Optical image capturing system

Abstract

The invention discloses an optical imaging system. The optical imaging system comprises a lens cone, an imaging group and a second spacing element, wherein the imaging group and the second spacing element are arranged in the lens cone. The imaging group sequentially comprises a linear polarization film, a reflective polarization element, a quarter-wave plate, a first lens, a second lens, a third lens, a fourth lens and a partial reflection layer from the first side to the second side along the optical axis; wherein the first lens and the second lens are glued, and the third lens and the fourth lens are glued. The second spacer element is disposed on the second side of the second lens and is in contact with the second side of the second lens. Wherein the outer diameter D0m of the second side end face of the lens barrel and the outer diameter D2m of the second side face of the second spacing element meet the condition that D0m-D2m is larger than or equal to 4.51 mm and smaller than or equal to 5.8 mm; the inner diameter d2m of the second side surface of the second spacing element, the inner diameter d2s of the first side surface of the second spacing element, and the axial distance T23 from the second side surface of the second lens to the first side surface of the third lens satisfy the following formula: (d2m-d2s) / T23 is greater than or equal to 0.97 and less than or equal to 2.79.

Description

Technical Field

[0001] The present application relates to the field of optical devices, and in particular to an optical imaging system. Background Art

[0002] With the introduction of the concept of the metaverse, people have put forward higher requirements for the optical imaging system of virtual reality devices or augmented reality devices. Optical imaging systems are mainly divided into three types: optical systems using aspherical lenses, optical systems using Fresnel lenses, and catadioptric optical systems. Among them, the catadioptric optical system is a major innovation of the optical imaging system itself, and it reserves space for the overall design of virtual reality devices or augmented reality devices, and has become the mainstream trend of research and development.

[0003] The catadioptric optical system shortens the length of the optical imaging system by bending the optical path, thereby moving the center of gravity of the virtual reality device or augmented reality device backward and improving the user experience. However, the existing catadioptric optical system usually uses two lenses, which will cause the catadioptric optical system to have more serious ghost images. Summary of the invention

[0004] On the one hand, the present application provides such an optical imaging system, which includes a lens barrel, an imaging group and a second spacing element placed in the lens barrel. The imaging group includes a linear polarization film, a reflective polarizing element, a quarter wave plate, a first lens, a second lens, a third lens, a fourth lens and a partial reflection layer in sequence from the first side to the second side along the optical axis; wherein the first lens and the second lens are glued, and the third lens and the fourth lens are glued. The second spacing element is placed on the second side of the second lens and contacts the second side of the second lens. Wherein, the number of lenses with optical power in the optical imaging system is four. The outer diameter D0m of the second side end face of the lens barrel and the outer diameter D2m of the second side of the second spacing element satisfy: 4.51mm≤D0m-D2m≤5.8mm; the inner diameter d2m of the second side of the second spacing element, the inner diameter d2s of the first side of the second spacing element and the axial distance T23 from the second side of the second lens to the first side of the third lens satisfy: 0.97≤(d2m-d2s) / T23≤2.79.

[0005] According to an exemplary embodiment of the present application, the curvature radius R4 of the second side surface of the second lens, the outer diameter D2s of the first side surface of the second spacer element and the refractive index N2 of the second lens satisfy: -2.78≤R4 / (D2s×N2)≤-1.8.

[0006] According to an exemplary embodiment of the present application, the maximum thickness CP2 of the second spacer element, the distance EP02 between the first side end surface of the lens barrel and the second spacer element along the optical axis, and the on-axis distance T23 from the second side surface of the second lens to the first side surface of the third lens satisfy: 4.46≤(CP2+EP02) / T23≤7.72.

[0007] According to an exemplary embodiment of the present application, the center thickness CT3 of the third lens on the optical axis, the center thickness CT4 of the fourth lens on the optical axis, the distance L between the first side end surface of the lens barrel and the second side end surface of the lens barrel along the optical axis, and the distance EP02 between the first side end surface of the lens barrel and the second spacing element along the optical axis satisfy: 0.72≤(CT3+CT4) / (L-EP02)≤1.4.

[0008] According to an exemplary embodiment of the present application, a curvature radius R5 of the first side surface of the third lens and an inner diameter d2m of the second side surface of the second spacing element satisfy: 4.45≤R5 / d2m≤5.45.

[0009] According to an exemplary embodiment of the present application, the distance EP02 between the effective focal length f2 of the second lens and the first side end surface of the lens barrel and the second spacing element along the optical axis satisfies: -25.74≤f2 / EP02≤-15.8.

[0010] According to an exemplary embodiment of the present application, a curvature radius R2 of the second side surface of the first lens and an inner diameter d2s of the first side surface of the second spacing element satisfy: -2.00≤R2 / d2s≤-1.15.

[0011] According to an exemplary embodiment of the present application, a radius of curvature R6 of the second side surface of the third lens and an inner diameter d0m of the second side end surface of the lens barrel satisfy: 0.88≤R6 / d0m≤1.27.

[0012] According to an exemplary embodiment of the present application, the distance L between the first side end surface of the lens barrel and the second side end surface of the lens barrel along the optical axis, the center thickness CT1 of the first lens on the optical axis, and the center thickness CT2 of the second lens on the optical axis satisfy: 2.53≤L / (CT1+CT2)≤3.89.

[0013] According to an exemplary embodiment of the present application, a combined focal length f34 of the third lens and the fourth lens and an outer diameter D0m of the second side end surface of the lens barrel satisfy: 1.57≤f34 / D0m≤2.69.

[0014] According to an exemplary embodiment of the present application, the first lens has positive or negative power, its first side is concave or flat, and its second side is convex. The second lens has negative power, and its second side is convex. The third lens has negative power, its first side is convex, and its second side is concave. The fourth lens has positive power, its first side is convex, and its second side is convex.

[0015] The optical imaging system provided by the present application adopts four lenses, and by controlling the difference range between the outer diameter of the second side end face of the lens barrel and the outer diameter of the second side face of the second spacing element, the ghost image of the optical imaging system can be reduced. However, in this case, the center thickness of the second lens will be limited, thereby causing the assembly stability of the second lens to deteriorate, the field curvature of the optical imaging system to deteriorate, and the imaging quality of the optical imaging system to be affected. Therefore, by reasonably configuring the relationship between the inner diameter of the second side face of the second spacing element, the inner diameter of the first side face of the second spacing element, and the on-axis distance from the second side face of the second lens to the first side face of the third lens, the assembly stability of the second lens can be improved, the assembly deformation of the second lens can be reduced, the field curvature of the optical imaging system can be reduced, and the imaging quality of the optical imaging system can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings, in which:

[0017] Figure 1 shows a parameter annotation diagram of an optical imaging system according to the present application;

[0018] Figure 2 A schematic diagram of a light path of an optical imaging system according to the present application is shown;

[0019] Figure 3 A schematic structural diagram of an optical imaging system according to Embodiment 1 of the present application is shown;

[0020] Figure 4 A schematic structural diagram of an optical imaging system according to Embodiment 2 of the present application is shown;

[0021] Figure 5 A schematic structural diagram of an optical imaging system according to Embodiment 3 of the present application is shown;

[0022] Figure 6 , Figure 7 , Figure 8 The axial chromatic aberration curve, astigmatism curve and distortion curve of the optical imaging system according to Embodiments 1, 2 and 3 of the present application are shown;

[0023] Fig. 9 A schematic structural diagram of an optical imaging system according to Embodiment 4 of the present application is shown;

[0024] Fig.10 A schematic structural diagram of an optical imaging system according to Embodiment 5 of the present application is shown;

[0025] Fig.11 A schematic structural diagram of an optical imaging system according to Embodiment 6 of the present application is shown;

[0026] Fig.12 , Fig.13 , Fig.14 The axial chromatic aberration curve, astigmatism curve and distortion curve of the optical imaging system according to Embodiments 4, 5 and 6 of the present application are shown;

[0027] Fig.15 A schematic structural diagram of an optical imaging system according to Embodiment 7 of the present application is shown;

[0028] Fig.16 A schematic structural diagram of an optical imaging system according to Embodiment 8 of the present application is shown;

[0029] Fig.17 A schematic structural diagram of an optical imaging system according to Embodiment 9 of the present application is shown;

[0030] Fig.18 , Fig.19 , Fig. 20 The axial chromatic aberration curve, astigmatism curve and distortion curve of the optical imaging system according to Examples 7, 8 and 9 of the present application are shown. DETAILED DESCRIPTION

[0031] In order to better understand the present application, a more detailed description will be made of various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0032] It should be noted that in this specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teaching of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0033] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0034] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the first side (e.g., the human eye side) is called the first side surface of the lens, and the surface of each lens closest to the second side (e.g., the display screen side) is called the second side surface of the lens.

[0035] The optical imaging system of the exemplary embodiment of the present application can be simulated by software and / or tools such as ZEMAX and CODEV. Alternatively, the optical imaging system can be simulated by CODEV software. In the process of simulation using the above software and / or tools, the surface shape of each lens can be appropriately adjusted according to the surface shape model of the software and / or tool used.

[0036] It should also be understood that the terms "including" and / or "having", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when describing the embodiments of the present application, the term "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0037] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as those commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0038] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0039] Figure 1 Parameters are marked in accordance with an exemplary embodiment of the present application. Figure 1, d0s represents the inner diameter of the first side end face of the lens barrel, D0s represents the outer diameter of the first side end face of the lens barrel, d0m represents the inner diameter of the second side end face of the lens barrel, D0m represents the outer diameter of the second side end face of the lens barrel, d2m represents the inner diameter of the second side face of the second spacing element, D2m represents the outer diameter of the second side face of the second spacing element, d2s represents the inner diameter of the first side face of the second spacing element, D2s represents the outer diameter of the first side face of the second spacing element, CP2 represents the maximum thickness of the second spacing element, EP02 represents the distance between the first side end face of the lens barrel and the second spacing element along the optical axis, and L represents the distance between the first side end face of the lens barrel and the second side end face of the lens barrel along the optical axis.

[0040] The first aspect of the present application provides such an optical imaging system, which may include an imaging group. The imaging group may include a linear polarization film, a reflective polarizing element, a quarter wave plate, a first lens, a second lens, a third lens, a fourth lens and a partial reflection layer arranged in sequence along the optical axis from the first side to the second side. The number of lenses with optical power in the optical imaging system is four. The reflective polarizing element, the quarter wave plate and the partial reflection layer can be used to achieve the refraction of the light path, effectively shorten the main body length of the optical imaging system, reduce the volume and weight of the optical imaging system, and realize the lightness of the optical imaging system.

[0041] In an exemplary embodiment, the first lens and the second lens are cemented to form a cemented lens. The third lens and the fourth lens are cemented to form a cemented lens.

[0042] In an exemplary embodiment, the first lens may have positive power or negative power. The second lens may have negative power. The third lens may have negative power. The fourth lens may have positive power.

[0043] In an exemplary embodiment, the first side of the first lens may be a concave surface or a plane, and the second side may be a convex surface. The first side of the first lens is set to be a concave surface, which can increase the maximum field of view of the optical imaging system, thereby increasing the field of view of the optical imaging system.

[0044] In an exemplary embodiment, the second side surface of the second lens may be a convex surface. In the case where the third lens has a relatively small central thickness, by setting the second side surface of the second lens to be a convex surface, the second side surface of the second lens can converge the light, so that the light on the image surface of the second side is converged as much as possible, ensuring that the optical imaging system has a relatively small image height, which is beneficial to reducing the size of the display screen on the second side, and reducing the weight and cost of the optical imaging system.

[0045] In exemplary embodiments, the first side surface of the third lens may be a convex surface, and the second side surface may be a concave surface.

[0046] In an exemplary embodiment, the first side surface of the fourth lens may be a convex surface, and the second side surface may be a convex surface. In the case where the third lens has a relatively small central thickness, by setting the second side surface of the fourth lens to be a convex surface, the second side surface of the fourth lens can converge the light, so that the light on the image surface of the second side is converged as much as possible, ensuring that the optical imaging system has a relatively small image height, which is conducive to reducing the size of the display screen on the second side, and reducing the weight and cost of the optical imaging system.

[0047] In an exemplary embodiment, a linear polarizing film may be disposed on a first side of a reflective polarizing element and at least partially adhered to the first side of the reflective polarizing element. The reflective polarizing element may be disposed on a first side of a quarter wave plate and at least partially adhered to the first side of the quarter wave plate. The quarter wave plate may be disposed on a first side of a first lens and at least partially adhered to the first side of the first lens.

[0048] In an exemplary embodiment, the partial reflective layer may be disposed on the second side surface of the fourth lens and at least partially adhered to the second side surface of the fourth lens. The partial reflective layer may have a semi-transmissive and semi-reflective effect on the light. By arranging the partial reflective layer on the second side surface of the fourth lens and combining the reflective polarizing element and the quarter wave plate, the light can be refracted multiple times, effectively reducing the main body length of the optical imaging system.

[0049] In an exemplary embodiment, the optical imaging system may further include an aperture, which may be disposed on the first side of the first lens. As an example, the aperture may be, for example, the pupil of the user. The image light from the second side is refracted and reflected multiple times by the partial reflection layer, the fourth lens, the third lens, the second lens, the first lens, the quarter wave plate, the reflective polarizing element, the linear polarizing film, etc., and is finally projected to the user's eye on the first side.

[0050] In an exemplary embodiment, the first side may be, for example, a human eye side, and the second side may be, for example, a display screen side. Accordingly, the first side of each element (such as the first lens, the second lens, the third lens, the fourth lens, the partial reflection layer, the quarter wave plate, the reflective polarizing element, and the linear polarizing film) may be referred to as a side near the human eye, and the second side may be referred to as a side near the screen.

[0051] In an exemplary embodiment, an imaging surface may be provided on the second side of the optical imaging system. A display screen may be provided on the imaging surface. The light from the display screen sequentially passes through the fourth lens, the third lens, the second lens, the first lens, and the quarter wave plate to reach the reflective polarizing element, and then is reflected at the reflective polarizing element to form a first reflected image light. The first reflected image light sequentially passes through the quarter wave plate, the first lens, the second lens, the third lens, the fourth lens and reaches the partial reflective layer on the second side of the fourth lens, and then is reflected at the partial reflective layer to form a second reflected image light. The second reflected image light sequentially passes through the fourth lens, the third lens, the second lens, the first lens, the quarter wave plate, the reflective polarizing element, the linear polarizing film to the aperture and is finally projected to the human eye. The optical imaging system provided in the present application folds the required optical path without affecting the projection quality by combining light reflection and refraction, thereby effectively shortening the main body length of the optical imaging system.

[0052] In an exemplary embodiment, the optical imaging system may further include a second spacing element. The second spacing element may be disposed on the second side of the second lens and at least partially contact the second side of the second lens. Proper use of the spacing element can effectively avoid stray light risks, reduce interference with image quality, and thereby improve the imaging quality of the optical imaging system.

[0053] In an exemplary embodiment, the optical imaging system may further include a lens barrel. The imaging group and the second spacing element are placed in the lens barrel. The end face of the lens barrel closest to the first side is the first side end face of the lens barrel, and the end face of the lens barrel closest to the second side is the second side end face of the lens barrel.

[0054] In an exemplary embodiment, the outer peripheral surface of at least one lens in the imaging group may have a trimmed portion and a non-trimmed portion, and the outer diameter of the trimmed portion of the lens may be smaller than the outer diameter of the non-trimmed portion of the lens. When the outer peripheral surface of the lens has a trimmed portion, the outer diameter of the lens generally refers to the outer diameter of the non-trimmed portion of the lens. For example, the outer diameter of the first side surface of the lens refers to the outer diameter of the portion of the non-trimmed portion of the lens closest to the first side, and the outer diameter of the second side surface of the lens refers to the outer diameter of the portion of the non-trimmed portion of the lens closest to the second side.

[0055] In an exemplary embodiment, the outer circumferential surface of the second spacer element may have a trimmed portion and a non-trimmed portion, and the outer diameter of the trimmed portion of the second spacer element may be smaller than the outer diameter of the non-trimmed portion of the second spacer element. When the outer circumferential surface of the second spacer element has a trimmed portion, the outer diameter of the second spacer element generally refers to the outer diameter of the non-trimmed portion of the second spacer element. For example, the outer diameter of the first side surface of the second spacer element refers to the outer diameter of the portion of the non-trimmed portion of the second spacer element closest to the first side, and the outer diameter of the second side surface of the second spacer element refers to the outer diameter of the portion of the non-trimmed portion of the second spacer element closest to the second side.

[0056] In an exemplary embodiment, the outer diameter D0m of the second side end face of the lens barrel and the outer diameter D2m of the second side face of the second spacing element satisfy: 4.51mm≤D0m-D2m≤5.8mm; the inner diameter d2m of the second side face of the second spacing element, the inner diameter d2s of the first side face of the second spacing element and the axial distance T23 from the second side face of the second lens to the first side face of the third lens satisfy: 0.97≤(d2m-d2s) / T23≤2.79. By controlling the difference range between the outer diameter of the second side end face of the lens barrel and the outer diameter of the second side face of the second spacing element, the ghost image of the optical imaging system can be reduced. However, in this case, the center thickness of the second lens will be limited, resulting in poor assembly stability of the second lens, poor field curvature of the optical imaging system, and affecting the imaging quality of the optical imaging system. Therefore, by reasonably configuring the relationship between the inner diameter of the second side surface of the second spacer element, the inner diameter of the first side surface of the second spacer element, and the on-axis distance from the second side surface of the second lens to the first side surface of the third lens, the assembly stability of the second lens can be improved, the assembly deformation of the second lens can be reduced, the field curvature of the optical imaging system can be reduced, and the imaging quality of the optical imaging system can be improved.

[0057] Table 1 is a structural sensitivity analysis table of the second side of the second lens. Table 2 is an optical sensitivity and comprehensive sensitivity analysis table of the second side of the second lens. Among them, lens 1 satisfies (d2m-d2s) / T23=1.26, lens 2 satisfies (d2m-d2s) / T23=0.08, and lens 3 satisfies (d2m-d2s) / T23=7.63.

[0058] In Table 1, surface S4 is the second side surface of the second lens, and ΔS4PV (i.e., structural sensitivity) is the amount of change in the surface shape of the second side surface of the second lens. Under stress, the center point and edge point of the second side surface of the second lens will shift, causing the surface shape PV of the second side surface of the second lens to change. The smaller the absolute value of ΔS4PV, the smaller the amount of change in the surface shape of the second side surface of the second lens, and the better the structural sensitivity of the second side surface of the second lens. The center point and edge point of the second side surface of the second lens can be referenced Figure 1 .

[0059] In Table 2, the S direction peak may be the S curve peak of the MTF curve under a 0.4 field of view, and the M direction peak may be the M curve peak of the MTF curve under a 0.4 field of view, "S" is the sagittal curve, and "M" is the meridian curve. When △S4PV changes, the S direction peak and / or the M direction peak will change with the change of △S4PV, and the change in the S direction peak and / or the M direction peak may be the optical sensitivity. The comprehensive sensitivity may be the product of the structural sensitivity and the optical sensitivity. It should be understood that the smaller the absolute value of the optical sensitivity, the better the optical sensitivity; the smaller the absolute value of the comprehensive sensitivity, the better the comprehensive sensitivity. Among them, MTF is the modulation transfer function.

[0060]

[0061]

[0062] Table 1

[0063]

[0064] Table 2

[0065] The structural sensitivity indicates the amount of change in the surface shape of the second side surface of the second lens of the lens when a certain load is applied to the lens. The same load is applied to lens 1, lens 2, and lens 3, and lenses 1, lens 2, and lens 3 are respectively subjected to the same external force on the second side surface of the second lens. Under the influence of stress, the center point and edge point of the second side surface of the second lens will be offset, thereby causing the surface shape PV of the second side surface of the second lens to change. For example, referring to Table 1, through simulation, the structural sensitivities of lens 1, lens 2, and lens 3 are 0.0188um, 0.783um, and 0.190um, respectively. It can be seen that the structural sensitivity of lens 1 is smaller, that is, the amount of surface shape change is smaller, and the structural sensitivity of lens 1 is better.

[0066] Optical sensitivity refers to the change in the MTF peak value of the lens when the change in the lens surface shape is constant. The surface shape changes of lens 1, lens 2 and lens 3 are the same. For example, referring to Table 2, through simulation, when △S4PV increases by 1um, the change in the 0.4 field MTF peak value in the S direction of lens 1, lens 2 and lens 3 is -0.46%, -0.66%, -0.91% respectively, and the change in the 0.4 field MTF peak value in the M direction is -0.38%, -0.83%, -0.61% respectively; when △S4PV decreases by 1um, the change in the 0.4 field MTF peak value in the S direction of lens 1, lens 2 and lens 3 is 0.95%, 0.46%, 0.63% respectively, and the change in the 0.4 field MTF peak value in the M direction is 0.81%, 0.49%, 0.47% respectively. It can be seen that the MTF peak value of lens 1 is less affected by the change in surface shape, and the optical sensitivity of lens 1 is better.

[0067] The comprehensive sensitivity indicates the effect of the surface shape change on the MTF peak of the lens. For example, referring to Table 2, the comprehensive sensitivities of Lens 1, Lens 2 and Lens 3 in the S direction are -0.00865μm, -0.517μm, -0.173μm, and the comprehensive sensitivities in the M direction are -0.00714μm, -0.650μm, -0.116μm, respectively. It can be seen that the force surface shape change of Lens 1 is small, and the effect of the surface shape change on the MTF peak is small. Lens 1 has a small comprehensive sensitivity and good assembly stability.

[0068] Combined with the above analysis, it can be seen that by making the optical imaging system satisfy "0.97≤(d2m-d2s) / T23≤2.79", it can be ensured that the second side surface of the second lens has a smaller surface shape change, thereby reducing the structural sensitivity and optical sensitivity of the optical imaging system, thereby reducing the comprehensive sensitivity of the optical imaging system and improving the assembly stability of the optical imaging system.

[0069] In an exemplary embodiment, the curvature radius R4 of the second side surface of the second lens, the outer diameter D2s of the first side surface of the second spacer element, and the refractive index N2 of the second lens satisfy: -2.78≤R4 / (D2s×N2)≤-1.8. By controlling the above conditional expression, the focal length of the second lens can be constrained within a certain range, thereby controlling the exit angle of the light emitted from the second lens and reducing the incident angle of the light on the display screen; at the same time, the outer diameter of the first side surface of the second spacer element can be limited, thereby improving the processability of the second spacer element.

[0070] In an exemplary embodiment, the maximum thickness CP2 of the second spacer element, the distance EP02 between the first side end face of the lens barrel and the second spacer element along the optical axis, and the on-axis distance T23 from the second side surface of the second lens to the first side surface of the third lens satisfy: 10.07≤(CP2+EP02) / T23≤15.74. By controlling the above conditional expression, the center thickness and edge thickness of the second lens and the third lens can be constrained within a reasonable range, and the assembly stability of the two groups of cemented lenses can be improved on the basis of ensuring that the second lens and the third lens have good processability; at the same time, the on-axis distance from the second side surface of the second lens to the first side surface of the third lens can be limited, effectively correcting the field curvature and improving the imaging quality of the optical imaging system.

[0071] In an exemplary embodiment, the center thickness CT3 of the third lens on the optical axis, the center thickness CT4 of the fourth lens on the optical axis, the distance L between the first side end face of the lens barrel and the second side end face of the lens barrel along the optical axis, and the distance EP02 between the first side end face of the lens barrel and the second spacing element along the optical axis satisfy: 0.72≤(CT3+CT4) / (L-EP02)≤1.4. By controlling the above conditional expression, the thickness ratio of the third lens and the fourth lens can be constrained within a reasonable range, which is beneficial to the molding and gluing of the third lens and the fourth lens; at the same time, the distance between the first side end face of the lens barrel and the second side end face of the lens barrel along the optical axis can be limited, the total length of the optical imaging system can be reduced, the weight of the optical imaging system can be reduced, the miniaturization of the optical imaging system can be achieved, and the wearing experience of the user can be improved.

[0072] In an exemplary embodiment, the radius of curvature R5 of the first side surface of the third lens and the inner diameter d2m of the second side surface of the second spacing element satisfy: 4.45≤R5 / d2m≤5.45. Reasonable configuration of the ratio of the radius of curvature of the first side surface of the third lens to the inner diameter of the second side surface of the second spacing element can constrain the overall shape of the third lens, reduce the sensitivity of the third lens, and improve the assembly yield of the third lens; at the same time, the refraction degree of the second spacing element and the third lens to light can be matched, and when the second spacing element intercepts ineffective light, the second spacing element can be shielded from effective light as much as possible, reduce stray light, and improve the light efficiency of the optical imaging system.

[0073] In an exemplary embodiment, the effective focal length f2 of the second lens and the distance EP02 along the optical axis between the first side end surface of the lens barrel and the second spacing element satisfy: -25.74≤f2 / EP02≤-15.8. By controlling the above conditional expression, the focal length of the second lens can be reasonably allocated, and the aberration contribution of the second lens can be effectively constrained, so that the aberration generated by the second lens is balanced with the aberration generated by other optical elements, ensuring that the aberration of the optical imaging system is at a reasonable level; at the same time, the maximum thickness of the second spacing element can be limited, so that the second spacing element and the lens adjacent to it can be stably supported, thereby improving the assembly stability and assembly yield of the optical imaging system.

[0074] In an exemplary embodiment, the radius of curvature R2 of the second side surface of the first lens and the inner diameter d2s of the first side surface of the second spacer element satisfy: -2.00≤R2 / d2s≤-1.15. By controlling the above conditional expression, the overall shape of the first lens can be constrained, which is beneficial to reducing the sensitivity of the first lens and improving the assembly yield of the first lens; at the same time, the refraction degree of the second spacer element and the first lens can be matched, and when the second spacer element intercepts the ineffective light, the second spacer element can be shielded from the effective light as much as possible, reduce stray light, and improve the light efficiency of the optical imaging system.

[0075] In an exemplary embodiment, the radius of curvature R6 of the second side surface of the third lens and the inner diameter d0m of the second side end surface of the lens barrel satisfy: 0.88≤R6 / d0m≤1.27. By controlling the above conditional expression, the overall shape of the third lens can be constrained, which is conducive to reducing the sensitivity of the third lens and improving the assembly yield of the third lens; at the same time, it can also ensure that the refraction degree of light by the lens barrel and the third lens matches, and when the lens barrel intercepts ineffective light, the lens barrel blocks effective light as much as possible, reduces stray light, and improves the light efficiency of the optical imaging system. In addition, it is also conducive to the molding of the lens barrel and the feasibility of assembling the third lens.

[0076] In an exemplary embodiment, the distance L between the first side end surface of the lens barrel and the second side end surface of the lens barrel along the optical axis, the center thickness CT1 of the first lens on the optical axis, and the center thickness CT2 of the second lens on the optical axis satisfy: 2.53≤L / (CT1+CT2)≤3.89. By controlling the ratio of the distance between the first side end surface of the lens barrel and the second side end surface of the lens barrel along the optical axis to the sum of the center thicknesses of the first lens and the second lens within a certain range, it is beneficial to reduce the total optical length of the optical imaging system and realize the miniaturization of the optical imaging system.

[0077] In an exemplary embodiment, the combined focal length f34 of the third lens and the fourth lens and the outer diameter D0m of the second side end face of the lens barrel satisfy: 1.57≤f34 / D0m≤2.69. By controlling the above conditional expression, the combined focal length of the third lens and the fourth lens can be constrained within a reasonable range, so that the cemented lens formed by the cementation of the third lens and the fourth lens produces negative spherical aberration and balances the positive spherical aberration produced by other lenses, thereby improving the imaging quality of the optical imaging system; at the same time, the outer diameter of the second side end face of the lens barrel can be limited, while ensuring that it plays a limiting role on the fourth lens, while improving the machinability of the lens barrel.

[0078] The optical imaging system according to the above-mentioned embodiment of the present application may adopt multiple lenses, such as the four lenses described above. By reasonably allocating the parameters of the linear polarization film, the reflective polarizing element, the quarter-wave plate, the partial reflection layer, each lens, the lens barrel and the second spacing element, the main body length of the optical imaging system can be reduced, and the processability, assembly stability and imaging quality of the optical imaging system can be improved. The optical imaging system configured as above has the characteristics of miniaturization and good imaging quality, which can well meet the use requirements of various portable electronic products in projection scenes, and the center of gravity of the optical imaging system and the electronic device including the optical imaging system is moved backward, which improves the user's wearing experience.

[0079] In an exemplary embodiment, at least one of the surfaces of each lens of the first lens to the fourth lens is an aspherical surface. The characteristic of an aspherical lens is that the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has a better curvature radius characteristic, and has the advantages of improving distortion aberration and improving astigmatism aberration. After using an aspherical lens, the aberration occurring during imaging can be eliminated as much as possible, thereby improving the imaging quality.

[0080] The second aspect of the present application provides such an optical imaging system, which may include a lens barrel and an imaging group assembled in the lens barrel. The imaging group may include a linear polarization film, a reflective polarizing element, a quarter wave plate, a first lens, a second lens, a third lens, a fourth lens and a partial reflection layer in sequence from the first side to the second side along the optical axis. The number of lenses with optical power in the optical imaging system is four.

[0081] The combined focal length f34 of the third lens and the fourth lens and the outer diameter D0m of the second side end face of the lens barrel satisfy: 1.57≤f34 / D0m≤2.69. By controlling the above conditional expression, the combined focal length of the third lens and the fourth lens can be constrained within a reasonable range, so that the cemented lens formed by the cementation of the third lens and the fourth lens produces negative spherical aberration and balances the positive spherical aberration produced by other lenses, thereby improving the imaging quality of the optical imaging system; at the same time, the outer diameter of the second side end face of the lens barrel can be limited, while ensuring that it plays a limiting role on the fourth lens, while improving the machinability of the lens barrel.

[0082] Those skilled in the art should understand that, without departing from the technical solution claimed in the present application, the number of lenses and spacer elements constituting the optical imaging system can be changed to obtain the various results and advantages described in this specification.

[0083] Specific embodiments of the optical imaging system applicable to the above-mentioned embodiments are further described below with reference to the accompanying drawings.

[0084] Example 1

[0085] The following reference Figure 2 and Figure 3 The optical imaging system according to the embodiment 1 of the present application is described. In which the aperture STO and the image plane IMA are not Figure 3 Shown in.

[0086] like Figure 3 As shown, the optical imaging system may include a lens barrel P0 and an imaging group and a second spacing element P2 assembled in the lens barrel P0. The imaging group includes a linear polarization film LP, a reflective polarization element RP, a quarter wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4 and a partial reflection layer BS arranged in sequence from the first side to the second side along the optical axis. The aperture STO is arranged between the first side and the linear polarization film LP (as shown in FIG. Figure 2 ).

[0087] The first lens E1 has positive focal power, its first side surface S1 is a plane, and the second side surface S2 is a convex surface. The second lens E2 has negative focal power, its first side surface S3 is a concave surface, and the second side surface S4 is a convex surface. The third lens E3 has negative focal power, its first side surface S5 is a convex surface, and the second side surface S6 is a concave surface. The fourth lens E4 has positive focal power, its first side surface S7 is a convex surface, and the second side surface S8 is a convex surface. The linear polarization film LP, the reflective polarizing element RP and the quarter wave plate QWP are attached to the first side surface S1 of the first lens E1. The partial reflection layer BS is attached to the second side surface S8 of the fourth lens E4.

[0088] In this example, the second side of the optical imaging system may be provided with an image surface IMA (eg, Figure 2). The image plane IMA may be provided with a display screen, for example. The light from the image plane IMA sequentially passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter wave plate QWP, reaches the reflective polarizing element RP, and then is reflected at the reflective polarizing element RP to form a first reflected image light. The first reflected image light sequentially passes through the quarter wave plate QWP, the first lens E1, the second lens E2, the third lens E3, the fourth lens E4 and reaches the partial reflective layer BS on the second side of the fourth lens, and then is reflected at the partial reflective layer BS to form a second reflected image light. The second reflected image light sequentially passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter wave plate QWP, the reflective polarizing element RP, the linear polarization film LP to the aperture STO and is finally projected to the human eye. For example, the light of the optical imaging system after two reflections is finally projected to the human eye.

[0089] Table 3 shows a basic parameter table of the optical imaging system of Example 1, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0090]

[0091] Table 3

[0092] In this embodiment, the effective focal length f2 of the second lens is -118.55 mm, and the combined focal length f34 of the third lens and the fourth lens is 126.88 mm.

[0093] The object side surface and the image side surface of any lens from the second side surface S2 of the first lens E1 to the second side surface S8 of the fourth lens E4 are aspherical surfaces, and the surface shape of each aspherical lens can be defined by but not limited to the following aspherical surface formula:

[0094]

[0095] Wherein, x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, c=1 / R (i.e., the paraxial curvature c is the reciprocal of the curvature radius R in Table 3 above); k is the cone coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface. Table 4 shows the cone coefficient k and the high-order coefficients A4, A6, A8, A10, A12 and A14 that can be used for each aspheric surface S2-S8 in Example 1.

[0096]

[0097]

[0098] Table 4

[0099] Example 2

[0100] The following reference Figure 2 and Figure 4 The optical imaging system according to the second embodiment of the present application is described. In which the aperture STO and the image plane IMA are not Figure 4 Shown in.

[0101] like Figure 4 As shown, the optical imaging system may include a lens barrel P0 and an imaging group and a second spacing element P2 assembled in the lens barrel P0. The imaging group includes a linear polarization film LP, a reflective polarization element RP, a quarter wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4 and a partial reflection layer BS arranged in sequence from the first side to the second side along the optical axis. The aperture STO is arranged between the first side and the linear polarization film LP (as shown in FIG. Figure 2 ).

[0102] The structure of the imaging group of this embodiment is the same as that of the imaging group of Embodiment 1, that is, the basic parameter table of the optical imaging system of this embodiment is the same as Table 3, and the aspheric coefficient table is the same as Table 4. The difference between this embodiment and Embodiment 1 is that the parameters such as the structural dimensions of the lens barrel P0 and the second spacing element P2 are different. The values ​​of multiple parameters of the lens barrel P0 and the second spacing element P2 included in the optical imaging system of this embodiment and Embodiment 1 are shown in Table 9 below.

[0103] Example 3

[0104] The following reference Figure 2 and Figure 5 The optical imaging system according to Embodiment 3 of the present application is described. In which the aperture STO and the image plane IMA are not Figure 5 Shown in.

[0105] like Figure 5 As shown, the optical imaging system may include a lens barrel P0 and an imaging group and a second spacing element P2 assembled in the lens barrel P0. The imaging group includes a linear polarization film LP, a reflective polarization element RP, a quarter wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4 and a partial reflection layer BS arranged in sequence from the first side to the second side along the optical axis. The aperture STO is arranged between the first side and the linear polarization film LP (as shown in FIG. Figure 2 ).

[0106] The structure of the imaging group of this embodiment is the same as that of the imaging group of Embodiment 1, that is, the basic parameter table of the optical imaging system of this embodiment is the same as Table 3, and the aspheric coefficient table is the same as Table 4. The difference between this embodiment and Embodiment 1 is that the parameters such as the structural dimensions of the lens barrel P0 and the second spacing element P2 are different. The values ​​of multiple parameters of the lens barrel P0 and the second spacing element P2 included in the optical imaging system of this embodiment and Embodiment 1 are shown in Table 9 below.

[0107] Figure 6 The axial chromatic aberration curves of the optical imaging systems of Examples 1, 2 and 3 are shown, which represent the deviation of the focal point of light of different wavelengths after passing through the optical imaging system. Figure 7 Astigmatism curves of the optical imaging systems of Examples 1, 2 and 3 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different half field angles. Figure 8 The distortion curves of the optical imaging systems of Examples 1, 2 and 3 are shown, which represent the distortion magnitude values ​​corresponding to different half-viewing angles. Figures 6 to 8 It can be seen that the optical imaging systems provided in Examples 1, 2 and 3 can achieve good imaging quality.

[0108] Example 4

[0109] The following reference Figure 2 and Fig. 9 The optical imaging system according to Embodiment 4 of the present application is described. In which the aperture STO and the image plane IMA are not Fig. 9 Shown in.

[0110] like Fig. 9 As shown, the optical imaging system may include a lens barrel P0 and an imaging group and a second spacing element P2 assembled in the lens barrel P0. The imaging group includes a linear polarization film LP, a reflective polarization element RP, a quarter wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4 and a partial reflection layer BS arranged in sequence from the first side to the second side along the optical axis. The aperture STO is arranged between the first side and the linear polarization film LP (as shown in FIG. Figure 2 ).

[0111] The first lens E1 has negative optical power, and its first side surface S1 is concave, and the second side surface S2 is convex. The second lens E2 has negative optical power, and its first side surface S3 is concave, and the second side surface S4 is convex. The third lens E3 has negative optical power, and its first side surface S5 is convex, and the second side surface S6 is concave. The fourth lens E4 has positive optical power, and its first side surface S7 is convex, and the second side surface S8 is convex. The linear polarization film LP, the reflective polarizing element RP and the quarter wave plate QWP are attached to the first side surface S1 of the first lens E1. The partial reflection layer BS is attached to the second side surface S8 of the fourth lens E4.

[0112] In this example, the second side of the optical imaging system may be provided with an image surface IMA (eg, Figure 2 ). The image surface IMA may be provided with a display screen, for example. The light from the impact surface IMA sequentially passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter-wave plate QWP, reaches the reflective polarizing element RP, and then reflects at the reflective polarizing element RP to form a first reflected image light. The first reflected image light sequentially passes through the quarter-wave plate QWP, the first lens E1, the second lens E2, the third lens E3, the fourth lens E4 and reaches the partial reflective layer BS on the second side of the fourth lens, and then reflects at the partial reflective layer BS to form a second reflected image light. The second reflected image light sequentially passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter-wave plate QWP, the reflective polarizing element RP, the linear polarization film LP to the aperture STO and is finally projected to the human eye. For example, the light of the optical imaging system after two reflections is finally projected to the human eye.

[0113] Table 5 shows a basic parameter table of the optical imaging system of Example 4, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0114]

[0115] Table 5

[0116] In this embodiment, the effective focal length f2 of the second lens is -193.08 mm, and the combined focal length f34 of the third lens and the fourth lens is 75.94 mm.

[0117] The object side surface and the image side surface of any lens from the second side surface S2 of the first lens E1 to the second side surface S8 of the fourth lens E4 are aspherical surfaces. Table 6 shows the cone coefficient k and the high-order coefficients A4, A6, A8, A10, A12, A14 and A16 of each aspherical surface S2-S8 that can be used in Example 4.

[0118] Face number k A4 A6 A8 A10 A12 A14 A16 S2 / S3 5.0699 3.12E-05 -1.41E-08 -3.19E-10 4.35E-12 -1.96E-14 3.35E-17 -1.36E-20 S4 8.6089 1.04E-05 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S5 -973.0233 1.00E-05 -3.24E-09 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S6 / S7 100.0000 1.50E-05 -3.02E-08 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 S8 0.4203 -3.65E-05 2.01E-08 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

[0119] Table 6

[0120] Example 5

[0121] The following reference Figure 2 and Fig.10 The optical imaging system according to Embodiment 5 of the present application is described. In which the aperture STO and the image plane IMA are not Fig.10 Shown in.

[0122] like Fig.10As shown, the optical imaging system may include a lens barrel P0 and an imaging group and a second spacing element P2 assembled in the lens barrel P0. The imaging group includes a linear polarization film LP, a reflective polarization element RP, a quarter wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4 and a partial reflection layer BS arranged in sequence from the first side to the second side along the optical axis. The aperture STO is arranged between the first side and the linear polarization film LP (as shown in FIG. Figure 2 ).

[0123] The structure of the imaging group of this embodiment is the same as that of the imaging group of Embodiment 4, that is, the basic parameter table of the optical imaging system of this embodiment is the same as Table 5, and the aspheric coefficient table is the same as Table 6. The difference between this embodiment and Embodiment 4 is that the parameters such as the structural dimensions of the lens barrel P0 and the second spacing element P2 are different. The values ​​of multiple parameters of the lens barrel P0 and the second spacing element P2 included in the optical imaging system of this embodiment and Embodiment 4 are shown in Table 9 below.

[0124] Example 6

[0125] The following reference Figure 2 and Fig.11 The optical imaging system according to Embodiment 6 of the present application is described. In which the aperture STO and the image plane IMA are not Fig.11 Shown in.

[0126] like Fig.11 As shown, the optical imaging system may include a lens barrel P0 and an imaging group and a second spacing element P2 assembled in the lens barrel P0. The imaging group includes a linear polarization film LP, a reflective polarization element RP, a quarter wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4 and a partial reflection layer BS arranged in sequence from the first side to the second side along the optical axis. The aperture STO is arranged between the first side and the linear polarization film LP (as shown in FIG. Figure 2 ).

[0127] The structure of the imaging group of this embodiment is the same as that of the imaging group of Embodiment 4, that is, the basic parameter table of the optical imaging system of this embodiment is the same as Table 5, and the aspheric coefficient table is the same as Table 6. The difference between this embodiment and Embodiment 4 is that the parameters such as the structural dimensions of the lens barrel P0 and the second spacing element P2 are different. The values ​​of multiple parameters of the lens barrel P0 and the second spacing element P2 included in the optical imaging system of this embodiment and Embodiment 4 are shown in Table 9 below.

[0128] Fig.12 The axial chromatic aberration curves of the optical imaging systems of Examples 4, 5 and 6 are shown, which represent the deviation of the focal point of light of different wavelengths after passing through the optical imaging system. Fig.13Astigmatism curves of the optical imaging systems of Examples 4, 5 and 6 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different half field angles. Fig.14 The distortion curves of the optical imaging systems of Examples 4, 5 and 6 are shown, which represent the distortion magnitude values ​​corresponding to different half-viewing angles. Figure 12 to Figure 14 It can be seen that the optical imaging systems provided in Examples 4, 5 and 6 can achieve good imaging quality.

[0129] Example 7

[0130] The following reference Figure 2 and Fig.15 The optical imaging system according to Embodiment 7 of the present application is described. The aperture STO and the image plane IMA are not Fig.15 Shown in.

[0131] like Fig.15 As shown, the optical imaging system may include a lens barrel P0 and an imaging group and a second spacing element P2 assembled in the lens barrel P0. The imaging group includes a linear polarization film LP, a reflective polarization element RP, a quarter wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4 and a partial reflection layer BS arranged in sequence from the first side to the second side along the optical axis. The aperture STO is arranged between the first side and the linear polarization film LP (as shown in FIG. Figure 2 ).

[0132] The first lens E1 has positive focal power, and its first side surface S1 is a plane, and the second side surface S2 is a concave surface. The second lens E2 has negative focal power, and its first side surface S3 is a concave surface, and the second side surface S4 is a convex surface. The third lens E3 has negative focal power, and its first side surface S5 is a convex surface, and the second side surface S6 is a concave surface. The fourth lens E4 has positive focal power, and its first side surface S7 is a convex surface, and the second side surface S8 is a convex surface. The linear polarization film LP, the reflective polarizing element RP and the quarter wave plate QWP are attached to the first side surface S1 of the first lens E1. The partial reflection layer BS is attached to the second side surface S8 of the fourth lens E4.

[0133] In this example, an image plane IMA may be provided on the second side of the optical imaging system. The image plane IMA may be provided with a display screen, for example. The light from the image plane IMA sequentially passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, and the quarter-wave plate QWP, reaches the reflective polarizing element RP, and then reflects at the reflective polarizing element RP to form the first reflected image light. The first reflected image light sequentially passes through the quarter-wave plate QWP, the first lens E1, the second lens E2, the third lens E3, and the fourth lens E4 and reaches the partial reflective layer BS on the second side of the fourth lens, and then reflects at the partial reflective layer BS to form the second reflected image light. The second reflected image light sequentially passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter-wave plate QWP, the reflective polarizing element RP, the linear polarizing film LP to the aperture STO and is finally projected to the human eye. For example, the light of the optical imaging system after two reflections is finally projected to the human eye.

[0134] Table 7 shows a basic parameter table of the optical imaging system of Example 7, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0135]

[0136] Table 7

[0137] In this embodiment, the effective focal length f2 of the second lens is -108.19 mm, and the combined focal length f34 of the third lens and the fourth lens is 121.26 mm.

[0138] The object side surface and the image side surface of any one of the first side surface S3 and the second side surface S4 of the second lens E2 and the first side surface S7 of the fourth lens E4 are aspherical surfaces. Table 8 shows the cone coefficient k and the high-order coefficients A4, A6, A8, A10, A12 and A14 that can be used for each aspherical surface S2-S8 in Example 7.

[0139] Face number k A4 A6 A8 A10 A12 A14 S2 / S3 0.7257 5.62E-05 -4.53E-07 5.96E-10 3.15E-12 -6.16E-15 0.00E+00 S4 41.4690 7.82E-06 -7.88E-08 2.61E-10 7.82E-14 -2.42E-16 -5.28E-19 S5 -77.9981 -6.13E-06 -7.20E-09 1.71E-10 -3.12E-13 0.00E+00 0.00E+00 S6 / S7 -95.7107 6.09E-06 -1.00E-07 1.78E-10 0.00E+00 0.00E+00 0.00E+00 S8 -29.8556 -7.89E-06 9.21E-09 3.55E-11 -9.09E-14 0.00E+00 0.00E+00

[0140] Table 8

[0141] Example 8

[0142] The following reference Figure 2 and Fig.16 The optical imaging system according to Embodiment 8 of the present application is described. In which the aperture STO and the image plane IMA are not Fig.16 Shown in.

[0143] like Fig.16As shown, the optical imaging system may include a lens barrel P0 and an imaging group and a second spacing element P2 assembled in the lens barrel P0. The imaging group includes a linear polarization film LP, a reflective polarization element RP, a quarter wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4 and a partial reflection layer BS arranged in sequence from the first side to the second side along the optical axis. The aperture STO is arranged between the first side and the linear polarization film LP (as shown in FIG. Figure 2 ).

[0144] The structure of the imaging group of this embodiment is the same as that of the imaging group of Embodiment 7, that is, the basic parameter table of the optical imaging system of this embodiment is the same as Table 7, and the aspheric coefficient table is the same as Table 8. The difference between this embodiment and Embodiment 7 is that the parameters such as the structural dimensions of the lens barrel P0 and the second spacing element P2 are different. The values ​​of multiple parameters of the lens barrel P0 and the second spacing element P2 included in the optical imaging system of this embodiment and Embodiment 7 are shown in Table 9 below.

[0145] Example 9

[0146] The following reference Figure 2 and Fig.17 The optical imaging system according to Embodiment 9 of the present application is described. In which the aperture STO and the image plane IMA are not Fig.17 Shown in.

[0147] like Fig.17 As shown, the optical imaging system may include a lens barrel P0 and an imaging group and a second spacing element P2 assembled in the lens barrel P0. The imaging group includes a linear polarization film LP, a reflective polarization element RP, a quarter wave plate QWP, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4 and a partial reflection layer BS arranged in sequence from the first side to the second side along the optical axis. The aperture STO is arranged between the first side and the linear polarization film LP (as shown in FIG. Figure 2 ).

[0148] The structure of the imaging group of this embodiment is the same as that of the imaging group of Embodiment 7, that is, the basic parameter table of the optical imaging system of this embodiment is the same as Table 7, and the aspheric coefficient table is the same as Table 8. The difference between this embodiment and Embodiment 7 is that the parameters such as the structural dimensions of the lens barrel P0 and the second spacing element P2 are different. The values ​​of multiple parameters of the lens barrel P0 and the second spacing element P2 included in the optical imaging system of this embodiment and Embodiment 7 are shown in Table 9 below.

[0149] Fig.18 The axial chromatic aberration curves of the optical imaging systems of Examples 7, 8 and 9 are shown, which represent the deviation of the focal point of light of different wavelengths after passing through the optical imaging system. Fig.19The astigmatism curves of the optical imaging systems of Examples 7, 8 and 9 are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different half field angles. Fig. 20 The distortion curves of the optical imaging systems of Examples 7, 8 and 9 are shown, which represent the distortion magnitude values ​​corresponding to different half-viewing angles. Figures 18 to 20 It can be seen that the optical imaging systems provided in Examples 7, 8 and 9 can achieve good imaging quality.

[0150] Table 9 shows the values ​​of d2s, d2m, D2s, D2m, d0m, D0m, EP02, CP2 and L parameters of each embodiment in Examples 1 to 9. At least some of the above parameters can be measured according to the marking method shown in the figure, and the units of the parameters listed in Table 9 are all mm.

[0151] Parameters\Example 1 2 3 4 5 6 7 8 9 d2s 35.196 39.009 37.587 37.726 38.499 37.726 39.151 39.151 38.574 d2m 41.042 41.042 40.882 41.601 41.010 41.284 41.038 41.038 41.038 D2s 41.060 40.731 41.060 41.532 41.532 41.532 43.108 43.108 42.230 D2m 41.788 41.788 41.629 43.010 43.010 42.827 43.285 43.285 42.835 d0m 45.295 45.296 45.089 46.045 46.043 46.041 45.507 45.506 45.503 D0m 47.586 47.586 47.147 48.332 48.332 48.332 47.797 47.797 47.797 EP02 6.105 5.518 6.105 7.502 7.502 7.502 6.847 6.847 6.847 CP2 3.454 3.822 3.454 2.675 2.675 2.675 2.903 2.903 2.903 L 14.090 13.871 13.140 13.618 13.033 13.618 14.849 13.911 14.849

[0152] Table 9

[0153] Table 10 shows the values ​​of the conditional expressions of each of Examples 1 to 9.

[0154] Conditional / Example 1 2 3 4 5 6 7 8 9 (CP2+EP02) / T23 4.57 4.46 4.57 6.78 6.78 6.78 7.72 7.72 7.72 R4 / (D2s×N2) -2.07 -2.09 -2.07 -2.78 -2.78 -2.78 -1.80 -1.80 -1.83 D0m-D2m 5.80 5.80 5.52 5.32 5.32 5.51 4.51 4.51 4.96 (CT3+CT4) / (L-EP02) 0.75 0.72 0.85 1.26 1.40 1.26 0.83 0.94 0.83 (d2m-d2s) / T23 2.79 0.97 1.57 2.58 1.67 2.37 1.49 1.49 1.95 R5 / d2m 4.45 4.45 4.47 5.38 5.45 5.42 4.45 4.45 4.45 f2 / EP02 -19.42 -21.49 -19.42 -25.74 -25.74 -25.74 -15.80 -15.80 -15.80 R2 / d2s -1.37 -1.24 -1.29 -2.00 -1.96 -2.00 -1.15 -1.15 -1.17 R6 / d0m 0.88 0.88 0.88 1.24 1.24 1.24 1.27 1.27 1.27 L / (CT1+CT2) 3.13 3.08 2.92 3.89 3.72 3.89 2.70 2.53 2.70 f34 / D0m 2.67 2.67 2.69 1.57 1.57 1.57 2.54 2.54 2.54

[0155] Table 10

[0156] The present application also provides an optical device, which may be an independent projection device such as a projector, or a projection module integrated in a mobile electronic device such as a virtual reality device. The optical device is equipped with the optical imaging system described above.

[0157] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of application involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the concept of the application. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other to form a technical solution.

Claims

1. An optical imaging system, characterized in that: include: An imaging group, comprising a linear polarization film, a reflective polarizing element, a quarter wave plate, a first lens, a second lens, a third lens, a fourth lens and a partial reflection layer in sequence from the first side to the second side along the optical axis; wherein the first lens and the second lens are glued together, and the third lens and the fourth lens are glued together; a second spacing element disposed on a second side surface of the second lens and in contact with the second side surface of the second lens; and a lens barrel, wherein the imaging group and the second spacing element are disposed in the lens barrel; Wherein, the number of lenses having optical power in the optical imaging system is four; The outer diameter D0m of the second side end surface of the lens barrel and the outer diameter D2m of the second side surface of the second spacing element satisfy the following conditions: 4.51 mm ≤ D0m - D2m ≤ 5.8 mm; An inner diameter d2m of the second side surface of the second spacing element, an inner diameter d2s of the first side surface of the second spacing element, and an axial distance T23 from the second side surface of the second lens to the first side surface of the third lens satisfy: 0.97≤(d2m-d2s) / T23≤2.

79.

2. The optical imaging system according to claim 1, characterized in that: The curvature radius R4 of the second side surface of the second lens, the outer diameter D2s of the first side surface of the second spacer element and the refractive index N2 of the second lens satisfy: -2.78≤R4 / (D2s×N2)≤-1.

8.

3. The optical imaging system according to claim 1, characterized in that: The maximum thickness CP2 of the second spacer element, the distance EP02 between the first side end surface of the lens barrel and the second spacer element along the optical axis, and the axial distance T23 from the second side surface of the second lens to the first side surface of the third lens satisfy: 4.46≤(CP2+EP02) / T23≤7.

72.

4. The optical imaging system according to claim 1, characterized in that: The center thickness CT3 of the third lens on the optical axis, the center thickness CT4 of the fourth lens on the optical axis, the distance L between the first side end surface of the lens barrel and the second side end surface of the lens barrel along the optical axis, and the distance EP02 between the first side end surface of the lens barrel and the second spacing element along the optical axis satisfy: 0.72≤(CT3+CT4) / (L-EP02)≤1.

4.

5. The optical imaging system according to claim 1, characterized in that: A curvature radius R5 of the first side surface of the third lens and an inner diameter d2m of the second side surface of the second spacing element satisfy: 4.45≤R5 / d2m≤5.

45.

6. The optical imaging system according to claim 1, characterized in that: The effective focal length f2 of the second lens and the distance EP02 between the first side end surface of the lens barrel and the second spacing element along the optical axis satisfy: -25.74≤f2 / EP02≤-15.

8.

7. The optical imaging system according to claim 1, characterized in that: A curvature radius R2 of the second side surface of the first lens and an inner diameter d2s of the first side surface of the second spacer element satisfy: -2.00≤R2 / d2s≤-1.

15.

8. The optical imaging system according to any one of claims 1 to 7, characterized in that: A curvature radius R6 of the second side surface of the third lens and an inner diameter d0m of the second side end surface of the lens barrel satisfy the following: 0.88≤R6 / d0m≤1.

27.

9. The optical imaging system according to any one of claims 1 to 7, characterized in that: The distance L between the first side end surface of the lens barrel and the second side end surface of the lens barrel along the optical axis, the center thickness CT1 of the first lens on the optical axis, and the center thickness CT2 of the second lens on the optical axis satisfy: 2.53≤L / (CT1+CT2)≤3.

89.

10. The optical imaging system according to any one of claims 1 to 7, characterized in that: A combined focal length f34 of the third lens and the fourth lens and an outer diameter D0m of the second side end surface of the lens barrel satisfy the following: 1.57≤f34 / D0m≤2.

69.

11. The optical imaging system according to any one of claims 1 to 7, characterized in that: The first lens has positive or negative optical power, a first side surface of the first lens is a concave surface or a flat surface, and a second side surface is a convex surface; The second lens has negative optical power, and the second side surface thereof is a convex surface; The third lens has negative optical power, a first side surface of the third lens is convex, and a second side surface of the third lens is concave; The fourth lens has positive optical power, and its first side surface is convex, and its second side surface is convex.

Images