Optical system

Abstract

The present application relates to an optical system, comprising a lens barrel with a receiving space, an imaging lens group and a plurality of spacer elements are arranged in the receiving space, the imaging lens group comprises six lenses with optical power in sequence from the object side to the image side along the optical axis; wherein the object side surface of the first lens is convex, the object side surface of the third lens is convex, the image side surface of the third lens is concave, and the image side surface of the sixth lens is concave. The optical system satisfies: 6.45 < R6 / d3s < 8.20; 0.50 < CT3 / (T34+EP23) < 0.75; 1.55 < (EP34+CP4) / CT4 < 2.00. The present application realizes the balance between miniaturization and structural stability by optimizing the ratio of lens center thickness and related spacing; improves the aberration correction effect and light imaging performance by constraining the matching relationship between lens curvature radius and spacer element inner diameter; strengthens the mechanical reliability and production consistency of the assembly by constraining the relationship between the size of the spacer element and the thickness of the lens, effectively solves the bottleneck of the prior art, and has far-reaching significance for meeting the industry technology upgrading and market high-quality application demand.

Description

Technical Field

[0001] This invention relates to the field of imaging lens technology, and more particularly to an optical system. Background Technology

[0002] As the optical imaging industry rapidly develops towards high resolution, miniaturization, and multi-scenario adaptability, downstream demands such as mobile phone imaging, automotive imaging intelligent assistance, and security monitoring are constantly increasing, and the market is placing higher requirements on the imaging quality, structural reliability, and mass production reliability of lenses.

[0003] However, in current lens design, key issues such as the matching of lens thickness and spacer elements, and the coordination of lens curvature and aperture have not yet been properly resolved. In particular, in the process of constraining the incident beam by the third and fourth lenses of a six-element optical imaging lens, the structural stability and assembly sensitivity of the third and fourth lenses and adjacent spacer elements are easily affected, resulting in a decrease in the lens's MTF performance and making it difficult to balance compact structure and overall performance. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a six-element optical system that, while ensuring a compact overall lens arrangement, improves the stability of the lens assembly process and batch production consistency, achieving a balance between excellent imaging performance and superior structural competitiveness.

[0005] To achieve the above-mentioned objective, the present invention provides an optical system comprising a lens barrel having a receiving space, characterized in that the receiving space is provided with an imaging lens group and a plurality of spacer elements.

[0006] The imaging lens group comprises, in sequence along the optical axis from the object side to the image side, six lenses with optical powers: a first lens with positive optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with negative optical power, and a sixth lens with negative optical power; wherein the object side of the first lens is convex, the object side of the third lens is convex and its image side is concave, and the image side of the sixth lens is concave.

[0007] The plurality of spacers includes at least: a second spacer located on the image side of the second lens and in at least partial contact with the image side of the second lens; a third spacer located on the image side of the third lens and in at least partial contact with the image side of the third lens; and a fourth spacer located on the image side of the fourth lens and in at least partial contact with the image side of the fourth lens.

[0008] The optical system satisfies:

[0009] 6.45 <R6 / d3s≤8.20;

[0010] 0.50≤CT3 / (T34+EP23)<0.75;

[0011] 1.55 < (EP34+CP4) / CT4 < 2.00;

[0012] Wherein, R6 is the radius of curvature of the image side of the third lens, d3s is the inner diameter of the object side of the third spacer, CT3 is the center thickness of the third lens, T34 is the air gap between the third lens and the fourth lens on the optical axis, EP23 is the spacing distance between the second spacer and the third spacer along the optical axis, EP34 is the spacing distance between the third spacer and the fourth spacer along the optical axis, CP4 is the maximum thickness of the fourth spacer along the optical axis, and CT4 is the center thickness of the fourth lens.

[0013] According to one technical solution of the present invention, the plurality of spacer elements further includes a first spacer element located on the image side of the first lens and in at least partial contact with the image side side of the first lens;

[0014] The optical system satisfies: -8.10 < EP01 / SAG12 < -5.10;

[0015] Wherein, EP01 is the distance between the object-side end face of the lens barrel and the first spacer element along the optical axis, and SAG12 is the axial displacement from the intersection of the image-side surface of the first lens and the optical axis to the vertex of the effective radius of the optical region of the image-side surface of the first lens.

[0016] According to one technical solution of the present invention, the plurality of spacer elements further includes a first spacer element located on the image side of the first lens and in at least partial contact with the image side side of the first lens;

[0017] The optical system satisfies: 2.15 <f12 / d1s<2.35;

[0018] Where f12 is the combined focal length of the first lens and the second lens, and d1s is the inner diameter of the object side of the first spacer element.

[0019] According to one technical solution of the present invention, the plurality of spacer elements further includes a first spacer element located on the image side of the first lens and in at least partial contact with the image side side of the first lens;

[0020] The optical system satisfies: 11.90 <D1m / CT2<18.45;

[0021] Wherein, D1m is the outer diameter of the image side of the first spacer element, and CT2 is the center thickness of the second lens.

[0022] According to one technical solution of the present invention, the optical system satisfies: 1.15 <d2s / R4<1.30;

[0023] Wherein, d2s is the inner diameter of the object side of the second spacer element, and R4 is the radius of curvature of the image side of the second lens.

[0024] According to one technical solution of the present invention, the optical system satisfies: 5.65 <f3 / (D3s-d3s)<6.75;

[0025] Wherein, f3 is the effective focal length of the third lens, D3s is the outer diameter of the object side of the third spacer element, and d3s is the inner diameter of the object side of the third spacer element.

[0026] According to one technical solution of the present invention, the optical system satisfies: 2.70 <f34 / d3s<3.05;

[0027] Wherein, f34 is the combined focal length of the third lens and the fourth lens, and d3s is the inner diameter of the object side surface of the third spacer element.

[0028] According to one technical solution of the present invention, the optical system satisfies: 19.85 <f4 / EP34<27.60;

[0029] Wherein, f4 is the effective focal length of the fourth lens, and EP34 is the spacing distance between the third and fourth spacers along the optical axis.

[0030] According to one technical solution of the present invention, the optical system satisfies: 7.05 < (D4s - d3s) / CT4 < 7.55;

[0031] Wherein, D4s is the outer diameter of the object side of the fourth spacer element, d3s is the inner diameter of the object side of the third spacer element, and CT4 is the center thickness of the fourth lens.

[0032] According to one technical solution of the present invention, the plurality of spacer elements further includes a fifth spacer element located on the image side of the fifth lens and in at least partial contact with the image side surface of the fifth lens;

[0033] The optical system satisfies: 1.30 < (EP34 + EP45) / (CT4 + CT5) < 1.55;

[0034] Wherein, EP34 is the distance between the third spacer element and the fourth spacer element along the optical axis, EP45 is the distance between the fourth spacer element and the fifth spacer element along the optical axis, CT4 is the center thickness of the fourth lens, and CT5 is the center thickness of the fifth lens.

[0035] According to one technical solution of the present invention, the optical system satisfies: -1.20≤T45 / SAG51<-1.00;

[0036] Wherein, T45 is the air gap between the fourth lens and the fifth lens on the optical axis, and SAG51 is the axial displacement from the intersection of the object-side surface of the fifth lens and the optical axis to the vertex of the effective radius of the optical region on the object-side surface of the fifth lens.

[0037] According to one technical solution of the present invention, the plurality of spacer elements further includes a sixth spacer element located on the image side of the sixth lens and in at least partial contact with the image side surface of the sixth lens;

[0038] The optical system satisfies: -1.50 <f6 / d6m<-0.95;

[0039] Where f6 is the effective focal length of the sixth lens, and d6m is the inner diameter of the image-side surface of the sixth spacer element.

[0040] According to one technical solution of the present invention, the plurality of spacers further includes: a fifth spacer located on the image side of the fifth lens and in at least partial contact with the image side surface of the fifth lens; and a sixth spacer located on the image side of the sixth lens and in at least partial contact with the image side surface of the sixth lens;

[0041] The optical system satisfies: -7.50 ≤ f6 / EP56 < -6.00;

[0042] Wherein, f6 is the effective focal length of the sixth lens, and EP56 is the spacing distance between the fifth and sixth spacers along the optical axis.

[0043] According to one technical solution of the present invention, the optical system satisfies: 0.65 <L / f34<0.75;

[0044] Where L is the maximum horizontal distance along the optical axis from the object-side end face to the image-side end face of the lens barrel, and f34 is the combined focal length of the third lens and the fourth lens.

[0045] According to one technical solution of the present invention, the optical system satisfies: 0.80 <d0m / d0s*tan(Semi-FOV)<0.90;

[0046] Where, d0m is the inner diameter of the image-side end face of the lens barrel, d0s is the inner diameter of the object-side end face of the lens barrel, and Semi-FOV is half of the maximum field angle of the optical system.

[0047] For the optical system of the present invention, the object side surface of the third lens is convex and its image side surface is concave. By defining that the ratio of the radius of curvature of the image side surface of the third lens to the inner diameter of the object side surface of the third spacer element satisfies the relationship of 6.45 < R6 / d3s ≤ 8.20, it can ensure that the light deflection ability of the image side surface of the third lens and the shielding ability of the inner wall of the lens barrel against stray light reach a balance. However, on this premise, after the third lens, the fourth lens and their adjacent spacer elements are assembled, problems such as insufficient structural strength and structural deformation of the structural members will occur, resulting in optical transmission within the deviation error due to eccentricity of the assembled optical system. This solution controls the optical system to simultaneously satisfy the relationships of 0.50 ≤ CT3 / (T34 + EP23) < 0.75 and 1.55 < (EP34 + CP4) / CT4 < 2.00, optimizes the design of the distances between the second spacer element, the third spacer element and the fourth spacer element and the dimensions of the centers of the third lens and the fourth lens, strengthens the bearing stability of each optical element between the second spacer element and the fourth spacer element, ensures the structural strength of the third lens and the fourth lens, reduces the problem of aberration superposition while ensuring the compactness of the lens, thereby improving the stability and consistency of lens assembly, and further ensuring the stable and reliable MTF performance of the lens and achieving high-quality imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the embodiments.

[0049] Figure 1 Shows a structural layout diagram of an optical system according to the present invention and a schematic diagram of some parameters;

[0050] Figure 2A 、 Figure 2B and Figure 2C Respectively show schematic diagrams of the structures of three optical systems according to Embodiment 1 of the present invention;

[0051] Figure 3 Shows the axial chromatic aberration curve and the astigmatism curve of the optical system according to Embodiment 1 of the present invention;

[0052] Figure 4 Shows the distortion curve and the lateral chromatic aberration curve of the optical system according to Embodiment 1 of the present invention;

[0053] Figure 5A 、 Figure 5B and Figure 5CSchematic diagrams of three optical systems according to Embodiment 2 of the present invention are shown respectively;

[0054] Figure 6 The on-axis chromatic aberration curve and astigmatism curve of the optical system according to Embodiment 2 of the present invention are shown;

[0055] Figure 7 The distortion curve and magnification chromatic aberration curve of the optical system according to Embodiment 2 of the present invention are shown;

[0056] Figure 8A , Figure 8B and Figure 8C Schematic diagrams of three optical systems according to Embodiment 3 of the present invention are shown respectively;

[0057] Figure 9 The on-axis chromatic aberration curve and astigmatism curve of the optical system according to Embodiment 3 of the present invention are shown;

[0058] Figure 10 The distortion curve and magnification chromatic aberration curve of the optical system according to Embodiment 3 of the present invention are shown;

[0059] Figure 11 The MTF defocus curve is shown when the optical system satisfies: R6 / d3s=7.50, CT3 / (T34+EP23)=0.30, (EP34+CP4) / CT4=0.85;

[0060] Figure 12 The MTF defocus curve is shown when the optical system satisfies: R6 / d3s=7.50, CT3 / (T34+EP23)=0.56, (EP34+CP4) / CT4=1.74;

[0061] Figure 13 The MTF defocus curve is shown when the optical system satisfies: R6 / d3s=7.50, CT3 / (T34+EP23)=0.68, (EP34+CP4) / CT4=1.89;

[0062] Figure 14 The MTF defocus curve is shown when the optical system satisfies: R6 / d3s=7.50, CT3 / (T34+EP23)=0.95, (EP34+CP4) / CT4=2.33. Detailed Implementation

[0063] To better understand the invention, various aspects of the invention will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of the invention and are not intended to limit the scope of the invention 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.

[0064] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of the invention, the first lens discussed below may also be referred to as the second lens or the third lens, or the first lens may also be referred to as the first lens element.

[0065] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0066] In this paper, the paraxial region refers to the area near the optical axis. If the lens surface is convex and its location is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and its location is not defined, it means that the lens surface is concave at least in the paraxial region. The surface shape in the paraxial region can be determined by the sign of the R value (R refers to the radius of curvature of the paraxial region). In this paper, the surface of each lens closest to the subject is called the object-side surface, and the surface of each lens closest to the image plane is called the image-side surface. For the object-side surface, when the R value is positive, it is considered convex, and when the R value is negative, it is considered concave; for the image-side surface, when the R value is positive, it is considered concave, and when the R value is negative, it is considered convex.

[0067] In this invention, the object side refers to the side of the optical system facing the object being photographed, and the image side refers to the side of the optical system facing the imaging plane. In the following text, the object side of a lens refers to the surface of the lens facing the object being photographed, and the image side of a lens refers to the surface of the lens facing the imaging plane. The object side of a spacer element refers to the surface of the spacer element facing the object being photographed, and the image side of the spacer element refers to the surface of the spacer element facing the imaging plane.

[0068] In the structural schematic diagram shown in this invention, the left side is the object side and the right side is the image side.

[0069] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense, unless expressly so defined herein.

[0070] It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this invention can be combined with each other. The following embodiments only illustrate several implementation methods of this invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this invention. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of this invention, and these all fall within the protection scope of this invention.

[0071] The present invention provides an optical system including a lens barrel, an imaging lens group and multiple spacer elements.

[0072] like Figure 1 As shown, the imaging lens group of an exemplary embodiment of the present invention includes six lenses with optical power, which are sequentially included from the object side to the image side along the optical axis as follows: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, wherein each lens is independent of the others and there is an air gap between each lens on the optical axis.

[0073] The plurality of spacer elements includes at least a first spacer element to a sixth spacer element; wherein, the first spacer element is located on the image side of the first lens and at least partially contacts the image side of the first lens; the second spacer element is located on the image side of the second lens and at least partially contacts the image side of the second lens; the third spacer element is located on the image side of the third lens and at least partially contacts the image side of the third lens; the fourth spacer element is located on the image side of the fourth lens and at least partially contacts the image side of the fourth lens; the fifth spacer element is located on the image side of the fifth lens and at least partially contacts the image side of the fifth lens; and the sixth spacer element is located on the image side of the sixth lens and at least partially contacts the image side of the sixth lens.

[0074] The imaging lens group and multiple spacer elements are housed within the lens barrel, which includes an object-side end face, an image-side end face, an outer ring surface, and an inner ring surface. Along the optical axis of the optical system, the inner ring surface of the lens barrel is stepped.

[0075] In some embodiments of the present invention, the optical system may also include color filters and / or protective glass.

[0076] The present invention provides an optical system, including an imaging lens group and a plurality of spacer elements. The imaging lens group sequentially includes, from the object side to the image side along the optical axis: a first lens with positive optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with negative optical power, and a sixth lens with negative optical power, which helps to balance the system aberration, meet the characteristics of high resolution, and thus has a better imaging effect.

[0077] Among them, the object side surface of the first lens is convex, the object side surface of the third lens is convex, its image side surface is concave, and the image side surface of the sixth lens is concave; and the optical system satisfies: 6.45 < R6 / d3s ≤ 8.20; 0.50 ≤ CT3 / (T34 + EP23) < 0.75; 1.55 < (EP34 + CP4) / CT4 < 2.00; where, R6 is the curvature radius of the image side surface of the third lens, d3s is the inner diameter of the object side surface of the third spacer element, CT3 is the central thickness of the third lens, T34 is the air gap between the third lens and the fourth lens on the optical axis, EP23 is the interval distance between the second spacer element and the third spacer element along the optical axis direction, EP34 is the interval distance between the third spacer element and the fourth spacer element along the optical axis direction, CP4 is the maximum thickness of the fourth spacer element along the optical axis direction, and CT4 is the central thickness of the fourth lens.

[0078] In the optical system of the present invention, the object side surface of the third lens is convex and its image side surface is concave. By defining the proportional relationship between the curvature radius of the image side surface of the third lens and the inner diameter of the object side surface of the third spacer element to satisfy 6.45 < R6 / d3s ≤ 8.20, it can ensure that the light deflection ability of the image side surface of the third lens and the shielding ability of the inner wall of the lens barrel against stray light reach a balance. However, on this premise, improper proportional dimensions of the central thickness of the third lens and the fourth lens and the air gap between them and the spacing between the second spacer element, the third spacer element and the fourth spacer element will cause problems such as insufficient strength of structural members and structural deformation, resulting in optical transmission within the deviation error due to eccentricity of the assembled optical system, affecting the MTF field curvature deviation degree and peak performance of the lens. This solution controls the optical system to simultaneously satisfy 0.50 ≤ CT3 / (T34 + EP23) < 0.75 and 1.55 < (EP34 + CP4) / CT4 < 2.00. By controlling the spacing between the second spacer element, the third spacer element and the fourth spacer element and optimizing the design of the dimensions of the centers of the third lens and the fourth lens, it alleviates the difficult problem of spacing control that is prone to occur during the assembly of the third lens and the fourth lens. While ensuring the compactness of the lens, it reduces the problem of superposition of structural deformation and aberration, thereby improving the stability and consistency of lens assembly, and further ensuring the stable and reliable MTF performance of the lens and achieving high-quality imaging.

[0079] In addition, refer to Figures 11 to 14 as shown Figure 11 The MTF defocus curve graph is shown when the optical system satisfies R6 / d3s = 7.5, CT3 / (T34 + EP23) = 0.3, and (EP34 + CP4) / CT4 = 0.85. The values of CT3 / (T34 + EP23) and (EP34 + CP4) / CT4 are beyond the lower limit of the range, increasing the risk of negative field curvature deviation. At the same time, there is a risk of MTF peak drop, reducing the imaging quality. Figure 12 The MTF defocus curve graph is shown when the optical system satisfies R6 / d3s = 7.5, CT3 / (T34 + EP23) = 0.56, and (EP34 + CP4) / CT4 = 1.74. The values of CT3 / (T34 + EP23) and (EP34 + CP4) / CT4 are within the range, and there is no abnormal deviation of the field curvature. Figure 13 The MTF defocus curve graph is shown when the optical system satisfies R6 / d3s = 7.5, CT3 / (T34 + EP23) = 0.68, and (EP34 + CP4) / CT4 = 1.89. The values of CT3 / (T34 + EP23) and (EP34 + CP4) / CT4 are within the range, and there is no abnormal deviation of the field curvature. Figure 14 The MTF defocus curve graph is shown when the optical system satisfies R6 / d3s = 7.5, CT3 / (T34 + EP23) = 0.95, and (EP34 + CP4) / CT4 = 2.33. The values of CT3 / (T34 + EP23) and (EP34 + CP4) / CT4 are beyond the upper limit of the range, increasing the risk of positive field curvature deviation. At the same time, there is a phenomenon of peak drop, affecting the imaging quality.

[0080] In some embodiments of the present invention, the optical system satisfies: -8.10 < EP01 / SAG12 < -5.10; where EP01 is the distance along the optical axis between the object-side end face of the lens barrel and the first spacer element, and SAG12 is the axial displacement from the intersection of the image side surface of the first lens and the optical axis to the vertex of the effective radius of the optical region of the image side surface of the first lens.

[0081] By constraining the matching relationship between the distance along the optical axis between the object-side end face of the lens barrel and the first spacer element and the axial displacement of the vertex of the effective radius of the optical region of the image side surface of the first lens, the structural stability of the head of the optical system is enhanced, the generation of initial aberration is reduced, laying a foundation for the aberration compensation and structural stability of the subsequent third and fourth lenses, and helping to achieve the balance of high image quality and light and small size.

[0082] In some embodiments of the present invention, the optical system satisfies: 2.15 < f12 / d1s < 2.35; where f12 is the combined focal length of the first lens and the second lens, and d1s is the inner diameter of the object side surface of the first spacer element.

[0083] By constraining the matching relationship between the focal lengths of the first and second lens combinations and the inner diameter of the object side surface of the first spacer element within this range, the lens has both a miniaturized structure and sufficient light transmission, effectively suppressing the superposition of eccentricity, stress, and aberration, and improving the MTF stability and mass production consistency. If the f12 / d1s ratio is too low, it will reduce the positioning stability of the first lens and the second lens, and easily cause problems such as assembly eccentricity and aberration deterioration; if the f12 / d1s ratio is too high, the inner diameter is too small, restricting the light transmission aperture, and there is a risk of aggravating vignetting and diffraction stray light generation.

[0084] In some embodiments of the present invention, the optical system satisfies: 11.90 < D1m / CT2 < 18.45; where D1m is the outer diameter of the image side surface of the first spacer element, and CT2 is the central thickness of the second lens.

[0085] By controlling the relationship between the outer diameter of the image side surface of the first spacer element and the central thickness of the second lens within this interval, the strength and assembly reliability of the second lens can be effectively improved, reducing the imaging deterioration of stress, eccentricity, and deformation waiting for materials, and taking into account the light miniaturization and high imaging quality of the lens. If the D1m / CT2 ratio is too small, stress extrusion occurs due to cramped assembly space, easily causing lens deformation; if the D1m / CT2 ratio is too high, the assembly strength is insufficient, and there is a risk of causing a decline in MTF performance after reliability testing.

[0086] In some embodiments of the present invention, the optical system satisfies: 1.15 < d2s / R4 < 1.30; where d2s is the inner diameter of the object side surface of the second spacer element, and R4 is the curvature radius of the image side surface of the second lens.

[0087] If the value of d2s / R4 is too small, it will cause the light angle in the second lens to be too large, increasing the sensitivity of the optical imaging lens and degrading the imaging quality. If the value of d2s / R4 is too large, it will cause the light angle in the second lens to be too small, resulting in a decrease in the light utilization efficiency of the optical imaging lens, and at the same time, more ineffective light will be generated, reducing the imaging quality. By restricting d2s / R4 within a reasonable range, the curvature radius of the image side surface of the second lens can be controlled appropriately, keeping the light angle within a reasonable range and effectively blocking the ineffective light reflected inside the second lens, reducing the risk of stray light generation and improving the imaging quality.

[0088] In some embodiments of the present invention, among multiple spacer elements, the optical system satisfies: 5.65 < f3 / (D3s - d3s) < 6.75; where f3 is the effective focal length of the third lens, D3s is the outer diameter of the object side surface of the third spacer element, and d3s is the inner diameter of the object side surface of the third spacer element.

[0089] By constraining the relationship between the effective focal length of the third lens and the difference between the outer diameter and the inner diameter of the third spacer element, it helps to optimize the structural adaptability between the third lens and the third spacer element. By constraining the support structure formed by the difference between the outer and inner diameters of the object side of the third spacer element, the reliability of the lens is improved.

[0090] In some embodiments of the present invention, the optical system satisfies: 2.70 < f34 / d3s < 3.05; where f34 is the combined focal length of the third lens and the fourth lens, and d3s is the inner diameter of the object side of the third spacer element.

[0091] By constraining the relationship between the combined focal length of the third and fourth lenses and the inner diameter of the third spacer element within this range, it effectively inhibits the increase in assembly eccentricity and assembly stress between the third lens and the fourth lens, can limit the divergence degree of light after passing through the third and fourth lenses, reduce the risk of aberration superposition, and helps to improve the stability of imaging.

[0092] In some embodiments of the present invention, the optical system satisfies: 19.85 < f4 / EP34 < 27.60; where f4 is the effective focal length of the fourth lens, and EP34 is the distance between the third spacer element and the fourth spacer element along the optical axis direction.

[0093] By constraining the optical system to satisfy 19.85 < f4 / EP34 < 27.60, it helps to improve the assembly adaptability between the fourth lens, the third spacer element and the fourth spacer element, strengthen the stability of the support structure inside the lens barrel, avoid structural displacement deviation under temperature change or vibration, stabilize the optical path transmission from the fourth lens to the fifth lens, and improve imaging clarity and field uniformity.

[0094] In some embodiments of the present invention, the optical system satisfies: 7.05 < (D4s - d3s) / CT4 < 7.55; where D4s is the outer diameter of the object side of the fourth spacer element, d3s is the inner diameter of the object side of the third spacer element, and CT4 is the central thickness of the fourth lens.

[0095] By constraining the relationship between the outer diameter of the object side of the fourth spacer element, the inner diameter of the image side of the third spacer element and the central thickness of the fourth lens, the structural stability of the fourth lens can be enhanced, the amount of assembly deformation caused by assembly stress can be reduced, and problems such as tilt, eccentricity, and looseness during the assembly process can be effectively inhibited, and the structural stiffness and stability can be improved.

[0096] In some embodiments of the present invention, the optical system satisfies: 1.30 < (EP34 + EP45) / (CT4 + CT5) < 1.55; where EP34 is the distance between the third spacer element and the fourth spacer element along the optical axis direction, EP45 is the distance between the fourth spacer element and the fifth spacer element along the optical axis direction, CT4 is the central thickness of the fourth lens, and CT5 is the central thickness of the fifth lens.

[0097] When this relationship is satisfied, it helps to optimize the stacking adaptability of the middle and rear elements in the lens barrel. Through the coordinated ratio of the spacer and the lens thickness, the assembly stability of the fourth and fifth lenses and the adjacent spacer elements is strengthened.

[0098] It can effectively resist the axial displacement and structural looseness caused by temperature change or vibration, and ensure the coaxiality of the optical system.

[0099] In some embodiments of the present invention, the optical system satisfies: -1.20 ≤ T45 / SAG51 < -1.00; where T45 is the air gap between the fourth lens and the fifth lens on the optical axis, and SAG51 is the axial displacement from the intersection of the object side surface of the fifth lens and the optical axis to the vertex of the effective radius of the optical region of the object side surface of the fifth lens.

[0100] By restricting the relationship between the air gap between the fourth and fifth lenses and the sagittal height of the object side surface of the fifth lens, it helps to restrict the incident angle and propagation path of the light entering the fifth lens, adapt to the concave characteristics of the object side surface of the fifth lens, and achieve the effect of efficiently correcting off-axis aberrations such as residual coma and distortion.

[0101] In some embodiments of the present invention, the optical system satisfies: -1.50 < f6 / d6m < -0.95; where f6 is the effective focal length of the sixth lens, and d6m is the inner diameter of the image side surface of the sixth spacer element.

[0102] By restricting the relationship between the focal length of the sixth lens and the sixth spacer element, the angle of the light exiting the sixth lens is restricted, and aberrations such as field curvature and distortion are corrected, which is beneficial to improving the uniformity of the full-field imaging and ensuring stability at high pixels. If the ratio of f6 / d6m is too large, the inner diameter of the image side of the sixth spacer element is too large, the optical propagation path is insufficiently restricted, and the residual aberrations are difficult to be fully corrected, which easily leads to a decrease in the imaging uniformity and MTF performance; if the ratio of f6 / d6m is too small, the increase in the light flux is blocked, and the vignetting of the edge field of view is aggravated, affecting the imaging clarity.

[0103] In some embodiments of the present invention, the optical system satisfies: -7.50 ≤ f6 / EP56 < -6.00; where f6 is the effective focal length of the sixth lens, and EP56 is the distance between the fifth spacer element and the sixth spacer element along the optical axis direction.

[0104] By constraining the relationship between the effective focal length of the sixth lens and the axial distance between the fifth and sixth spacer elements, the support stability of the sixth lens and its adjacent spacer elements is ensured, avoiding position offsets caused by temperature changes or vibrations, guaranteeing the coaxiality at the end of the optical system, and thus ensuring the imaging quality.

[0105] In some embodiments of the present invention, the optical system satisfies: 0.65 < L / f34 < 0.75; where L is the maximum horizontal distance along the optical axis from the object-side end face to the image-side end face of the lens barrel, and f34 is the combined focal length of the third lens and the fourth lens.

[0106] By constraining the relationship between the total length of the lens barrel and the ratio of the combined focal length of the third and fourth lenses, it helps to balance the miniaturization of the lens and the optical performance, while strictly controlling the size of the lens barrel, guaranteeing the core requirements of light convergence and aberration correction, achieving a lightweight and compact design of the lens, and achieving a high imaging quality in a limited space.

[0107] In some embodiments of the present invention, the optical system satisfies: 0.80 < d0m / d0s * tan(Semi-FOV) < 0.90; where d0m is the inner diameter of the image-side end face of the lens barrel, d0s is the inner diameter of the object-side end face of the lens barrel, and Semi-FOV is half of the maximum field angle of the optical system.

[0108] In the optical system of the present invention, the lens group is assembled in sequence from the first lens to the sixth lens. The inner diameter of the image-side end face of the lens barrel is greater than the inner diameter of the object-side end face of the lens barrel. By constraining the range of the product of the ratio of the inner diameter of the image-side face to the inner diameter of the object-side face of the lens barrel and the tangent value of the half field angle, while ensuring that the optical system has a large field angle, the force distribution at both ends of the lens barrel after assembly is optimized, the structural rigidity and anti-deformation ability of the lens barrel are improved, and the influence of external environmental changes on the deformation of the lens barrel and thus its optical performance is reduced.

[0109] The optical system according to the above-described embodiment of the present invention can use multiple lenses, such as the six lenses described above. By reasonably distributing the optical power, surface shape of each lens, and the arrangement of each spacer element, etc., the span of each gear in the cooperation between the lens and the lens barrel is relatively uniform, enhancing the ability of light convergence and improving the imaging quality of the optical system.

[0110] In some embodiments of the present invention, the lens material in the optical system provided by the present invention can be glass or plastic. When the lens material is plastic, the production cost can be effectively reduced. On the other hand, when the lens material is glass, due to the low dispersion characteristic of the glass itself, the geometric chromatic aberration of the optical system can be effectively corrected. The optical system provided by the present invention can adopt a fully plastic lens structure, which not only enables the lens to have excellent imaging performance, but also makes the structure of the lens relatively compact, and can better achieve the balance between the miniaturization of the lens and high image quality.

[0111] In some embodiments of the present invention, the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens can be spherical lenses or aspherical lenses. Compared with spherical structures, aspherical structures can effectively reduce the aberrations of the optical system, thereby reducing the number of lenses and the size of the lenses, and better achieving lens miniaturization. More specifically, the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens of the present invention can all be aspherical lenses, which can effectively reduce the aberrations of the optical system, thereby reducing the number of lenses and the size of the lenses, and achieving lens miniaturization.

[0112] When aspherical lenses are used, the surface shape of each aspherical lens in the optical system can be defined using, but is not limited to, the following aspherical formulas:

[0113]

[0114] In the above formula, The height perpendicular to the optical axis is along the optical axis. The axial distance from the vertex to the surface at the location; This represents the curvature at the vertex of the aspherical surface. The conic coefficient; , , , , , , ... represent aspherical coefficients of order 4, 6, 6, 10, 12, 14, 16... respectively.

[0115] The present invention will be further described below with reference to several embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical system are different. For specific differences, please refer to the parameter tables of each embodiment. The following embodiments are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments. Any changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be considered as equivalent substitutions and are included within the protection scope of the present invention. In addition, it should be noted that in the following Embodiment 1, there are three examples of optical systems 1001, 1002, and 1003; in Embodiment 2, there are three examples of optical systems 2001, 2002, and 2003; and in Embodiment 3, there are three examples of optical systems 3001, 3002, and 3003. The structures of the optical systems in different examples are different, but the optical parameters of the optical systems in the three examples in the same embodiment are the same, that is, the radius of curvature, center thickness, and other parameters of the first to sixth lenses, as well as the spacing distance and higher-order coefficients between the lenses are the same.

[0116] Example 1

[0117] The following is for reference Figures 2A to 4 Optical systems 1001, 1002, and 1003 according to Embodiment 1 of the present invention are described. Figure 2A , Figure 2B and Figure 2C Schematic diagrams of optical systems 1001, 1002, and 1003 according to Embodiment 1 of the present invention are shown respectively.

[0118] like Figure 2A , Figure 2B and Figure 2C As shown, the structural schematic diagrams of optical systems 1001, 1002, and 1003 all include a lens barrel P0, imaging lens groups E1 to E6, and multiple spacer elements P1 to P6.

[0119] In Embodiment 1, the schematic diagrams of optical systems 1001, 1002, and 1003 use the same imaging lens group. The imaging lens group, from the object side to the image side, includes: a first lens E1 with positive optical power, a second lens E2 with negative optical power, a third lens E3 with positive optical power, a fourth lens E4 with positive optical power, a fifth lens E5 with negative optical power, and a sixth lens E6 with negative optical power. Specifically, the object side S1 and image side S2 of the first lens E1 are both convex; the object side S3 of the second lens E2 is convex, and its image side S4 is concave; the object side S5 of the third lens E3 is convex, and its image side S6 is concave; the object side S7 of the fourth lens E4 is convex, and its image side S8 is concave; the object side S9 of the fifth lens E5 is concave, and its image side S10 is convex; and the object side S11 of the sixth lens E6 is convex, and its image side S12 is concave. Light from the object passes sequentially through surfaces S1 to S14 and is finally imaged onto the imaging surface S15 (not shown in the figure). Surfaces S13 (not shown in the figure) and S14 (not shown in the figure) can be the object-side and image-side surfaces of filters or protective glass, OBJ (not shown in the figure) is the object surface, and STO (not shown in the figure) is the aperture stop located on the object side of the first lens E1.

[0120] Table 1 lists the relevant parameters of each lens in the optical system of this embodiment, including: surface type, radius of curvature, thickness, refractive index of the material, Abbe number and conic coefficient, wherein the units of radius of curvature and thickness are millimeters (mm).

[0121]

[0122] Table 1

[0123] Table 2 lists the aspherical coefficients of each aspherical lens in the optical system of this embodiment, including: A4, A6, A8, A... 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 A 30 .

[0124]

[0125] Table 2

[0126] like Figure 2A , 2B As shown in Figure 2C, optical systems 1001, 1002, and 1003 all include a first spacer element P1, a second spacer element P2, a third spacer element P3, a fourth spacer element P4, a fifth spacer element P5, and a sixth spacer element P6.

[0127] Unlike optical systems 1002 and 1003, optical system 1001 further includes a first auxiliary spacer element P1b, which is disposed on the image side of the first spacer element P1 and at least partially contacts the image side of the first spacer element P1.

[0128] Figure 3 (A) shows the on-axis chromatic aberration curve of the optical system of Embodiment 1, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 3 (B) shows the astigmatism curves of the optical system of Embodiment 1, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 4 (A) shows the distortion curves of the optical system of Embodiment 1, which represent the distortion magnitude values ​​corresponding to different field of view angles. Figure 4 (B) shows the magnification chromatic aberration curve of the optical system of Embodiment 1, which represents the deviation of different image heights on the imaging plane after light passes through the lens. According to Figures 3 to 4 As can be seen, the optical system given in Example 1 can achieve good imaging quality.

[0129] Example 2

[0130] The following is for reference Figures 5A to 7 Optical systems 2001, 2002, and 2003 according to Embodiment 2 of the present invention are described. Figure 5A , Figure 5B and Figure 5CSchematic diagrams of optical systems 2001, 2002 and 2003 according to Embodiment 2 of the present invention are shown respectively.

[0131] like Figure 5A , Figure 5B and Figure 5C As shown, the structural schematic diagrams of optical systems 2001, 2002, and 2003 all include a lens barrel P0, imaging lens groups E1 to E6, and multiple spacer elements P1 to P6.

[0132] In Embodiment 2, the structural schematic diagrams of optical systems 2001, 2002, and 2003 employ the same imaging lens group. The imaging lens group, from the object side to the image side, sequentially includes: a first lens E1 with positive optical power, a second lens E2 with negative optical power, a third lens E3 with positive optical power, a fourth lens E4 with positive optical power, a fifth lens E5 with negative optical power, and a sixth lens E6 with negative optical power. Specifically, the object side S1 of the first lens E1 is convex, and its image side S2 is concave; the object side S3 of the second lens E2 is convex, and its image side S4 is concave; the object side S5 of the third lens E3 is convex, and its image side S6 is concave; the object side S7 of the fourth lens E4 is convex, and its image side S8 is concave; both the object side S9 and image side S10 of the fifth lens E5 are concave; and the object side S11 of the sixth lens E6 is convex, and its image side S12 is concave. Light from the object passes sequentially through surfaces S1 to S14 and is finally imaged onto the imaging surface S15 (not shown in the figure). Surfaces S13 (not shown in the figure) and S14 (not shown in the figure) can be the object-side and image-side surfaces of filters or protective glass, OBJ (not shown in the figure) is the object surface, and STO (not shown in the figure) is the aperture stop located on the object side of the first lens E1.

[0133] Table 3 lists the relevant parameters of each lens in the optical system of this embodiment, including: surface type, radius of curvature, thickness, refractive index of the material, Abbe number and conic coefficient, wherein the units of radius of curvature and thickness are millimeters (mm).

[0134]

[0135] Table 3

[0136] Table 4 lists the aspherical coefficients of each aspherical lens in the optical system of this embodiment, including: A4, A6, A8, A... 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A26 A 28 A 30 .

[0137]

[0138] Table 4

[0139] like Figure 5A , 5B As shown in Figure 5C, optical systems 2001, 2002, and 2003 all include a first spacer element P1, a second spacer element P2, a third spacer element P3, a fourth spacer element P4, a fifth spacer element P5, and a sixth spacer element P6.

[0140] Unlike optical systems 2002 and 2003, optical system 2001 further includes a first auxiliary spacer element P1b, which is disposed on the image side of the first spacer element P1 and at least partially contacts the image side of the first spacer element P1.

[0141] Figure 6 (A) shows the on-axis chromatic aberration curve of the optical system of Embodiment 2, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 6 (B) shows the astigmatism curves of the optical system of Embodiment 2, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 7 (A) shows the distortion curves of the optical system of Embodiment 2, which represent the distortion magnitude values ​​corresponding to different field of view angles. Figure 7 (B) shows the magnification chromatic aberration curve of the optical system of Embodiment 2, which represents the deviation of different image heights on the imaging plane after light passes through the lens. According to Figures 6 to 7 It can be seen that the optical system given in Example 2 can achieve good imaging quality.

[0142] Example 3

[0143] The following is for reference Figures 8A to 10 The optical systems 3001, 3002, and 3003 according to Embodiment 3 of the present invention are described. Figure 8A , Figure 8B and Figure 8C Schematic diagrams of optical systems 3001, 3002 and 3003 according to Embodiment 3 of the present invention are shown respectively.

[0144] like Figure 8A , Figure 8B and Figure 8C As shown, the structural schematic diagrams of optical systems 3001, 3002, and 3003 all include a lens barrel P0, imaging lens groups E1 to E6, and multiple spacer elements P1 to P6.

[0145] In Embodiment 3, the structural schematic diagrams of optical systems 3001, 3002, and 3003 employ the same imaging lens group. The imaging lens group, from the object side to the image side, sequentially includes: a first lens E1 with positive optical power, a second lens E2 with negative optical power, a third lens E3 with positive optical power, a fourth lens E4 with positive optical power, a fifth lens E5 with negative optical power, and a sixth lens E6 with negative optical power. Specifically, the object-side surface S1 and image-side surface S2 of the first lens E1 are both convex; the object-side surface S3 of the second lens E2 is convex, and its image-side surface S4 is concave; the object-side surface S5 of the third lens E3 is convex, and its image-side surface S6 is concave; the object-side surface S7 of the fourth lens E4 is convex, and its image-side surface S8 is concave; the object-side surface S9 of the fifth lens E5 is concave, and its image-side surface S10 is convex; and the object-side surface S11 of the sixth lens E6 is convex, and its image-side surface S12 is concave. Light from the object passes sequentially through surfaces S1 to S14 and is finally imaged on the imaging surface S15 (not shown). Surfaces S13 (not shown) and S14 (not shown) can be the object-side and image-side surfaces of filters or protective glass, OBJ (not shown) is the object surface, and STO (not shown) is the aperture stop located on the object side of the first lens E1.

[0146] Table 5 lists the relevant parameters of each lens in the optical system of this embodiment, including: surface type, radius of curvature, thickness, refractive index of the material, Abbe number and conic coefficient, wherein the units of radius of curvature and thickness are millimeters (mm).

[0147]

[0148] Table 5

[0149] Table 6 lists the aspherical coefficients of each aspherical lens in the optical system of this embodiment, including: A4, A6, A8, A... 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 A 30 .

[0150]

[0151] Table 6

[0152] like Figure 8A , 8BAs shown in Figure 8C, optical systems 3001, 3002, and 3003 all include a first spacer element P1, a second spacer element P2, a third spacer element P3, a fourth spacer element P4, a fifth spacer element P5, and a sixth spacer element P6.

[0153] Unlike optical systems 3002 and 3003, optical system 3001 further includes a first auxiliary spacer element P1b, which is disposed on the image side of the first spacer element P1 and at least partially contacts the image side of the first spacer element P1.

[0154] Figure 9 (A) shows the on-axis chromatic aberration curve of the optical system of Embodiment 3, which represents the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 9 (B) shows the astigmatism curves of the optical system of Embodiment 3, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 10 (A) shows the distortion curves of the optical system of Embodiment 3, which represent the distortion magnitude values ​​corresponding to different field of view angles. Figure 10 (B) shows the magnification chromatic aberration curve of the optical system of Embodiment 3, which represents the deviation of different image heights on the imaging plane after light passes through the lens. According to Figures 9 to 10 As can be seen, the optical system given in Example 3 can achieve good imaging quality.

[0155] In summary, the optical parameters of the optical systems 1001, 1002, 1003, 2001, 2002, 2003, 3001, 3002 and 3003 of Embodiments 1 to 3 are shown in Table 7 below.

[0156]

[0157] Table 7

[0158] The basic parameters of the spacer elements and lens barrels of the optical systems 1001, 1002, 1003, 2001, 2002, 2003, 3001, 3002 and 3003 of Examples 1 to 3 are shown in Table 8 below, where the unit of each parameter is mm.

[0159]

[0160] Table 8

[0161] The optical systems 1001, 1002, 1003, 2001, 2002, 2003, 3001, 3002, and 3003 of Examples 1 to 3 satisfy the relationships shown in Table 9.

[0162]

[0163] Table 9

[0164] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention is not limited to the specific combination of the above-described technical features, but also includes other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this invention.

Claims

1. An optical system comprising a lens barrel having a receiving space, characterized in that, The containment space is equipped with an imaging lens group and multiple spacer elements. The imaging lens group comprises, in sequence along the optical axis from the object side to the image side, six lenses with optical powers: a first lens with positive optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with negative optical power, and a sixth lens with negative optical power; wherein the object side of the first lens is convex, the object side of the third lens is convex and its image side is concave, and the image side of the sixth lens is concave. The plurality of spacers includes at least: a second spacer located on the image side of the second lens and in at least partial contact with the image side of the second lens; a third spacer located on the image side of the third lens and in at least partial contact with the image side of the third lens; and a fourth spacer located on the image side of the fourth lens and in at least partial contact with the image side of the fourth lens. The optical system satisfies: 6.45 <R6 / d3s≤8.20; 0.50≤CT3 / (T34+EP23)<0.75; 1.55 < (EP34 + CP4) / CT4 < 2.00; Wherein, R6 is the radius of curvature of the image side of the third lens, d3s is the inner diameter of the object side of the third spacer, CT3 is the center thickness of the third lens, T34 is the air gap between the third lens and the fourth lens on the optical axis, EP23 is the spacing distance between the second spacer and the third spacer along the optical axis, EP34 is the spacing distance between the third spacer and the fourth spacer along the optical axis, CP4 is the maximum thickness of the fourth spacer along the optical axis, and CT4 is the center thickness of the fourth lens.

2. The optical system according to claim 1, characterized in that, The plurality of spacer elements further includes a first spacer element located on the image side of the first lens and in at least partial contact with the image side of the first lens; The optical system satisfies: -8.10 < EP01 / SAG12 < -5.10; Wherein, EP01 is the distance between the object-side end face of the lens barrel and the first spacer element along the optical axis, and SAG12 is the axial displacement from the intersection of the image-side surface of the first lens and the optical axis to the vertex of the effective radius of the optical region of the image-side surface of the first lens.

3. The optical system according to claim 1, characterized in that, The plurality of spacer elements further includes a first spacer element located on the image side of the first lens and in at least partial contact with the image side of the first lens; The optical system satisfies: 2.15 <f12 / d1s<2.35; Where f12 is the combined focal length of the first lens and the second lens, and d1s is the inner diameter of the object side of the first spacer element.

4. The optical system according to claim 1, characterized in that, The plurality of spacer elements further includes a first spacer element located on the image side of the first lens and in at least partial contact with the image side of the first lens; The optical system satisfies: 11.90 <D1m / CT2<18.45; Wherein, D1m is the outer diameter of the image side of the first spacer element, and CT2 is the center thickness of the second lens.

5. The optical system according to claim 1, characterized in that, The optical system satisfies: 1.15 <d2s / R4<1.30; Wherein, d2s is the inner diameter of the object side of the second spacer element, and R4 is the radius of curvature of the image side of the second lens.

6. The optical system according to claim 1, characterized in that, The optical system satisfies: 5.65 <f3 / (D3s-d3s)<6.75; Wherein, f3 is the effective focal length of the third lens, D3s is the outer diameter of the object side of the third spacer element, and d3s is the inner diameter of the object side of the third spacer element.

7. The optical system according to claim 1, characterized in that, The optical system satisfies: 2.70 <f34 / d3s<3.05; Wherein, f34 is the combined focal length of the third lens and the fourth lens, and d3s is the inner diameter of the object side surface of the third spacer element.

8. The optical system according to claim 1, characterized in that, The optical system satisfies: 19.85 <f4 / EP34<27.60; Wherein, f4 is the effective focal length of the fourth lens, and EP34 is the spacing distance between the third and fourth spacers along the optical axis.

9. The optical system according to claim 1, characterized in that, The optical system satisfies: 7.05 < (D4s - d3s) / CT4 < 7.55; Wherein, D4s is the outer diameter of the object side of the fourth spacer element, d3s is the inner diameter of the object side of the third spacer element, and CT4 is the center thickness of the fourth lens.

10. The optical system according to claim 1, characterized in that, The plurality of spacer elements also includes a fifth spacer element located on the image side of the fifth lens and in at least partial contact with the image side surface of the fifth lens; The optical system satisfies: 1.30 < (EP34 + EP45) / (CT4 + CT5) < 1.55; Wherein, EP34 is the distance between the third spacer element and the fourth spacer element along the optical axis, EP45 is the distance between the fourth spacer element and the fifth spacer element along the optical axis, CT4 is the center thickness of the fourth lens, and CT5 is the center thickness of the fifth lens.

Images