CN112987252B - Optical systems, infrared receiving modules and electronic equipment - Google Patents

Abstract

The invention relates to an optical system, an infrared receiving module and electronic equipment. The optical system sequentially comprises from an object side to an image side along an optical axis: a first lens element with positive refractive power having a concave image-side surface at a paraxial region; a second lens element with refractive power having a concave object-side surface at a paraxial region; a third lens element with refractive power having a concave image-side surface at a paraxial region; and the optical system satisfies the following conditional expression: FNO is more than or equal to 1.4 and less than or equal to 1.8; TT/f is more than or equal to 0.8 and less than or equal to 1.0; wherein FNO is the f-number of the optical system, TT is the distance from the object side surface of the first lens to the image side surface of the third lens on the optical axis, and f is the effective focal length of the optical system. The optical system has sufficient light flux and can meet the requirement of miniaturization design.

Description

Optical systems, infrared receiving modules and electronic equipment

Technical field

The invention relates to the field of infrared detection, and in particular to an optical system, an infrared receiving module and an electronic device.

Background technique

With the rapid development of technologies such as Time of Flight (TOF) and Laser Detection and Ranging (LiDAR) systems, infrared light is used in face unlocking, autonomous driving, human-machine interfaces and games, and industrial machines. Applications in fields such as vision and measurement, security monitoring and imaging systems are becoming more and more widespread. As a result, the market demand for optical systems for receiving infrared light is also increasing, and there is an urgent need for optical systems that have sufficient light transmission and can meet the needs of miniaturization design.

Contents of the invention

Based on this, it is necessary to provide an optical system, infrared receiving module and electronic equipment to provide sufficient light transmission and meet the needs of miniaturization design.

An optical system, including along the optical axis from the object side to the image side:

A first lens with positive refractive power, the image side of the first lens being concave at the paraxial axis;

A second lens with refractive power, the object side of the second lens being concave at the paraxial axis;

A third lens with refractive power, the image side of the third lens being concave at the paraxial axis;

And the optical system satisfies the following conditional expression:

1.4≤FNO≤1.8;

0.8≤TT/f≤1.0;

Wherein, FNO is the aperture number of the optical system, TT is the distance on the optical axis from the object side of the first lens to the image side of the third lens, and f is the effective focal length of the optical system.

In the above-mentioned optical system, the image side of the first lens is concave at the paraxial axis, which is conducive to the divergence and deflection of light, and can reduce the deflection angle borne by each lens on the image side of the first lens, thus helping to balance the light rays in each lens. deflection angle. The first lens has positive refractive power, which is beneficial to shortening the total system length of the optical system to meet the needs of miniaturization design. The object side of the second lens is concave at the paraxial axis, which is helpful for correcting field curvature and astigmatism of the optical system, thereby improving the imaging quality of the optical system. The image side of the third lens is concave at the paraxial axis, which is beneficial to improving the field curvature aberration of the optical system.

When 1.4 ≤ FNO ≤ 1.8 is satisfied, the amount of light transmitted by the optical system can be increased, allowing the optical system to obtain clear detailed information of the subject in low-light environments, and at the same time improving the brightness of the edge field of view, thus improving the imaging of the optical system quality. When 0.8≤TT/f≤1.0 is satisfied, the ratio of TT and the effective focal length of the optical system can be reasonably configured, which is conducive to shortening the total length of the optical system and achieving miniaturization design. It is also conducive to better focusing of light on the optical system. on the imaging surface of the system.

In one embodiment, the optical system satisfies the following conditional expression:

0.6≤tan(HFOV)*(SD32/IMGH)≤1.1;

Wherein, HFOV is half of the maximum field angle of the optical system, SD32 is the maximum effective semi-aperture of the image side of the third lens, and IMGH is half of the image height corresponding to the maximum field angle of the optical system. When the above conditional expression is satisfied, the field of view of the optical system, the maximum effective half aperture of the image side of the third lens, and the half image height of the optical system can be reasonably configured, so that the optical system can be designed with a large field of view and miniaturization. Striking a balance will not only achieve a miniaturized design but also help increase the field of view of the optical system; in addition, it will also help increase the focal depth of the optical system's imaging, which will help obtain the three-dimensional contour information of the object. If it is lower than the lower limit of the above conditional expression, it is not conducive to expanding the field of view of the optical system while achieving miniaturization design, which is not conducive to the optical system having a sense of layering in imaging objects within a large field of view. Exceeding the upper limit of the above conditional expression, the field of view of the optical system is too large, making it difficult to correct the distortion aberration of the optical system, resulting in unclear imaging and severe image deformation.

In one embodiment, the optical system satisfies the following conditional expression:

0.10mm≤T12+T23≤1.1mm;

Wherein, T12 is the distance on the optical axis from the image side of the first lens to the object side of the second lens, and T23 is the distance on the optical axis from the image side of the second lens to the object side of the third lens. distance on. When the above conditional expression is satisfied, the spacing between two adjacent lenses of the optical system can be reasonably configured, thereby further shortening the total length of the optical system and conducive to the miniaturization design of the optical system. Below the lower limit of the above conditional expression, the distance between two adjacent lenses is too small, resulting in an increase in the sensitivity of the optical system, which is not conducive to the assembly of the optical system. If the upper limit of the above conditional expression is exceeded, the distance between two adjacent lenses is too large, and additional connecting components such as spacers are required to connect the two adjacent lenses, which increases the cost of the optical system and is not conducive to the miniaturization of the optical system. design.

In one embodiment, the optical system satisfies the following conditional expression:

1.0≤f1/f≤18.0;

Where, f1 is the effective focal length of the first lens. When the above conditional expression is satisfied, the ratio between the effective focal length of the first lens and the effective focal length of the optical system can be reasonably configured, so that the first lens provides sufficient positive refractive power for the optical system, which is beneficial to the convergence of light. When the upper limit of the above conditional expression is exceeded, the positive refractive power provided by the first lens to the optical system is insufficient, resulting in a decrease in the light collection capability of the optical system. Below the lower limit of the above conditional expression, the positive refractive power provided by the first lens to the optical system is too large, which is not conducive to the correction of the aberrations produced by the first lens by the second lens and the third lens as a whole, thereby reducing the imaging quality of the optical system. At the same time, the surface shape of the first lens is excessively curved, which is not conducive to the molding of the first lens, thereby reducing the manufacturing yield of the first lens.

In one embodiment, the optical system satisfies the following conditional expression:

-45≤R3/CT2≤-1;

Wherein, R3 is the radius of curvature of the object side of the second lens at the optical axis, and CT2 is the thickness of the second lens on the optical axis. When the above conditional expression is satisfied, the ratio of the radius of curvature of the object side of the second lens at the optical axis and the central thickness of the second lens can be reasonably configured, so that the second lens can effectively correct the field curvature and astigmatism of the optical system. Improve the imaging quality of the optical system. Below the lower limit of the above conditional expression, the surface shape of the second lens is too smooth, which is not conducive to correcting the field curvature and astigmatism of the optical system. Exceeding the upper limit of the above conditional expression, the object side of the second lens is prone to excessive recurvature near the maximum effective aperture, resulting in an increase in stray light in the optical system, thereby reducing the imaging quality of the optical system.

In one embodiment, the optical system satisfies the following conditional expression:

0.80mm≤FFL≤1.05mm;

Wherein, FFL is the shortest distance in the optical axis direction from the image side of the third lens to the imaging surface of the optical system. Exceeding the lower limit of the above conditional expression is conducive to allowing the optical system to have sufficient assembly and debugging space during assembly, thereby improving the assembly yield of the optical system; at the same time, it is also conducive to increasing the focal depth of the optical system so that the optical system can Obtain more depth information of the object space. Being lower than the upper limit of the above conditional expression is conducive to compressing the axial size of the optical system, thereby conducive to the miniaturization design of the optical system.

In one embodiment, the optical system satisfies the following conditional expression:

0.9≤f23/f≤2.5;

Wherein, f23 is the combined focal length of the second lens and the third lens. When the above conditional expression is satisfied, the ratio of the combined focal length of the second lens and the third lens and the effective focal length of the optical system can be reasonably configured, which is beneficial to shortening the total system length of the optical system, and can also avoid excessive increase in high-order spherical aberration of the optical system. Large, thus helping to improve the imaging quality of the optical system. If the upper limit of the above conditional expression is exceeded, the combined focal length of the second lens and the third lens is too large, which is not conducive to shortening the total system length of the optical system while correcting the spherical aberration of the optical system. Below the lower limit of the above conditional expression, if the combined focal length of the second lens and the third lens is too small, the overall refractive power of the second lens and the third lens will be too strong, which will easily cause excessive correction of spherical aberration, thereby affecting the imaging quality of the optical system. decline.

In one embodiment, the optical system satisfies the following conditional expression:

1.2≤(R2+R1)/(R2-R1)≤50;

Wherein, R1 is the radius of curvature of the object side of the first lens at the optical axis, and R2 is the radius of curvature of the image side of the first lens at the optical axis. When the above conditional expression is satisfied, the curvature radii of the object side and image side of the first lens at the optical axis can be reasonably configured, and the first lens can be reasonably distributed according to the surface shape of the image side of the first lens at the paraxial axis. Bearing the optical deflection angle, it is helpful to expand the maximum field of view of the optical system; it is also helpful to correct the astigmatism of the off-axis field of view, thereby improving the imaging quality of the optical system.

An infrared receiving module includes a photosensitive element and the optical system described in any of the above embodiments, and the photosensitive element is arranged on the image side of the optical system. The use of the above-mentioned optical system in the infrared receiving module is beneficial to increasing the amount of light transmitted by the infrared receiving module, and is also beneficial to the miniaturization design of the infrared receiving module.

An electronic device includes a housing and the above-mentioned infrared receiving module, and the infrared receiving module is arranged on the housing. The use of the above-mentioned infrared receiving module in electronic equipment is beneficial to increasing the amount of light transmitted by the electronic equipment, and is conducive to the miniaturization design of the electronic equipment.

Description of the drawings

Figure 1 is a schematic structural diagram of the optical system in the first embodiment of the present application;

Figure 2 is a longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the optical system in the first embodiment of the present application;

Figure 3 is a schematic structural diagram of the optical system in the second embodiment of the present application;

Figure 4 is a longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the optical system in the second embodiment of the present application;

Figure 5 is a schematic structural diagram of the optical system in the third embodiment of the present application;

Figure 6 is a longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the optical system in the third embodiment of the present application;

Figure 7 is a schematic structural diagram of the optical system in the fourth embodiment of the present application;

Figure 8 is a longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the optical system in the fourth embodiment of the present application;

Figure 9 is a schematic structural diagram of the optical system in the fifth embodiment of the present application;

Figure 10 is a longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the optical system in the fifth embodiment of the present application;

Figure 11 is a schematic structural diagram of the optical system in the sixth embodiment of the present application;

Figure 12 is a longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the optical system in the sixth embodiment of the present application;

Figure 13 is a schematic diagram of an infrared receiving module in an embodiment of the present application;

Figure 14 is a schematic diagram of an electronic device in an embodiment of the present application.

Detailed ways

In order to make the above objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, the present invention can be implemented in many other ways different from those described here. Those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " "Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inside", "Outside", "Clockwise", "Counterclockwise", "Axis" The orientations or positional relationships indicated by "radial direction", "circumferential direction", etc. are based on the orientations or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply the device or device referred to. Elements must have a specific orientation, be constructed and operate in a specific orientation and therefore are not to be construed as limitations of the invention.

In addition, the terms “first” and “second” are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Therefore, features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

In the present invention, unless otherwise clearly stated and limited, the terms "installation", "connection", "connection", "fixing" and other terms should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection. , or integrated into one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be an internal connection between two elements or an interactive relationship between two elements, unless otherwise specified restrictions. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

In the present invention, unless otherwise expressly stated and limited, a first feature being "on" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. touch. Furthermore, the terms "above", "above" and "above" the first feature is above the second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "below" and "beneath" the first feature to the second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature has a smaller horizontal height than the second feature.

It should be noted that when an element is referred to as being "mounted" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is said to be "connected" to another element, it can be directly connected to the other element or there may also be intervening elements present. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation manner.

Referring to FIG. 1 , in some embodiments of the present application, the optical system 100 includes a first lens L1 , a second lens L2 , and a third lens L3 in order from the object side to the image side. Specifically, the first lens L1 includes an object side S1 and an image side S2, the second lens L2 includes an object side S3 and an image side S4, and the third lens L3 includes an object side S5 and an image side S6.

Among them, the first lens L1 has positive refractive power, which is conducive to shortening the total system length of the optical system 100 to meet the demand for miniaturization design. The image side S2 of the first lens L1 is concave at the pared optical axis 110, which is conducive to the divergence and deflection of light, and can reduce the deflection angle borne by each lens on the image side of the first lens L1, thus facilitating the balance of light in each lens. deflection angle. Both the second lens L2 and the third lens L3 have refractive power. The object side surface S3 of the second lens L2 is concave at the parenchyma axis 110 , which is helpful for correcting the field curvature and astigmatism of the optical system 100 , thereby improving the imaging quality of the optical system 100 . The image side S6 of the third lens L3 is concave at the parenchyma axis 110 , which is beneficial to improving the field curvature aberration of the optical system 100 .

In some embodiments, both the object side S5 and the image side S6 of the third lens L3 are aspherical, which helps improve the design flexibility of the third lens L3, effectively corrects the spherical aberration of the optical system 100, and improves imaging quality. In some embodiments, at least one of the object side S5 and the image side S6 of the third lens L3 has an inflection point, which is beneficial to correcting the aberration of the vertical axis field of view and further improving the imaging quality of the optical system 100 .

In some embodiments, both the second lens L2 and the third lens L3 have positive refractive power, which is conducive to the convergence of light, thereby conducive to shortening the total system length of the optical system 100 and further meeting the requirements of miniaturization design. In other embodiments, when the second lens L2 has a positive refractive power and the third lens L3 has a negative refractive power, in cooperation with the positive refractive power of the first lens L1, the total length of the system and the field of view can be balanced, and the total length of the system can be shortened. At the same time, it is also beneficial to expand the field of view of the optical system 100.

In addition, in some embodiments, the optical system 100 is provided with an aperture STO, and the aperture STO may be disposed on the object side of the first lens L1, or on the object side of the first lens L1. In some embodiments, the optical system 100 further includes an infrared bandpass filter L4 disposed on the image side of the third lens L3. The infrared bandpass filter L4 includes an object side S7 and an image side S8. Further, the optical system 100 also includes an image surface S9 located on the image side of the third lens L3. The image surface S9 is the imaging surface of the optical system 100. The incident light is adjusted by the first lens L1, the second lens L2 and the third lens L3. Finally, it can be imaged on the image plane S9. It can be understood that the infrared bandpass filter L4 is used to transmit infrared light. For example, in some embodiments, the infrared bandpass filter L4 can allow infrared light of 930nm-950nm to pass. Therefore, in some embodiments, the optical system 100 can be used to receive infrared light, and can be specifically used in TOF, LiDAR and other technologies that use infrared light detection. Specifically, the optical system 100 can be used in fields such as face unlocking, automatic driving of automobiles, human-machine interfaces and games, industrial machine vision and measurement, security monitoring and imaging systems, etc., to meet the needs of receiving infrared light.

In some embodiments, both the object side and the image side of each lens of the optical system 100 are aspherical. The use of aspherical structures can improve the flexibility of lens design, effectively correct spherical aberration, and improve imaging quality. In other embodiments, both the object side and the image side of each lens of the optical system 100 may 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 system 100 may be any combination of aspherical or spherical.

In some embodiments, each lens in the optical system 100 may be made of glass or plastic. Using lenses made of plastic material can reduce the weight of the optical system 100 and reduce production costs. Together with the smaller size of the optical system, a thin and light design of the optical system can be achieved. The lens made of glass enables the optical system 100 to have excellent optical performance and high temperature resistance. It should be noted that the material of each lens in the optical system 100 can also be any combination of glass and plastic, and it does not have to be all glass or all plastic.

It should be noted that the first lens L1 does not mean that there is only one lens. In some embodiments, there may be two or more lenses in the first lens L1, and two or more lenses can form a cemented lens. The surface of the cemented lens closest to the object side can be regarded as the object side S1, and the surface closest to the image side can be regarded as the image side S2. Alternatively, a cemented lens is not formed between the lenses in the first lens L1, but the distance between the lenses is relatively fixed. At this time, the object side of the lens closest to the object side is the object side S1, and the lens closest to the image side The image side is image side S2. In addition, the number of lenses in the second lens L2 or the third lens L3 in some embodiments may be greater than or equal to two, and a cemented lens or a non-cemented lens may be formed between any adjacent lenses.

Further, in some embodiments, the optical system 100 satisfies the conditional expression: 1.4≤FNO≤1.8; where FNO is the aperture number of the optical system 100. Specifically, FNO can be: 1.4, 1.42, 1.46, 1.48, 1.50, 1.51, 1.55, 1.58, 1.62 or 1.76. When the above conditional expression is satisfied, the amount of light transmitted by the optical system 100 can be increased, so that the optical system 100 can obtain clear detailed information of the subject in a low-light environment, and at the same time improve the brightness of the edge field of view, thereby improving the performance of the optical system 100 Imaging quality.

In some embodiments, the optical system 100 satisfies the conditional expression: 0.8≤TT/f≤1.0; where TT is the distance from the object side S1 of the first lens L1 to the image side S6 of the third lens L3 on the optical axis 110, f is the effective focal length of the optical system 100 . Specifically, TT/f can be: 0.855, 0.864, 0.877, 0.896, 0.915, 0.926, 0.955, 0.967, 0.971 or 0.992. When the above conditional expression is satisfied, the ratio of the TT and the effective focal length of the optical system 100 can be reasonably configured, which is beneficial to shortening the total system length of the optical system 100 and realizing a miniaturized design, and is also beneficial to better focusing of light on the optical system 100 of the imaging surface.

In some embodiments, the optical system 100 satisfies the conditional expression: 0.6≤tan(HFOV)*(SD32/IMGH)≤1.1; where HFOV is half of the maximum field of view of the optical system 100, and SD32 is the third lens L3 The maximum effective half aperture of the image side S6, IMGH, is half of the image height corresponding to the maximum field angle of the optical system 100 . Specifically, tan(HFOV)*(SD32/IMGH) can be: 0.636, 0.673, 0.710, 0.725, 0.788, 0.843, 0.852, 0.901, 0.963 or 1. When the above conditional expression is satisfied, the field of view of the optical system 100, the maximum effective semi-aperture of the image side S6 of the third lens L3, and the half-image height of the optical system 100 can be reasonably configured, so that the optical system 100 can operate at a large field of view. To achieve a balance with the miniaturization design, while realizing the miniaturization design, it is also conducive to increasing the field of view of the optical system 100; in addition, it is also conducive to increasing the focal depth of the optical system 100 for imaging, thereby conducive to three-dimensional objects. Acquisition of contour information. Below the lower limit of the above conditional expression, it is not conducive to enlarging the field of view of the optical system 100 while achieving miniaturization design, and thus is not conducive to the optical system 100 having a layered image for objects within a wide field of view. If the upper limit of the above conditional expression is exceeded, the field of view of the optical system 100 is too large, making it difficult to correct the distortion aberration of the optical system 100 , resulting in unclear imaging and severe image deformation.

It should be noted that in some embodiments, the optical system 100 can be matched with a photosensitive element having a rectangular photosensitive surface, and the imaging surface of the optical system 100 coincides with the photosensitive surface of the photosensitive element. At this time, the effective pixel area on the imaging surface of the optical system 100 has horizontal and diagonal directions, then HFOV can be understood as half of the maximum field of view in the diagonal direction of the optical system 100, and ImgH can be understood as the imaging surface of the optical system 100 Half the length of the upper effective pixel area in the diagonal direction.

In some embodiments, the optical system 100 satisfies the conditional expression: 0.10mm≤T12+T23≤1.1mm; where T12 is the distance from the image side S2 of the first lens L1 to the object side S3 of the second lens L2 on the optical axis 110 The distance T23 is the distance on the optical axis 110 from the image side S4 of the second lens L2 to the object side S5 of the third lens L3. Specifically, T12+T23 can be: 0.179, 0.252, 0.367, 0.412, 0.557, 0.623, 0.771, 0.823, 0.996 or 1.065, and the numerical unit is mm. When the above conditional expression is satisfied, the spacing between two adjacent lenses of the optical system 100 can be reasonably configured, thereby further shortening the total system length of the optical system 100 and conducive to the miniaturization design of the optical system 100 . Below the lower limit of the above conditional expression, the distance between two adjacent lenses is too small, which causes the sensitivity of the optical system 100 to increase, which is not conducive to the assembly of the optical system 100 . If the upper limit of the above conditional expression is exceeded, the distance between two adjacent lenses is too large, and additional connecting components such as spacers are required to connect the two adjacent lenses, which increases the cost of the optical system 100 and is not conducive to the performance of the optical system 100 Miniature design.

In some embodiments, the optical system 100 satisfies the conditional expression: 1.0≤f1/f≤18.0; where f1 is the effective focal length of the first lens L1. Specifically, f1/f can be: 1.34, 2.01, 3.25, 5.36, 7.15, 8.33, 10.21, 12.07, 15.15 or 16.22. When the above conditional expression is satisfied, the ratio between the effective focal length of the first lens L1 and the effective focal length of the optical system 100 can be reasonably configured, so that the first lens L1 provides sufficient positive refractive power for the optical system 100, which is beneficial to the convergence of light. When the upper limit of the above conditional expression is exceeded, the positive refractive power provided by the first lens L1 to the optical system 100 is insufficient, resulting in a decrease in the light collection capability of the optical system 100 . Below the lower limit of the above conditional expression, the positive refractive power provided by the first lens L1 to the optical system 100 is too large, which is not conducive to the correction of the aberration produced by the first lens L1 by the second lens L2 and the third lens L3 as a whole, and further The imaging quality of the optical system 100 is reduced. At the same time, the surface shape of the first lens L1 is excessively curved, which is not conducive to the molding of the first lens L1, thereby reducing the manufacturing yield of the first lens L1.

In some embodiments, the optical system 100 satisfies the conditional expression: -45≤R3/CT2≤-1; where R3 is the radius of curvature of the object side S3 of the second lens L2 at the optical axis 110, and CT2 is the second lens L2 thickness on the optical axis 110. Specifically, R3/CT2 can be: -40, -32.01, -21.65, -11.33, -9.54, -8.03, -6.52, -5.36, -3.99 or -2.14. When the above conditional expression is satisfied, the ratio of the curvature radius of the object side S3 of the second lens L2 at the optical axis 100 to the center thickness of the second lens L2 can be reasonably configured, so that the second lens L2 can effectively correct the optical system 100 Field curvature and astigmatism improve the imaging quality of the optical system 100 . Below the lower limit of the above conditional expression, the surface shape of the second lens L2 is too smooth, which is not conducive to correcting the field curvature and astigmatism of the optical system 100 . Exceeding the upper limit of the above conditional expression, the object side surface S3 of the second lens L2 is prone to excessive recurvature near the maximum effective aperture, causing an increase in stray light in the optical system 100 and thus reducing the imaging quality of the optical system 100 .

In some embodiments, the optical system 100 satisfies the conditional expression: 0.80 mm ≤ FFL ≤ 1.05 mm; where FFL is the shortest distance from the image side S6 of the third lens L3 to the imaging surface of the optical system 100 in the direction of the optical axis 110 . Specifically, FFL can be: 0.84, 0.86, 0.87, 0.89, 0.91, 0.93, 0.95, 0.97, 1.01 or 1.03, and the numerical unit is mm. Exceeding the lower limit of the above conditional expression is conducive to allowing the optical system 100 to have sufficient assembly and debugging space during assembly, thereby improving the assembly yield of the optical system 100; at the same time, it is also conducive to increasing the focal depth of the optical system 100 so that The optical system 100 can obtain more depth information of the object side. Being lower than the upper limit of the above conditional expression is beneficial to compressing the axial size of the optical system 100, thereby facilitating the miniaturization design of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: 0.9≤f23/f≤2.5; where f23 is the combined focal length of the second lens L2 and the third lens L3. Specifically, f23/f can be: 0.975, 1.325, 1.561, 1.685, 1.703, 1.872, 1.963, 2.015, 2.225 or 2.313. When the above conditional expression is satisfied, the ratio of the combined focal length of the second lens L2 and the third lens L3 and the effective focal length of the optical system 100 can be reasonably configured, which is beneficial to shortening the total system length of the optical system 100 and also avoiding the need for the optical system 100 to The high-order spherical aberration is excessively increased, which is beneficial to improving the imaging quality of the optical system 100 . Exceeding the upper limit of the above conditional expression, the combined focal length of the second lens L2 and the third lens L3 is too large, which is not conducive to shortening the total system length of the optical system 100 while correcting the spherical aberration of the optical system 100 . Below the lower limit of the above conditional expression, if the combined focal length of the second lens L2 and the third lens L3 is too small, the overall refractive power of the second lens L2 and the third lens L3 will be too strong, which may easily cause excessive correction of spherical aberration, resulting in The image quality of the optical system 100 decreases.

In some embodiments, the optical system 100 satisfies the conditional expression: 1.2≤(R2+R1)/(R2-R1)≤50; where R1 is the radius of curvature of the object side S1 of the first lens L1 at the optical axis 110, R2 is the radius of curvature of the image side surface S2 of the first lens L1 at the optical axis 110 . Specifically, (R2+R1)/(R2-R1) can be: 1.575, 1.785, 1.993, 2.052, 2.133, 2.287, 10.637, 19.852, 30.647 or 47.328. When the above conditional expression is satisfied, the curvature radii of the object side S1 and the image side S2 of the first lens L1 at the optical axis 110 can be reasonably configured to match the surface shape of the image side S2 of the first lens L1 at the paraxial axis 110. , can reasonably allocate the optical deflection angle assumed by the first lens L1, thereby conducive to expanding the maximum field of view of the optical system 100; at the same time, it is also conducive to correcting astigmatism in the off-axis field of view, thereby improving the imaging quality of the optical system 100.

Based on the description of the above embodiments, more specific embodiments and drawings are provided below for detailed description.

First embodiment

Please refer to Figures 1 and 2. Figure 1 is a schematic structural diagram of the optical system 100 in the first embodiment. The optical system 100 includes in order from the object side to the image side a diaphragm STO, a first lens L1 with positive refractive power, The second lens L2 with negative refractive power and the third lens L3 with positive refractive power. 2 shows graphs of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the first embodiment from left to right. The reference wavelength of the astigmatism graph and the distortion graph is 940 nm, and other embodiments are the same.

The object side surface S1 of the first lens L1 is convex at the paraxial axis 110 and convex at the circumference;

The image side surface S2 of the first lens L1 is concave at the paraxial axis 110 and concave at the circumference;

The object side surface S3 of the second lens L2 is concave at the paraxial axis 110 and concave at the circumference;

The image side surface S4 of the second lens L2 is concave at the paraxial axis 110 and convex at the circumference;

The object side surface S5 of the third lens L3 is convex at the paraxial axis 110 and concave at the circumference;

The image side surface S6 of the third lens L3 is concave at the paraxial axis 110 and convex at the circumference.

The object side and image side of the first lens L1, the second lens L2, and the third lens L3 are all aspherical surfaces.

It should be noted that in this application, when one surface of a lens is described as convex at the paraxial axis 110 (the central area of the surface), it can be understood that the surface of the lens is convex in the area near the optical axis 110 . When a surface of a lens is described as being concave around the circumference, it is understood that the surface is concave in a region near the maximum effective radius. For example, when the surface is convex at the paraxial axis 110 and is also convex at the circumference, the shape of the surface from the center (the intersection of the surface and the optical axis 110) to the edge direction can be a pure convex surface; Or it first transitions from a convex shape in the center to a concave shape, and then becomes convex as it approaches the maximum effective radius. This is only an example to illustrate the relationship between the optical axis 110 and the circumference. The various shape structures (concave-convex relationship) of the surface are not fully reflected, but other situations can be deduced based on the above examples.

The first lens L1, the second lens L2 and the third lens L3 are all made of plastic.

Further, the optical system 100 satisfies the conditional expression: FNO=1.4; where FNO is the aperture number of the optical system 100 . When the above conditional expression is satisfied, the amount of light transmitted by the optical system 100 can be increased, so that the optical system 100 can obtain clear detailed information of the subject in a low-light environment, and at the same time improve the brightness of the edge field of view, thereby improving the performance of the optical system 100 Imaging quality.

The optical system 100 satisfies the conditional expression: TT/f=0.968; where TT is the distance on the optical axis 110 from the object side S1 of the first lens L1 to the image side S6 of the third lens L3, and f is the effective focal length of the optical system 100 . When the above conditional expression is satisfied, the ratio of the TT and the effective focal length of the optical system 100 can be reasonably configured, which is beneficial to shortening the total system length of the optical system 100 and realizing a miniaturized design, and is also beneficial to better focusing of light on the optical system 100 of the imaging surface.

The optical system 100 satisfies the conditional expression: tan(HFOV)*(SD32/IMGH)=0.7; where HFOV is half of the maximum field of view of the optical system 100, and SD32 is the maximum effective semi-aperture of the image side S6 of the third lens L3 , IMGH is half of the image height corresponding to the maximum field of view angle of the optical system 100 . When the above conditional expression is satisfied, the field of view of the optical system 100, the maximum effective semi-aperture of the image side S6 of the third lens L3, and the half-image height of the optical system 100 can be reasonably configured, so that the optical system 100 can operate at a large field of view. To achieve a balance with the miniaturization design, while realizing the miniaturization design, it is also conducive to increasing the field of view of the optical system 100; in addition, it is also conducive to increasing the focal depth of the optical system 100 for imaging, thereby conducive to three-dimensional objects. The acquisition of contour information; furthermore, it is also beneficial to the correction of distortion aberration of the optical system 100, thereby avoiding unclear imaging and severe image deformation.

The optical system 100 satisfies the conditional expression: T12+T23=1.065mm; where T12 is the distance from the image side S2 of the first lens L1 to the object side S3 of the second lens L2 on the optical axis 110, and T23 is the distance between the image side S2 of the first lens L1 and the object side S3 of the second lens L2. The distance on the optical axis 110 from the image side S4 to the object side S5 of the third lens L3. When the above conditional expression is satisfied, the distance between two adjacent lenses of the optical system 100 can be reasonably configured, thereby further shortening the total system length of the optical system 100, which is conducive to the miniaturization design of the optical system 100; it is also conducive to reducing the cost of the optical system. The sensitivity of the optical system 100 is 100, which is beneficial to the assembly of the optical system 100; in addition, the cost of the optical system 100 can also be reduced.

The optical system 100 satisfies the conditional expression: f1/f=1.41; where f1 is the effective focal length of the first lens L1. When the above conditional expression is satisfied, the ratio between the effective focal length of the first lens L1 and the effective focal length of the optical system 100 can be reasonably configured, so that the first lens L1 provides sufficient positive refractive power for the optical system 100, which is conducive to the convergence of light; In addition, the positive refractive power provided by the first lens L1 to the optical system 100 will not be too large, which is beneficial to the second lens L2 and the third lens L3 as a whole in correcting the aberrations generated by the first lens L1, thereby improving the optical system 100 The imaging quality of the first lens L1 is improved; at the same time, the surface shape of the first lens L1 will not be excessively curved, which is conducive to the molding of the first lens L1, thereby improving the manufacturing yield of the first lens L1.

The optical system 100 satisfies the conditional expression: R3/CT2=-9.03; where R3 is the radius of curvature of the object side S3 of the second lens L2 at the optical axis 110, and CT2 is the thickness of the second lens L2 on the optical axis 110. When the above conditional expression is satisfied, the ratio of the curvature radius of the object side S3 of the second lens L2 at the optical axis 100 to the center thickness of the second lens L2 can be reasonably configured, so that the second lens L2 can effectively correct the optical system 100 Field curvature and astigmatism can also reduce stray light in the optical system 100, thereby improving the imaging quality of the optical system 100.

The optical system 100 satisfies the conditional expression: FFL = 0.94 mm; where, FFL is the shortest distance from the image side S6 of the third lens L3 to the imaging surface of the optical system 100 in the direction of the optical axis 110 . Exceeding the lower limit of the above conditional expression is conducive to allowing the optical system 100 to have sufficient assembly and debugging space during assembly, thereby improving the assembly yield of the optical system 100; at the same time, it is also conducive to increasing the focal depth of the optical system 100 so that The optical system 100 can obtain more depth information of the object side. Being lower than the upper limit of the above conditional expression is beneficial to compressing the axial size of the optical system 100, thereby facilitating the miniaturization design of the optical system 100.

The optical system 100 satisfies the conditional expression: f23/f=2.313; where f23 is the combined focal length of the second lens L2 and the third lens L3. When the above conditional expression is satisfied, the ratio of the combined focal length of the second lens L2 and the third lens L3 and the effective focal length of the optical system 100 can be reasonably configured, which is beneficial to shortening the total system length of the optical system 100 and also avoiding the need for the optical system 100 to The high-order spherical aberration is excessively increased, which is beneficial to improving the imaging quality of the optical system 100 .

The optical system 100 satisfies the conditional expression: (R2+R1)/(R2-R1)=1.877; where R1 is the radius of curvature of the object side S1 of the first lens L1 at the optical axis 110, and R2 is the image of the first lens L1 The radius of curvature of side S2 at the optical axis 110. When the above conditional expression is satisfied, the curvature radii of the object side S1 and the image side S2 of the first lens L1 at the optical axis 110 can be reasonably configured to match the surface shape of the image side S2 of the first lens L1 at the paraxial axis 110. , can reasonably allocate the optical deflection angle assumed by the first lens L1, thereby conducive to expanding the maximum field of view of the optical system 100; at the same time, it is also conducive to correcting astigmatism in the off-axis field of view, thereby improving the imaging quality of the optical system 100.

In addition, various parameters of the optical system 100 are given in Table 1. Among them, the image plane S9 in Table 1 can be understood as the imaging plane of the optical system 100 . The elements from the object plane (not shown) to the image plane S9 are arranged in sequence from top to bottom in Table 1. The Y radius in Table 1 is the curvature radius of the object side or image side of the corresponding plane number at the optical axis 110. The surface number S1 and the surface number S2 are the object side S1 and the image side S2 of the first lens L1 respectively. That is, in the same lens, the surface with a smaller surface number is the object side and the surface with a larger surface number is the image side. The first value in the "Thickness" parameter column of the first lens L1 is the thickness of the lens on the optical axis 110, and the second value is the rear surface of the lens from the image side to the image side on the optical axis 110. distance.

It should be noted that in this embodiment and the following embodiments, the optical system 100 may not be provided with the infrared bandpass filter L4, but at this time, the distance from the image side S6 to the image surface S9 of the third lens L3 remains unchanged. .

In the first embodiment, the effective focal length of the optical system 100 is f=2.87mm, the aperture number FNO=1.40, the half of the maximum angle of view HFOV=39.7°, and the total optical length TTL=3.98mm.

Moreover, the reference wavelength for the focal length of each lens is 940 nm, and the reference wavelength for the refractive index and Abbe number of each lens is 587.56 nm. The same applies to other embodiments.

Table 1

Further, the aspheric coefficients of the image side or object side of each lens of the optical system 100 are given in Table 2. Among them, the surface numbers from S1 to S6 respectively represent the image side or the object side S1 to S6. K-A20 from top to bottom respectively represents the type of aspherical coefficient, where K represents the conic coefficient, A4 represents the fourth-order aspherical coefficient, A6 represents the sixth-order aspherical coefficient, and A8 represents the eighth-order aspherical coefficient. analogy. In addition, the aspheric coefficient formula is as follows:

Among them, Z is the distance from the corresponding point on the aspheric surface to the plane tangent to the surface vertex, r is the distance from the corresponding point on the aspheric surface to the optical axis 110, c is the curvature of the aspheric surface vertex, k is the cone coefficient, and Ai is the non-spherical surface. The coefficient corresponding to the i-th higher-order term in the spherical surface shape formula.

Table 2

In addition, FIG. 2 includes a longitudinal spherical aberration diagram (Longitudinal Spherical Aberration) of the optical system 100, which represents the deviation of the convergence focus of light of different wavelengths after passing through the lens. The ordinate of the longitudinal spherical aberration diagram represents the normalized pupil coordinate from the pupil center to the pupil edge (Normalized Pupil Coordinator), and the abscissa represents the distance from the imaging surface to the intersection of the light ray and the optical axis 110 (unit: mm) . It can be seen from the longitudinal spherical aberration diagram that in the first embodiment, the degree of deviation of the focus point of light of each wavelength tends to be consistent, and the diffuse spots or color halo in the imaging picture are effectively suppressed. Figure 2 also includes a field curvature diagram (ASTIGMATIC FIELD CURVES) of the optical system 100, in which the S curve represents the sagittal field curvature at 940 nm, and the T curve represents the meridional field curvature at 940 nm. It can be seen from the figure that the field curvature of the optical system 100 is small, the field curvature and astigmatism of each field of view are well corrected, and the center and edge of the field of view have clear imaging. Figure 2 also includes a distortion diagram (DISTORTION) of the optical system 100. It can be seen from the diagram that the image distortion caused by the main beam is small, and the imaging quality of the system is excellent.

Second embodiment

Please refer to Figures 3 and 4. Figure 3 is a schematic structural diagram of the optical system 100 in the second embodiment. The optical system 100 includes, in order from the object side to the image side, the aperture STO, the first lens L1 with positive refractive power, The second lens L2 with negative refractive power and the third lens L3 with positive refractive power. FIG. 2 is a graph showing longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the second embodiment from left to right.

The object side surface S1 of the first lens L1 is convex at the paraxial axis 110 and convex at the circumference;

The image side surface S2 of the first lens L1 is concave at the paraxial axis 110 and concave at the circumference;

The object side surface S3 of the second lens L2 is concave at the paraxial axis 110 and concave at the circumference;

The image side surface S4 of the second lens L2 is concave at the paraxial axis 110 and convex at the circumference;

The object side S5 of the third lens L3 is convex at the paraxial axis 110 and convex at the circumference;

The image side surface S6 of the third lens L3 is concave at the paraxial axis 110 and convex at the circumference.

The object side and image side of the first lens L1, the second lens L2, and the third lens L3 are all aspherical surfaces.

The first lens L1, the second lens L2 and the third lens L3 are all made of plastic.

In addition, various parameters of the optical system 100 are given in Table 3, and the definitions of each parameter can be derived from the first embodiment and will not be described again here.

table 3

Furthermore, the aspheric coefficients of the image side or object side of each lens of the optical system 100 are given in Table 4, and the definitions of each parameter can be derived from the first embodiment and will not be described again here.

Table 4

Moreover, based on the parameter information provided above, the following data can be derived:

FNO 1.650 R3/CT2 -40.000 TT/f 0.992 FFL 0.840mm T12+T23 0.470mm f23/f 1.397 tan(HFOV)*(SD32/IMGH) 0.787 (R2+R1)/(R2-R1) 2.225 f1/f 2.070

In addition, it can be seen from the aberration diagram in FIG. 4 that the longitudinal spherical aberration, field curvature and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Third embodiment

Please refer to Figures 5 and 6. Figure 5 is a schematic structural diagram of the optical system 100 in the third embodiment. The optical system 100 includes in order from the object side to the image side a diaphragm STO, a first lens L1 with positive refractive power, The second lens L2 with positive refractive power and the third lens L3 with positive refractive power. 6 is a graph showing longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the third embodiment from left to right.

The object side surface S1 of the first lens L1 is convex at the paraxial axis 110 and convex at the circumference;

The image side surface S2 of the first lens L1 is concave at the paraxial axis 110 and concave at the circumference;

The object side surface S3 of the second lens L2 is concave at the paraxial axis 110 and concave at the circumference;

The image side surface S4 of the second lens L2 is convex at the paraxial axis 110 and convex at the circumference;

The object side surface S5 of the third lens L3 is convex at the paraxial axis 110 and concave at the circumference;

The image side surface S6 of the third lens L3 is concave at the paraxial axis 110 and convex at the circumference.

The object side and image side of the first lens L1, the second lens L2, and the third lens L3 are all aspherical surfaces.

The first lens L1, the second lens L2 and the third lens L3 are all made of plastic.

In addition, various parameters of the optical system 100 are given in Table 5, and the definitions of each parameter can be derived from the first embodiment and will not be described again here.

table 5

Furthermore, the aspheric coefficients of the image side or object side of each lens of the optical system 100 are given in Table 6, and the definitions of each parameter can be derived from the first embodiment and will not be described again here.

Table 6

Moreover, based on the parameter information provided above, the following data can be derived:

FNO 1.760 R3/CT2 -2.140 TT/f 0.855 FFL 0.950mm T12+T23 0.395mm f23/f 2.010 tan(HFOV)*(SD32/IMGH) 0.636 (R2+R1)/(R2-R1) 1.575 f1/f 1.340

In addition, it can be seen from the aberration diagram in FIG. 6 that the longitudinal spherical aberration, field curvature and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Fourth embodiment

Please refer to Figures 7 and 8. Figure 7 is a schematic structural diagram of the optical system 100 in the fourth embodiment. The optical system 100 includes in order from the object side to the image side a diaphragm STO, a first lens L1 with positive refractive power, The second lens L2 with positive refractive power and the third lens L3 with negative refractive power. 8 is a graph showing longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fourth embodiment from left to right.

The object side surface S1 of the first lens L1 is convex at the paraxial axis 110 and concave at the circumference;

The image side surface S2 of the first lens L1 is concave at the paraxial axis 110 and convex at the circumference;

The object side surface S3 of the second lens L2 is concave at the paraxial axis 110 and concave at the circumference;

The image side surface S4 of the second lens L2 is convex at the paraxial axis 110 and convex at the circumference;

The object side S5 of the third lens L3 is convex at the paraxial axis 110 and convex at the circumference;

The image side surface S6 of the third lens L3 is concave at the paraxial axis 110 and convex at the circumference.

The object side and image side of the first lens L1, the second lens L2, and the third lens L3 are all aspherical surfaces.

The first lens L1, the second lens L2 and the third lens L3 are all made of plastic.

In addition, various parameters of the optical system 100 are given in Table 7, and the definitions of each parameter can be derived from the first embodiment and will not be described again here.

Table 7

Furthermore, the aspheric coefficients of the image side or object side of each lens of the optical system 100 are given in Table 8, and the definitions of each parameter can be derived from the first embodiment and will not be described again here.

Table 8

Moreover, based on the parameter information provided above, the following data can be derived:

FNO 1.650 R3/CT2 -7.290 TT/f 0.874 FFL 1.030mm T12+T23 0.230mm f23/f 0.975 tan(HFOV)*(SD32/IMGH) 0.761 (R2+R1)/(R2-R1) 47.328 f1/f 16.220

In addition, it can be seen from the aberration diagram in FIG. 8 that the longitudinal spherical aberration, field curvature and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Fifth embodiment

Please refer to Figures 9 and 10. Figure 9 is a schematic structural diagram of the optical system 100 in the fifth embodiment. The optical system 100 includes in order from the object side to the image side a diaphragm STO, a first lens L1 with positive refractive power, The second lens L2 with positive refractive power and the third lens L3 with negative refractive power. FIG. 10 is a graph showing longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fifth embodiment from left to right.

The object side surface S1 of the first lens L1 is convex at the paraxial axis 110 and convex at the circumference;

The image side surface S2 of the first lens L1 is concave at the paraxial axis 110 and convex at the circumference;

The object side surface S3 of the second lens L2 is concave at the paraxial axis 110 and convex at the circumference;

The image side surface S4 of the second lens L2 is convex at the paraxial axis 110 and concave at the circumference;

The object side surface S5 of the third lens L3 is convex at the paraxial axis 110 and concave at the circumference;

The image side surface S6 of the third lens L3 is concave at the paraxial axis 110 and convex at the circumference.

The object side and image side of the first lens L1, the second lens L2, and the third lens L3 are all aspherical surfaces.

The first lens L1, the second lens L2 and the third lens L3 are all made of plastic.

In addition, various parameters of the optical system 100 are given in Table 9, and the definitions of each parameter can be derived from the first embodiment and will not be described again here.

Table 9

Furthermore, the aspheric coefficients of the image side or object side of each lens of the optical system 100 are given in Table 10, and the definitions of each parameter can be derived from the first embodiment and will not be described again here.

Table 10

Moreover, based on the parameter information provided above, the following data can be derived:

FNO 1.650 R3/CT2 -3.210 TT/f 0.948 FFL 0.840mm T12+T23 0.206mm f23/f 1.463 tan(HFOV)*(SD32/IMGH) 1.000 (R2+R1)/(R2-R1) 1.790 f1/f 2.120

In addition, it can be seen from the aberration diagram in FIG. 10 that the longitudinal spherical aberration, field curvature and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Sixth embodiment

Please refer to Figures 11 and 12. Figure 11 is a schematic structural diagram of the optical system 100 in the sixth embodiment. The optical system 100 includes in order from the object side to the image side a diaphragm STO, a first lens L1 with positive refractive power, The second lens L2 with positive refractive power and the third lens L3 with negative refractive power. FIG. 12 is a graph showing longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the sixth embodiment from left to right.

The object side surface S1 of the first lens L1 is convex at the paraxial axis 110 and convex at the circumference;

The image side surface S2 of the first lens L1 is concave at the paraxial axis 110 and convex at the circumference;

The object side surface S3 of the second lens L2 is concave at the paraxial axis 110 and convex at the circumference;

The image side surface S4 of the second lens L2 is convex at the paraxial axis 110 and concave at the circumference;

The object side surface S5 of the third lens L3 is convex at the paraxial axis 110 and concave at the circumference;

The image side surface S6 of the third lens L3 is concave at the paraxial axis 110 and convex at the circumference.

The object side and image side of the first lens L1, the second lens L2, and the third lens L3 are all aspherical surfaces.

The first lens L1, the second lens L2 and the third lens L3 are all made of plastic.

In addition, various parameters of the optical system 100 are given in Table 11, and the definitions of each parameter can be derived from the first embodiment and will not be described again here.

Table 11

Furthermore, the aspheric coefficients of the image side or object side of each lens of the optical system 100 are given in Table 12, and the definitions of each parameter can be derived from the first embodiment and will not be described again here.

Table 12

Moreover, based on the parameter information provided above, the following data can be derived:

FNO 1.650 R3/CT2 -3.010 TT/f 0.930 FFL 0.950 T12+T23 0.179mm f23/f 1.472 tan(HFOV)*(SD32/IMGH) 0.802 (R2+R1)/(R2-R1) 2.093 f1/f 2.050

In addition, it can be seen from the aberration diagram in FIG. 12 that the longitudinal spherical aberration, field curvature and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Referring to FIG. 13 , in some embodiments, the optical system 100 can be assembled with the photosensitive element 210 to form an infrared receiving module 200 . At this time, the photosensitive surface of the photosensitive element 210 can be regarded as the image surface S9 of the optical system 100 . The infrared receiving module 200 may also be provided with an infrared bandpass filter L4. The infrared bandpass filter L4 is disposed between the image side S6 and the image surface S9 of the third lens L3. Specifically, the photosensitive element 210 may be a Charge Coupled Device (CCD) or a Complementary Metal-Oxide Semiconductor Sensor (CMOS Sensor). More specifically, the photosensitive element 210 can be an infrared image sensor, and the infrared receiving module 200 is used to receive infrared light and image it on the photosensitive element 210 . Using the above-mentioned optical system 100 in the infrared receiving module 200 is beneficial to increasing the amount of light transmitted by the infrared receiving module 200, and is also beneficial to the miniaturization design of the infrared receiving module 200.

Referring to FIGS. 13 and 14 , in some embodiments, the infrared receiving module 200 can be used in an electronic device 300 . The electronic device includes a housing 310 , and the infrared receiving module 200 is disposed in the housing 310 . Specifically, the electronic device 300 may be, but is not limited to, a mobile phone, a video phone, a smartphone, an electronic book reader, a vehicle-mounted camera device such as a driving recorder, or a wearable device such as a smart watch. In addition, the electronic device 300 can use TOF or LiDAR technology, and can be used in areas such as face unlocking, autonomous vehicle driving, human-machine interface and games, industrial machine vision and measurement, security monitoring imaging systems, and other fields. In some embodiments, the electronic device 300 further includes a transmitting module 320. The transmitting module 320 is configured to emit infrared rays. For example, the electronic device 300 may emit infrared light in the wavelength range of 930 nm to 950 nm. For example, when the electronic device 300 adopts TOF technology, the electronic device 300 can be used to obtain the depth information of the object being measured, and then the infrared rays emitted by the transmitting module 320 are reflected by the object and are received by the infrared receiving module 200 . Using the infrared receiving module 200 in the electronic device 300 is beneficial to increasing the amount of light transmitted by the electronic device 300, and is also beneficial to the miniaturization design of the electronic device 300.

The technical features of the above-described embodiments can be combined in any way. To simplify the description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, All should be considered to be within the scope of this manual.

The above-mentioned embodiments only express several implementation modes of the present invention. The descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the scope of protection of the patent of the present invention should be determined by the appended claims.

Claims (10)

1. An optical system, characterized in that the number of lenses with refractive power in the optical system is three, and the optical system sequentially comprises, from an object side to an image side along an optical axis:

a first lens element with positive refractive power having a concave image-side surface at a paraxial region;

a second lens element with refractive power having a concave object-side surface at a paraxial region;

A third lens element with refractive power having a concave image-side surface at a paraxial region;

and the optical system satisfies the following conditional expression:

1.4≤FNO≤1.8；

0.8≤TT/f≤1.0；

0.9≤f23/f≤2.5；

wherein FNO is the f-number of the optical system, TT is the distance between the object side surface of the first lens and the image side surface of the third lens on the optical axis, f is the effective focal length of the optical system, and f23 is the combined focal length of the second lens and the third lens.

2. The optical system according to claim 1, wherein the following conditional expression is satisfied:

0.6≤tan(HFOV)*(SD32/IMGH)≤1.1；

wherein HFOV is half of the maximum field angle of the optical system, SD32 is the maximum effective half aperture of the image side surface of the third lens, and IMGH is half of the image height corresponding to the maximum field angle of the optical system.

3. The optical system according to claim 1, wherein the following conditional expression is satisfied:

0.10mm≤T12+T23≤1.1mm；

wherein T12 is a distance between the image side surface of the first lens element and the object side surface of the second lens element on the optical axis, and T23 is a distance between the image side surface of the second lens element and the object side surface of the third lens element on the optical axis.

4. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1.0≤f1/f≤18.0；

Wherein f1 is the effective focal length of the first lens.

5. The optical system according to claim 1, wherein the following conditional expression is satisfied:

-45≤R3/CT2≤-1；

wherein R3 is the radius of curvature of the object side surface of the second lens on the optical axis, and CT2 is the thickness of the second lens on the optical axis.

6. The optical system according to claim 1, wherein the following conditional expression is satisfied:

0.80mm≤FFL≤1.05mm；

wherein FFL is the shortest distance between the image side surface of the third lens and the imaging surface of the optical system in the optical axis direction.

7. The optical system of claim 1, wherein the object side and the image side of the first lens, the second lens, and the third lens are aspheric.

8. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1.2≤(R2+R1)/(R2-R1)≤50；

wherein R1 is a radius of curvature of the object side surface of the first lens element at the optical axis, and R2 is a radius of curvature of the image side surface of the first lens element at the optical axis.

9. An infrared receiving module comprising a photosensitive element and the optical system of any one of claims 1-8, the photosensitive element being disposed on an image side of the optical system.

10. An electronic device comprising a housing and the infrared receiving module of claim 9, wherein the infrared receiving module is disposed on the housing.