Optical imaging system, imaging device and electronic device

Abstract

The present application relates to an optical imaging system, an imaging device and an electronic device. The optical imaging system is used for infrared light imaging, and includes, in order from the object side to the image side along the optical axis, a first lens with refractive power; a second lens with refractive power; a third lens with positive refractive power, the image side surface of the third lens is convex at the circumference; a fourth lens with negative refractive power; a fifth lens with positive refractive power, the image side surface of the fifth lens is concave at the optical axis, the object side surface and the image side surface of the fifth lens are both aspherical, and at least one of the object side surface and the image side surface contains at least one inflection point; the optical imaging system satisfies the following relationship: TT / f<1.5; wherein TT is the distance from the object side surface of the first lens to the image side surface of the fifth lens on the optical axis, and f is the effective focal length of the optical imaging system. The above-mentioned optical imaging system can capture images with high resolution, and also has the characteristics of large aperture and miniaturization.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to an optical imaging system, an imaging device and an electronic device suitable for infrared light imaging. Background Art

[0002] With the rapid development of time-of-flight (TOF) technology, combined with the photosensitive elements of TOF 3D technology, the application areas of TOF lenses have become very wide, including face unlocking of mobile devices, autonomous driving of cars, human-machine interface and gaming, industrial machine vision and measurement, security monitoring, etc.

[0003] A TOF lens receives light from a TOF transmitter that's reflected off the subject. Unlike conventional optical lenses, a TOF lens requires an infrared bandpass filter to ensure only light with the same wavelength as the transmitter is captured by the sensor. The TOF lens not only records the depth of the subject to form an image, but also allows for varying blur intensities for objects and people at different depths, significantly enhancing the quality of the shot.

[0004] However, traditional TOF lenses are mostly four-element structures, which make it difficult to obtain accurate depth information of the subject, resulting in low imaging resolution and poor user shooting experience. Summary of the Invention

[0005] Based on this, it is necessary to provide an improved optical imaging system to address the problems of low resolution and poor imaging effect of traditional TOF lenses.

[0006] An optical imaging system for infrared light imaging comprises, in order from the object side to the image side along the optical axis, a first lens having refractive power; a second lens having refractive power; a third lens having positive refractive power, the image side surface of the third lens being convex at the circumference; a fourth lens having negative refractive power; a fifth lens having positive refractive power, the image side surface of the fifth lens being concave at the optical axis; both the object side surface and the image side surface of the fifth lens being aspherical, and at least one of the object side surface and the image side surface includes at least one inflection point; the optical imaging system satisfies the following relationship:

[0007] TT / f<1.5;

[0008] Wherein, TT is the distance from the object side of the first lens to the image side of the fifth lens on the optical axis, and f is the effective focal length of the optical imaging system.

[0009] The above-mentioned optical imaging system can be suitable for infrared light imaging by reasonably allocating the refractive power, surface shape and effective focal length of each lens; at the same time, by controlling the distance from the object side of the first lens to the image side of the fifth lens on the optical axis and the effective focal length of the optical imaging system to satisfy the above-mentioned relationship, the light projected by the above-mentioned optical imaging system can be better converged to the imaging surface, thereby improving its imaging resolution capability, and can also effectively shorten the overall length of the optical imaging system, thereby realizing the miniaturization of the system.

[0010] In one embodiment, the optical imaging system satisfies the following relationship:

[0011] 0.7 mm < CT1 + CT2 + CT3 < 1.6 mm; wherein CT1 is the thickness of the first lens on the optical axis, CT2 is the thickness of the second lens on the optical axis, and CT3 is the thickness of the third lens on the optical axis.

[0012] By controlling the thicknesses of the first lens, the second lens, and the third lens on the optical axis to satisfy the above relationship, the environmental tolerance of the first lens can be enhanced. Configuring the thicknesses of the second lens and the third lens on the optical axis on this basis is beneficial to the miniaturization design of the optical imaging system. It can also avoid the problems of low lens strength and low manufacturing yield caused by excessively thin lenses.

[0013] In one embodiment, the optical imaging system satisfies the following relationship:

[0014] 0.25mm<T12+T23+T34+T45<0.95mm; wherein, T12 is the distance from the image side surface of the first lens to the objective side surface of the second lens on the optical axis, T23 is the distance from the image side surface of the second lens to the objective side surface of the third lens on the optical axis, T34 is the distance from the image side surface of the third lens to the objective side surface of the fourth lens on the optical axis, and T45 is the distance from the image side surface of the fourth lens to the objective side surface of the fifth lens on the optical axis.

[0015] By controlling the air spacing between adjacent lenses on the optical axis to satisfy the above relationship, it is beneficial to achieve miniaturization of the optical imaging system and improve the assembly yield of the lens; when the sum of the air spacing between adjacent lenses on the optical axis is less than or equal to 0.25mm, the adjustable space between adjacent lenses will be too small, which will easily increase the system sensitivity and be unfavorable for the assembly of the lens; and when the sum of the air spacing between adjacent lenses on the optical axis is greater than or equal to 0.95mm, it is not conducive to the miniaturization of the optical imaging system.

[0016] In one embodiment, the optical imaging system satisfies the following relationship:

[0017] 0.5<f3 / f5<3.5; wherein f3 is the effective focal length of the third lens, and f5 is the effective focal length of the fifth lens.

[0018] By controlling the effective focal lengths of the third and fifth lenses to satisfy the above relationship, it is beneficial to allocate appropriate positive refractive power to the third and fifth lenses to balance the negative spherical aberration generated by the fourth lens, thereby reducing the tolerance sensitivity of the optical imaging system and improving its imaging quality. However, when the ratio of the effective focal length of the third lens to the effective focal length of the fifth lens is less than or equal to 0.5, the third lens needs to provide the majority of the positive refractive power, resulting in excessive curvature of the object side of the third lens and poor molding, which in turn affects the manufacturing yield of the lens. When the ratio of the effective focal length of the third lens to the effective focal length of the fifth lens is greater than or equal to 3.5, it is easy to cause an unbalanced distribution of refractive power between the second and fourth lenses, resulting in excessive aberrations in the optical imaging system and hindering aberration correction.

[0019] In one embodiment, the optical imaging system satisfies the following relationship: FNO≤1.3; wherein FNO is the aperture number of the optical imaging system.

[0020] By controlling the aperture number of the optical imaging system to satisfy the above relationship, the light transmittance of the optical imaging system can be effectively increased, so that the detailed information of the subject can be clearly obtained even under low-light conditions, thereby improving the imaging quality.

[0021] In one embodiment, the optical imaging system satisfies the following relationship: 1.4<nd1<1.7; 1.4<nd2<1.7; 1.4<nd4<1.7; wherein nd1 is the refractive index of the first lens, nd2 is the refractive index of the second lens, and nd4 is the refractive index of the fourth lens.

[0022] By properly selecting lens materials, the refractive indices of the first lens, the second lens, and the fourth lens satisfy the above relationship, which is beneficial for eliminating chromatic aberration of the optical imaging system and improving the imaging quality of the optical imaging system.

[0023] In one embodiment, the optical imaging system satisfies the following relationship:

[0024] 0.85<SD32 / SD11<1.3;

[0025] Among them, SD32 is the maximum effective semi-aperture of the image side of the third lens, and SD11 is the maximum effective semi-aperture of the object side of the first lens.

[0026] By controlling the maximum effective semi-aperture of the image-side surface of the third lens and the maximum effective semi-aperture of the object-side surface of the first lens to satisfy the above relationship, the structural design of the optical imaging system can be made more compact, thereby reducing its space occupation volume and achieving miniaturization; at the same time, more light can be incident on the optical imaging system, thereby improving the relative brightness of the image.

[0027] In one embodiment, the optical imaging system satisfies the following relationship: FFL>0.7mm;

[0028] Wherein, FFL is the distance from the point on the optical axis farthest from the center of the lens surface projected on the side surface of the fifth lens image to the imaging surface of the optical imaging system.

[0029] By controlling the image-side surface of the fifth lens to satisfy the above relationship, the optical imaging system can have sufficient focusing space during the installation of the lens module, thereby improving the assembly yield of the lens module. At the same time, it can also effectively increase the focal depth of the optical imaging system to obtain more depth information of the subject.

[0030] In one embodiment, the optical imaging system satisfies the following relationship: R9 / R10<1.0; wherein R9 is the curvature radius of the object side of the fifth lens at the optical axis, and R10 is the curvature radius of the image side of the fifth lens at the optical axis.

[0031] By rationally configuring the radius of curvature of the object-side surface of the fifth lens at the optical axis and the radius of curvature of the image-side surface of the fifth lens at the optical axis so that the two satisfy the aforementioned relationship, the machinability of the fifth lens can be enhanced, thereby facilitating correction of coma aberration of the optical imaging system and preventing other aberrations of the optical imaging system from being excessive.

[0032] In one embodiment, the optical imaging system satisfies the following relationship:

[0033] 1.0<|f3 / R6|<6.0; wherein f3 is the effective focal length of the third lens element, and R6 is the radius of curvature of the image side surface of the third lens element at the optical axis.

[0034] By controlling the effective focal length of the third lens and the radius of curvature of the image-side surface of the third lens at the optical axis to satisfy the above relationship, it is beneficial to correct the astigmatism aberration of the optical imaging system, thereby improving the imaging quality of the optical imaging system.

[0035] The present application also provides an imaging device.

[0036] An imaging device comprises the optical imaging system as described above; and a photosensitive element, wherein the photosensitive element is arranged on the image side of the optical imaging system.

[0037] The above-mentioned imaging device, using the aforementioned optical imaging system, can image the infrared light emitted or reflected by the subject, and capture an image with bright pictures, high resolution and small aberration. At the same time, the imaging device also has the characteristics of miniaturization, which is convenient for adaptation to devices with limited size such as thin and light electronic devices.

[0038] The present application also provides an electronic device.

[0039] An electronic device comprises a housing and the imaging device as described above, wherein the imaging device is mounted on the housing.

[0040] The electronic device has a light and thin structure. The imaging device can be used to capture clearer images containing depth information of the object. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the structure of the optical imaging system of Example 1 of the present application is shown;

[0042] Figure 2 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical imaging system of Example 1 are respectively shown;

[0043] Figure 3 Schematic diagram of the structure of the optical imaging system of Example 2 of the present application is shown;

[0044] Figure 4 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical imaging system of Example 2 are respectively shown;

[0045] Figure 5 Schematic diagram of the structure of the optical imaging system of Example 3 of the present application is shown;

[0046] Figure 6 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical imaging system of Example 3 are respectively shown;

[0047] Figure 7 A schematic structural diagram of an optical imaging system according to Example 4 of the present application is shown;

[0048] Figure 8 1. The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical imaging system of Example 4 are respectively shown;

[0049] Figure 9 Schematic diagram of the structure of the optical imaging system of Example 5 of the present application is shown;

[0050] Figure 10 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical imaging system of Example 5 are respectively shown;

[0051] Figure 11 Schematic diagram of the structure of the optical imaging system of Example 6 of the present application is shown;

[0052] Figure 12 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical imaging system of Example 6 are respectively shown. DETAILED DESCRIPTION

[0053] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0054] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may also be an element centered thereon. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an element centered thereon at the same time. The terms "vertical", "horizontal", "left", "right", "up", "down", "front", "rear", "circumferential" and similar expressions used herein are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0055] 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.

[0056] For ease of explanation, the shapes of spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0058] Traditional time-of-flight (TOF) lenses typically use a four-element structure to ensure miniaturization. However, these four-element TOF lenses struggle to obtain more accurate depth information of the subject, and their image resolution is also low, resulting in a poor user experience.

[0059] The defects in the above solutions are the results obtained by the inventor after practice and careful research. Therefore, the process of discovering the above problems and the solutions proposed in the embodiments of this application below should be the contributions made by the inventor to this application during the application process.

[0060] The features, principles and other aspects of the present application will be described in detail below.

[0061] Please also refer to Figure 1 、 Figure 3 、 Figure 5 、 Figure 7 、 Figure 9 and Figure 11 The present invention provides a five-lens TOF optical imaging system. This optical imaging system is capable of imaging infrared light while maintaining high resolution while ensuring miniaturization. Specifically, it includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens, arranged in order from the object side to the image side along the optical axis. The imaging plane of the optical imaging system is located on the image side of the fifth lens.

[0062] The first lens and the second lens have refractive power so that the light emitted from the TOF emission end and reflected by the object can be captured by the optical imaging system.

[0063] The third lens element has positive refractive power, and the image-side surface of the third lens element is convex at the optical axis, which is beneficial for correcting astigmatism and aberration of the optical imaging system, thereby improving the imaging quality of the optical imaging system.

[0064] The fourth lens element has negative refractive power, which is beneficial for correcting chromatic aberration of the optical imaging system, thereby improving the imaging quality of the optical imaging system.

[0065] The fifth lens element has positive refractive power, and the image-side surface of the fifth lens element is concave at the optical axis, which is beneficial for combining with the positive refractive power of the third lens element to balance the negative spherical aberration produced by the fourth lens element and correct the coma of the optical imaging system; the object-side surface and the image-side surface of the fifth lens element are both aspherical, which is beneficial for further correcting the aberration of the optical imaging system; at least one of the object-side surface and the image-side surface of the fifth lens element contains at least one inflection point, which can effectively suppress the angle of off-axis field of view light incident on the photosensitive element, so that it can more accurately match the photosensitive element, thereby improving the light energy receiving efficiency of the photosensitive element.

[0066] Specifically, the optical imaging system satisfies the following relationship: TT / f<1.5; wherein TT is the distance on the optical axis from the object side of the first lens to the image side of the fifth lens, and f is the effective focal length of the optical imaging system. TT / f can be 1.0, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40 or 1.45. Under the condition that the above relationship is satisfied, the total length of the optical imaging system can be shortened and the miniaturization of the lens can be ensured while the light projected by the optical imaging system can be better converged to the imaging surface, thereby improving its imaging resolution capability. When TT / f is greater than or equal to 1.5, the distance on the optical axis from the object side of the first lens to the image side of the fifth lens will be too long, which is not conducive to the miniaturization of the system; or the effective focal length of the optical imaging system will be too small, which will reduce the imaging resolution capability of the system.

[0067] When the above optical imaging system is used for imaging, the infrared light emitted or reflected by the subject enters the optical imaging system from the object side, passes through the first lens, the second lens, the third lens, the fourth lens and the fifth lens in sequence, and finally converges onto the imaging surface.

[0068] By rationally allocating the refractive power, surface shape, and effective focal length of each lens, the above-mentioned optical imaging system can enhance its infrared imaging resolution and low-light shooting capabilities while ensuring its miniaturization. Furthermore, the optical imaging system of the present application can maintain good imaging quality across a wide infrared wavelength range, thus meeting the operational requirements of a TOF lens.

[0069] In an exemplary embodiment, the object side surface and image side surface of each lens in the first to fifth lenses can be set to be aspherical, thereby improving the flexibility of lens design, effectively correcting aberrations, and improving the imaging resolution of the optical imaging system. In other embodiments, the object side surface and image side surface of each lens in the optical imaging system can also be spherical. It should be noted that the above embodiments are only examples of some embodiments of the present application. In some embodiments, the surface of each lens in the optical imaging system can be any combination of aspherical or spherical surfaces.

[0070] In an exemplary embodiment, an infrared bandpass filter is disposed between the fifth lens and the imaging surface of the optical imaging system. This infrared bandpass filter can select the wavelength of light incident on the imaging surface of the optical imaging system. For example, only infrared light emitted by the TOF transmitter, which is reflected by the object being photographed, can be passed through, thereby ensuring that the optical imaging system meets the application requirements of TOF technology. In other embodiments, a filter film can be disposed on the object side or image side of one of the first to fifth lenses to achieve the same wavelength selection effect, which is not limited in this application.

[0071] In an exemplary embodiment, the optical imaging system satisfies the following relationship:

[0072] 0.7mm<CT1+CT2+CT3<1.6mm; where CT1 is the thickness of the first lens on the optical axis, CT2 is the thickness of the second lens on the optical axis, and CT3 is the thickness of the third lens on the optical axis. CT1+CT2+CT3 can be 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1.0mm, 1.10mm, 1.20mm, 1.30mm, 1.35mm, or 1.40mm. Under the condition that the above relationship is met, the environmental tolerance of the first lens can be enhanced, and the thickness of the second and third lenses on the optical axis can be configured on this basis, which is conducive to the miniaturization design of the optical imaging system. However, when CT1+CT2+CT3 is less than or equal to 0.7mm, the lens will be too thin, resulting in low lens strength and low manufacturing yield; and when CT1+CT2+CT3 is greater than or equal to 1.6mm, the lens will be too thick, which is not conducive to the miniaturization of the optical imaging system.

[0073] In an exemplary embodiment, the optical imaging system satisfies the following relationship:

[0074] 0.25mm<T12+T23+T34+T45<0.95mm; wherein, T12 is the distance from the image side of the first lens to the object side of the second lens on the optical axis, T23 is the distance from the image side of the second lens to the object side of the third lens on the optical axis, T34 is the distance from the image side of the third lens to the object side of the fourth lens on the optical axis, and T45 is the distance from the image side of the fourth lens to the object side of the fifth lens on the optical axis. T12+T23+T34+T45 can be 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm or 0.9mm. Under the condition that the above relationship is met, it is conducive to the miniaturization of the optical imaging system and the improvement of the assembly yield of the lens. When T12+T23+T34+T45 is less than or equal to 0.25mm, the adjustable space between adjacent lenses will be too small, which will easily increase the system sensitivity and be unfavorable for lens assembly; when T12+T23+T34+T45 is greater than or equal to 0.95mm, it will be unfavorable for the miniaturization and ultra-thinness of the optical imaging system.

[0075] In an exemplary embodiment, the optical imaging system satisfies the following relationship: 0.5 < f3 / f5 < 3.5; wherein f3 is the effective focal length of the third lens, and f5 is the effective focal length of the fifth lens. f3 / f5 can be 0.6, 0.7, 0.75, 0.85, 0.95, 1.2, 1.25, 2.0, 2.5, 3.0, 3.1, or 3.2. Under the condition that the above relationship is satisfied, it is beneficial to allocate appropriate positive refractive power to the third and fifth lenses to balance the negative spherical aberration generated by the fourth lens, thereby reducing the tolerance sensitivity of the optical imaging system and improving its imaging quality. However, when f3 / f5 is less than or equal to 0.5, the third lens needs to provide most of the positive refractive power, resulting in excessive curvature of the object side of the third lens, resulting in poor molding, which in turn affects the manufacturing yield of the lens. When f3 / f5 is greater than or equal to 3.5, it is easy to cause an unbalanced distribution of the refractive power of the second and fourth lenses, resulting in excessive aberrations in the optical imaging system, which is not conducive to aberration correction.

[0076] In an exemplary embodiment, the optical imaging system satisfies the following relationship: FNO≤1.3; wherein FNO is the aperture number of the optical imaging system. FNO can be 1.1, 1.13, 1.16, 1.19, 1.22, 1.25, 1.28 or 1.29. Preferably, FNO≤1.1. By controlling the aperture number of the optical imaging system to satisfy the above relationship, the light throughput of the optical imaging system can be effectively increased, so that the detailed information of the subject can be clearly obtained even under low-light conditions, thereby improving the imaging quality. When FNO is greater than 1.3, the light throughput of the optical imaging system is reduced, resulting in a darker picture. At the same time, it is more difficult to retain the detailed information of the subject, resulting in reduced imaging quality.

[0077] In an exemplary embodiment, the optical imaging system satisfies the following relationships: 1.4 < nd1 < 1.7; 1.4 < nd2 < 1.7; 1.4 < nd4 < 1.7, where nd1 is the refractive index of the first lens, nd2 is the refractive index of the second lens, and nd4 is the refractive index of the fourth lens. nd1, nd2, and nd4 can each be 1.5, 1.54, 1.545, 1.546, 1.548, 1.550, 1.6, 1.64, or 1.66. By properly selecting lens materials so that the refractive indices of the first, second, and fourth lenses satisfy the above relationships, chromatic aberration in the optical imaging system is eliminated, thereby improving the imaging quality of the optical imaging system.

[0078] In an exemplary embodiment, the optical imaging system satisfies the following relationship: 0.85 < SD32 / SD11 < 1.3; where SD32 is the maximum effective semi-aperture of the image-side surface of the third lens element, and SD11 is the maximum effective semi-aperture of the object-side surface of the first lens element. SD32 / SD11 can be 0.89, 0.94, 0.99, 1.04, 1.09, 1.13, 1.17, 1.21, 1.25, or 1.29. Satisfying this relationship allows for a more compact design of the optical imaging system, reducing its footprint and achieving miniaturization. Furthermore, it allows more light to enter the optical imaging system, improving the relative brightness of the image. When SD32 / SD11 is less than or equal to 0.85, it is difficult to shorten the distance between lenses to ensure the amount of light entering, which easily increases the space occupied by the optical imaging system and is not conducive to the miniaturization design of the lens; when SD32 / SD11 is greater than or equal to 1.3, the effective aperture of the first lens will be small and the amount of light entering the optical imaging system cannot be guaranteed, resulting in a relatively low brightness of the image.

[0079] In an exemplary embodiment, the optical imaging system satisfies the following relationship: FFL>0.7mm; wherein FFL is the distance from the point on the optical axis where the side projection of the fifth lens image is farthest from the center of the lens surface to the imaging surface of the optical imaging system. FFL can be 0.72mm, 0.74mm, 0.76mm, 0.78mm, 0.80mm, 0.82mm, 0.84mm or 0.86mm. Under the condition that the above relationship is satisfied, the optical imaging system can have sufficient focusing space during the installation process of the lens module, thereby improving the assembly yield of the lens module, and at the same time effectively increasing the focal depth of the optical imaging system to obtain more depth information of the subject. When FFL is less than or equal to 0.7, the focal depth of the optical imaging system is small, making it difficult to improve the resolution of the image, and also affecting the assembly yield of the lens module.

[0080] In an exemplary embodiment, the optical imaging system satisfies the following relationship: R9 / R10<1.0; wherein R9 is the radius of curvature of the object side of the fifth lens at the optical axis, and R10 is the radius of curvature of the image side of the fifth lens at the optical axis. R9 / R10 can be 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95 or 0.99. By rationally configuring the radius of curvature of the object side of the fifth lens at the optical axis and the radius of curvature of the image side of the fifth lens at the optical axis so that the two satisfy the above relationship, the machinability of the fifth lens can be enhanced, which is beneficial for correcting the coma of the optical imaging system and preventing other aberrations of the optical imaging system from being too large. When R9 / R10 is greater than or equal to 1.0, the processing difficulty of the fifth lens will increase, which is not conducive to correcting the coma of the optical imaging system and suppressing other aberrations of the optical imaging system.

[0081] In an exemplary embodiment, the optical imaging system satisfies the following relationship: 1.0 < |f3 / R6| < 6.0; where f3 is the effective focal length of the third lens element, and R6 is the radius of curvature of the image-side surface of the third lens element at the optical axis. |f3 / R6| can be 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0, 3.5, 4.0, 4.5, 4.75, 5.0, or 5.5. Satisfying this relationship facilitates correcting astigmatism and aberrations in the optical imaging system, thereby improving the imaging quality of the optical imaging system. However, when |f3 / R6| is less than or equal to 1.0 or greater than or equal to 6.0, the processing difficulty of the third lens element increases, making it difficult to correct astigmatism and aberrations in the optical imaging system.

[0082] In an exemplary embodiment, each lens in the optical imaging system can be made entirely of glass or entirely of plastic. Plastic lenses can reduce the weight and production costs of the optical imaging system, while glass lenses can provide the optical imaging system with better temperature tolerance and excellent optical performance. It should be noted that the material of each lens in the optical imaging system can be any combination of glass and plastic, and does not necessarily have to be entirely glass or entirely plastic.

[0083] In an exemplary embodiment, a stop is further provided in the optical imaging system to effectively suppress the excessive increase in the incident angle of the main light of the off-axis field of view, so that the optical imaging system can better match the photosensitive element of traditional specifications. Specifically, the stop includes an aperture stop and a field stop, and can be provided on the object side of the first lens or between the first lens and the fifth lens. Preferably, the stop is an aperture stop. The aperture stop can be located on the surface of the first lens and the second lens (for example, the object side and the image side), and form an operative relationship with the lens, for example, by coating a light-blocking coating on the surface of the lens to form an aperture stop on the surface; or by fixing the surface of the clamping lens by a clamping member, and the clamping member structure located on the surface can limit the width of the imaging beam of the object point on the axis, thereby forming an aperture stop on the surface.

[0084] In an exemplary embodiment, the optical imaging system further includes a protective glass for protecting a photosensitive element, wherein the photosensitive element is located on an imaging surface of the optical imaging system. Further, the imaging surface can be a photosensitive surface of the photosensitive element.

[0085] The optical imaging system according to the above embodiment of the present application can use multiple lenses, such as the five lenses mentioned above. By reasonably allocating the focal length, refractive power, surface shape, thickness of each lens and the on-axis spacing between each lens, it is possible to ensure that the total length of the above optical imaging system is small and has a high imaging resolution, while also having a large aperture (FNO can be 1.1), thereby better meeting the application requirements of infrared light imaging in lightweight electronic devices such as car lenses, mobile phones, and tablets. It is understandable that although five lenses are described as an example in the embodiment, the optical imaging system is not limited to including five lenses. If necessary, the optical imaging system can also include other numbers of lenses.

[0086] Specific embodiments of the optical imaging system applicable to the above-mentioned embodiments will be further described below with reference to the accompanying drawings.

[0087] Example 1

[0088] The following reference Figures 1 to 2 The optical imaging system of Example 1 of the present application is described.

[0089] Figure 1 FIG. 1 shows a schematic structural diagram of the optical imaging system of Example 1. Figure 1 As shown, the optical imaging system includes, in order from the object side to the image side along the optical axis, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5 and an imaging surface S13.

[0090] The first lens L1 has positive refractive power, and its object-side surface S1 and image-side surface S2 are both aspherical surfaces. The object-side surface S1 is convex at the optical axis and concave at the circumference, and the image-side surface S2 is concave at the optical axis and convex at the circumference.

[0091] The second lens L2 has positive refractive power, and its object-side surface S3 and image-side surface S4 are both aspherical surfaces. The object-side surface S3 is convex at the optical axis and convex at the circumference, and the image-side surface S4 is concave at the optical axis and concave at the circumference.

[0092] The third lens L3 has positive refractive power, and its object-side surface S5 and image-side surface S6 are both aspherical surfaces. The object-side surface S5 is convex at the optical axis and concave at the circumference, and the image-side surface S6 is concave at the optical axis and convex at the circumference.

[0093] The fourth lens L4 has negative refractive power, and its object-side surface S7 and image-side surface S8 are both aspherical surfaces. The object-side surface S7 is concave at the optical axis and concave at the circumference, and the image-side surface S8 is convex at the optical axis and concave at the circumference.

[0094] The fifth lens L5 has positive refractive power, and its object-side surface S9 and image-side surface S10 are both aspherical surfaces. The object-side surface S9 is convex at the optical axis and concave at the circumference, and the image-side surface S10 is concave at the optical axis and convex at the circumference.

[0095] Setting the lens surfaces S1 to S10 to be aspherical is beneficial for solving the problem of field of view distortion, and can also enable the lens to achieve excellent optical imaging effects while being smaller, thinner and flatter, thereby making the optical imaging system miniaturized.

[0096] Lenses L1 through L5 are all made of plastic, reducing the weight and production costs of the optical imaging system. A stop STO is also provided on the object side of lens L1 to further enhance the imaging quality of the optical imaging system.

[0097] The optical imaging system also includes an infrared bandpass filter L6 having an object-side surface S11 and an image-side surface S12. This infrared bandpass filter L6 is positioned between the fifth lens element L5 and the imaging surface S13. Light from the object OBJ sequentially passes through each of the surfaces S1 to S12 and is ultimately imaged on the imaging surface S13. Furthermore, the infrared bandpass filter L6 is used to filter out light outside the wavelength range of 840 nm to 950 nm to meet the application requirements of the TOF lens. Specifically, the infrared bandpass filter L6 is made of glass.

[0098] Table 1 shows the surface type, radius of curvature, thickness, material, refractive index, Abbe number (i.e., dispersion coefficient) and effective focal length of each lens of the optical imaging system of Example 1, wherein the units of radius of curvature, thickness, and effective focal length of each lens are all in millimeters (mm). Wherein TTL is the distance from the object side surface S1 of the first lens L1 to the imaging surface S13 on the optical axis. The surface closest to the object in each lens is called the object side surface, and the surface closest to the imaging surface in each lens is called the image side surface. In addition, taking the first lens L1 as an example, the first value in the "thickness" parameter column of the first lens L1 is the thickness of the lens on the optical axis, and the second value is the distance from the image side surface of the lens to the object side surface of the next lens in the image side direction on the optical axis. The reference wavelength of Table 1 is 940nm.

[0099] Table 1

[0100]

[0101] The aspheric surface shape of each lens is defined by the following formula:

[0102]

[0103] Where x is the distance vector from the vertex of the aspheric surface at a height h along the optical axis; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., paraxial curvature c is the reciprocal of the curvature radius R in Table 1); k is the conic coefficient; and Ai is the i-th order coefficient of the aspheric surface. Table 2 below lists the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for the aspheric surfaces S1-S10 of the lens in Example 1.

[0104] Table 2

[0105]

[0106]

[0107] The half of the diagonal length of the effective pixel area on the imaging surface S13 of the optical imaging system of this embodiment is 2.1 mm. Combining the data in Table 1 and Table 2, it can be seen that the optical imaging system in Example 1 meets the following requirements:

[0108] TT / f=1.366, where TT is the distance along the optical axis from the object-side surface S1 of the first lens element L1 to the image-side surface S10 of the fifth lens element L5, and f is the effective focal length of the optical imaging system.

[0109] CT1+CT2+CT3=1.32 mm, where CT1 is the thickness of the first lens L1 on the optical axis, CT2 is the thickness of the second lens L2 on the optical axis, and CT3 is the thickness of the third lens L3 on the optical axis;

[0110] T12+T23+T34+T45=0.78mm, where T12 is the distance on the optical axis from the image-side surface S2 of the first lens L1 to the object-side surface S3 of the second lens L2, T23 is the distance on the optical axis from the image-side surface S4 of the second lens L2 to the object-side surface S5 of the third lens L3, T34 is the distance on the optical axis from the image-side surface S6 of the third lens L3 to the object-side surface S7 of the fourth lens L4, and T45 is the distance on the optical axis from the image-side surface S8 of the fourth lens L4 to the object-side surface S9 of the fifth lens L5.

[0111] f3 / f5=1.291, where f3 is the effective focal length of the third lens element L3, and f5 is the effective focal length of the fifth lens element L5;

[0112] FNO = 1.17, where FNO is the aperture number of the optical imaging system;

[0113] nd1=1.545, nd2=1.541, nd4=1.546, where nd1 is the refractive index of the first lens L1, nd2 is the refractive index of the second lens L2, and nd4 is the refractive index of the fourth lens L4;

[0114] SD32 / SD11=1.06, where SD32 is the maximum effective semi-aperture of the image-side surface S6 of the third lens L3, and SD11 is the maximum effective semi-aperture of the object-side surface S1 of the first lens L1;

[0115] FFL=0.76 mm, where FFL is the distance between the point on the optical axis where the image-side surface S10 of the fifth lens element L5 is projected on the lens surface farthest from the center of the lens surface and the imaging surface S13 of the optical imaging system;

[0116] R9 / R10=0.881, where R9 is the radius of curvature of the object-side surface S9 of the fifth lens element L5 at the optical axis, and R10 is the radius of curvature of the image-side surface S10 of the fifth lens element L5 at the optical axis;

[0117] |f3 / R6|=1.73, where f3 is the effective focal length of the third lens element L3, and R6 is the radius of curvature of the image-side surface S6 of the third lens element L3 at the optical axis.

[0118] Figure 2 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical imaging system of Example 1 are shown respectively. The longitudinal spherical aberration curve shows the deviation of the focus point of infrared light with wavelengths of 930nm, 940nm and 950nm after passing through the optical imaging system; the astigmatism curve shows the meridional image curvature and sagittal image curvature of the optical imaging system of Example 1; the distortion curve shows the distortion rate of the optical imaging system of Example 1 at different image heights. Figure 2 It can be seen that the optical imaging system provided in Example 1 can achieve good imaging quality.

[0119] Example 2

[0120] The following reference Figures 3 and 4 The optical imaging system of Example 2 of the present application is described. In this embodiment, for the sake of brevity, some descriptions similar to those of Example 1 will be omitted. Figure 3 A structural schematic diagram of the optical imaging system of Example 2 of the present application is shown.

[0121] like Figure 3 As shown, the optical imaging system includes, in order from the object side to the image side along the optical axis, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5 and an imaging surface S13.

[0122] The first lens L1 has positive refractive power, and its object-side surface S1 and image-side surface S2 are both aspherical surfaces. The object-side surface S1 is convex at the optical axis and concave at the circumference, and the image-side surface S2 is concave at the optical axis and convex at the circumference.

[0123] The second lens L2 has negative refractive power, and its object-side surface S3 and image-side surface S4 are both aspherical surfaces. The object-side surface S3 is concave at the optical axis and concave at the circumference, and the image-side surface S4 is convex at the optical axis and convex at the circumference.

[0124] The third lens L3 has positive refractive power, and its object-side surface S5 and image-side surface S6 are both aspherical surfaces. The object-side surface S5 is convex at the optical axis and concave at the circumference, and the image-side surface S6 is concave at the optical axis and convex at the circumference.

[0125] The fourth lens L4 has negative refractive power, and its object-side surface S7 and image-side surface S8 are both aspherical surfaces. The object-side surface S7 is concave at the optical axis and concave at the circumference, and the image-side surface S8 is convex at the optical axis and concave at the circumference.

[0126] The fifth lens L5 has positive refractive power, and its object-side surface S9 and image-side surface S10 are both aspherical surfaces. The object-side surface S9 is convex at the optical axis and concave at the circumference, and the image-side surface S10 is concave at the optical axis and convex at the circumference.

[0127] Setting the lens surfaces S1 to S10 to be aspherical is beneficial for solving the problem of field of view distortion, and can also enable the lens to achieve excellent optical imaging effects while being smaller, thinner and flatter, thereby making the optical imaging system miniaturized.

[0128] Lenses L1 through L5 are all made of plastic, reducing the weight and production costs of the optical imaging system. A stop STO is also provided on the object side of lens L1 to further enhance the imaging quality of the optical imaging system.

[0129] The optical imaging system also includes an infrared bandpass filter L6 having an object-side surface S11 and an image-side surface S12, which is used to filter out light in the wavelength range of 840nm to 950nm to meet the application requirements of the TOF lens. Specifically, the infrared bandpass filter L6 is made of glass.

[0130] Table 3 shows the surface type, radius of curvature, thickness, material, refractive index, Abbe number (i.e., dispersion coefficient), and effective focal length of each lens of the optical imaging system of Example 2, where the units of the radius of curvature, thickness, and effective focal length of each lens are all in millimeters (mm). The reference wavelength of Table 3 is 940 nm. Table 4 shows the high-order coefficients of the aspheric surfaces S1-S10 of the lenses that can be used in Example 2, where the aspheric surface shape can be defined by formula (1) given in Example 1; Table 5 shows the relevant parameter values ​​of the optical imaging system of Example 2.

[0131] Table 3

[0132]

[0133] Table 4

[0134]

[0135]

[0136] Table 5

[0137]

[0138] Figure 4 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical imaging system of Example 2 are shown respectively. The longitudinal spherical aberration curve shows the deviation of the focus point of infrared light with wavelengths of 930nm, 940nm and 950nm after passing through the optical imaging system; the astigmatism curve shows the meridional image curvature and sagittal image curvature of the optical imaging system of Example 2; the distortion curve shows the distortion rate of the optical imaging system of Example 2 at different image heights. Figure 4 It can be seen that the optical imaging system provided in Example 2 can achieve good imaging quality.

[0139] Example 3

[0140] The following reference Figures 5 and 6 The optical imaging system of Example 3 of the present application is described. In this embodiment, for the sake of brevity, some descriptions similar to those of Example 1 will be omitted. Figure 5 A schematic structural diagram of the optical imaging system of Example 3 of the present application is shown.

[0141] like Figure 5 As shown, the optical imaging system includes, in order from the object side to the image side along the optical axis, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5 and an imaging surface S13.

[0142] The first lens L1 has positive refractive power, and its object-side surface S1 and image-side surface S2 are both aspherical surfaces. The object-side surface S1 is convex at the optical axis and concave at the circumference, and the image-side surface S2 is concave at the optical axis and convex at the circumference.

[0143] The second lens L2 has negative refractive power, and its object-side surface S3 and image-side surface S4 are both aspherical surfaces. The object-side surface S3 is concave at the optical axis and concave at the circumference, and the image-side surface S4 is convex at the optical axis and convex at the circumference.

[0144] The third lens L3 has positive refractive power, and its object-side surface S5 and image-side surface S6 are both aspherical surfaces. The object-side surface S5 is convex at the optical axis and concave at the circumference, and the image-side surface S6 is concave at the optical axis and convex at the circumference.

[0145] The fourth lens L4 has negative refractive power, and its object-side surface S7 and image-side surface S8 are both aspherical surfaces. The object-side surface S7 is concave at the optical axis and concave at the circumference, and the image-side surface S8 is convex at the optical axis and concave at the circumference.

[0146] The fifth lens L5 has positive refractive power, and its object-side surface S9 and image-side surface S10 are both aspherical surfaces. The object-side surface S9 is convex at the optical axis and concave at the circumference, and the image-side surface S10 is concave at the optical axis and convex at the circumference.

[0147] Setting the lens surfaces S1 to S10 to be aspherical is beneficial for solving the problem of field of view distortion, and can also enable the lens to achieve excellent optical imaging effects while being smaller, thinner and flatter, thereby making the optical imaging system miniaturized.

[0148] Lenses L1 through L5 are all made of plastic, reducing the weight and production costs of the optical imaging system. A stop STO is also provided on the object side of lens L1 to further enhance the imaging quality of the optical imaging system.

[0149] The optical imaging system also includes an infrared bandpass filter L6 having an object-side surface S11 and an image-side surface S12, which is used to filter out light in the wavelength range of 840nm to 950nm to meet the application requirements of the TOF lens. Specifically, the infrared bandpass filter L6 is made of glass.

[0150] Table 6 shows the surface type, radius of curvature, thickness, material, refractive index, Abbe number (i.e., dispersion coefficient), and effective focal length of each lens of the optical imaging system of Example 3, where the units of the radius of curvature, thickness, and effective focal length of each lens are all in millimeters (mm). The reference wavelength of Table 6 is 940 nm. Table 7 shows the high-order coefficients of the aspheric surfaces S1-S10 of the lenses that can be used in Example 3, where the aspheric surface shape can be defined by formula (1) given in Example 1. Table 8 shows the numerical values ​​of the relevant parameters of the optical imaging system of Example 3.

[0151] Table 6

[0152]

[0153]

[0154] Table 7

[0155]

[0156] Table 8

[0157]

[0158]

[0159] Figure 6 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical imaging system of Example 3 are shown respectively. The longitudinal spherical aberration curve shows the deviation of the focus point of infrared light with wavelengths of 930nm, 940nm and 950nm after passing through the optical imaging system; the astigmatism curve shows the meridional image curvature and sagittal image curvature of the optical imaging system of Example 3; the distortion curve shows the distortion rate of the optical imaging system of Example 3 at different image heights. Figure 6 It can be seen that the optical imaging system provided in Example 3 can achieve good imaging quality.

[0160] Example 4

[0161] The following reference Figures 7 and 8 The optical imaging system of Example 4 of the present application is described. In this embodiment, for the sake of brevity, some descriptions similar to those of Example 1 will be omitted. Figure 7 A structural schematic diagram of the optical imaging system of Example 4 of the present application is shown.

[0162] like Figure 7 As shown, the optical imaging system includes, in order from the object side to the image side along the optical axis, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5 and an imaging surface S13.

[0163] The first lens L1 has negative refractive power, and its object-side surface S1 and image-side surface S2 are both aspherical surfaces. The object-side surface S1 is convex at the optical axis and convex at the circumference, and the image-side surface S2 is concave at the optical axis and convex at the circumference.

[0164] The second lens L2 has positive refractive power, and its object-side surface S3 and image-side surface S4 are both aspherical surfaces. The object-side surface S3 is convex at the optical axis and concave at the circumference, and the image-side surface S4 is concave at the optical axis and convex at the circumference.

[0165] The third lens L3 has positive refractive power, and its object-side surface S5 and image-side surface S6 are both aspherical surfaces. The object-side surface S5 is concave at the optical axis and concave at the circumference, and the image-side surface S6 is convex at the optical axis and convex at the circumference.

[0166] The fourth lens L4 has negative refractive power, and its object-side surface S7 and image-side surface S8 are both aspherical surfaces. The object-side surface S7 is concave at the optical axis and concave at the circumference, and the image-side surface S8 is convex at the optical axis and concave at the circumference.

[0167] The fifth lens L5 has positive refractive power, and its object-side surface S9 and image-side surface S10 are both aspherical surfaces. The object-side surface S9 is convex at the optical axis and concave at the circumference, and the image-side surface S10 is concave at the optical axis and convex at the circumference.

[0168] Setting the lens surfaces S1 to S10 to be aspherical is beneficial for solving the problem of field of view distortion, and can also enable the lens to achieve excellent optical imaging effects while being smaller, thinner and flatter, thereby making the optical imaging system miniaturized.

[0169] Lenses L1 through L5 are all made of plastic, reducing the weight and production costs of the optical imaging system. A stop STO is also provided on the object side of lens L1 to further enhance the imaging quality of the optical imaging system.

[0170] The optical imaging system also includes an infrared bandpass filter L6 having an object-side surface S11 and an image-side surface S12, which is used to filter out light in the wavelength range of 840nm to 950nm to meet the application requirements of the TOF lens. Specifically, the infrared bandpass filter L6 is made of glass.

[0171] Table 9 shows the surface type, radius of curvature, thickness, material, refractive index, Abbe number (i.e., dispersion coefficient), and effective focal length of each lens of the optical imaging system of Example 4, where the units of the radius of curvature, thickness, and effective focal length of each lens are all in millimeters (mm). The reference wavelength of Table 9 is 940 nm. Table 10 shows the higher-order coefficients of the aspheric surfaces S1-S10 of the lenses that can be used in Example 4, where the aspheric surface shape can be defined by formula (1) given in Example 1. Table 11 shows the numerical values ​​of the relevant parameters of the optical imaging system of Example 4.

[0172] Table 9

[0173]

[0174] Table 10

[0175]

[0176]

[0177] Table 11

[0178]

[0179] Figure 8The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical imaging system of Example 4 are shown respectively. The longitudinal spherical aberration curve shows the deviation of the focus point of infrared light with wavelengths of 930nm, 940nm and 950nm after passing through the optical imaging system; the astigmatism curve shows the meridional image curvature and sagittal image curvature of the optical imaging system of Example 4; the distortion curve shows the distortion rate of the optical imaging system of Example 4 at different image heights. Figure 8 It can be seen that the optical imaging system provided in Example 4 can achieve good imaging quality.

[0180] Example 5

[0181] The following reference Figures 9 and 10 The optical imaging system of Example 5 of the present application is described. In this embodiment, for the sake of brevity, some descriptions similar to those of Example 1 will be omitted. Figure 9 A structural schematic diagram of the optical imaging system of Example 5 of the present application is shown.

[0182] like Figure 7 As shown, the optical imaging system includes, in order from the object side to the image side along the optical axis, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5 and an imaging surface S13.

[0183] The first lens L1 has negative refractive power, and its object-side surface S1 and image-side surface S2 are both aspherical surfaces. The object-side surface S1 is convex at the optical axis and concave at the circumference, and the image-side surface S2 is concave at the optical axis and convex at the circumference.

[0184] The second lens L2 has positive refractive power, and its object-side surface S3 and image-side surface S4 are both aspherical surfaces. The object-side surface S3 is convex at the optical axis and concave at the circumference, and the image-side surface S4 is convex at the optical axis and convex at the circumference.

[0185] The third lens L3 has positive refractive power, and its object-side surface S5 and image-side surface S6 are both aspherical surfaces. The object-side surface S5 is convex at the optical axis and convex at the circumference, and the image-side surface S6 is concave at the optical axis and convex at the circumference.

[0186] The fourth lens L4 has negative refractive power, and its object-side surface S7 and image-side surface S8 are both aspherical surfaces. The object-side surface S7 is concave at the optical axis and at the circumference, and the image-side surface S8 is concave at the optical axis and at the circumference.

[0187] The fifth lens L5 has positive refractive power, and its object-side surface S9 and image-side surface S10 are both aspherical surfaces. The object-side surface S9 is convex at the optical axis and concave at the circumference, and the image-side surface S10 is concave at the optical axis and convex at the circumference.

[0188] Setting the lens surfaces S1 to S10 to be aspherical is beneficial for solving the problem of field of view distortion, and can also enable the lens to achieve excellent optical imaging effects while being smaller, thinner and flatter, thereby making the optical imaging system miniaturized.

[0189] Lenses L1 through L5 are all made of plastic, reducing the weight and production costs of the optical imaging system. A stop STO is also provided between lens L1 and lens L2 to further enhance the imaging quality of the optical imaging system.

[0190] The optical imaging system also includes an infrared bandpass filter L6 having an object-side surface S11 and an image-side surface S12, which is used to filter out light in the wavelength range of 840nm to 950nm to meet the application requirements of the TOF lens. Specifically, the infrared bandpass filter L6 is made of glass.

[0191] Table 12 shows the surface type, radius of curvature, thickness, material, refractive index, Abbe number (i.e., dispersion coefficient), and effective focal length of each lens of the optical imaging system of Example 5, where the units of the radius of curvature, thickness, and effective focal length of each lens are all in millimeters (mm). The reference wavelength of Table 12 is 940 nm. Table 13 shows the high-order coefficients of the aspheric surfaces S1-S10 of the lenses that can be used in Example 5, where the aspheric surface shape can be defined by formula (1) given in Example 1. Table 14 shows the numerical values ​​of the relevant parameters of the optical imaging system of Example 5.

[0192] Table 12

[0193]

[0194] Table 13

[0195]

[0196]

[0197] Table 14

[0198]

[0199] Figure 10 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical imaging system of Example 5 are shown respectively. The longitudinal spherical aberration curve shows the deviation of the focus point of infrared light with wavelengths of 930nm, 940nm and 950nm after passing through the optical imaging system; the astigmatism curve shows the meridional image curvature and sagittal image curvature of the optical imaging system of Example 5; the distortion curve shows the distortion rate of the optical imaging system of Example 5 at different image heights. Figure 10It can be seen that the optical imaging system provided in Example 5 can achieve good imaging quality.

[0200] Example 6

[0201] The following reference Figures 11 to 12 The optical imaging system of Example 6 of the present application is described. In this embodiment, for the sake of brevity, some descriptions similar to those of Example 1 will be omitted. Figure 11 A structural schematic diagram of the optical imaging system of Example 6 of the present application is shown.

[0202] like Figure 7 As shown, the optical imaging system includes, in order from the object side to the image side along the optical axis, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5 and an imaging surface S13.

[0203] The first lens L1 has positive refractive power, and its object-side surface S1 and image-side surface S2 are both aspherical surfaces. The object-side surface S1 is convex at the optical axis and concave at the circumference, and the image-side surface S2 is concave at the optical axis and convex at the circumference.

[0204] The second lens L2 has positive refractive power, and its object-side surface S3 and image-side surface S4 are both aspherical surfaces. The object-side surface S3 is concave at the optical axis and concave at the circumference, and the image-side surface S4 is convex at the optical axis and convex at the circumference.

[0205] The third lens L3 has positive refractive power, and its object-side surface S5 and image-side surface S6 are both aspherical surfaces. The object-side surface S5 is convex at the optical axis and concave at the circumference, and the image-side surface S6 is concave at the optical axis and convex at the circumference.

[0206] The fourth lens L4 has negative refractive power, and its object-side surface S7 and image-side surface S8 are both aspherical surfaces. The object-side surface S7 is concave at the optical axis and concave at the circumference, and the image-side surface S8 is convex at the optical axis and concave at the circumference.

[0207] The fifth lens L5 has positive refractive power, and its object-side surface S9 and image-side surface S10 are both aspherical surfaces. The object-side surface S9 is convex at the optical axis and concave at the circumference, and the image-side surface S10 is concave at the optical axis and convex at the circumference.

[0208] Setting the lens surfaces S1 to S10 to be aspherical is beneficial for solving the problem of field of view distortion, and can also enable the lens to achieve excellent optical imaging effects while being smaller, thinner and flatter, thereby making the optical imaging system miniaturized.

[0209] Lenses L1 through L5 are all made of plastic, reducing the weight and production costs of the optical imaging system. A stop STO is also provided between lens L1 and lens L2 to further enhance the imaging quality of the optical imaging system.

[0210] The optical imaging system also includes an infrared bandpass filter L6 having an object-side surface S11 and an image-side surface S12, which is used to filter out light in the wavelength range of 840nm to 950nm to meet the application requirements of the TOF lens. Specifically, the infrared bandpass filter L6 is made of glass.

[0211] Table 15 shows the surface type, radius of curvature, thickness, material, refractive index, Abbe number (i.e., dispersion coefficient), and effective focal length of each lens of the optical imaging system of Example 6, where the units of the radius of curvature, thickness, and effective focal length of each lens are all in millimeters (mm). The reference wavelength of Table 15 is 940 nm. Table 16 shows the higher-order coefficients of the aspheric surfaces S1-S10 of the lenses that can be used in Example 6, where the aspheric surface shape can be defined by formula (1) given in Example 1. Table 17 shows the numerical values ​​of the relevant parameters of the optical imaging system of Example 6.

[0212] Table 15

[0213]

[0214]

[0215] Table 16

[0216]

[0217] Table 17

[0218]

[0219]

[0220] Figure 12 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical imaging system of Example 6 are shown respectively. The longitudinal spherical aberration curve shows the deviation of the focus point of infrared light with wavelengths of 930nm, 940nm and 950nm after passing through the optical imaging system; the astigmatism curve shows the meridional image curvature and sagittal image curvature of the optical imaging system of Example 6; the distortion curve shows the distortion rate of the optical imaging system of Example 6 at different image heights. Figure 12 It can be seen that the optical imaging system provided in Example 6 can achieve good imaging quality.

[0221] The present application also provides an imaging module, comprising the optical imaging system described above; and a photosensitive element, the photosensitive element being disposed on the image side of the optical imaging system to receive light projected by the optical imaging system. Specifically, the photosensitive element may be a complementary metal oxide semiconductor (CMOS) image sensor or a charge-coupled device (CCD) image sensor.

[0222] The above-mentioned imaging module, using the aforementioned optical imaging system, can image the infrared light emitted or reflected by the subject, and capture images with bright pictures, high resolution and small aberration. At the same time, the imaging device is also miniaturized, which makes it easy to adapt to devices with limited size such as thin and light electronic devices.

[0223] The present application also provides an electronic device, comprising a housing and an imaging module as described above, wherein the imaging module is mounted on the housing to capture images.

[0224] Specifically, the imaging device is arranged in the shell and exposed from the shell to capture images. The shell can provide the imaging device with dustproof, waterproof and drop-proof protection. A hole corresponding to the imaging device is opened on the shell to allow light to enter or exit the shell through the hole.

[0225] The electronic device has a lightweight and thin structure. The imaging device can be used to capture clearer images containing depth information of the object.

[0226] In other embodiments, the "electronic device" used may include, but is not limited to, a device configured to receive or send communication signals via a wired connection and / or via a wireless interface. An electronic device configured to communicate via a wireless interface may be referred to as a "wireless communication terminal," "wireless terminal," or "mobile terminal." Examples of mobile terminals include, but are not limited to, satellite or cellular phones; personal communication system (PCS) terminals that can combine cellular radiotelephones with data processing, fax, and data communication capabilities; personal digital assistants (PDAs) that can include radiotelephones, pagers, Internet / Intranet access, web browsers, notepads, calendars, and / or global positioning system (GPS) receivers; and conventional laptop and / or palmtop receivers or other electronic devices that include radiotelephone transceivers.

[0227] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0228] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. An optical imaging system, characterized in that: The optical imaging system is used for infrared imaging and includes, in order from the object side to the image side along the optical axis: a first lens having refractive power; a second lens having refractive power; a third lens element having positive refractive power, wherein the image-side surface of the third lens element is convex at the circumference; a fourth lens element having negative refractive power; a fifth lens having positive refractive power, wherein the image-side surface of the fifth lens is concave at the optical axis, the object-side surface and the image-side surface of the fifth lens are both aspherical, and at least one of the object-side surface and the image-side surface includes at least one inflection point; The optical imaging system satisfies the following relationship: TT / f<1.5; Wherein, TT is the distance from the object side of the first lens to the image side of the fifth lens on the optical axis, and f is the effective focal length of the optical imaging system.

2. The optical imaging system according to claim 1, wherein: The optical imaging system satisfies the following relationship: 0.7mm<CT1+CT2+CT3<1.6mm; Wherein, CT1 is the thickness of the first lens on the optical axis, CT2 is the thickness of the second lens on the optical axis, and CT3 is the thickness of the third lens on the optical axis.

3. The optical imaging system according to claim 1, wherein: The optical imaging system satisfies the following relationship: 0.25mm<T12+T23+T34+T45<0.95mm; Among them, T12 is the distance from the image side of the first lens to the objective side of the second lens on the optical axis, T23 is the distance from the image side of the second lens to the objective side of the third lens on the optical axis, T34 is the distance from the image side of the third lens to the objective side of the fourth lens on the optical axis, and T45 is the distance from the image side of the fourth lens to the objective side of the fifth lens on the optical axis.

4. The optical imaging system according to claim 1, wherein: The optical imaging system satisfies the following relationship: 0.5<f3 / f5<3.5; Wherein, f3 is the effective focal length of the third lens, and f5 is the effective focal length of the fifth lens.

5. The optical imaging system according to claim 1, wherein: The optical imaging system satisfies the following relationship: FNO≤1.3; Wherein, FNO is the aperture number of the optical imaging system.

6. The optical imaging system according to claim 1, wherein: The optical imaging system satisfies the following relationship: 1.4<nd1<1.7; 1.4<nd2<1.7; 1.4<nd4<1.7; Wherein, nd1 is the refractive index of the first lens, nd2 is the refractive index of the second lens, and nd4 is the refractive index of the fourth lens.

7. The optical imaging system according to claim 1, wherein: The optical imaging system satisfies the following relationship: 0.85<SD32 / SD11<1.3; Among them, SD32 is the maximum effective semi-aperture of the image side of the third lens, and SD11 is the maximum effective semi-aperture of the object side of the first lens.

8. The optical imaging system according to claim 1, wherein: The optical imaging system satisfies the following relationship: FFL>0.7mm; Wherein, FFL is the distance from the point on the optical axis farthest from the center of the lens surface projected on the side surface of the fifth lens image to the imaging surface of the optical imaging system.

9. The optical imaging system according to claim 1, wherein: The optical imaging system satisfies the following relationship: R9 / R10<1.0; Wherein, R9 is the curvature radius of the object side of the fifth lens at the optical axis, and R10 is the curvature radius of the image side of the fifth lens at the optical axis.

10. The optical imaging system according to claim 1, wherein: The optical imaging system satisfies the following relationship: 1.0<|f3 / R6|<6.0; Wherein, f3 is the effective focal length of the third lens, and R6 is the radius of curvature of the image side surface of the third lens at the optical axis.

11. An imaging device, characterized in that: include: The optical imaging system according to any one of claims 1 to 10; and A photosensitive element is arranged on the image side of the optical imaging system.

12. An electronic device, characterized in that: include: case; as well as, The imaging device according to claim 11, wherein the imaging device is mounted on the housing.

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