Optical system

Abstract

The utility model discloses an optical system, the optical system comprises a lens barrel, and a lens group and a spacing element group which are arranged in the lens barrel, and the lens group sequentially comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with negative focal power and a fourth lens with negative focal power from an object side to an image side along an optical axis; the second lens has positive focal power; the third lens has positive focal power; the fourth lens has negative focal power; the spacing element group comprises a first spacing element and a second spacing element, the first spacing element is arranged on the image side of the first lens and at least partially contacts with the image side surface of the first lens, and the second spacing element is arranged on the image side of the second lens and at least partially contacts with the image side surface of the second lens; the center thickness CT2 of the second lens on the optical axis and the distance EP12 from the image side surface of the first spacing element to the object side surface of the second spacing element in the optical axis direction meet the following conditions: 1.40 lt; cT2 / EP12lt; 1.91, 1.91; the inner diameter d1s of the object side surface of the first spacing element and the inner diameter d2s of the object side surface of the second spacing element satisfy 1.8 lt; d1s / d2slt; 3.1.

Description

Technical Field

[0001] This application relates to the field of optical elements, and specifically, to an optical system. Background Art

[0002] For a four-piece lens, when meeting the requirement of ultra-wide angle, the air gap between the second lens and the third lens on the optical axis is usually the largest. The light passing through the front two lenses is likely to generate ghost images or stray light in the subsequent lenses. At the same time, if the size design of the spacer element between adjacent two lenses is unreasonable, it will also seriously affect the imaging quality of the lens. For example, if the inner diameter of the spacer element is too large, the interception of non-imaging light is insufficient, resulting in ghost images and stray light interference on the imaging surface; if the inner diameter of the spacer element is too small, it will intercept some imaging light, resulting in phenomena such as reduced imaging clarity, poor quality, and insufficient authenticity of the restored object.

[0003] Therefore, reasonably setting the spatial arrangement and related parameters of the lens and the spacer element is of great significance for the further development of the lens field while reducing the risk of ghost images and stray light and improving the clarity of the lens and the authenticity of the restored object. Summary of the Utility Model

[0004] The first aspect of this application provides such an optical system, which includes: a lens barrel and a lens group and a spacer element group placed in the lens barrel. Among them, the lens group includes, in sequence from the object side to the image side along the optical axis: a first lens with a negative optical power; a second lens with a positive optical power; a third lens with a positive optical power; and a fourth lens with a negative optical power; the spacer element group includes: a first spacer element and a second spacer element. The first spacer element is placed on the image side of the first lens and at least partially contacts the image side surface of the first lens. The second spacer element is placed on the image side of the second lens and at least partially contacts the image side surface of the second lens; there is an air gap on the optical axis between any two adjacent lenses among the first lens to the fourth lens, and the air gap T23 between the second lens and the third lens on the optical axis is the largest; the central thickness CT2 of the second lens on the optical axis and the distance EP12 from the image side surface of the first spacer element to the object side surface of the second spacer element along the optical axis satisfy: 1.40 < CT2 / EP12 < 1.91; the inner diameter d1s of the object side surface of the first spacer element and the inner diameter d2s of the object side surface of the second spacer element satisfy: 1.8 < d1s / d2s < 3.1; the number of lenses with optical power in the optical system is four.

[0005] In one embodiment, the spacer element group further includes: a third spacer element disposed on the image side of the third lens and at least partially contacting the image side surface of the third lens; the central thickness of the third lens on the optical axis is greater than the central thickness of the second lens on the optical axis; the optical system satisfies: 1.7 < f23 / EP23 < 4.1, where EP23 is the distance along the optical axis between the image side surface of the second spacer element and the object side surface of the third spacer element, and f23 is the combined focal length of the second lens and the third lens.

[0006] In one embodiment, the optical system satisfies: -10.3 < R1 / R2 < -9.9 and -2.3 < d1m / f1 < -1.8, where R1 is the radius of curvature of the object side surface of the first lens, R2 is the radius of curvature of the image side surface of the first lens, d1m is the inner diameter of the image side surface of the first spacer element, and f1 is the effective focal length of the first lens.

[0007] In one embodiment, the optical system satisfies: 3.6 < (d0s - d0m) / f < 4.8, where d0s is the inner diameter of the object side end face of the lens barrel, d0m is the inner diameter of the image side end face of the lens barrel, and f is the effective focal length of the optical system.

[0008] In one embodiment, the optical system satisfies: 1.1 < f2 / (D1m - D2s) < 2.7, where f2 is the effective focal length of the second lens, D1m is the outer diameter of the image side surface of the first spacer element, and D2s is the outer diameter of the object side surface of the second spacer element.

[0009] In one embodiment, the optical system satisfies: 1.5 < EP12 / (T23 - T12) < 2.1, where EP12 is the distance along the optical axis from the image side surface of the first spacer element to the object side surface of the second spacer element, T23 is the air gap between the second lens and the third lens on the optical axis, and T12 is the air gap between the first lens and the second lens on the optical axis.

[0010] In one embodiment, the optical system satisfies: 2.7 < V1 / V2 < 3.0 and 13.2 < (CT2 - CT1) / CP1 < 16.3, where V1 is the Abbe number of the first lens, V2 is the Abbe number of the second lens, CT1 is the central thickness of the first lens on the optical axis, CT2 is the central thickness of the second lens on the optical axis, and CP1 is the maximum thickness of the first spacer along the optical axis.

[0011] In one embodiment, the optical system satisfies: 2.6 < EP01 / EPD < 3.0, where EP01 is the distance along the optical axis from the object side end face of the lens barrel to the object side surface of the first spacer element, and EPD is the entrance pupil diameter of the optical system.

[0012] In one embodiment, the spacer element group includes: a third spacer element disposed on the image side of the third lens and at least partially contacting the image side surface of the third lens; the optical system satisfies: 1.1 < R5 / d2m < 3.3 and -3.9 < d3s / R6 < -2.8, where R5 is the radius of curvature of the object side surface of the third lens, R6 is the radius of curvature of the image side surface of the third lens, d2m is the inner diameter of the image side surface of the second spacer element, and d3s is the inner diameter of the object side surface of the third spacer element.

[0013] In one embodiment, the spacer element group further includes: an auxiliary spacer element disposed on the object side of the first lens and at least partially contacting the object side surface of the first lens; the optical system satisfies: 1.9 < EPa1 / CT1 < 2.4, where EPa1 is the distance along the optical axis from the image side surface of the auxiliary spacer element to the object side surface of the first spacer element, and CT1 is the central thickness of the first lens on the optical axis.

[0014] In one embodiment, the optical system satisfies: 0.7 < SAG21 / EP12 < 1.3, where SAG21 is the axial distance between the intersection of the object side surface of the second lens and the optical axis and the vertex of the effective radius of the object side surface of the second lens, and EP12 is the distance along the optical axis from the image side surface of the first spacer element to the object side surface of the second spacer element.

[0015] In one embodiment, the spacer element group includes: a third spacer element disposed on the image side of the third lens and at least partially contacting the image side surface of the third lens; the optical system satisfies: 0.5 < CP3 / T34 < 12.4, where CP3 is the maximum thickness of the third spacer element along the optical axis, and T34 is the air gap between the third lens and the fourth lens on the optical axis.

[0016] In one embodiment, the spacer element group further includes: an auxiliary spacer element and a third spacer element. The auxiliary spacer element is disposed on the object side of the first lens and at least partially contacts the object side surface of the first lens. The third spacer element is disposed on the image side of the third lens and at least partially contacts the image side surface of the third lens. The outer diameters of the object side surfaces and image side surfaces of the auxiliary spacer element, the first spacer element, the second spacer element, and the third spacer element are sequentially decreasing; the inner diameters of the object side surfaces and image side surfaces of the auxiliary spacer element, the first spacer element, and the second spacer element are sequentially decreasing.

[0017] In one embodiment, the object side surface of the first lens is concave, and the image side surface is concave; the object side surface of the second lens is convex, and the image side surface is concave; the object side surface of the third lens is convex, and the image side surface is convex; the object side surface of the fourth lens is convex, and the image side surface is concave.

[0018] The present application provides a four-lens optical system having an ultra-wide-angle feature. While ensuring that the air gap T23 between the second lens and the third lens on the optical axis is maximized, the CT2 / EP12 ratio is kept within a reasonable range, which can maintain the thickness ratio of the second lens within a reasonable range, facilitating the molding of the second lens. When the CT2 / EP12 ratio is less than 1.4, the lens is prone to molding problems such as weld marks. When the CT2 / EP12 ratio is greater than 1.91, the contact area between the structural portion of the lens and the lens barrel is too small. At the same time, the excessively thin edge thickness of the lens will also cause the surface shape of the effective diameter edge of the lens to change during assembly, affecting the imaging of the lens. While maintaining the above two conditions, light passing through the first lens element is likely to generate stray light in subsequent lenses. When d1s / d2s is controlled within a reasonable range, it can ensure that the first spacer element blocks the stray light incident from the first lens element to the structural part of the second lens element. When the d1s / d2s ratio is greater than 3.1, non-imaging light can be incident from the edge of the first lens element to the structural part of the second lens element, and then reflect inside the lens element, and finally form an image on the image plane, resulting in the formation of stray light. When the d1s / d2s ratio is less than 1.8, the first spacer element will block part of the imaging light, causing the relative illumination (RI) value of the optical system to decrease, affecting the final imaging effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0020] Figure 1 A schematic diagram showing the structural arrangement of an optical system and some parameters according to the present application is shown;

[0021] Figure 2A 1 shows a schematic structural diagram of an optical system according to Example 1 of the present application;

[0022] Figure 2B 1 shows a schematic structural diagram of an optical system according to Example 2 of the present application;

[0023] Figure 2C 1 shows a schematic structural diagram of an optical system according to Example 3 of the present application;

[0024] Figures 3A to 3B axial chromatic aberration curves and astigmatism curves of the optical systems according to Examples 1 to 3 of the present application are respectively shown;

[0025] Figure 4A 1 shows a schematic structural diagram of an optical system according to Example 4 of the present application;

[0026] Figure 4B1 shows a schematic structural diagram of an optical system according to Example 5 of the present application;

[0027] Figure 4C 1 shows a schematic structural diagram of an optical system according to Example 6 of the present application;

[0028] Figures 5A to 5B axial chromatic aberration curves and astigmatism curves of the optical systems according to Examples 4 to 6 of the present application are respectively shown;

[0029] Figure 6A 1 shows a schematic structural diagram of an optical system according to Example 7 of the present application;

[0030] Figure 6B 1 shows a schematic structural diagram of an optical system according to Example 8 of the present application;

[0031] Figure 6C shows a schematic structural diagram of an optical system according to Example 9 of the present application; and

[0032] 7A to 7B axial chromatic aberration curves and astigmatism curves of the optical systems according to Examples 7 to 9 of the present application are respectively shown;

[0033] Figure 8A and Figure 8B The ray diagram and the spot diagram on the imaging surface of the optical system are shown respectively when T23 is maximum, CT2 / EP12=1.69 and d1s / d2s=8;

[0034] Figure 9A and Figure 9B The ray diagram and the spot diagram on the imaging surface of the optical system are shown respectively when T23 is maximum, CT2 / EP12=1.69 and d1s / d2s=2.58;

[0035] Figure 10A and Figure 10B The ray diagram and the spot diagram on the imaging plane of the optical system are shown when T23 is maximum, CT2 / EP12=1.69 and d1s / d2s=0.2. DETAILED DESCRIPTION

[0036] For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely 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.

[0037] It should be noted that in this specification, the terms "first," "second," "third," etc., are used solely to distinguish one feature from another and do not limit the features. Thus, the first lens discussed below could also be referred to as the second lens or the third lens without departing from the teachings of this application.

[0038] In the drawings, the thickness, size, and shape of the lenses are slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical and aspherical surfaces shown in the drawings are provided by way of example. That is, the shapes of the spherical and aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0039] In this article, the paraxial region refers to the area near the optical axis. If a lens surface is convex and the location of the convex surface is undefined, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the location of the concave surface is undefined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane is called the image-side surface of the lens.

[0040] It should also be understood that the terms "comprises," "including," "having," "includes," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "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.

[0041] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and will not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0042] It should be noted that, in the absence of any conflict, the embodiments and features of the embodiments in this application can be combined with each other. The following embodiments only express several implementation methods of the present application, and their descriptions are relatively specific and detailed, but they should not be understood as limiting the scope of the patent of this application. It should be pointed out that for those skilled in the art, several variations and improvements can be made without departing from the concept of the present application, and these all fall within the scope of protection of this application. For example, the lens groups, lens barrels, and spacer elements in the various embodiments of the present application can be combined arbitrarily, and are not limited to the lens group in one embodiment being combined only with the lens barrel, spacer element, etc. of that embodiment.

[0043] The present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments. Figure 1 The following diagram shows the structure of an optical system according to the present application and a schematic diagram of some parameters. It should be understood by those skilled in the art that some parameters of lenses commonly used in the art (such as the center thickness CT2 of the second lens on the optical axis) are not shown in the figure. Figure 1 As shown in Figure 1 Only some parameters of the lens barrel and the spacer element of an optical system of the present application are shown as examples to facilitate a better understanding of the present invention. Figure 1 As shown, EP01 is the distance from the object side end face of the lens barrel to the object side face of the first spacer element along the optical axis, CP1 is the maximum thickness of the first spacer element along the optical axis, CP3 is the maximum thickness of the third spacer element along the optical axis, EPa1 is the distance from the image side face of the auxiliary spacer element to the object side face of the first spacer element along the optical axis, EP12 is the distance from the image side face of the first spacer element to the object side face of the second spacer element along the optical axis, EP23 is the distance from the image side face of the second spacer element to the object side face of the third spacer element The distance from the object side surface along the optical axis is d0s, d2s is the outer diameter of the object side surface of the second spacing element, d1s is the inner diameter of the object side surface of the first spacing element, d3s is the inner diameter of the object side surface of the third spacing element, d2s is the inner diameter of the object side surface of the second spacing element, d2m is the inner diameter of the image side surface of the second spacing element, d1m is the inner diameter of the image side surface of the first spacing element, d0m is the inner diameter of the image side end surface of the lens barrel, and D1m is the outer diameter of the image side surface of the first spacing element.

[0044] An optical system according to an exemplary embodiment of the present application may include a lens barrel, a lens assembly disposed within the lens barrel, and a spacer assembly. The lens assembly may include four lenses having optical power, namely a first lens, a second lens, a third lens, and a fourth lens. The four lenses are arranged in sequence along the optical axis from the object side to the image side. Any two adjacent lenses among the first to fourth lenses may be spaced apart by a distance.

[0045] In example embodiments, the first lens may have negative power, the second lens may have positive power, the third lens may have positive power, and the fourth lens may have negative power.

[0046] In an exemplary embodiment, the object-side surface of the first lens is concave and the image-side surface is concave; the object-side surface of the second lens is convex and the image-side surface is concave; the object-side surface of the third lens is convex and the image-side surface is convex; and the object-side surface of the fourth lens is convex and the image-side surface is concave.

[0047] In an exemplary embodiment, the spacer element group of the optical system may include at least one of a first spacer element, a second spacer element, and a third spacer element. The first spacer element is positioned on the image side of the first lens and at least partially contacts the image side surface of the first lens. The second spacer element is positioned on the image side of the second lens and at least partially contacts the image side surface of the second lens. The third spacer element is positioned on the image side of the third lens and at least partially contacts the image side surface of the third lens.

[0048] In example embodiments, the spacer element group of the optical system may include an auxiliary spacer element disposed on the object side of the first lens and in at least partial contact with the object-side surface of the first lens.

[0049] It should be understood that this application does not specifically limit the number of spacer elements; any number of spacer elements may be included between any two lenses, and the entire optical system may also include any number of spacer elements. Spacer elements help the optical system intercept excess refractive and reflective light paths, reducing stray light and ghosting. Adding auxiliary support between the spacer element and the lens barrel can help alleviate problems such as poor assembly stability and low performance yield caused by large step differences between lenses.

[0050] In an exemplary embodiment, the optical system may further include an aperture for limiting the light beam to further improve the imaging quality of the optical lens. For example, the aperture may be positioned between the second and third lenses. However, it should be noted that the aperture position disclosed herein is merely illustrative and not limiting; in alternative embodiments, the aperture may be positioned elsewhere as needed.

[0051] In an exemplary embodiment, the maximum field of view (FOV) of the optical system according to the present application may satisfy: 120° <FOV<140°。

[0052] In an exemplary embodiment, the center thickness CT2 of the second lens on the optical axis and the distance EP12 from the image side of the first spacer element to the object side of the second spacer element along the optical axis direction may satisfy: 1.40 < CT2 / EP12 < 1.91. Ensuring that CT2 / EP12 is within a reasonable range can keep the thickness ratio of the second lens within a reasonable range, which is beneficial to the lens forming of the second lens. When the CT2 / EP12 ratio is less than 1.40, molding problems such as welding marks are likely to occur on the lens. When the CT2 / EP12 ratio is greater than 1.91, the contact part between the structural part of the lens and the lens barrel will be too small. At the same time, the edge thickness of the lens being too thin will also cause the surface shape of the effective diameter edge of the lens to change during assembly, affecting the imaging of the lens.

[0053] In an exemplary embodiment, the inner diameter d1s of the object side of the first spacer element and the inner diameter d2s of the object side of the second spacer element satisfy: 1.8 < d1s / d2s < 3.1. When d1s / d2s is controlled within a reasonable range, it can ensure that the first spacer element blocks the stray light from the first lens incident on the structural part of the second lens. When the d1s / d2s ratio is greater than 3.1, non-imaging light can enter the structural part of the second lens from the edge of the first lens, then reflect inside the lens, and finally form an image at the image plane, resulting in the formation of stray light. When the d1s / d2s ratio is less than 1.8, the first spacer element will block part of the imaging light, causing a decrease in the relative illuminance (RI) value of the optical system and affecting the final imaging effect.

[0054] An optical system according to an exemplary embodiment of the present application includes: a lens barrel, and a lens group and a spacer element group disposed within the lens barrel. Among them, the lens group sequentially includes, from the object side to the image side along the optical axis: a first lens with a negative optical power, a second lens with a positive optical power, a third lens with a positive optical power, and a fourth lens with a negative optical power. The number of lenses with optical power in the optical system is four; the spacer element group includes: a first spacer element and a second spacer element. The first spacer element is disposed on the image side of the first lens and at least partially contacts the image side surface of the first lens. The second spacer element is disposed on the image side of the second lens and at least partially contacts the image side surface of the second lens; there is an air gap on the optical axis between any two adjacent lenses among the first lens to the fourth lens, and the air gap T23 on the optical axis between the second lens and the third lens is the largest. The optical system has the characteristics of an ultra-wide angle, and also satisfies 1.40 < CT2 / EP12 < 1.91 and 1.8 < d1s / d2s < 3.1. Among them, CT2 is the central thickness of the second lens on the optical axis, EP12 is the distance along the optical axis direction from the image side surface of the first spacer element to the object side surface of the second spacer element, d1s is the inner diameter of the object side surface of the first spacer element, and d2s is the inner diameter of the object side surface of the second spacer element. The optical system has a reasonable combination of positive and negative optical powers. When satisfying the ultra-wide angle and the largest air gap T23 on the optical axis between the second lens and the third lens, ensuring that CT2 / EP12 is within a reasonable range can keep the thickness ratio of the second lens within a reasonable range, which is beneficial to the lens forming of the second lens. When the CT2 / EP12 ratio is less than 1.4, forming problems such as welding marks are likely to occur on the lens. When the CT2 / EP12 ratio is greater than 1.91, it will cause the contact part between the structural part of the lens and the lens barrel to be too small. At the same time, the edge thickness of the lens being too thin will also cause the surface shape of the effective diameter edge of the lens to change during assembly, affecting the imaging of the lens. When maintaining the above two conditions, light passing through the first lens is likely to generate stray light in the subsequent lenses. When d1s / d2s is controlled within a reasonable range, it can ensure that the first spacer element blocks the stray light from the structural part of the first lens incident on the second lens. When the d1s / d2s ratio is greater than 3.1, non-imaging light can enter the structural part of the second lens from the edge of the first lens, then reflect inside the lens, and finally form an image at the image plane, resulting in the formation of stray light. When the d1s / d2s ratio is less than 1.8, the first spacer element will block part of the imaging light, causing the relative illuminance (RI) value of the optical system to decrease and affecting the final imaging effect.

[0055] The air gap T23 between the second lens and the third lens of the optical system of the present application is the largest on the optical axis, featuring an ultra-wide angle. At the same time, it satisfies 1.40 < CT2 / EP12 < 1.91 and 1.8 < d1s / d2s < 3.1. Controlling d1s / d2s within a reasonable range can ensure that the first spacer element blocks the stray light from the structural part of the first lens incident on the second lens, having the beneficial effect of reducing stray light and ghost images. The following combines 8A to 10B , and further illustrates the role of the technical solution of the present application in reducing the risk of stray light or ghost images and improving the imaging quality.

[0056] Figure 8A and Figure 8B respectively show the ray diagram of the optical system 1 and the spot diagram on the imaging surface when CT2 / EP12 = 1.69 and d1s / d2s = 8; Figure 9A and Figure 9B [[ID=!12]]respectively show the ray diagram of the optical system 2 and the spot diagram on the imaging surface when CT2 / EP12 = 1.69 and d1s / d2s = 2.58; Figure 10A and Figure 10B show the ray diagram of the optical system 3 and the spot diagram on the imaging surface when CT2 / EP12 = 1.69 and d1s / d2s = 0.2.

[0057] More specifically, Figure 8A shows the ray diagram of the stray light generated by the non-effective rays of the first lens of the optical system 1. CT2 / EP12 = 1.69 of the optical system 1 is within the scope of the present application, d1s / d2s = 8 is not within the scope of the present application, and d1s / d2s is on the large side. The non-imaging rays can enter the first spacer element from the edge of the first lens and then be reflected on the structural part of the first lens. The first spacer element cannot effectively block the stray light from the structural part of the first lens incident on the second lens, and finally serious spots are generated on the imaging surface. Figure 8B shows the spot diagram. The spot area is large and the energy is strong. Its maximum stray light energy is about 0.0014 lm.

[0058] Figure 9A shows the ray diagram of the stray light generated by the non-effective rays of the first lens of the optical system 2. CT2 / EP12 = 1.69 of the optical system 2 is within the scope of the present application, d1s / d2s = 2.58 is within the scope of the present application, and d1s / d2s is designed reasonably. The first spacer element can block a certain amount of non-effective rays, effectively reducing the stray light generated after the non-effective rays are reflected on the structural part of the image side of the first lens. Therefore, <! Figure 9B the spot area on the imaging surface of the optical system 2 in

[0059] It should be noted that there seems to be an error in the original text where "光学系统2的成像面上的光斑图" in and is not properly formatted in the English translation. It should be something like "the spot diagram on the imaging surface of the optical system 2" instead of the incorrect "中光学系统2的成像面上的光斑图". The above translation has made the best attempt based on the original text while keeping the tags intact. Figure 10A Fig. shows the ray diagram of stray light generated by ineffective rays of the first lens of the optical system 3. CT2 / EP12 = 1.69 of the optical system 3 is within the scope of this application, while d1s / d2s = 0.2 is not within the scope of this application. d1s / d2s is too small, and the first spacer element will block part of the imaging rays, resulting in a decrease in the relative illuminance (RI) value of the optical system. At the same time, the combination of the first spacer element and the second spacer element is unreasonable, causing the rays passing through the second lens to be reflected at the second spacer element to generate new stray light spots. Figure 10B Fig. shows the spot generated on the imaging surface of the optical system 3. The spot area is large and the energy is strong, and its maximum stray light energy is about 0.003 lm.

[0060] In an exemplary embodiment, the central thickness of the third lens of the optical system according to this application on the optical axis is greater than the central thickness of the second lens on the optical axis and satisfies: 1.7 < f23 / EP23 < 4.1, where EP23 is the distance along the optical axis between the image side of the second spacer element and the object side of the third spacer element, and f23 is the combined focal length of the second lens and the third lens. When 1.7 < f23 / EP23 < 4.1 and the ratio of f23 / EP23 is within a reasonable range, and by controlling the central thickness of the third lens on the optical axis to be greater than the central thickness of the second lens on the optical axis, it helps to control the thickness of the second lens and the third lens near their edges, keeping the thickness ratio of the lens in a suitable range, which is helpful for the molding of the lens.

[0061] In an exemplary embodiment, the optical system according to this application can satisfy: -10.3 < R1 / R2 < -9.9 and -2.3 < d1m / f1 < -1.8, where R1 is the curvature radius of the object side of the first lens, R2 is the curvature radius of the image side of the first lens, d1m is the inner diameter of the image side of the first spacer element, and f1 is the effective focal length of the first lens. The curvature radii of the object side and the image side of the first lens and the focal length control the surface shape of the first lens. Therefore, restricting the magnitudes of the curvature radii of the object side and the image side of the first lens within a reasonable range can effectively control the diopter of the first lens. At the same time, by controlling the inner diameter of the image side of the first spacer element and the effective focal length of the first lens within a reasonable range, it can block the stray light directly transmitted through the edge of the first lens, improving the imaging quality of the lens.

[0062] In an exemplary embodiment, the optical system according to the present application may satisfy: 3.6 < (d0s - d0m) / f < 4.8, where d0s is the inner diameter of the object-side end face of the lens barrel, d0m is the inner diameter of the image-side end face of the lens barrel, and f is the effective focal length of the optical system. Satisfying 3.6 < (d0s - d0m) / f < 4.8 can ensure that the bearing positions between the lenses do not shift significantly, which is beneficial to the assembly stability of the lens. When the ratio of (d0s - d0m) / f is greater than 5, the bearing positions of each lens will shift, and the assembly stability of the lens will decrease. When the ratio of (d0s - d0m) / f is less than 3, the outer diameter step difference between adjacent lenses is too small, which is not conducive to the molding of the lens barrel.

[0063] In an exemplary embodiment, the optical system according to the present application may satisfy: 1.1 < f2 / (D1m - D2s) < 2.7, where f2 is the effective focal length of the second lens, D1m is the outer diameter of the image-side face of the first spacer element, and D2s is the outer diameter of the object-side face of the second spacer element. By controlling f2 / (D1m - D2s) within a reasonable range, the structural part length of the second lens is maintained within a reasonable interval. When the ratio of f2 / (D1m - D2s) is greater than 3, the structural part length of the second lens is too long, and the surface shape of the remote part of the effective diameter is prone to deformation when leaving the mold, affecting the imaging quality. When the ratio of f2 / (D1m - D2s) is less than 1, the structural part length of the second lens is too short, and an effective step difference cannot be formed with the outer diameter of the third lens, affecting the assembly quality.

[0064] In an exemplary embodiment, the optical system according to the present application may satisfy: 1.5 < EP12 / (T23 - T12) < 2.1, where EP12 is the distance along the optical axis from the image-side face of the first spacer element to the object-side face of the second spacer element, T23 is the air gap between the second lens and the third lens on the optical axis, and T12 is the air gap between the first lens and the second lens on the optical axis. By controlling EP12 / (T23 - T12) within a reasonable range, it helps to control the structural part thickness of the second lens and ensure the molding of the second lens. At the same time, since a too large edge thickness of the lens will cause an increase in the internal reflection paths of the lens, which is not conducive to the improvement of the shooting effect of the lens, so satisfying 1.5 < EP12 / (T23 - T12) < 2.1 within a reasonable range is also beneficial to meet the need of improving the stray light of the optical imaging lens.

[0065] In an exemplary embodiment, the optical system according to the present application may satisfy: 2.7 < V1 / V2 < 3.0 and 13.2 < (CT2 - CT1) / CP1 < 16.3, where V1 is the Abbe number of the first lens, V2 is the Abbe number of the second lens, CT1 is the central thickness of the first lens on the optical axis, CT2 is the central thickness of the second lens on the optical axis, and CP1 is the maximum thickness of the first spacer along the optical axis direction. Controlling V1 / V2 within a reasonable range allows high-transmittance and high-refractive-index lenses to replace one or two low-refractive-index plastic lenses, which can not only effectively reduce the thickness of the lens but also improve the imaging effect. On the basis of keeping V1 / V2 within a reasonable range, controlling (CT2 - CT1) / CP1 within a reasonable range can effectively control the curvature of the effective radii of the first lens and the second lens, reasonably distribute the optical power of the first lens and the second lens, improve the performance upper limit of the optical imaging lens, ensure the wall thickness of the first spacer element, and thus improve the uniformity and overall structural strength of the first spacer element.

[0066] In an exemplary embodiment, the optical system according to the present application may satisfy: 2.6 < EP01 / EPD < 3.0, where EP01 is the distance from the object-side end face of the lens barrel to the object-side surface of the first spacer element along the optical axis, and EPD is the entrance pupil diameter of the optical system. Satisfying 2.6 < EP01 / EPD < 3.0 can ensure that the thickness of the structural part of the first lens and the size of the aperture stop are within a reasonable range. When the ratio of EP01 / EPD is greater than 3.5, the light flux of the lens is small, and the thickness of the edge of the first lens is relatively large, resulting in a large difference between the thick and thin parts of the first lens, which in turn affects the molding of the first lens. When the ratio of EP01 / EPD is less than 2, the entrance pupil of the lens will correspondingly become larger, and the edge of the first lens will become thinner. Due to the limitation of the effective diameter, the gap between the first lens and the second lens will become larger, and multiple spacer elements are required to meet the requirements, thus increasing the cost of the lens.

[0067] In an exemplary embodiment, the optical system according to the present application may satisfy: 1.1 < R5 / d2m < 3.3 and -3.9 < d3s / R6 < -2.8, where R5 is the curvature radius of the object-side surface of the third lens, R6 is the curvature radius of the image-side surface of the third lens, d2m is the inner diameter of the image-side surface of the second spacer element, and d3s is the inner diameter of the object-side surface of the third spacer element. Satisfying 1.1 < R5 / d2m < 3.3 and -3.9 < d3s / R6 < -2.8, by controlling R5 / d2m within a reasonable range, it can ensure that the second spacer element effectively blocks the stray light generated by the incident light in the first lens and the second lens without affecting the main optical path of the incident light; at the same time, by controlling the inner diameter size of the third spacer element, it can well block the stray light caused by internal reflection in the third lens.

[0068] In an exemplary embodiment, the optical system according to the present application may satisfy: 1.9 < EPa1 / CT1 < 2.4, where EPa1 is the distance along the optical axis from the image side of the auxiliary spacer element to the object side of the first spacer element, and CT1 is the central thickness of the first lens on the optical axis. By controlling the ratio of the distance along the optical axis from the image side of the auxiliary spacer element to the object side of the first spacer element to the central thickness of the first lens, the ratio of the central thickness to the edge thickness of the first lens can be maintained within a reasonable range, reducing problems such as joint lines that occur during the molding of the first lens, ensuring the molding of the first lens, and avoiding molding problems caused by a large distance between the first lens and the second lens.

[0069] In an exemplary embodiment, the optical system according to the present application may satisfy: 0.7 < SAG21 / EP12 < 1.3, where SAG21 is the axial distance between the intersection of the object side of the second lens and the optical axis and the vertex of the effective radius of the object side of the second lens, and EP12 is the distance along the optical axis from the image side of the first spacer element to the object side of the second spacer element. Satisfying 0.7 < SAG21 / EP12 < 1.3 can control the sag height of the object side of the second lens and the size of the air gap between the first lens and the second lens, avoiding a situation where the edge thickness of the lens is relatively large and the middle is relatively thin, which affects the molding of the lens.

[0070] In an exemplary embodiment, the optical system according to the present application may satisfy: 0.5 < CP3 / T34 < 12.4, where CP3 is the maximum thickness of the third spacer element along the optical axis, and T34 is the air gap between the third lens and the fourth lens on the optical axis. Satisfying 0.5 < CP3 / T34 < 12.4 can control the edge thickness of the third lens and the fourth lens and the surface shape of the edge of the effective diameter, avoiding a situation where the edge of the effective diameter is thin and the structure part and the middle thickness are relatively large, and avoiding possible joint line problems.

[0071] In an exemplary embodiment, the outer diameters of the object side and the image side of the auxiliary spacer element, the first spacer element, the second spacer element, and the third spacer element of the optical system according to the present application are each successively decreasing; the inner diameters of the object side and the image side of the auxiliary spacer element, the first spacer element, and the second spacer element are each successively decreasing. This setting is beneficial for controlling the size of the lens. The first lens with the largest effective diameter length is set as the largest lens, and the size of the lens is controlled in the reverse order, thereby achieving the purpose of miniaturizing the lens.

[0072] In an embodiment of the present application, at least one of the mirror surfaces of each lens is an aspherical mirror surface, that is, at least one of the mirror surfaces from the object side of the first lens to the image side of the fourth lens is an aspherical mirror 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 with 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 adopting an aspherical lens, the aberration that occurs during imaging can be eliminated as much as possible, thereby improving the imaging quality. Optionally, the object side and image side of all lenses from the first lens to the fourth lens are aspherical mirror surfaces.

[0073] In an exemplary embodiment, the optical system may further include a filter for correcting color deviation and / or a protective glass for protecting a photosensitive element located on the imaging surface.

[0074] The optical system according to the above-described embodiments of the present application can utilize multiple lenses, such as the four lenses described above. By rationally allocating the optical power and surface shape of each lens, as well as the arrangement of the spacer elements, the span of each gear of the lens and the lens barrel can be made more uniform, thereby enhancing the light convergence capability and improving the imaging quality of the optical system. However, those skilled in the art will appreciate that, without departing from the technical solutions claimed in this application, the number of lenses comprising the optical system can be varied to achieve the various results and advantages described herein. For example, although the embodiments are described using four lenses as an example, the optical system is not limited to including four lenses. If desired, the optical system may also include other numbers of lenses.

[0075] The following further describes a specific embodiment of the optical system applicable to the above-mentioned embodiment with reference to the accompanying drawings. Figures 2A to 3B Describe the optical system according to Examples 1 to 3 of the present application; refer to Figures 4A to 5B Describe the optical system according to Examples 4 to 6 of the present application; refer to Figures 6A to 7B Optical systems according to Examples 7 to 9 of the present application are described.

[0076] Example 1

[0077] Figure 2A FIG. 1 shows a schematic structural diagram of an optical system 1001 according to Example 1 of the present application. Figure 2A As shown, the optical system 1001 includes a lens barrel P0, a lens group, and a spacer element group.

[0078] like Figure 2AAs shown, the lens group of optical system 1001 includes, from the object side to the image side, a first lens E1, a second lens E2, a third lens E3, and a fourth lens E4. The first lens E1 has an object-side surface S1 and an image-side surface S2. The second lens E2 has an object-side surface S3 and an image-side surface S4. The third lens E3 has an object-side surface S5 and an image-side surface S6. The fourth lens E4 has an object-side surface S7 and an image-side surface S8. The optical system 1001 also includes an aperture stop STO (not shown) disposed between the second and third lenses, and a filter (not shown) for correcting chromatic aberration, the filter having an object-side surface S9 and an image-side surface S10. Light from an object sequentially passes through each surface S1 to S10 and is ultimately imaged on an imaging surface (not shown).

[0079] Table 1 shows basic parameters of the lens group of the optical system 1001 of Example 1, wherein the units of curvature radius, thickness / distance and effective focal length are all millimeters (mm).

[0080]

[0081] Table 1

[0082] In Example 1, the object-side surface and the image-side surface of any lens among the first lens E1 to the fourth lens E4 are both aspherical surfaces. The surface shape x of each aspherical lens can be defined by, but is not limited to, the following aspherical surface formula:

[0083]

[0084] Wherein, x is the distance vector height of the aspheric surface from the vertex of the aspheric surface 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 1 above); k is the conic coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface. Table 2 shows the high-order coefficients A4, A6, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, A21, A22, A23, A24, A25, A26, A27, A28, A30, A31, A32, A33, A34, A35, A36, A37, A38, A39, A40, 10 、A 12 、A 14 、A 16 、A 18 and A 20 .

[0085] Face number A4 A6 A8 A10 A12 A14 A16 A18 A20 S1 3.8765E-01 -7.9283E-02 3.5168E-02 -1.8817E-02 9.7455E-03 -4.8188E-03 2.1773E-03 -7.7519E-04 1.8661E-04 S2 -1.3386E-01 -5.3355E-02 1.9781E-02 -7.6999E-03 -2.9015E-04 1.3891E-03 -3.2585E-04 8.9619E-04 -3.7590E-04 S3 -1.0651E-01 -1.0990E-02 6.8549E-03 -1.4706E-03 -6.4191E-04 3.2961E-04 -5.6719E-06 4.8227E-04 7.6362E-05 S4 4.9275E-02 4.8072E-03 1.6555E-03 4.2915E-04 1.9947E-04 3.5059E-05 3.1326E-05 1.2406E-05 1.1019E-07 S5 -1.1245E-02 -5.3460E-04 9.7139E-04 2.9002E-04 -6.3870E-06 -1.8705E-05 -2.8388E-06 0.0000E+00 0.0000E+00 S6 1.1983E-01 -6.0473E-02 2.1411E-02 -8.5099E-03 6.0609E-03 -2.3008E-03 1.9767E-03 -1.1907E-03 9.0288E-04 S7 -9.6804E-02 -6.7787E-02 1.6744E-02 -6.3845E-03 3.1796E-03 -1.7210E-03 8.7691E-04 -8.7561E-04 4.1472E-04 S8 -6.7546E-02 -7.6668E-02 2.5136E-02 -1.0680E-02 2.8802E-03 -1.8969E-03 8.7729E-04 -7.2891E-04 5.9829E-04

[0086] Table 2

[0087] Table 3 shows the maximum field of view FOV, effective focal length f, entrance pupil diameter EPD, combined focal length f23, and sag height SAG21 of the object side surface of the second lens of the optical system 1001.

[0088] parameter FOV(°) f(mm) EPD(mm) f23(mm) SAG21(mm) Numerical 137.0000 0.7800 0.5600 1.3747 0.4745

[0089] Table 3

[0090] like Figure 2A As shown, optical system 1001 further includes four spacers: an auxiliary spacer Pa, a first spacer P1, a second spacer P2, and a third spacer P3. Auxiliary spacer Pa is positioned on the object side of the first lens element and is in at least partial contact with the object-side surface of the first lens element. First spacer P1 is positioned on the image side of the first lens element and is in at least partial contact with the image-side surface of the first lens element. Second spacer P2 is positioned on the image side of the second lens element and is in at least partial contact with the image-side surface of the second lens element. Third spacer P3 is positioned on the image side of the third lens element and is in at least partial contact with the image-side surface of the third lens element. Table 4 shows basic parameters of the spacers and lens barrel of optical system 1001. The units of each parameter in Table 4 are millimeters (mm).

[0091] parameter d1s d1m D1m d2s d2m D2s d3s d0s Numerical 2.0466 2.0466 4.7980 0.7864 0.7864 3.5450 1.8065 5.6256 parameter d0m EPa1 EP01 CP1 EP12 EP23 CP3 / Numerical 2.8114 1.0008 1.5820 0.0180 0.3864 0.6215 0.5563 /

[0092] Table 4

[0093] Example 2

[0094] Figure 2B FIG2 is a schematic structural diagram of an optical system 1002 according to Embodiment 2 of the present application. In this embodiment and the following embodiments, for the sake of brevity, some descriptions similar to those in Embodiment 1 will be omitted.

[0095] like Figure 2B As shown, optical system 1002 includes a lens barrel P0, a lens group, and a spacer group. Optical system 1002 also includes an aperture stop STO (not shown) disposed between the second and third lenses, and a filter (not shown) for correcting chromatic aberration, the filter having an object-side surface S9 and an image-side surface S10. The lens group of optical system 1002 is identical to that of optical system 1001 in Example 1. Their basic parameters are detailed in Tables 1 to 3 and are not further detailed here.

[0096] like Figure 2B As shown, optical system 1002 further includes four spacers: an auxiliary spacer Pa, a first spacer P1, a second spacer P2, and a third spacer P3. Auxiliary spacer Pa is positioned on the object side of the first lens and is in at least partial contact with the object-side surface of the first lens. First spacer P1 is positioned on the image side of the first lens and is in at least partial contact with the image-side surface of the first lens. Second spacer P2 is positioned on the image side of the second lens and is in at least partial contact with the image-side surface of the second lens. Third spacer P3 is positioned on the image side of the third lens and is in at least partial contact with the image-side surface of the third lens. Table 5 shows basic parameters of the spacers and lens barrel of optical system 1002. The units of each parameter in Table 5 are millimeters (mm).

[0097] parameter d1s d1m D1m d2s d2m D2s d3s d0s Numerical 1.9642 1.9642 4.7980 0.9061 2.1717 3.3411 1.8065 5.6256 parameter d0m EPa1 EP01 CP1 EP12 EP23 CP3 / Numerical 2.8114 0.9236 1.5048 0.0180 0.3822 0.3395 0.5563 /

[0098] Table 5

[0099] Example 3

[0100] Figure 2C A schematic structural diagram of the optical system 1003 according to Example 3 of the present application is shown.

[0101] like Figure 2C As shown, optical system 1003 includes a lens barrel P0, a lens group, and a spacer element group. Optical system 1003 also includes an aperture stop STO (not shown) disposed between the second and third lenses, and a filter (not shown) for correcting chromatic aberration, the filter having an object-side surface S9 and an image-side surface S10. The lens group of optical system 1003 is identical to that of optical system 1001 in Example 1. Their basic parameters are detailed in Tables 1 to 3 and are not further described.

[0102] like Figure 2C As shown, optical system 1003 further includes four spacers: an auxiliary spacer Pa, a first spacer P1, a second spacer P2, and a third spacer P3. Auxiliary spacer Pa is positioned on the object side of the first lens element and is in at least partial contact with the object-side surface of the first lens element. First spacer P1 is positioned on the image side of the first lens element and is in at least partial contact with the image-side surface of the first lens element. Second spacer P2 is positioned on the image side of the second lens element and is in at least partial contact with the image-side surface of the second lens element. Third spacer P3 is positioned on the image side of the third lens element and is in at least partial contact with the image-side surface of the third lens element. Table 6 shows basic parameters of the spacers and lens barrel of optical system 1003. The units of each parameter in Table 6 are millimeters (mm).

[0103] parameter d1s d1m D1m d2s d2m D2s d3s d0s Numerical 2.0288 2.0288 4.7980 0.7864 0.7864 3.5450 2.4076 5.6256 parameter d0m EPa1 EP01 CP1 EP12 EP23 CP3 / Numerical 2.8114 1.0008 1.5820 0.0180 0.3864 0.5094 0.6683 /

[0104] Table 6

[0105] Figure 3A The axial chromatic aberration curves of the optical systems of Examples 1 to 3 are shown, which indicate the deviation of the convergence point of light of different wavelengths after passing through the lens. Figure 3B The astigmatism curves of the optical systems of Examples 1 to 3 are shown, which represent the meridional field curvature and the sagittal field curvature. Figures 3A to 3B It can be seen that the optical systems provided in Examples 1 to 3 can achieve good imaging quality.

[0106] Example 4

[0107] Figure 4A FIG. 2 shows a schematic structural diagram of an optical system 2001 according to embodiment 4 of the present application. Figure 4A As shown, the optical system 2001 includes a lens barrel P0, a lens group, and a spacer element group.

[0108] like Figure 4A As shown, the lens group of optical system 2001 includes, from the object side to the image side, a first lens E1, a second lens E2, a third lens E3, and a fourth lens E4. The first lens E1 has an object-side surface S1 and an image-side surface S2. The second lens E2 has an object-side surface S3 and an image-side surface S4. The third lens E3 has an object-side surface S5 and an image-side surface S6. The fourth lens E4 has an object-side surface S7 and an image-side surface S8. The optical system 2001 also includes an aperture stop STO (not shown) disposed between the second and third lenses, and a filter (not shown) for correcting chromatic aberration, the filter having an object-side surface S9 and an image-side surface S10. Light from an object sequentially passes through each surface S1 to S10 and is ultimately imaged on an imaging surface (not shown).

[0109] Table 7 shows the basic parameters of the lens assembly of optical system 2001 in Example 4, where the units of curvature radius, thickness / distance, and effective focal length are all in millimeters (mm). Tables 8-1 and 8-2 show the high-order coefficients of the various aspheric mirror surfaces that can be used in Example 4, where the surface shape of each aspheric surface can be defined by formula (1) given in Example 1 above.

[0110]

[0111] Table 7

[0112] Face number A4 A6 A8 A10 A12 A14 A16 S1 3.7200E-01 -7.6321E-02 3.3781E-02 -1.8023E-02 9.0926E-03 -4.3235E-03 1.8956E-03 S2 -1.3537E-01 -5.3141E-02 2.0095E-02 -7.8227E-03 -1.5906E-04 1.1768E-03 -2.6119E-04 S3 -1.0234E-01 -1.0504E-02 6.3685E-03 -1.2462E-03 -7.0929E-04 3.9471E-04 4.3767E-05 S4 4.9102E-02 5.0780E-03 1.5417E-03 4.5360E-04 1.7428E-04 4.4307E-05 2.8349E-05 S5 -1.1231E-02 -1.1820E-03 1.0955E-03 3.5996E-04 -1.9122E-06 -6.8192E-05 -1.8356E-05 S6 1.1849E-01 -5.6092E-02 1.8019E-02 -8.2459E-03 5.2256E-03 -2.1445E-03 1.5971E-03 S7 -5.1802E-02 -6.1154E-02 1.5569E-02 -6.2095E-03 3.2774E-03 -1.5359E-03 9.0747E-04 S8 -8.0390E-02 -5.7506E-02 2.3263E-02 -6.9012E-03 2.3309E-03 -1.1898E-03 5.1495E-04

[0113] Table 8-1

[0114]

[0115]

[0116] Table 8-2

[0117] Table 9 shows the values of the maximum field of view FOV, effective focal length f, entrance pupil diameter EPD, combined focal length f23, and sag SAG21 of the object side surface of the second lens of the optical system 2001.

[0118] parameter FOV(°) f(mm) EPD(mm) f23(mm) SAG21(mm) Numerical 125.0878 0.7737 0.5552 1.4819 0.3952

[0119] Table 9

[0120] like Figure 4AAs shown, optical system 2001 further includes four spacers: an auxiliary spacer Pa, a first spacer P1, a second spacer P2, and a third spacer P3. Auxiliary spacer Pa is positioned on the object side of the first lens element and is in at least partial contact with the object-side surface of the first lens element. First spacer P1 is positioned on the image side of the first lens element and is in at least partial contact with the image-side surface of the first lens element. Second spacer P2 is positioned on the image side of the second lens element and is in at least partial contact with the image-side surface of the second lens element. Third spacer P3 is positioned on the image side of the third lens element and is in at least partial contact with the image-side surface of the third lens element. Table 10 shows basic parameters of the spacers and lens barrel of optical system 2001. The units of each parameter in Table 10 are all in millimeters (mm).

[0121] parameter d1s d1m D1m d2s d2m D2s d3s d0s Numerical 2.0218 2.0218 5.0773 0.7853 0.7853 4.4496 1.7913 5.8107 parameter d0m EPa1 EP01 CP1 EP12 EP23 CP3 / Numerical 2.7000 0.8653 1.5057 0.0220 0.5204 0.6883 0.5090 /

[0122] Table 10

[0123] Example 5

[0124] Figure 4B A schematic structural diagram of an optical system 2002 according to embodiment 5 of the present application is shown.

[0125] like Figure 4B As shown, optical system 2002 includes a lens barrel P0, a lens assembly, and a spacer element assembly. Optical system 2002 also includes a stop STO (not shown) disposed between the second and third lenses, and a filter (not shown) for correcting chromatic aberration, the filter having an object-side surface S9 and an image-side surface S10. The lens assembly of optical system 2002 is identical to that of optical system 2001 in Example 4. Their basic parameters are detailed in Tables 7 to 9 and are not further detailed here.

[0126] like Figure 4B As shown, optical system 2002 further includes four spacers: an auxiliary spacer Pa, a first spacer P1, a second spacer P2, and a third spacer P3. Auxiliary spacer Pa is positioned on the object side of the first lens element and is in at least partial contact with the object-side surface of the first lens element. First spacer P1 is positioned on the image side of the first lens element and is in at least partial contact with the image-side surface of the first lens element. Second spacer P2 is positioned on the image side of the second lens element and is in at least partial contact with the image-side surface of the second lens element. Third spacer P3 is positioned on the image side of the third lens element and is in at least partial contact with the image-side surface of the third lens element. Table 11 shows basic parameters of the spacers and lens barrel of optical system 2002. The units of each parameter in Table 11 are millimeters (mm).

[0127] parameter d1s d1m D1m d2s d2m D2s d3s d0s Numerical 1.9989 1.9989 5.0773 1.0670 1.2927 4.1226 1.7913 5.8107 parameter d0m EPa1 EP01 CP1 EP12 EP23 CP3 / Numerical 2.7000 0.8773 1.5178 0.0220 0.4166 0.4559 0.5090 /

[0128] Table 11

[0129] Example 6

[0130] Figure 4C A schematic structural diagram of the optical system 2003 according to Example 6 of the present application is shown.

[0131] like Figure 4C As shown, optical system 2003 includes a lens barrel P0, a lens assembly, and a spacer element assembly. Optical system 2003 also includes a stop STO (not shown) disposed between the second lens and the third lens. The lens assembly of optical system 2003 is identical to that of optical system 2001 in Example 4. Their basic parameters are detailed in Tables 7 to 9 and are not further described.

[0132] like Figure 4C As shown, optical system 2003 also includes three spacer elements: a first spacer element P1, a second spacer element P2, and a third spacer element P3. First spacer element P1 is positioned on the image side of the first lens and at least partially contacts the image-side surface of the first lens; second spacer element P2 is positioned on the image side of the second lens and at least partially contacts the image-side surface of the second lens; and third spacer element P3 is positioned on the image side of the third lens and at least partially contacts the image-side surface of the third lens. Table 12 shows basic parameters of the spacer elements and lens barrel of optical system 2003. All parameters in Table 12 are in millimeters (mm).

[0133] parameter d1s d1m D1m d2s d2m D2s d3s d0s Numerical 1.9989 1.9989 5.0773 1.0670 1.2927 3.8744 1.7913 5.8107 parameter d0m EPa1 EP01 CP1 EP12 EP23 CP3 / Numerical 2.7000 0.8773 1.5178 0.0220 0.4166 0.8020 0.5361 /

[0134] Table 12

[0135] Figure 5A The axial chromatic aberration curves of the optical systems of Examples 4 to 6 are shown, which indicate the deviation of the convergence point of light of different wavelengths after passing through the lens. Figure 5B The astigmatism curves of the optical systems of Examples 4 to 6 are shown, which represent the meridional field curvature and the sagittal field curvature. Figures 5A to 5B It can be seen that the optical systems provided in Examples 4 to 6 can achieve good imaging quality.

[0136] Example 7

[0137] Figure 6A FIG. 3 shows a schematic structural diagram of an optical system 3001 according to Example 7 of the present application. Figure 6A As shown, the optical system 3001 includes a lens barrel P0, a lens group, and a spacer element group.

[0138] like Figure 6AAs shown, the lens group of optical system 3001 includes, from the object side to the image side, a first lens E1, a second lens E2, a third lens E3, and a fourth lens E4. The first lens E1 has an object-side surface S1 and an image-side surface S2. The second lens E2 has an object-side surface S3 and an image-side surface S4. The third lens E3 has an object-side surface S5 and an image-side surface S6. The fourth lens E4 has an object-side surface S7 and an image-side surface S8. The optical system 3001 also includes an aperture stop STO (not shown) disposed between the second and third lenses, and a filter (not shown) for correcting chromatic aberration, the filter having an object-side surface S9 and an image-side surface S10. Light from an object sequentially passes through each surface S1 to S10 and is ultimately imaged on an imaging surface (not shown).

[0139] Table 13 shows the basic parameters of the lens assembly of the optical system 3001 of Example 7, where the units of curvature radius, thickness / distance, and effective focal length are all in millimeters (mm). Table 14 shows the high-order coefficients of the various aspheric mirror surfaces that can be used in Example 7, where the surface shape of each aspheric surface can be defined by formula (1) given in Example 1 above.

[0140]

[0141]

[0142] Table 13

[0143] Face number A4 A6 A8 A10 A12 A14 A16 S1 3.8972E-01 -7.9168E-02 3.4820E-02 -1.8844E-02 9.7031E-03 -4.6821E-03 2.1334E-03 S2 -1.4677E-01 -5.4701E-02 2.0596E-02 -8.4066E-03 2.7508E-04 1.4244E-03 -1.7835E-04 S3 -1.0240E-01 -1.0503E-02 6.3726E-03 -1.2471E-03 -7.0721E-04 3.9755E-04 4.6106E-05 S4 5.1998E-02 5.7724E-03 1.8312E-03 5.7483E-04 2.2647E-04 6.6936E-05 3.8618E-05 S5 -6.5043E-03 -1.4015E-03 1.5298E-04 8.4365E-05 3.0500E-05 -1.1010E-06 1.2165E-05 S6 1.1699E-01 -5.2171E-02 1.6524E-02 -8.2237E-03 4.4620E-03 -2.1364E-03 1.4710E-03 S7 -5.8371E-02 -6.3039E-02 1.6059E-02 -6.3311E-03 3.3831E-03 -1.6050E-03 9.0679E-04 S8 -7.9317E-02 -5.7360E-02 2.3135E-02 -6.8415E-03 2.3287E-03 -1.1723E-03 5.2067E-04

[0144] Table 14-1

[0145] Face number A18 A20 A22 A24 A26 A28 A30 S1 -7.7334E-04 1.7467E-04 -1.1937E-05 -5.1690E-06 3.3571E-06 1.8044E-07 7.5348E-07 S2 7.8979E-04 -4.8770E-04 -1.5848E-04 8.9577E-06 9.0022E-05 -4.5704E-05 1.6215E-05 S3 5.2895E-04 5.7441E-05 -1.0278E-05 -2.9126E-05 1.4492E-05 -3.0174E-05 4.8394E-06 S4 1.3571E-05 5.0737E-06 1.0166E-06 -1.2968E-06 -6.8759E-06 -3.6028E-06 -8.4071E-06 S5 1.4200E-06 -8.7720E-07 -3.1979E-06 3.1452E-07 -3.4508E-07 5.8460E-07 -1.3625E-07 S6 -8.7161E-04 6.3690E-04 -3.8649E-04 2.7978E-04 -1.7255E-04 1.4224E-04 -7.1113E-05 S7 -6.6276E-04 3.6180E-04 -2.3488E-04 1.7607E-04 -1.2048E-04 4.1013E-05 -1.2489E-05 S8 -4.8092E-04 3.0789E-04 -2.1088E-04 1.2856E-04 -1.5724E-04 7.6165E-05 -1.2557E-05

[0146] Table 14-2

[0147] Table 15 shows the values of the maximum field of view FOV, effective focal length f, entrance pupil diameter EPD, combined focal length f23, and sag SAG21 of the object side surface of the second lens of the optical system 3001.

[0148] parameter FOV(°) f(mm) EPD(mm) f23(mm) SAG21(mm) Numerical 125.7901 0.7702 0.5527 1.4759 0.4899

[0149] Table 15

[0150] like Figure 6AAs shown, optical system 3001 further includes four spacers: an auxiliary spacer Pa, a first spacer P1, a second spacer P2, and a third spacer P3. Auxiliary spacer Pa is positioned on the object side of the first lens element and is in at least partial contact with the object-side surface of the first lens element. First spacer P1 is positioned on the image side of the first lens element and is in at least partial contact with the image-side surface of the first lens element. Second spacer P2 is positioned on the image side of the second lens element and is in at least partial contact with the image-side surface of the second lens element. Third spacer P3 is positioned on the image side of the third lens element and is in at least partial contact with the image-side surface of the third lens element. Table 16 shows basic parameters of the spacers and lens barrel of optical system 3001. The units of each parameter in Table 16 are millimeters (mm).

[0151] parameter d1s d1m D1m d2s d2m D2s d3s d0s Numerical 2.0004 2.0040 5.6483 0.7854 0.7854 4.3551 1.8409 6.3819 parameter d0m EPa1 EP01 CP1 EP12 EP23 CP3 / Numerical 2.6914 0.9581 1.5986 0.0220 0.4465 0.8611 0.0220 /

[0152] Table 16

[0153] Example 8

[0154] Figure 6B A schematic structural diagram of the optical system 3002 according to Example 8 of the present application is shown.

[0155] like Figure 6B As shown, optical system 3002 includes a lens barrel P0, a lens group, and a spacer group. Optical system 3002 also includes a stop STO (not shown) disposed between the second and third lenses, and a filter (not shown) for correcting chromatic aberration, the filter having an object-side surface S9 and an image-side surface S10. The lens group of optical system 3002 is identical to that of optical system 3001 in Example 7. Their basic parameters are detailed in Tables 13 to 15 and are not further detailed here.

[0156] like Figure 6B As shown, optical system 3002 further includes four spacers: an auxiliary spacer Pa, a first spacer P1, a second spacer P2, and a third spacer P3. Auxiliary spacer Pa is positioned on the object side of the first lens element and is in at least partial contact with the object-side surface of the first lens element. First spacer P1 is positioned on the image side of the first lens element and is in at least partial contact with the image-side surface of the first lens element. Second spacer P2 is positioned on the image side of the second lens element and is in at least partial contact with the image-side surface of the second lens element. Third spacer P3 is positioned on the image side of the third lens element and is in at least partial contact with the image-side surface of the third lens element. Table 17 shows basic parameters of the spacers and lens barrel of optical system 3002. The units of each parameter in Table 17 are millimeters (mm).

[0157] parameter d1s d1m D1m d2s d2m D2s d3s d0s Numerical 2.0466 2.0466 5.6483 0.7857 0.7854 4.3551 1.8435 6.3819 parameter d0m EPa1 EP01 CP1 EP12 EP23 CP3 / Numerical 2.6914 0.9581 1.6159 0.0180 0.4332 0.6623 0.5291 /

[0158] Table 17

[0159] Example 9

[0160] Figure 6C A schematic structural diagram of the optical system 3003 according to Example 9 of the present application is shown.

[0161] like Figure 6C As shown, optical system 3003 includes a lens barrel P0, a lens group, and a spacer group. Optical system 3003 also includes an aperture stop STO (not shown) disposed between the second and third lenses, and a filter (not shown) for correcting chromatic aberration, the filter having an object-side surface S9 and an image-side surface S10. The lens group of optical system 3003 is identical to that of optical system 3001 in Example 7. Their basic parameters are detailed in Tables 13 to 15 and are not further detailed here.

[0162] like Figure 6C As shown, optical system 3003 further includes four spacers: an auxiliary spacer Pa, a first spacer P1, a second spacer P2, and a third spacer P3. Auxiliary spacer Pa is positioned on the object side of the first lens element and is in at least partial contact with the object-side surface of the first lens element. First spacer P1 is positioned on the image side of the first lens element and is in at least partial contact with the image-side surface of the first lens element. Second spacer P2 is positioned on the image side of the second lens element and is in at least partial contact with the image-side surface of the second lens element. Third spacer P3 is positioned on the image side of the third lens element and is in at least partial contact with the image-side surface of the third lens element. Table 18 shows basic parameters of the spacers and lens barrel of optical system 3003. The units of each parameter in Table 18 are millimeters (mm).

[0163] parameter d1s d1m D1m d2s d2m D2s d3s d0s Numerical 2.4066 2.0466 5.6483 0.7859 0.7859 4.4551 1.8435 6.3819 parameter d0m EPa1 EP01 CP1 EP12 EP23 CP3 / Numerical 2.6914 0.9236 1.5640 0.0220 0.4811 0.6623 0.5291 /

[0164] Table 18

[0165] Figure 7A The axial chromatic aberration curves of the optical systems of Examples 7 to 9 are shown, which indicate the deviation of the convergence point of light of different wavelengths after passing through the lens. Figure 7B The astigmatism curves of the optical systems of Examples 7 to 9 are shown, which represent the meridional field curvature and the sagittal field curvature. 7A to 7B It can be seen that the optical systems provided in Examples 7 to 9 can achieve good imaging quality.

[0166] In summary, the optical systems of Examples 1 to 9 satisfy the relationship shown in Table 19.

[0167]

[0168]

[0169] Table 19

[0170] The present application also provides an imaging device, wherein the electronic photosensitive element thereof may be a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The imaging device may be a standalone imaging device such as a digital camera, or an imaging module integrated into a mobile electronic device such as a mobile phone. The imaging device is equipped with the optical system described above.

[0171] The above description is merely a preferred embodiment of the present application and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of the invention herein is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the inventive concept. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features having similar functions disclosed in this application.

Claims

1. An optical system, characterized in that: Comprising: A lens barrel and a lens group and a spacer element group disposed within the lens barrel, wherein, The lens group sequentially includes, from the object side to the image side along the optical axis: A first lens having a negative optical power; A second lens having a positive optical power; A third lens having a positive optical power; and A fourth lens having a negative optical power; The spacer element group includes: a first spacer element and a second spacer element. The first spacer element is disposed on the image side of the first lens and at least partially contacts the image side surface of the first lens. The second spacer element is disposed on the image side of the second lens and at least partially contacts the image side surface of the second lens; There is an air gap on the optical axis between any two adjacent lenses from the first lens to the fourth lens, and the air gap T23 on the optical axis between the second lens and the third lens is the largest; The central thickness CT2 of the second lens on the optical axis and the distance EP12 from the image side surface of the first spacer element to the object side surface of the second spacer element along the optical axis direction satisfy: 1.40 < CT2 / EP12 < 1.91; The inner diameter d1s of the object side surface of the first spacer element and the inner diameter d2s of the object side surface of the second spacer element satisfy: 1.8 < d1s / d2s < 3.1; The number of lenses having optical power in the optical system is four.

2. The optical system according to claim 1, wherein, The spacer element group further includes: a third spacer element disposed on the image side of the third lens and at least partially contacting the image side surface of the third lens; The central thickness of the third lens on the optical axis is greater than the central thickness of the second lens on the optical axis; The optical system satisfies: 1.7 < f²³ / EP²³ < 4.1, where EP²³ is the distance along the optical axis between the image side surface of the second spacer element and the object side surface of the third spacer element, and f²³ is the combined focal length of the second lens and the third lens.

3. The optical system according to claim 1, wherein, The optical system satisfies: -10.3 < R1 / R2 < -9.9 and -2.3 < d1m / f1 < -1.8, where R1 is the curvature radius of the object side surface of the first lens, R2 is the curvature radius of the image side surface of the first lens, d1m is the inner diameter of the image side surface of the first spacer element, and f1 is the effective focal length of the first lens.

4. The optical system according to claim 1, wherein, The optical system satisfies: 3.6 < (d0s - d0m) / f < 4.8, where d0s is the inner diameter of the object side end face of the lens barrel, d0m is the inner diameter of the image side end face of the lens barrel, and f is the effective focal length of the optical system.

5. The optical system according to claim 1, wherein, The optical system satisfies: t1 < f2 / (D1m - D2s) < 2.7, where f2 is the effective focal length of the second lens, D1m is the outer diameter of the image side surface of the first spacer element, and D2s is the outer diameter of the object side surface of the second spacer element.

6. The optical system according to claim 1, wherein: the optical system satisfies: 1.5 < EP12 / (T23 - T12) < 2.1, where EP12 is the distance along the optical axis from the image side surface of the first spacer element to the object side surface of the second spacer element, T23 is the air gap on the optical axis between the second lens and the third lens, and T12 is the air gap on the optical axis between the first lens and the second lens.

7. The optical system according to claim 1, wherein: the optical system satisfies: 2.7 < V1 / V2 < 3.0 and 13.2 < (CT2 - CT1) / CP1 < 16.3, where V1 is the Abbe number of the first lens, V2 is the Abbe number of the second lens, CT1 is the central thickness of the first lens on the optical axis, CT2 is the central thickness of the second lens on the optical axis, and CP1 is the maximum thickness of the first spacer element along the optical axis.

8. The optical system according to any one of claims 1-7, wherein: the optical system satisfies: 2.6 < EP01 / EPD < 3.0, where EP01 is the distance along the optical axis from the object side end face of the lens barrel to the object side surface of the first spacer element, and EPD is the entrance pupil diameter of the optical system.

9. The optical system according to any one of claims 1, 3-7, wherein: the spacer element group includes: a third spacer element disposed on the image side of the third lens and at least partially contacting the image side surface of the third lens; the optical system satisfies: 1.1 < R5 / d2m < 3.3 and -3.9 < d3s / R6 < -2.8, where R5 is the curvature radius of the object side surface of the third lens, R6 is the curvature radius of the image side surface of the third lens, d2m is the inner diameter of the image side surface of the second spacer element, and d3s is the inner diameter of the object side surface of the third spacer element.

10. The optical system according to any one of claims 1-7, wherein: the spacer element group further includes: an auxiliary spacer element disposed on the object side of the first lens and at least partially contacting the object side surface of the first lens; the optical system satisfies: 1.9 < EPa1 / CT1 < 2.4, where EPa1 is the distance along the optical axis from the image side surface of the auxiliary spacer element to the object side surface of the first spacer element, and CT1 is the central thickness of the first lens on the optical axis.

11. The optical system according to any one of claims 1-7, wherein: the optical system satisfies: 0.7 < SAG21 / EP12 < 1.3, where SAG21 is the axial distance between the intersection of the object side surface of the second lens and the optical axis and the vertex of the effective radius of the object side surface of the second lens, and EP12 is the distance along the optical axis from the image side surface of the first spacer element to the object side surface of the second spacer element.

12. The optical system according to any one of claims 1, 3-7, wherein: The spacer element group includes: a third spacer element disposed on the image side of the third lens and at least partially contacting the image side surface of the third lens; The optical system satisfies: 0.5 < CP3 / T34 < 12.4, where CP3 is the maximum thickness of the third spacer element along the optical axis direction, and T34 is the air gap between the third lens and the fourth lens on the optical axis.

13. The optical system according to any one of claims 1, 3 - 7, wherein The spacer element group further includes: an auxiliary spacer element and a third spacer element. The auxiliary spacer element is disposed on the object side of the first lens and at least partially contacts the object side surface of the first lens. The third spacer element is disposed on the image side of the third lens and at least partially contacts the image side surface of the third lens; The outer diameters of the object side surface and the image side surface of the auxiliary spacer element, the first spacer element, the second spacer element, and the third spacer element are sequentially decreasing; the inner diameters of the object side surface and the image side surface of the auxiliary spacer element, the first spacer element, and the second spacer element are sequentially decreasing.

14. The optical system according to claim 1, wherein The object side surface of the first lens is concave, and the image side surface is concave; The object side surface of the second lens is convex, and the image side surface is concave; The object side surface of the third lens is convex, and the image side surface is convex; The object side surface of the fourth lens is convex, and the image side surface is concave.

Images