Optical image capturing system

Abstract

The utility model 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, in particular to an optical imaging system. BACKGROUND

[0002] With the proposal of the concept of the meta-universe, people have higher requirements for the optical imaging system of virtual reality devices or augmented reality devices. The optical imaging system is mainly divided into three types: optical system using aspherical lens, optical system using Fresnel lens, and catadioptric optical system. Among them, the catadioptric optical system is a major innovation of the optical imaging system itself, and leaves space for the overall design of the virtual reality device or augmented reality device, and has become the mainstream trend of research and development.

[0003] The catadioptric optical system shortens the length of the optical imaging system by light path folding, so as to move the center of gravity of the virtual reality device or augmented reality device backward and improve the experience of the user. However, the existing catadioptric optical system usually adopts two lenses, which will cause the catadioptric optical system to have a more serious ghost image. UTILITY MODEL CONTENT

[0004] The present application provides an optical imaging system, which includes a lens barrel and an imaging group and a second spacing element arranged in the lens barrel. The imaging group includes, in order from a first side to a second side along an optical axis, a linear polarizer 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. The first lens and the second lens are cemented, and the third lens and the fourth lens are cemented. The second spacing element is arranged on the second side of the second lens and in contact with the second side of the second lens. The number of lenses with 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: 4.51mm≤D0m-D2m≤5.8mm. 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 of the second lens to the first side of the third lens satisfy: 0.97≤(d2m-d2s) / T23≤2.79.

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

[0006] According to one exemplary embodiment of the present application, the maximum thickness CP2 of the second spacer element, the distance EP02 of 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 one exemplary embodiment of the present application, the central thickness CT3 of the third lens on the optical axis, the central thickness CT4 of the fourth lens on the optical axis, the distance L of 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 of the first side end surface of the lens barrel and the second spacer element along the optical axis satisfy: 0.72 ≤ (CT3 + CT4) / (L - EP02) ≤ 1.4.

[0008] According to one exemplary embodiment of the present application, 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 spacer element satisfy: 4.45 ≤ R5 / d2m ≤ 5.45.

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

[0010] According to one exemplary embodiment of the present application, 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.

[0011] According to one exemplary embodiment of the present application, 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.

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

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

[0014] According to an example embodiment of the present application, the first lens has positive or negative focal power, the first side thereof is concave or flat, and the second side thereof is convex. The second lens has negative focal power, and the second side thereof is convex. The third lens has negative focal power, the first side thereof is convex, and the second side thereof is concave. The fourth lens has positive focal power, the first side thereof is convex, and the second side thereof 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 surface of the lens barrel and the outer diameter of the second side surface of the second spacer element, the ghost image of the optical imaging system can be reduced. However, in this case, the center thickness of the second lens is limited, thereby 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 amount 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 DRAWINGS

[0016] Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting examples made with reference to the accompanying drawings. In which:

[0017] Figure 1 A parameter annotation diagram of the optical imaging system according to the present application is shown;

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

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

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

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

[0022] Figure 6 、 Figure 7 、 Figure 8 Axial chromatic aberration curves, astigmatism curves, and distortion curves of the optical imaging systems according to the present application are shown;

[0023] Figure 9 A structure schematic diagram of the optical imaging system according to the present application is shown;

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

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

[0026] Figure 12 Figure 13 Figure 14 Axial chromatic aberration curves, astigmatism curves, and distortion curves of the optical imaging systems according to Embodiments 4, 5, and 6 of the present application are shown;

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

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

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

[0030] Figure 18 Figure 19 Figure 20 Axial chromatic aberration curves, astigmatism curves, and distortion curves of the optical imaging systems according to Embodiments 7, 8, and 9 of the present application are shown. DETAILED DESCRIPTION

[0031] For a better understanding of the present application, various aspects of the present application will be described in greater detail below with reference to the accompanying drawings. It is to be understood that the detailed description is merely descriptive of exemplary embodiments of the present application and is not intended, in any way, to limit the scope of the present application. Throughout the specification, like reference numerals refer to like elements. The expression “and / or” includes any and all combinations of one or more of the associated listed items.

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

[0033] In the drawings, the thickness, size, and shape of lenses have been slightly exaggerated for ease 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. ​​​​

[0034] In this document, 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 (for example, the side of the human eye) is referred to as the first side surface of the lens, and the surface of each lens closest to the second side (for example, the side of the display screen) is referred to as the second side surface of the lens.

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

[0036] It should also be understood that the words “comprise” and / or “have”, when used in this specification, indicate the existence 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 their combinations. In addition, when describing the embodiments of the present application, the word “may” means “one or more embodiments of the present application”. And the word “exemplary” is intended to refer to an example or illustration.

[0037] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that the terms (for example, terms defined in commonly used dictionaries) should be interpreted as having a meaning that is consistent with their meaning in the context of 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 accompanying drawings and in combination with the embodiments.

[0039] Figure 1 The parameter labeling diagram according to the exemplary embodiments of the present application. Referring to Figure 1, d0s represents an inner diameter of the first side end surface of the lens barrel, D0s represents an outer diameter of the first side end surface of the lens barrel, d0m represents an inner diameter of the second side end surface of the lens barrel, D0m represents an outer diameter of the second side end surface of the lens barrel, d2m represents an inner diameter of the second side surface of the second spacer element, D2m represents an outer diameter of the second side surface of the second spacer element, d2s represents an inner diameter of the first side surface of the second spacer element, D2s represents an outer diameter of the first side surface of the second spacer element, CP2 represents a maximum thickness of the second spacer element, EP02 represents a distance along the optical axis from the first side end surface of the lens barrel to the second spacer element, and L represents a distance along the optical axis from the first side end surface of the lens barrel to the second side end surface of the lens barrel.

[0040] The first aspect of the present application provides such an optical imaging system, which can include an imaging group. The imaging group can include, in order from a first side to a second side along an optical axis, a linear polarizing film, a reflective polarizing element, a quarter-wave plate, a first lens, a second lens, a third lens, a fourth lens, and a partially reflective layer. The optical imaging system has a number of lenses with optical power of four. The catadioptric of the light path can be achieved by using the reflective polarizing element, the quarter-wave plate, and the partially reflective layer, effectively shortening the body length of the optical imaging system, reducing the volume and weight of the optical imaging system, and realizing the lightweight of the optical imaging system.

[0041] In an example 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 example embodiment, the first lens can have a positive optical power or a negative optical power. The second lens can have a negative optical power. The third lens can have a negative optical power. The fourth lens can have a positive optical power.

[0043] In an example embodiment, the first side surface of the first lens can be a concave surface or a plane, and the second side surface can be a convex surface. The first side surface of the first lens is provided as a concave surface, which can increase the maximum field angle of the optical imaging system, thereby increasing the field range of the optical imaging system.

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

[0045] In an example embodiment, the first side surface of the third lens can be a convex surface, and the second side surface can be a concave surface.

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

[0047] In an example embodiment, the linear polarizing film can be disposed on and at least partially conform to the first side of the reflective polarizing element. The reflective polarizing element can be disposed on and at least partially conform to the first side of the quarter-wave plate. The quarter-wave plate can be disposed on and at least partially conform to the first side of the first lens.

[0048] In an example embodiment, the partially reflective layer can be disposed on and at least partially conform to the second side of the fourth lens. The partially reflective layer can have a semi-transmissive and semi-reflective effect on light rays. By setting the partially reflective layer on the second side of the fourth lens, in combination with the reflective polarizing element and the quarter-wave plate, the light rays can be folded and reflected multiple times, effectively reducing the length of the optical imaging system.

[0049] In an example embodiment, the optical imaging system can further include a stop, which can be disposed on the first side of the first lens. As an example, the stop can be, for example, the eye pupil of a user. The image light from the second side passes through the partially reflective 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, and the like multiple times, and is finally projected to the eye of the user on the first side.

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

[0051] In the example embodiment, the second side of the optical imaging system can be provided with an image plane. The image plane can be provided with a display screen. Light from the display screen passes through the fourth lens, the third lens, the second lens, the first lens, the quarter wave plate, reaches the reflective polarizer, and is reflected at the reflective polarizer to form first reflected image light. The first reflected image light passes through the quarter wave plate, the first lens, the second lens, the third lens, the fourth lens, reaches the partially reflective layer of the second side of the fourth lens, and is reflected at the partially reflective layer to form second reflected image light. The second reflected image light passes through the fourth lens, the third lens, the second lens, the first lens, the quarter wave plate, the reflective polarizer, the linear polarizer film, reaches the aperture, and is finally projected to the human eye. The optical imaging system provided in the present application effectively shortens the length of the optical imaging system by folding the required optical path in a combination of light reflection and refraction without affecting the projection quality.

[0052] In the example embodiment, the optical imaging system can further include a second spacer element. The second spacer element can be disposed on the second side of the second lens and at least partially in contact with the second side of the second lens. Reasonable use of the spacer element can effectively avoid stray light risk, reduce interference with image quality, and thus improve the imaging quality of the optical imaging system.

[0053] In the example embodiment, the optical imaging system can further include a lens barrel. The imaging group and the second spacer element are disposed 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 the example embodiment, the outer peripheral surface of at least one lens in the imaging group can have a cut edge portion and a non-cut edge portion, and the outer diameter of the cut edge portion of the lens can be smaller than the outer diameter of the non-cut edge portion of the lens. When the outer peripheral surface of the lens has a cut edge portion, the outer diameter of the lens generally refers to the outer diameter of the non-cut edge portion of the lens. For example, the outer diameter of the first side of the lens refers to the outer diameter of the portion of the non-cut edge portion of the lens closest to the first side, and the outer diameter of the second side of the lens refers to the outer diameter of the portion of the non-cut edge portion of the lens closest to the second side.

[0055] In the example embodiment, the outer peripheral surface of the second spacer element can have a cut edge portion and a non-cut edge portion, and the outer diameter of the cut edge portion of the second spacer element can be smaller than the outer diameter of the non-cut edge portion of the second spacer element. When the outer peripheral surface of the second spacer element has a cut edge portion, the outer diameter of the second spacer element generally refers to the outer diameter of the non-cut edge portion of the second spacer element. For example, the outer diameter of the first side of the second spacer element refers to the outer diameter of the portion of the non-cut edge portion of the second spacer element closest to the first side, and the outer diameter of the second side of the second spacer element refers to the outer diameter of the portion of the non-cut edge portion of the second spacer element closest to the second side.

[0056] In the example embodiment, 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 spacer element satisfy: 4.51 mm≤D0m-D2m≤5.8 mm; the inner diameter d2m of the second side surface of the second spacer element, the inner diameter d2s of the first side surface of the second spacer element, 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: 0.97≤(d2m-d2s) / T23≤2.79. By controlling the difference range of the outer diameter of the second side end surface of the lens barrel and the outer diameter of the second side surface of the second spacer element, the ghost image of the optical imaging system can be reduced, however, in this case, the center thickness of the second lens is limited, thereby leading to 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 T23 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 amount 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 structure sensitivity analysis table of the second side surface of the second lens. Table 2 is an optical sensitivity and comprehensive sensitivity analysis table of the second side surface of the second lens. In Table 1, surface S4 is the second side surface of the second lens, and ΔS4PV (i.e., structure sensitivity) is the surface profile variation of the second side surface of the second lens. Under the action of stress, the center point and the edge point of the second side surface of the second lens will be offset, thereby causing the surface profile PV of the second side surface of the second lens to change. The smaller the absolute value of ΔS4PV is, the smaller the surface profile variation of the second side surface of the second lens is, and the better the structure sensitivity of the second side surface of the second lens is. The center point and the edge point of the second side surface of the second lens can refer to the center point and the edge point of the second side surface of the second lens in the example embodiment.

[0058] In Table 1, surface S4 is the second side surface of the second lens, and ΔS4PV (i.e., structure sensitivity) is the surface profile variation of the second side surface of the second lens. Under the action of stress, the center point and the edge point of the second side surface of the second lens will be offset, thereby causing the surface profile PV of the second side surface of the second lens to change. The smaller the absolute value of ΔS4PV is, the smaller the surface profile variation of the second side surface of the second lens is, and the better the structure sensitivity of the second side surface of the second lens is. The center point and the edge point of the second side surface of the second lens can refer to the center point and the edge point of the second side surface of the second lens in the example embodiment. Figure 1 .

[0059] In Table 2, the S-direction peak can be the S-curve peak of the MTF curve at a 0.4 field of view, and the M-direction peak can be the M-curve peak of the MTF curve at a 0.4 field of view. "S" represents the sagittal curve, and "M" represents the meridional curve. When the ΔS4PV changes, the S-direction peak and / or the M-direction peak will change accordingly. The amount of change in the S-direction peak and / or the M-direction peak can be the optical sensitivity. The overall sensitivity can 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 overall sensitivity, the better the overall sensitivity. MTF stands for Modulation Transfer Function.

[0060]

[0061]

[0062] Table 1

[0063]

[0064] Table 2

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

[0066] Optical sensitivity indicates the change in the lens's MTF peak value for a given change in surface shape. Lenses 1, 2, and 3 all have the same surface shape change. For example, referring to Table 2, simulations show that when ΔS4PV increases by 1μm, the changes in the 0.4-field MTF peak values ​​for Lenses 1, 2, and 3 in the S direction are -0.46%, -0.66%, and -0.91%, respectively, and in the M direction are -0.38%, -0.83%, and -0.61%, respectively. When ΔS4PV decreases by 1μm, the changes in the 0.4-field MTF peak values ​​for Lenses 1, 2, and 3 in the S direction are 0.95%, 0.46%, and 0.63%, respectively, and in the M direction are 0.81%, 0.49%, and 0.47%, respectively. This indicates that Lens 1's MTF peak value is less affected by surface shape change, indicating that Lens 1 has superior optical sensitivity.

[0067] Comprehensive sensitivity indicates the effect of surface shape variation on the lens's MTF peak. For example, referring to Table 2, the comprehensive sensitivities in the S direction for Lenses 1, 2, and 3 are -0.00865μm, -0.517μm, and -0.173μm, respectively, and in the M direction are -0.00714μm, -0.650μm, and -0.116μm, respectively. This indicates that Lens 1 experiences minimal surface shape variation, and its effect on the MTF peak is minimal. Consequently, Lens 1 exhibits a low comprehensive sensitivity and exhibits superior assembly stability.

[0068] Based on the above analysis, it can be seen that by ensuring that the optical imaging system satisfies "0.97≤(d2m-d2s) / T23≤2.79", the second side surface of the second lens can be guaranteed to have a smaller surface profile variation, thereby reducing the structural sensitivity and optical sensitivity of the optical imaging system, thereby reducing the overall sensitivity of the optical imaging system and improving the assembly stability of the optical imaging system.

[0069] In an exemplary embodiment, the radius of curvature 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 the following equation: -2.78 ≤ R4 / (D2s × N2) ≤ -1.8. By controlling this conditional equation, the focal length of the second lens can be constrained within a certain range, thereby controlling the angle of incidence of light emitted from the second lens and reducing the angle of incidence of light on the display screen. Furthermore, the outer diameter of the first side surface of the second spacer element can be limited, improving the workability of the second spacer element.

[0070] In the example implementation, the maximum thickness CP2 of the second spacing element, the distance EP02 of the first side end surface of the lens barrel and the second spacing 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 the edge thickness of the second lens and the third lens can be constrained in a reasonable range, on the basis of ensuring that the second lens and the third lens have good processability, the assembly stability of the two groups of cemented lenses is improved; 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 also be limited, the field curvature is effectively corrected, and the imaging quality of the optical imaging system is improved.

[0071] In the example implementation, the center thickness CT3 of the third lens along the optical axis, the center thickness CT4 of the fourth lens along the optical axis, the distance L of 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 of 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. By controlling the above conditional expression, the thickness ratio of the third lens and the fourth lens can be constrained in a reasonable range, which is beneficial to the molding and cementing of the third lens and the fourth lens; at the same time, the distance of the first side end surface of the lens barrel and the second side end surface of the lens barrel along the optical axis can also be limited, the total length of the optical imaging system is reduced, the weight of the optical imaging system is reduced, the miniaturization of the optical imaging system is realized, and the wearing experience of the user is improved.

[0072] In the example implementation, 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. Reasonably configuring the ratio of the radius of curvature of the first side surface of the third lens and 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 degree of refraction of light by the second spacing element and the third lens can also be matched, in the case that the second spacing element intercepts non-effective light, the occlusion of effective light by the second spacing element is reduced as much as possible, the stray light is reduced, and the light efficiency of the optical imaging system is improved.

[0073] In the example implementation, the effective focal length f2 of the second lens and the distance EP02 of 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. By controlling the above conditional expression, the power of the second lens can be reasonably distributed, 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, and the aberration of the optical imaging system is ensured to be at a reasonable level; meanwhile, the maximum thickness of the second spacing element can also be limited, so that the second spacing element and the lens adjacent thereto are stably supported, and the assembly stability and assembly yield of the optical imaging system are improved.

[0074] In the example implementation, the curvature radius R2 of the second side surface of the first lens and the inner diameter d2s of the first side surface of the second spacing 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 conducive to reducing the sensitivity of the first lens and improving the assembly yield of the first lens; meanwhile, the degree of refraction of light by the second spacing element and the first lens can be matched, and in the case that the second spacing element intercepts the non-effective light, the obstruction of the effective light by the second spacing element is reduced as much as possible, the stray light is reduced, and the light efficiency of the optical imaging system is improved.

[0075] In the example implementation, the curvature radius 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; meanwhile, the degree of refraction of light by the lens barrel and the third lens can be matched, and in the case that the lens barrel intercepts the non-effective light, the obstruction of the effective light by the lens barrel is reduced as much as possible, the stray light is reduced, and the light efficiency of the optical imaging system is improved, in addition, it is also conducive to the molding of the lens barrel and the assembly feasibility of the third lens.

[0076] In the example implementation, the distance L of the first side end surface of the lens barrel and the second side end surface of the lens barrel along the optical axis, the central thickness CT1 of the first lens on the optical axis, and the central 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 of 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 central thicknesses of the first lens and the second lens within a certain range, the optical total length of the optical imaging system can be reduced, and miniaturization of the optical imaging system can be realized.

[0077] In the example 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 condition formula, 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 cementing 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 also be limited, which ensures that it plays a limiting role on the fourth lens while improving the processability of the lens barrel.

[0078] The optical imaging system according to the above embodiment of the present application can adopt multiple lenses, for example, the four lenses described above. By reasonably allocating the parameters of the linear polarizing film, the reflective polarizing element, the quarter-wave plate, the partial reflection layer, the lenses, the lens barrel, and the second spacing element, the 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 in the above manner has the characteristics of miniaturization and good imaging quality, and can well meet the use requirements of various portable electronic products in the projection scene. The optical imaging system and the electronic device containing the optical imaging system have a rear gravity center, which improves the wearing experience of the user.

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

[0080] The second aspect of the present application provides an optical imaging system which can include a lens barrel and an imaging group assembled in the lens barrel. The imaging group can include, in order from a first side to a second side along an optical axis, a linear polarizing 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. The optical imaging system has a number of lenses with optical power of four.

[0081] The combined focal length f34 of the third and fourth lenses and the outer diameter D0m of the second side end surface of the lens barrel satisfy the following condition: 1.57≤f34 / D0m≤2.69. By controlling this conditional expression, the combined focal length of the third and fourth lenses can be constrained within a reasonable range, resulting in negative spherical aberration in the cemented lens formed by the third and fourth lenses, which balances the positive spherical aberration generated by the other lenses, thereby improving the imaging quality of the optical imaging system. Furthermore, the outer diameter of the second side end surface of the lens barrel can be limited, ensuring that it serves as a position limit for 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 will be 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 embodiment 1 of the present application is described. 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 optical power, with its first side surface S1 being flat and its second side surface S2 being convex. The second lens E2 has negative optical power, with its first side surface S3 being concave and its second side surface S4 being convex. The third lens E3 has negative optical power, with its first side surface S5 being convex and its second side surface S6 being concave. The fourth lens E4 has positive optical power, with its first side surface S7 being convex and its second side surface S8 being convex. A linear polarizing film LP, a reflective polarizer RP, and a quarter-wave plate QWP are attached to the first side surface S1 of the first lens E1. A partially reflective 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 imaging surface IMA (eg, Figure 2). The image plane IMA can be provided with a display screen, for example. Light from the image plane IMA passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter wave plate QWP in turn, reaches the reflective polarizing element RP, and then is reflected at the reflective polarizing element RP to form first reflected image light. The first reflected image light passes through the quarter wave plate QWP, the first lens E1, the second lens E2, the third lens E3, the fourth lens E4 in turn and reaches the partially reflective layer BS of the second side of the fourth lens, and then is reflected at the partially reflective layer BS to form second reflected image light. The second reflected image light 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 stop STO and finally projects to the human eye. For example, the light rays of the optical imaging system after two reflections finally project 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, thickness / distance are 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 and the image side of any one of the first lens E1, the second lens E2, the third lens E3 and the fourth lens E4 are aspherical surfaces. The surface type of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0094]

[0095] wherein x is the sag of the aspherical surface at a height h along the optical axis, c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the inverse of the radius of curvature R in Table 3 above), k is the conic coefficient, and Ai is the correction coefficient of the i-th order of the aspherical surface. Table 4 shows 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 S2-S8 in Example 1.

[0096]

[0097]

[0098] Table 4

[0099] Example 2

[0100] An optical imaging system according to Embodiment 2 of the present application is described below with reference to Figure 2 and Figure 4 An optical imaging system according to Embodiment 3 of the present application is described below with reference to Figure 4 and

[0101] As shown in Figure 4 , the optical imaging system can include a lens barrel P0 and an imaging group and a second spacer element P2 assembled in the lens barrel P0. The imaging group includes, in order from a first side to a second side along an optical axis, a linear polarizer film LP, a reflective polarizing 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 partially reflective layer BS. The stop STO is disposed between the first side and the linear polarizer film LP (as shown in Figure 2 ).

[0102] The structure of the imaging group of this embodiment is the same as that of the imaging group of Embodiment 1, i.e., the basic parameter table of the optical imaging system of this embodiment is the same as Table 3, and the aspherical coefficient table is the same as Table 4. The difference between this embodiment and Embodiment 1 is that the structure size and other parameters of the lens barrel P0 and the second spacer element P2 are different. The values of the parameters of the lens barrel P0 and the second spacer element P2 included in the optical imaging system of this embodiment and Embodiment 1 are shown in Table 9 below.

[0103] Embodiment 3

[0104] An optical imaging system according to Embodiment 3 of the present application is described below with reference to Figure 2 and Figure 5 An optical imaging system according to Embodiment 3 of the present application is described below with reference to Figure 5 and

[0105] As shown in Figure 5 , the optical imaging system can include a lens barrel P0 and an imaging group and a second spacer element P2 assembled in the lens barrel P0. The imaging group includes, in order from a first side to a second side along an optical axis, a linear polarizer film LP, a reflective polarizing 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 partially reflective layer BS. The stop STO is disposed between the first side and the linear polarizer film LP (as shown in Figure 2 ).

[0106] The structure of the imaging system of this embodiment is identical to that of Example 1. Specifically, the basic parameter table of the optical imaging system of this embodiment is identical to Table 3, and the aspheric coefficient table is identical to Table 4. This embodiment differs from Example 1 in parameters such as the structural dimensions of the lens barrel P0 and the second spacer element P2. The numerical values ​​of various parameters of the lens barrel P0 and the second spacer element P2 included in the optical imaging systems of this embodiment and Example 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 values ​​corresponding to different half-field angles. Figure 6 to Figure 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 Figure 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 Figure 9 Shown in.

[0110] like Figure 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, with its first side surface S1 being concave and its second side surface S2 being convex. The second lens E2 has negative optical power, with its first side surface S3 being concave and its second side surface S4 being convex. The third lens E3 has negative optical power, with its first side surface S5 being convex and its second side surface S6 being concave. The fourth lens E4 has positive optical power, with its first side surface S7 being convex and its second side surface S8 being convex. A linear polarizing film LP, a reflective polarizer RP, and a quarter-wave plate QWP are attached to the first side surface S1 of the first lens E1. A partially reflective 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 imaging 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 passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter-wave plate QWP in sequence, reaches the reflective polarizer RP, and is then reflected at the reflective polarizer RP to form a first reflected image light. The first reflected image light passes through the quarter-wave plate QWP, the first lens E1, the second lens E2, the third lens E3, the fourth lens E4 in sequence and reaches the partial reflective layer BS on the second side of the fourth lens, and is then reflected at the partial reflective layer BS to form a second reflected image light. The second reflected image light 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 polarizer 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 the basic parameters of the optical imaging system of Example 4, wherein the units of curvature radius 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 of 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 conic coefficient k and the higher-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 Figure 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 Figure 10 Shown in.

[0122] like Figure 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 system of this embodiment is identical to that of Example 4. Specifically, the basic parameter table of the optical imaging system of this embodiment is identical to Table 5, and the aspheric coefficient table is identical to Table 6. This embodiment differs from Example 4 in parameters such as the structural dimensions of the lens barrel P0 and the second spacer element P2. The numerical values ​​of various parameters of the lens barrel P0 and the second spacer element P2 included in the optical imaging systems of this embodiment and Example 4 are shown in Table 9 below.

[0124] Example 6

[0125] The following reference Figure 2 and Figure 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 Figure 11 Shown in.

[0126] like Figure 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 system of this embodiment is identical to that of Example 4. Specifically, the basic parameter table of the optical imaging system of this embodiment is identical to Table 5, and the aspheric coefficient table is identical to Table 6. This embodiment differs from Example 4 in parameters such as the structural dimensions of the lens barrel P0 and the second spacer element P2. The numerical values ​​of various parameters of the lens barrel P0 and the second spacer element P2 included in the optical imaging systems of this embodiment and Example 4 are shown in Table 9 below.

[0128] Figure 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. Figure 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. Figure 14 The distortion curves of the optical imaging systems of Examples 4, 5 and 6 are shown, which represent the distortion values ​​corresponding to different half-field 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 Figure 15 The optical imaging system according to embodiment 7 of the present application is described. In which, the aperture STO and the image plane IMA are not Figure 15 Shown in.

[0131] like Figure 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 optical power, with its first side surface S1 being flat and its second side surface S2 being concave. The second lens E2 has negative optical power, with its first side surface S3 being concave and its second side surface S4 being convex. The third lens E3 has negative optical power, with its first side surface S5 being convex and its second side surface S6 being concave. The fourth lens E4 has positive optical power, with its first side surface S7 being convex and its second side surface S8 being convex. A linear polarizing film LP, a reflective polarizer RP, and a quarter-wave plate QWP are attached to the first side surface S1 of the first lens E1. A partially reflective layer BS is attached to the second side surface S8 of the fourth lens E4.

[0133] In the present example, the second side of the optical imaging system can be provided with an image surface IMA. The image surface IMA can be provided with a display screen for example. Light from the image surface IMA passes through the fourth lens E4, the third lens E3, the second lens E2, the first lens E1, the quarter wave plate QWP in turn, reaches the reflective polarizing element RP, and is reflected at the reflective polarizing element RP to form the first reflected image light. The first reflected image light passes through the quarter wave plate QWP, the first lens E1, the second lens E2, the third lens E3, the fourth lens E4 in turn and reaches the partially reflective layer BS of the second side surface of the fourth lens, and is reflected at the partially reflective layer BS to form the second reflected image light. The second reflected image light 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 stop STO and is finally projected to the human eye. For example, the light rays of the optical imaging system after two reflections are finally projected to the human eye.

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

[0135]

[0136] Table 7

[0137] In the present example, 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 and the image side 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, and Table 8 gives the conic constant k and the high-order term coefficients A4, A6, A8, A10, A12 and A14 of the aspherical surfaces S2-S8 that can be used 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 optical imaging system according to Example 8 of the present application is described below with reference to Figure 2 and Figure 16 The optical imaging system according to Example 8 of the present application is described below with reference to Figure 16 .

[0143] As Figure 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 system of this embodiment is identical to that of Example 7. Specifically, the basic parameter table of the optical imaging system of this embodiment is identical to Table 7, and the aspheric coefficient table is identical to Table 8. This embodiment differs from Example 7 in parameters such as the structural dimensions of the lens barrel P0 and the second spacer element P2. The numerical values ​​of various parameters of the lens barrel P0 and the second spacer element P2 included in the optical imaging systems of this embodiment and Example 7 are shown in Table 9 below.

[0145] Example 9

[0146] The following reference Figure 2 and Figure 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 Figure 17 Shown in.

[0147] like Figure 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 system of this embodiment is identical to that of Example 7. Specifically, the basic parameter table of the optical imaging system of this embodiment is identical to Table 7, and the aspheric coefficient table is identical to Table 8. This embodiment differs from Example 7 in parameters such as the structural dimensions of the lens barrel P0 and the second spacer element P2. The numerical values ​​of various parameters of the lens barrel P0 and the second spacer element P2 included in the optical imaging systems of this embodiment and Example 7 are shown in Table 9 below.

[0149] Figure 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. Figure 19The astigmatism curves of the optical imaging systems of embodiments 7, 8 and 9 are shown, which represent the meridional image surface curvature and sagittal image surface curvature corresponding to different half field angles. Figure 20 The distortion curves of the optical imaging systems of embodiments 7, 8 and 9 are shown, which represent the distortion size values corresponding to different half field angles. According to Figure 18 to Figure 20 It can be seen that the optical imaging systems given by embodiments 7, 8 and 9 can achieve good imaging quality.

[0150] Table 9 shows the values of the d2s, d2m, D2s, D2m, d0m, D0m, EP02, CP2 and L parameters of each of embodiments 1-9. Wherein, at least part of the above parameters can be measured according to the labeling method shown in the figure, and the units of the parameters listed in Table 9 are mm.

[0151] Parameter\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 embodiments 1-9.

[0154] Conditional expression\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 can be a separate projection device such as a projector, or a projection module integrated on 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 merely preferred embodiments of the present application and a description of the principles of the technology used. Those skilled in the art should understand that the scope of the application involved in 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 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 disclosed in the present application (but not limited to) having similar functions to form technical solutions.

Claims

1. An optical imaging system, characterized in that include: An imaging group, comprising, in order from the first side to the second side along the optical axis, a linear polarizing film, a reflective polarizing element, a quarter-wave plate, a first lens, a second lens, a third lens, a fourth lens, and a partially reflective layer; wherein the first lens and the second lens are cemented together, and the third lens and the fourth lens are cemented together; a second spacer element disposed on and in contact with the second side surface of the second lens; and a lens barrel, wherein the imaging group and the second spacer 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: 4.51mm≤D0m-D2m≤5.8mm; An inner diameter d2m of the second side surface of the second spacer element, an inner diameter d2s of the first side surface of the second spacer 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, wherein: 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, wherein: 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.

4. The optical imaging system according to claim 1, wherein: 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 spacer element along the optical axis satisfy: 0.72≤(CT3+CT4) / (L-EP02)≤1.

4.

5. The optical imaging system according to claim 1, wherein: 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 spacer element satisfy the following: 4.45≤R5 / d2m≤5.

45.

6. The optical imaging system according to claim 1, wherein: 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 spacer element along the optical axis satisfy the following: -25.74≤f2 / EP02≤-15.

8.

7. The optical imaging system according to claim 1, wherein: 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 the following: -2.00≤R2 / d2s≤-1.

15.

8. The optical imaging system according to any one of claims 1 to 7, characterized in that: The curvature radius 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 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 concave or flat, and a second side surface is convex; The second lens has negative optical power, and the second side surface thereof is convex; 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.

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