiece lens according to Embodiment 3 of the present application is shown.

[0028] Figure 8 A field curvature graph and a distortion graph of the eyepiece lens according to Embodiment 3 of the present application are shown.

[0029] Figure 9 An MTF (Modulation Transfer Function) graph of the eyepiece lens according to Embodiment 3 of the present application is shown.

[0030] Figure 10 A structural diagram of an eyepiece lens according to Embodiment 4 of the present application is shown.

[0031] Figure 11 A field curvature graph and a distortion graph of the eyepiece lens according to Embodiment 4 of the present application are shown.

[0032] Figure 12 An MTF (Modulation Transfer Function) graph of the eyepiece lens according to Embodiment 4 of the present application is shown. DETAILED DESCRIPTION

[0033] For a better understanding of the present application, various aspects of the present application will be described in detail with reference to the accompanying drawings. It should be understood that these detailed description is merely a description of exemplary embodiments of the present application, and does not limit the scope of the present application in any way.

[0034] In the drawings, the thickness, size, and shape of lenses have been slightly exaggerated for the sake of explanation. Specifically, the shape of a spherical surface or an aspherical surface shown in the drawings is shown by way of example. That is, the shape of a spherical surface or an aspherical surface is not limited to the shape of a spherical surface or an aspherical surface shown in the drawings. The drawings are merely examples and are not drawn to scale.

[0035] In this document, the paraxial region refers to a region near the optical axis. If a lens surface is convex and the position of the convex surface is not specified, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the position of the concave surface is not specified, it means that the lens surface is concave at least in the paraxial region.

[0036] It should also be understood that the words "comprise", "comprising", "include", "including", and / or "contain", when used in this specification, specify the presence of stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or groups thereof. It should be noted that the expressions first, second, third, etc. in this specification are only used to distinguish one feature from another feature, and do not represent any limitation on the features. It should be noted that the longitudinal direction stated herein is the direction perpendicular to the optical axis.

[0037] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Terms should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0038] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0039] The eyepiece lens according to the exemplary embodiments of the present application can include, in order along the optical axis from the first side to the second side, a first lens, a reflective polarizing element, a quarter-wave plate, a second lens, a partially reflective element, and a third lens.

[0040] In the exemplary embodiments, the first lens can have a positive focal power, and a first-side paraxial region thereof can be convex. The first lens having a positive focal power has a function of collecting light rays, so that the exiting light rays of the first lens are close to the optical axis, reducing the aperture of the rear lens and being conducive to miniaturization. In addition, the first-side paraxial region being convex enables the optical system to receive edge light rays at a gentler angle, reducing various aberrations (such as coma and astigmatism) caused by excessively large light ray incidence angles, thereby reducing the difficulty of correcting off-axis aberrations of the system and being conducive to improving the imaging quality of the lens. In the exemplary embodiments, a second-side paraxial region of the first lens can be convex or concave or planar.

[0041] In the exemplary embodiments, the reflective polarizing element can be disposed on or attached to the second side of the first lens, and the quarter-wave plate can be disposed on or attached to the second side of the reflective polarizing element. For example, the first side of the reflective polarizing element can at least partially abut the second side of the first lens, and the first side of the quarter-wave plate can at least partially abut the second side of the reflective polarizing element.

[0042] In the exemplary embodiments, the second lens can have a negative focal power, and a first-side paraxial region thereof can be concave, and a second-side paraxial region thereof can be convex. The second lens having a negative focal power and the first-side paraxial region being concave and the second-side paraxial region being convex can effectively correct various aberrations of the system, which is conducive to improving the imaging quality of the lens while reducing the distortion of the eyepiece lens, thereby meeting the low-distortion requirement.

[0043] In the exemplary embodiments, the partially reflective element can be disposed on the second side of the second lens. For example, the partially reflective element can be a semi-transparent and semi-reflective film layer coated on the second side of the second lens.

[0044] In the example embodiment, the third lens can have a positive focal power, the first side surface paraxial region can be convex, and the second side surface paraxial region can be concave. The third lens having a positive focal power and the first side surface paraxial region being convex and the second side surface paraxial region being concave can reduce the incidence angle of the on-axis light, so that the light transitions smoothly between the third lens and the image plane, thereby reducing the generation of system spherical aberration, which is conducive to reducing the system tolerance sensitivity and improving the lens production yield. In addition, it can effectively reduce the generation of various aberrations of the lens itself and correct the off-axis aberration generated by the second lens, which is conducive to improving the lens imaging quality. At the same time, it is also conducive to correcting the system distortion, which is conducive to realizing the low distortion requirement of the lens.

[0045] In the example embodiment, the eyepiece lens can further include a polarizer composed of a flat substrate, a quarter-wave plate and a linear polarization element in sequence, and the polarizer is located between the third lens and the image plane.

[0046] In the example embodiment, the eyepiece lens uses a folded optical path design (Pancake), so that the optical architecture of the entire eyepiece lens is more compact, thereby reducing the volume and weight of the eyepiece lens, which is conducive to realizing the miniaturization requirement of the eyepiece lens, and at the same time, the exit pupil diameter reaches 25 mm, thereby meeting the requirement of large exit pupil diameter.

[0047] In the example embodiment, the eyepiece lens can further include a diaphragm. The diaphragm can be located before the first side surface of the first lens, which can effectively limit the amount of light entering the optical system, shorten the total optical length of the eyepiece lens, and reduce the aperture of the rear lens, which is conducive to realizing the miniaturization of the eyepiece lens.

[0048] In the example embodiment, the total optical length TTL of the eyepiece lens can satisfy: TTL≤28.5mm, and further, TTL can satisfy: 25.9mm≤TTL≤28.41mm, thereby realizing the small volume requirement of the eyepiece lens.

[0049] In the example embodiment, the aperture FNO of the eyepiece lens can satisfy: FNO≤2.4, and further, FNO can satisfy: 1.4≤FNO≤2.4, thereby realizing the large aperture requirement of the eyepiece lens.

[0050] In the example embodiment, the absolute value of the distortion DIS of the eyepiece lens can satisfy: DIS≤2%, and further, DIS can satisfy: 0.2%≤DIS≤1.8%, thereby realizing the low distortion requirement of the eyepiece lens.

[0051] In the example embodiments, any one of the first lens to the third lens can adopt a glass lens or a plastic lens. The glass lens can effectively suppress the shift of the back focal length of the eyepiece lens due to temperature change, improve the stability of the eyepiece lens, and effectively avoid the imaging blur caused by high-temperature environment or low-temperature environment, ensuring the normal use of the eyepiece lens, being conducive to realizing the athermalization of the eyepiece lens, and better correcting the chromatic aberration of the optical system and improving the resolving power of the eyepiece lens. The plastic lens can effectively reduce the cost of the eyepiece lens. According to the eyepiece lens of the present application, the first lens, the second lens and the third lens are all glass materials, which is conducive to correcting the chromatic aberration of the optical system, improving the saturation of the lens color, and improving the imaging quality.

[0052] In the example embodiments, the present application is conducive to reducing the processing difficulty of the lens by adopting the combination of the spherical lens and the aspherical lens. The present application does not specifically limit the specific number of the spherical lens and the aspherical lens. When the imaging quality is emphasized, the number of the aspherical lens can be increased, and even all the lenses use aspherical lenses. The aspherical lens has the characteristic that the curvature is continuously changed from the center of the lens to the periphery. Unlike the spherical lens which has constant curvature from the center of the lens to the periphery, the aspherical lens has better curvature radius characteristics, and has the advantages of improving the distortion aberration and improving the astigmatism aberration. According to the eyepiece lens of the present application, the third lens is spherical or aspherical, and the first lens and the second lens are both spherical, which not only can effectively correct the chromatic aberration of the optical system, improve the saturation of the lens color, but also can eliminate the aberration as much as possible during imaging, thereby improving the imaging quality of the lens, and being conducive to reducing the distortion of the entire optical system, thereby realizing the low distortion requirement.

[0053] In the example embodiments, the eyepiece lens can satisfy 0.38≤ENPD / F≤0.77, where ENPD is the exit pupil diameter of the eyepiece lens, and F is the effective focal length of the eyepiece lens. By making the eyepiece lens satisfy the above condition, the ratio range of the exit pupil diameter of the eyepiece lens to the effective focal length of the eyepiece lens is controlled, so that the system has a larger exit pupil diameter, so that the light entering the human eye has a higher energy value, which is conducive to improving the picture clarity, and is conducive to meeting the large aperture requirement. Preferably, the eyepiece lens can further satisfy 0.42≤ENPD / F≤0.70, which is more conducive to improving the picture clarity and meeting the large aperture requirement.

[0054] In the example embodiment, the eyepiece lens can satisfy: 0.43≤TTL / F≤0.81, where TTL is the distance from the first side 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. By making the eyepiece lens satisfy the above condition, the ratio range of the distance from the first side of the first lens to the center of the image plane of the eyepiece lens and the effective focal length of the eyepiece lens is controlled, and by controlling the total optical length of the eyepiece lens, the total optical length of the eyepiece lens is short, which is beneficial to realize the miniaturization of the lens. Preferably, the eyepiece lens can further satisfy: 0.48≤TTL / F≤0.73, which is more beneficial to realize the miniaturization of the lens.

[0055] In the example embodiment, the eyepiece lens can satisfy: 0.14≤BFL / TTL≤0.27, where BFL is the distance from the second side of the third lens to the center of the image plane of the eyepiece lens, and TTL is the distance from the first side of the first lens to the center of the image plane of the eyepiece lens. By making the eyepiece lens satisfy the above condition, the ratio range of the distance from the second side of the third lens to the center of the image plane of the eyepiece lens and the distance from the first side of the first lens to the center of the image plane of the eyepiece lens is controlled, so that the total optical length of the eyepiece lens is short, which is beneficial to realize the miniaturization of the lens. Preferably, the eyepiece lens can further satisfy: 0.16≤BFL / TTL≤0.25, which is more beneficial to realize the miniaturization of the lens.

[0056] In the example embodiment, the eyepiece lens can satisfy: 0.30≤D / F≤0.62, where D is the exit pupil distance of the eyepiece lens, and F is the effective focal length of the eyepiece lens. By making the eyepiece lens satisfy the above condition, the ratio range of the exit pupil distance of the eyepiece lens and the effective focal length of the eyepiece lens is controlled, which can effectively control the system field of view and magnification, and is beneficial to realize the high resolution requirement of the lens. Preferably, the eyepiece lens can further satisfy: 0.34≤D / F≤0.56, which is more beneficial to realize the high resolution requirement of the lens.

[0057] In the example embodiment, the eyepiece lens can satisfy: 3.03≤F / H≤6.08, where F is the effective focal length of the eyepiece lens, and H is the maximum image plane of the eyepiece lens. By making the eyepiece lens satisfy the above condition, the ratio range of the effective focal length of the lens and the maximum image plane of the eyepiece lens is controlled, so that the system has a higher magnification, which is beneficial to the observation of object details by the eyepiece lens. Preferably, the eyepiece lens can further satisfy: 3.36≤F / H≤5.52, which is more beneficial to the observation of object details by the eyepiece lens.

[0058] In an exemplary embodiment, the eyepiece lens can satisfy the condition: 0.53 ≤ F1 / F ≤ 2.25, where F1 is the effective focal length of the first lens and F is the effective focal length of the eyepiece lens. By making the eyepiece lens satisfy the above condition, the ratio range of the effective focal length of the first lens to the effective focal length of the eyepiece lens can be controlled, which can effectively collect light and make the emitted light from the first lens as close as possible to the optical axis of the system, thereby reducing the aperture of the rear lens and facilitating lens miniaturization. Preferably, the eyepiece lens can further satisfy the condition: 0.59 ≤ F1 / F ≤ 2.04, which is even more conducive to lens miniaturization.

[0059] In an exemplary embodiment, the eyepiece lens can satisfy the condition: -6.20 ≤ F2 / F ≤ -0.54, where F2 is the effective focal length of the second lens and F is the effective focal length of the eyepiece lens. By making the eyepiece lens satisfy the above condition, the ratio range of the effective focal length of the second lens to the effective focal length of the eyepiece lens can be controlled, which can effectively correct the chromatic aberration of the system, which is beneficial to meeting high image quality requirements. At the same time, it can further reduce lens distortion, which is beneficial to achieving low distortion requirements. Preferably, the eyepiece lens can further satisfy the condition: -5.64 ≤ F2 / F ≤ -0.60, which is more conducive to meeting the requirements of high image quality and low distortion.

[0060] In an exemplary embodiment, the eyepiece lens can satisfy the condition: 0.21 ≤ F3 / F ≤ 1.11, where F3 is the effective focal length of the third lens and F is the effective focal length of the eyepiece lens. By making the eyepiece lens satisfy the above condition, the ratio range of the effective focal length of the third lens to the effective focal length of the eyepiece lens can be controlled, which can effectively correct the chromatic aberration of the system, thus helping to meet high image quality requirements. At the same time, it can further reduce lens distortion, thus helping to achieve low distortion requirements. Preferably, the eyepiece lens can further satisfy the condition: 0.24 ≤ F3 / F ≤ 1.01, which is even more conducive to meeting the requirements of high image quality and low distortion.

[0061] In an exemplary embodiment, the eyepiece lens can satisfy the condition: -6.46 ≤ F2 / F3 ≤ -2.25, where F2 is the effective focal length of the second lens and F3 is the effective focal length of the third lens. By making the eyepiece lens satisfy the above condition, the ratio range of the effective focal lengths of the second and third lenses can be controlled, effectively reducing the distortion generated by the first and second lenses, which is beneficial for achieving the requirements of high resolution and low distortion of the lens. Preferably, the eyepiece lens can further satisfy the condition: -5.87 ≤ F2 / F3 ≤ -2.51, which is even more beneficial for achieving the requirements of high resolution and low distortion of the lens.

[0062] In the exemplary embodiments, the eyepiece lens can satisfy: 0.24≤d1 / d12≤0.36, where d1 is the center distance from the first side of the first lens to the second side of the quarter-wave plate, and d12 is the center distance from the second side of the quarter-wave plate to the first side of the second lens. By making the eyepiece lens satisfy the above condition, the ratio range of the center distance from the first side of the first lens to the second side of the quarter-wave plate and the center distance from the second side of the quarter-wave plate to the first side of the second lens is controlled, which can effectively improve the assembly manufacturability of the lens and is conducive to improving the production yield of the lens. Preferably, the eyepiece lens can further satisfy: 0.27≤d1 / d12≤0.33, which is more conducive to improving the production yield of the lens.

[0063] In the exemplary embodiments, the eyepiece lens can satisfy: 0.06≤d2 / d12≤0.26, where d2 is the center thickness of the second lens, and d12 is the center distance from the second side of the quarter-wave plate to the first side of the second lens. By making the eyepiece lens satisfy the above condition, the ratio range of the center thickness of the second lens and the center distance from the second side of the quarter-wave plate to the first side of the second lens is controlled, which can effectively improve the assembly manufacturability of the lens and is conducive to improving the production yield of the lens. Preferably, the eyepiece lens can further satisfy: 0.07≤d2 / d12≤0.24, which is more conducive to improving the production yield of the lens.

[0064] In the exemplary embodiments, the eyepiece lens can satisfy: 0.28≤BFL / d12≤0.6, where BFL is the center distance from the second side of the third lens to the image plane of the eyepiece lens, and d12 is the center distance from the second side of the quarter-wave plate to the first side of the second lens. By making the eyepiece lens satisfy the above condition, the ratio range of the center distance from the second side of the third lens to the image plane of the eyepiece lens and the center distance from the second side of the quarter-wave plate to the first side of the second lens is controlled, which can effectively increase the adaptability of the eyepiece lens to different interfaces and the accommodative ability, and is conducive to improving the cost performance of the lens. Preferably, the eyepiece lens can further satisfy: 0.31≤BFL / d12≤0.55, which is more conducive to improving the cost performance of the lens.

[0065] The eyepiece lens according to the above embodiments of the present application can achieve at least one of the following beneficial effects: F1.4 large aperture (F1.4-F2.4 aperture range), high resolution, small size (TTL≤28.5mm), low distortion (DIS≤2%), large exit pupil diameter (ENPD≤25mm), etc.

[0066] However, those skilled in the art will understand that the number of lenses constituting the eyepiece lens can be changed without departing from the technical solutions claimed by the present application, to obtain the various results and advantages described in the specification.

[0067] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of the eyepiece lens applicable to the above-described embodiments.

[0068] Example 1

[0069] The following is for reference Figures 1 to 3 The eyepiece lens according to Embodiment 1 of this application is described.

[0070] like Figure 1 As shown, the eyepiece lens, along the optical axis from the first side to the second side, sequentially includes a first lens L1, a reflective polarizing element RP, a quarter-wave plate QWP1, a second lens L2, a partially reflective element BS, and a third lens L3. Specifically, the first lens L1 has positive optical power, with a convex paraxial region on its first side and a planar paraxial region on its second side; the second lens L2 has negative optical power, with a concave paraxial region on its first side and a convex paraxial region on its second side; the third lens L3 has positive optical power, with a convex paraxial region on its first side and a concave paraxial region on its second side; the reflective polarizing element RP is disposed on the second side of the first lens L1; the quarter-wave plate QWP1 is disposed on the second side of the reflective polarizing element RP; and the partially reflective polarizing element BS is disposed on the second side of the second lens L2.

[0071] The eyepiece lens also includes an aperture stop located in front of the first lens L1, a flat substrate CG1 between the second side of the third lens L3 and the image plane Img, a quarter-wave plate QWP2, a linear polarizer LP, and a protective glass CG2.

[0072] In a specific application, according to the eyepiece lens of this example, image light from the image plane Img sequentially passes through the protective glass CG2, the linear polarizer LP, the quarter-wave plate QWP2, the flat substrate CG1, the third lens L3, the partial reflective element BS, the second lens L2, and the quarter-wave plate QWP1 to reach the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and then passes again through the quarter-wave plate QWP1 and the second lens L2 to reach the partial reflective element BS. Afterward, it is reflected again at the partial reflective element BS and sequentially passes through the second lens L2, the quarter-wave plate QWP1, the reflective polarizing element RP, and the first lens L1 to reach the aperture stop STO and finally imaged at a predetermined position. For example, the light from this eyepiece lens, after two reflections, can ultimately be projected onto the user's pupil.

[0073] Table 1 shows the basic parameters of the eyepiece lens of Example 1, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0074] Table 1

[0075]

[0076] In Embodiment 1, the first side surface and the second side surface of the third lens are both aspherical surfaces, and the surface type of the aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0077]

[0078] wherein x is the distance from the vertex of the aspherical surface when the aspherical surface is at a position along the optical axis with a height of h; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the inverse of the curvature radius R in Table 1 above); k is the conic coefficient; and Ai is the correction coefficient of the i-th order of the aspherical surface. Table 2 below gives the conic coefficient k and the high-order term coefficients A4, A6, A8, A10, A12 and A14 that can be used for each aspherical surface S14 to S15 in Embodiment 1.

[0079] Table 2

[0080] Face number k A4 A6 A8 A10 A12 A14 S14 10.322 -8.33E-04 2.43E-06 6.49E-07 -4.54E-08 1.03E-09 -8.65E-12 S15 29.293 -1.35E-03 4.32E-05 -1.27E-06 1.85E-08 -1.12E-10 1.15E-13

[0081] Figure 2 Figures showing the field curvature curve and the distortion curve of the eyepiece lens according to Embodiment 1 of the present application are as follows, Figure 3 Figures showing the MTF (Modulation Transfer Function) curve of the optical lens according to Embodiment 1 of the present application are as follows, Figure 2 and Figure 3 It can be seen that the eyepiece lens according to Embodiment 1 of the present application has the characteristics of low distortion and high resolution.

[0082] Example 2

[0083] The following refers to Figures 4 to 6 and describes an eyepiece lens according to Embodiment 2 of the present application.

[0084] As shown in Figure 4 , the eyepiece lens comprises, in order along the optical axis from the first side to the second side, a first lens L1, a reflective polarizing element RP, a quarter-wave plate QWP1, a second lens L2, a partial reflective element BS, and a third lens L3. The first lens L1 has a positive focal power, the first side surface thereof has a convex surface in the paraxial region, and the second side surface thereof has a plane in the paraxial region. The second lens L2 has a negative focal power, the first side surface thereof has a concave surface in the paraxial region, and the second side surface thereof has a convex surface in the paraxial region. The third lens L3 has a positive focal power, the first side surface thereof has a convex surface in the paraxial region, and the second side surface thereof has a concave surface in the paraxial region. The reflective polarizing element RP is disposed on the second side surface of the first lens L1. The quarter-wave plate QWP1 is disposed on the second side surface of the reflective polarizing element RP. The partial reflective element BS is disposed on the second side surface of the second lens L2.

[0085] The eyepiece lens further comprises a diaphragm disposed in front of the first lens L1, a flat substrate CG1 between the second side of the third lens L3 and the image plane Img, a quarter wave plate QWP2, a linear polarizer LP and a protective glass CG2.

[0086] According to the eyepiece lens of the present example, in a specific application, the image light from the image plane Img can pass through the protective glass CG2, the linear polarizer LP, the quarter wave plate QWP2, the flat substrate CG1, the third lens L3, the partially reflective element BS, the second lens L2, the quarter wave plate QWP1 in sequence to reach the reflective polarizing element RP, be reflected at the reflective polarizing element RP and pass through the quarter wave plate QWP1, the second lens L2 again to reach the partially reflective element BS, then be reflected again at the partially reflective element BS and pass through the second lens L2, the quarter wave plate QWP1, the reflective polarizing element RP and the first lens L1 in sequence to the diaphragm STO and finally be imaged at a predetermined position. For example, the light rays after two reflections of the eyepiece lens can finally project onto the eye pupil of a user.

[0087] Table 3 shows the basic parameter table of the eyepiece lens of Example 2, wherein the units of the radius of curvature, thickness / distance are millimeters (mm).

[0088] Table 3

[0089]

[0090]

[0091] Figure 5 The field curvature and distortion curves of the eyepiece lens according to Example 2 of the present application are shown in FIGS. 8A and 8B, respectively. Figure 6 The MTF (Modulation Transfer Function) curves of the optical lens according to Example 2 of the present application are shown in FIGS. 9A and 9B, respectively, wherein the horizontal axis represents the spatial frequency (cycles / mm) and the vertical axis represents the MTF value. Figure 5 and Figure 6 It can be seen that the eyepiece lens according to Example 2 of the present application has the characteristics of low distortion and high resolution

[0092] Example 3

[0093] The eyepiece lens according to Example 3 of the present application is described below with reference to Figures 7 to 9 FIG. 10.

[0094] As Figure 7As shown, the eyepiece lens sequentially includes, along the optical axis from the first side to the second side, a first lens L1, a reflective polarizing element RP, a quarter-wave plate QWP1, a second lens L2, a partial reflective element BS, and a third lens L3. Among them, the first lens L1 has positive focal power, the first side near-axial area is a convex surface, and the second side near-axial area is a plane; the second lens L2 has negative focal power, the first side near-axial area is a concave surface, and the second side near-axial area is a convex surface; the third lens L3 has positive focal power, the first side near-axial area is a convex surface, and the second side near-axial area is a concave surface; the reflective polarizing element RP is arranged on the second side of the first lens L1; the quarter-wave plate QWP1 is arranged on the second side of the reflective polarizing element RP; and the partial reflective element BS is arranged on the second side of the second lens L2.

[0095] The eyepiece lens further includes a diaphragm arranged before the first lens L1, a flat substrate CG1 between the second side of the third lens L3 and the image plane Img, a quarter-wave plate QWP2, a linear polarizer LP, and a protective glass CG2.

[0096] According to the eyepiece lens of the present example, in a specific application, image light from the image plane Img can sequentially pass through the protective glass CG2, the linear polarizer LP, the quarter-wave plate QWP2, the flat substrate CG1, the third lens L3, the partial reflective element BS, the second lens L2, the quarter-wave plate QWP1, reach the reflective polarizing element RP, be reflected at the reflective polarizing element RP, and pass through the quarter-wave plate QWP1 and the second lens L2 again to reach the partial reflective element BS, then be reflected again at the partial reflective element BS and sequentially pass through the second lens L2, the quarter-wave plate QWP1, the reflective polarizing element RP, and the first lens L1 to the diaphragm STO and finally be imaged at a predetermined position. For example, the light rays after two reflections of the eyepiece lens can finally project onto the user's eye pupil.

[0097] Table 4 shows the basic parameter table of the eyepiece lens of Example 3, wherein the units of the curvature radius and the thickness / distance are millimeters (mm).

[0098] Table 4

[0099]

[0100] Figure 8 The field curvature curve and the distortion curve of the eyepiece lens according to Example 3 of the present application are shown, Figure 9 The MTF (Modulation Transfer Function) curve of the optical lens according to Example 3 of the present application is shown, Figure 8 and Figure 9 It can be seen that the eyepiece lens according to Example 3 of the present application has the characteristics of low distortion and high resolution.

[0101] Example 4

[0102] The following is for reference Figures 10 to 12 The eyepiece lens according to Embodiment 4 of this application is described.

[0103] like Figure 10 As shown, the eyepiece lens, along the optical axis from the first side to the second side, sequentially includes a first lens L1, a reflective polarizing element RP, a quarter-wave plate QWP1, a second lens L2, a partially reflective element BS, and a third lens L3. Specifically, the first lens L1 has positive optical power, with a convex paraxial region on its first side and a planar paraxial region on its second side; the second lens L2 has negative optical power, with a concave paraxial region on its first side and a convex paraxial region on its second side; the third lens L3 has positive optical power, with a convex paraxial region on its first side and a concave paraxial region on its second side; the reflective polarizing element RP is disposed on the second side of the first lens L1; the quarter-wave plate QWP1 is disposed on the second side of the reflective polarizing element RP; and the partially reflective polarizing element BS is disposed on the second side of the second lens L2.

[0104] The eyepiece lens also includes an aperture stop located in front of the first lens L1, a flat substrate CG1 between the second side of the third lens L3 and the image plane Img, a quarter-wave plate QWP2, a linear polarizer LP, and a protective glass CG2.

[0105] In a specific application, according to the eyepiece lens of this example, image light from the image plane Img sequentially passes through the protective glass CG2, the linear polarizer LP, the quarter-wave plate QWP2, the flat substrate CG1, the third lens L3, the partial reflective element BS, the second lens L2, and the quarter-wave plate QWP1 to reach the reflective polarizing element RP. It is reflected at the reflective polarizing element RP and then passes again through the quarter-wave plate QWP1 and the second lens L2 to reach the partial reflective element BS. Afterward, it is reflected again at the partial reflective element BS and sequentially passes through the second lens L2, the quarter-wave plate QWP1, the reflective polarizing element RP, and the first lens L1 to reach the aperture stop STO and finally imaged at a predetermined position. For example, the light from this eyepiece lens, after two reflections, can ultimately be projected onto the user's pupil.

[0106] Table 5 shows the basic parameters of the eyepiece lens in Example 4, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0107] Table 5

[0108]

[0109]

[0110] Figure 11A field curvature curve and a distortion curve of the eyepiece lens according to Embodiment 4 of the present application are shown, Figure 12 An MTF (Modulation Transfer Function) curve of the optical lens according to Embodiment 4 of the present application is shown, which is obtained by Figure 11 and Figure 12 It can be seen that the eyepiece lens according to Embodiment 4 of the present application has the characteristics of low distortion and high resolution.

[0111] In summary, the conditional expressions in Embodiments 1 to 4 satisfy the relationships shown in Table 6. In Table 6, the units of all parameters are millimeters (mm).

[0112] Table 6

[0113] Conditional / Example 1 2 3 4 ENPD / F 0.541 0.650 0.700 0.427 TTL / F 0.562 0.695 0.728 0.485 BFL / TTL 0.162 0.224 0.246 0.161 D / F 0.433 0.520 0.560 0.342 F / H 4.358 3.630 3.367 5.520 F1 / F 1.073 1.930 2.040 0.595 F2 / F -3.128 -5.568 -5.635 -0.603 F3 / F 0.934 1.001 0.961 0.240 F1 / F2 -0.343 -0.347 -0.362 -0.987 d1 / d12 0.286 0.276 0.294 0.324 d2 / d12 0.231 0.221 0.170 0.074 BFL / d12 0.330 0.489 0.546 0.315

[0114] The above description is merely preferred embodiments of the present application and a principle of applied technologies. It should be understood by those skilled in the art that the scope of the present application is not limited to the technical solutions formed by the specific combinations of the above technical features, and should also cover other technical solutions formed by the combinations of the above technical features or equivalent features without departing from the inventive concept. For example, the technical solutions formed by the mutual replacement of the above features and the technical features disclosed in the present application (but not limited to) having similar functions.

Claims

1. An eyepiece lens, characterized in that, Along the optical axis, from the first side to the second side, the following are included in sequence: A first lens with positive optical power; Reflective polarizing element; Quarter wave plate; A second lens with negative optical power; Partial reflective elements; A third lens with positive optical power; The number of lenses with optical power in the eyepiece lens is 3.

2. The eyepiece lens according to claim 1, characterized in that, The first side paraxial region of the first lens is convex, and the second side paraxial region is planar, convex, or concave. The first paraxial region of the second lens is concave, and the second paraxial region is convex; and The first side paraxial region of the third lens is convex, and the second side paraxial region is concave.

3. The eyepiece lens according to any one of claims 1-2, characterized in that, The eyepiece lens satisfies the following condition: 0.38≤ENPD / F≤0.77 Wherein, ENPD is the exit pupil diameter of the eyepiece lens, and F is the effective focal length of the eyepiece lens.

4. The eyepiece lens according to any one of claims 1-2, characterized in that, The eyepiece lens satisfies at least one of the following conditions: 0.43≤TTL / F≤0.81, 0.14≤BFL / TTL≤0.27 Wherein, TTL is the center distance from the first side surface of the first lens to the center of the image surface of the eyepiece lens, F is the effective focal length of the eyepiece lens, and BFL is the center distance from the second side surface of the third lens to the center of the image surface of the eyepiece lens.

5. The eyepiece lens according to any one of claims 1-2, characterized in that, The eyepiece lens satisfies the following condition: 0.30≤D / F≤0.62 Where D is the exit pupil distance of the eyepiece lens, and F is the effective focal length of the eyepiece lens.

6. The eyepiece lens according to any one of claims 1-2, characterized in that, The eyepiece lens satisfies the following condition: 3.03≤F / H≤6.08 Wherein, F is the effective focal length of the eyepiece lens, and H is the maximum image area of ​​the eyepiece lens.

7. The eyepiece lens according to any one of claims 1-2, characterized in that, The eyepiece lens satisfies at least one of the following conditions: 0.53≤F1 / F≤2.25, -6.20≤F2 / F≤-0.54, 0.21≤F3 / F≤1.11, -6.46≤F2 / F3≤-2.25 Wherein, F1 is the effective focal length of the first lens, F2 is the effective focal length of the second lens, F3 is the effective focal length of the third lens, and F is the effective focal length of the eyepiece lens.

8. The eyepiece lens according to any one of claims 1-2, characterized in that, The eyepiece lens satisfies at least one of the following conditions: 0.24≤d1 / d12≤0.36, 0.06≤d2 / d12≤0.26 Wherein, d1 is the center distance from the first side of the first lens to the center of the second side of the quarter-wave plate, d12 is the center distance from the second side of the quarter-wave plate to the center of the first side of the second lens, and d2 is the center thickness of the second lens.

9. The eyepiece lens according to any one of claims 1-2, characterized in that, The eyepiece lens satisfies the following condition: 0.28≤BFL / d12≤0.6, Wherein, BFL is the center distance from the second side surface of the third lens to the center of the image surface of the eyepiece lens, and d12 is the center distance from the second side surface of the quarter-wave plate to the center of the first side surface of the second lens.

10. The eyepiece lens according to any one of claims 1-2, characterized in that, The eyepiece lens satisfies at least one of the following conditions: 0.42≤ENPD / F≤0.70, 0.48≤TTL / F≤0.73, 0.16≤BFL / TTL≤0.25, 0.34≤D / F≤0.56, 3.36≤F / H≤5.52, 0.59≤F1 / F≤2.04, -5.64≤F2 / F≤-0.60, 0.24≤F3 / F≤1.01, -5.87≤F2 / F3≤-2.51, 0.27≤d1 / d12≤0.33, 0.07≤d2 / d12≤0.24, 0.31≤BFL / d12≤0.55, Wherein, ENPD is the exit pupil diameter of the eyepiece lens, F is the effective focal length of the eyepiece lens, TTL is the center distance from the first side of the first lens to the image plane of the eyepiece lens, BFL is the center distance from the second side of the third lens to the image plane of the eyepiece lens, D is the exit pupil distance of the eyepiece lens, H is the maximum image plane of the eyepiece lens, F1 is the effective focal length of the first lens, F2 is the effective focal length of the second lens, F3 is the effective focal length of the third lens, d1 is the center distance from the first side of the first lens to the second side of the quarter-wave plate, d12 is the center distance from the second side of the quarter-wave plate to the first side of the second lens, and d2 is the center thickness of the second lens.

Images