Optical System, Camera Module, and Electronic Device

Abstract

The present invention provides an optical system, an imaging module, and an electronic device. The optical system sequentially includes, along the optical axis from the object side to the image side: a prism; a first lens group having a positive refractive power, the first lens group including a first lens; a second lens group having a negative refractive power, the second lens group including a second lens, a third lens, and a fourth lens; a third lens group having a positive refractive power, the third lens group including a fifth lens, a sixth lens, and a seventh lens; the distances between the first lens group, the second lens group, and the third lens group are adjustable so that the optical system is in a telephoto end, a mid-telephoto end, and a wide-angle end, and the focal lengths of the optical system at the telephoto end, the mid-telephoto end, and the wide-angle end are different. The present invention solves the technical problem that existing lenses cannot simultaneously meet the requirements of large-range zoom and lens miniaturization.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical imaging, and particularly relates to an optical system, a camera module, and an electronic device. Background Art

[0002] In recent years, electronic devices equipped with multiple lenses have emerged. Such electronic devices achieve the effects of ultra-clear shooting, wide-angle shooting, and telephoto shooting by switching different lenses. Although the lens configuration of such electronic devices meets the user's photo-taking needs in different scenarios, it will increase the lens cost, occupy the space of the electronic device, make the electronic device thicker and heavier, and affect the user experience. Therefore, the existing lenses cannot meet the requirements of large-range zoom and lens miniaturization at the same time. Summary of the Invention

[0003] The purpose of this application is to provide an optical system, a camera module, and an electronic device to solve the above technical problems.

[0004] The present invention provides an optical system, which sequentially includes, along the optical axis from the object side to the image side: a prism; a first lens group with positive refractive power, the first lens group includes a first lens; a second lens group with negative refractive power, the second lens group includes a second lens, a third lens, and a fourth lens; a third lens group with positive refractive power, the third lens group includes a fifth lens, a sixth lens, and a seventh lens; the distances between the first lens group, the second lens group, and the third lens group are adjustable, so that the optical system is in the telephoto end, the middle focal end, and the short focal end, and the focal lengths of the optical system at the telephoto end, the middle focal end, and the short focal end are different. By reasonably configuring the refractive powers of the first lens group, the second lens group, and the third lens group, and by reasonably configuring the distances between the first lens group, the second lens group, and the third lens group, this application can make the optical system meet the requirements of large-range zoom and miniaturization at the same time. At the same time, the setting of the prism deflects the light rays to form a folded periscope structure. On the one hand, it shortens the lateral distance and reduces the space occupied by the optical system; on the other hand, it provides enough length for the optical system to achieve the zoom characteristic.

[0005] In some embodiments, the optical system satisfies the conditional formula: Fc / Fd>1.45, where Fc is the focal length of the optical system at the telephoto end, and Fd is the focal length of the optical system at the short focal end. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the focal length at the telephoto end to the focal length at the short focal end, the optical system can obtain a higher zoom ratio, thereby achieving a larger shooting magnification range.

[0006] In some embodiments, the optical system satisfies the conditional formula: 4deg / mm < FOVc / ImgH < 5.5deg / mm, where FOVc is the maximum field of view angle of the optical system at the telephoto end, and ImgH is half of the diagonal length of the effective imaging area of the imaging surface. When the optical system satisfies the above conditional formula, by configuring the ratio of the full field of view angle at the telephoto end to the half image height within a reasonable range, the telephoto characteristics of the zoom lens can be achieved, and at the same time, a higher pixel chip can be matched to achieve high-definition shooting.

[0007] In some embodiments, the optical system satisfies the conditional formula: 40 < TTL / (ATg2 - ATg3) < 95, where TTL is the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis, ATg2 is the sum of the air gaps between adjacent lenses of the second lens group on the optical axis, and ATg3 is the sum of the air gaps between adjacent lenses of the third lens group on the optical axis. When the optical system satisfies the above conditional formula, by controlling the sum of the air gaps between adjacent lenses of the second lens group on the optical axis and the sum of the air gaps between adjacent lenses of the third lens group on the optical axis, on the basis of achieving a large zoom ratio, the total length of the optical system can be effectively shortened, saving space for the electronic device equipped with the zoom lens.

[0008] In some embodiments, the optical system satisfies the conditional formula: 2 < (R3 + R4) / (R7 + R8) < 8.5, where R3 is the curvature radius of the object side surface of the second lens on the optical axis, R4 is the curvature radius of the image side surface of the second lens on the optical axis, R7 is the curvature radius of the object side surface of the fourth lens on the optical axis, and R8 is the curvature radius of the image side surface of the fourth lens on the optical axis. When the optical system satisfies the above conditional formula, by controlling the curvature radii of the object side and image side surfaces of the first and last lenses of the second lens group within a reasonable range, it is beneficial to control the aberration generated by the second lens group, so that it reaches an equilibrium state with the aberration components contributed by the front and rear lens groups, thereby improving the imaging quality of the optical system; in addition, it is also beneficial to reasonably constrain the surface shapes of the second and fourth lenses, reducing the forming and processing difficulty.

[0009] In some embodiments, the optical system satisfies the conditional formula: F2 / F234 < 7.5, where F2 is the focal length of the second lens, and F234 is the focal length of the second lens group. When the optical system satisfies the above conditional formula, the negative refractive power of the second lens is part of the overall negative refractive power of the second lens group. Therefore, by controlling the negative refractive power borne by the second lens within a reasonable range, it is beneficial for the second lens group to balance the spherical aberration generated by the front lens group, providing a reasonable and controllable negative refractive power for the zoom lens, further improving the imaging quality, and in addition, it is also beneficial to shorten the total length of the system.

[0010] In some embodiments, the optical system satisfies the conditional formula: 4 < F1 / F567 < 13, where F1 is the focal length of the first lens group and F567 is the focal length of the third lens group. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the focal length of the first lens group to the focal length of the third lens group, it is beneficial to obtain a wider zoom range. Additionally, by reasonably controlling the positive refractive power borne by the first lens group and the third lens, and coordinating with the negative refractive power contributed by the second lens group, and by moving the position of the lens group with the aid of the action of the cam, different focal lengths in three zoom states are jointly achieved, thereby achieving the required zoom characteristics.

[0011] In some embodiments, the optical system satisfies the conditional formula: 1.9 < F1 / Fc < 6, where F1 is the focal length of the first lens group and Fc is the focal length of the optical system at the telephoto end. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the focal length of the first lens group to the focal length at the telephoto end, it is beneficial to obtain a wider zoom range in the telephoto direction. At the same time, by assigning an appropriate refractive power to the first lens group, it is beneficial to correct distortion and spherical aberration, and further improve the resolution of the system.

[0012] In some embodiments, the optical system satisfies the conditional formula: g3 / (g1 + g2) < 2, where g1 is the distance on the optical axis from the object side surface of the first lens to the image side surface of the first lens, g2 is the distance on the optical axis from the object side surface of the second lens to the image side surface of the fourth lens, and g3 is the distance on the optical axis from the object side surface of the fifth lens to the image side surface of the seventh lens. When the optical system satisfies the above conditional formula, by reasonably configuring the total thickness of the three lens groups, it is beneficial to shorten the overall length of the optical system, and control the thickness and spacing of the lenses in each lens group within a reasonable range. On the one hand, it saves materials, and on the other hand, it can ensure good processability.

[0013] In some embodiments, the optical system satisfies the conditional formula: 2 < R14 / F7 < 12, where R14 is the radius of curvature of the image side surface of the seventh lens at the optical axis and F7 is the focal length of the seventh lens. When the optical system satisfies the above conditional formula, by controlling the ratio of the radius of curvature of the image side surface of the seventh lens at the optical axis to the effective focal length of the seventh lens, it helps the surface shape of the seventh lens to be easily processed and balance the aberration generated by the front lens group.

[0014] The present invention provides an imaging module, which includes a lens barrel, an electronic photosensitive element, and the optical system as described above. The first lens to the seventh lens of the optical system are installed in the lens barrel, and the electronic photosensitive element is disposed on the image side of the optical system for converting the light of an object incident on the electronic photosensitive element through the first lens to the seventh lens into an electrical signal of an image. By installing the first lens to the seventh lens of the optical system in the imaging module and reasonably configuring the surface types and refractive powers of the lenses of the first lens to the seventh lens, the imaging module can meet the requirements of both large-range zoom and miniaturization at the same time.

[0015] The present invention provides an electronic device, which includes a housing and the imaging module as described above, and the imaging module is disposed in the housing. By providing the above imaging module in the electronic device, the electronic device can meet the requirements of both large-range zoom and miniaturization at the same time.

[0016] In summary, by providing a prism part capable of changing the optical path direction and laterally placing the lens in the housing of the electronic device during installation, the lateral length and overall height of the lens can be reduced, meeting the requirements of gradually increasing pixel count, gradually expanding zoom range, and miniaturization of the optical imaging lens, and further realizing the requirement of thinning of the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1a is a schematic structural diagram of the optical system in the short focal length end of the first embodiment;

[0019] Figure 1b is the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system in the short focal length end of the first embodiment;

[0020] Figure 1c is a schematic structural diagram of the optical system in the middle focal length end of the first embodiment;

[0021] Figure 1d is the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system in the middle focal length end of the first embodiment;

[0022] Figure 1e is a schematic structural diagram of the optical system in the long focal length end of the first embodiment;

[0023] Figure 1fThe longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the first embodiment at the telephoto end;

[0024] Figure 2a Schematic structural diagram of the optical system of the second embodiment at the wide-angle end;

[0025] Figure 2b The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the second embodiment at the wide-angle end;

[0026] Figure 2c Schematic structural diagram of the optical system of the second embodiment at the mid-focal length end;

[0027] Figure 2d The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the second embodiment at the mid-focal length end;

[0028] Figure 2e Schematic structural diagram of the optical system of the second embodiment at the telephoto end;

[0029] Figure 2f The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the second embodiment at the telephoto end;

[0030] Figure 3a Schematic structural diagram of the optical system of the third embodiment at the wide-angle end;

[0031] Figure 3b The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the third embodiment at the wide-angle end;

[0032] Figure 3c Schematic structural diagram of the optical system of the third embodiment at the mid-focal length end;

[0033] Figure 3d The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the third embodiment at the mid-focal length end;

[0034] Figure 3e Schematic structural diagram of the optical system of the third embodiment at the telephoto end;

[0035] Figure 3f The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the third embodiment at the telephoto end;

[0036] Figure 4a Schematic structural diagram of the optical system of the fourth embodiment at the wide-angle end;

[0037] Figure 4b The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the fourth embodiment at the wide-angle end;

[0038] Figure 4c It is a schematic structural diagram of the optical system of the fourth embodiment at the mid-focal end;

[0039] Figure 4d It is the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fourth embodiment at the mid-focal end;

[0040] Figure 4e It is a schematic structural diagram of the optical system of the fourth embodiment at the long-focal end;

[0041] Figure 4f It is the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fourth embodiment at the long-focal end;

[0042] Figure 5a It is a schematic structural diagram of the optical system of the fifth embodiment at the short-focal end;

[0043] Figure 5b It is the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fifth embodiment at the short-focal end;

[0044] Figure 5c It is a schematic structural diagram of the optical system of the fifth embodiment at the mid-focal end;

[0045] Figure 5d It is the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fifth embodiment at the mid-focal end;

[0046] Figure 5e It is a schematic structural diagram of the optical system of the fifth embodiment at the long-focal end;

[0047] Figure 5f It is the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fifth embodiment at the long-focal end;

[0048] Figure 6a It is a schematic structural diagram of the optical system of the sixth embodiment at the short-focal end;

[0049] Figure 6b It is the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the sixth embodiment at the short-focal end;

[0050] Figure 6c It is a schematic structural diagram of the optical system of the sixth embodiment at the mid-focal end;

[0051] Figure 6d It is the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the sixth embodiment at the mid-focal end;

[0052] Figure 6e It is a schematic structural diagram of the optical system of the sixth embodiment at the long-focal end;

[0053] Figure 6f They are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the sixth embodiment at the telephoto end. Detailed implementation manners

[0054] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part rather than all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0055] The embodiment of the present application provides an imaging module. The imaging module includes a lens barrel, an electronic photosensitive element, and the optical system provided by the embodiment of the present invention. The first lens to the seventh lens of the optical system are installed in the lens barrel, and the electronic photosensitive element is disposed on the image side of the optical system for converting the light of an object incident on the electronic photosensitive element through the first lens to the seventh lens into an electrical signal of an image. The electronic photosensitive element can be a Complementary Metal Oxide Semiconductor (CMOS) or a Charge-coupled Device (CCD). The imaging module can be an independent lens of a digital camera or an imaging module integrated on an electronic device such as a smart phone. By installing the first lens to the seventh lens of the optical system in the imaging module and reasonably configuring the surface types and refractive powers of the lenses of the first lens to the seventh lens, the imaging module can simultaneously meet the requirements of large-range zoom and miniaturization.

[0056] The embodiment of the present application provides an electronic device. The electronic device includes a housing and the imaging module provided by the embodiment of the present application. The imaging module and the electronic photosensitive element are disposed in the housing. The electronic device can be a smart phone, a Personal Digital Assistant (PDA), a tablet computer, a smart watch, a drone, an e-book reader, a dash cam, a wearable device, etc. By providing the imaging module in the electronic device, the electronic device can simultaneously meet the requirements of large-range zoom and miniaturization.

[0057] An embodiment of the present application provides an optical system, which sequentially includes, from the object side to the image side along the optical axis direction: a prism; a first lens group having a positive refractive power, the first lens group including a first lens; a second lens group having a negative refractive power, the second lens group including a second lens, a third lens, and a fourth lens; a third lens group having a positive refractive power, the third lens group including a fifth lens, a sixth lens, and a seventh lens. An air gap can be provided between any two adjacent lenses among the first lens to the seventh lens.

[0058] The distances between the first lens group, the second lens group, and the third lens group are adjustable so that the optical system is in the telephoto end, the mid-telephoto end, and the wide-angle end, and the focal lengths of the optical system in the telephoto end, the mid-telephoto end, and the wide-angle end are different.

[0059] In the present application, by reasonably configuring the refractive powers of the first lens group, the second lens group, and the third lens group, and by reasonably configuring the distances between the first lens group, the second lens group, and the third lens group, the optical system can simultaneously meet the requirements of large-range zoom and miniaturization. At the same time, the setting of the prism deflects the light rays to form a folded periscope structure. On the one hand, the lateral distance is shortened, and the space occupied by the optical system is reduced; on the other hand, sufficient length is provided for the optical system to achieve the zoom characteristic.

[0060] It can be understood that when zooming from the wide-angle end to the telephoto end position, the prism, the first lens group, and the image plane remain stationary, the distance between the first lens group and the second lens group increases, and the distance between the third lens group and the image plane also increases, and the optical system includes at least one aspheric plastic lens.

[0061] In a specific embodiment, the optical system satisfies the conditional formula: Fc / Fd>1.45, where Fc is the focal length of the optical system at the telephoto end, and Fd is the focal length of the optical system at the wide-angle end. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the focal length at the telephoto end to the focal length at the wide-angle end, the optical system can obtain a higher zoom ratio, thereby achieving a larger shooting magnification. When Fc / Fd≤1.45, it is not sufficient to meet the higher requirements of users for the shooting experience.

[0062] In a specific embodiment, the optical system satisfies the conditional formula: 4deg / mm<FOVc / ImgH<5.5deg / mm, where FOVc is the maximum field of view angle of the optical system at the telephoto end, and ImgH is half of the diagonal length of the effective imaging area of the imaging plane. When the optical system satisfies the above conditional formula, by configuring the ratio of the maximum field of view angle at the telephoto end to the half image height within a reasonable range, the telephoto characteristic of the zoom lens can be achieved, and at the same time, a higher pixel chip can be matched to achieve high-definition shooting.

[0063] In a specific embodiment, the optical system satisfies the conditional formula: 40 < TTL / (ATg2 - ATg3) < 95, where TTL is the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis, ATg2 is the sum of the air gaps between adjacent lenses of the second lens group on the optical axis, and ATg3 is the sum of the air gaps between adjacent lenses of the third lens group on the optical axis. When the optical system satisfies the above conditional formula, by controlling the sum of the air gaps between adjacent lenses of the second lens group and the sum of the air gaps between adjacent lenses of the third lens group on the optical axis, on the basis of achieving a large zoom ratio, the total length of the optical system can be effectively shortened, saving space for the electronic device equipped with the zoom lens.

[0064] In a specific embodiment, TTL ≤ 34 mm. When the optical system satisfies the above conditional formula, the length of the optical system can be made appropriate, without increasing the pressure on the spatial configuration of the electronic device, without squeezing other parts, and the stability of the optical system is relatively good. When TTL > 34 mm, the total length of the optical system is too large, which is likely to increase the pressure on the spatial configuration of the electronic device, easily squeeze other parts, and also reduce the stability of the optical system itself.

[0065] In a specific embodiment, the optical system satisfies the conditional formula: 2 < (R3 + R4) / (R7 + R8) < 8.5, where R3 is the curvature radius of the object side surface of the second lens on the optical axis, R4 is the curvature radius of the image side surface of the second lens on the optical axis, R7 is the curvature radius of the object side surface of the fourth lens on the optical axis, and R8 is the curvature radius of the image side surface of the fourth lens on the optical axis. It can be understood that the second lens and the fourth lens are respectively the first lens and the last lens of the second lens group. When the optical system satisfies the above conditional formula, by controlling the curvature radii of the object side and the image side of the first lens and the last lens of the second lens group within a reasonable range, it is beneficial to control the aberration generated by the second lens group, making it reach an equilibrium state with the aberration components contributed by the front and rear lens groups, thereby improving the imaging quality of the optical system; in addition, it is also beneficial to reasonably constrain the surface shapes of the second lens and the fourth lens, reducing the forming and processing difficulty.

[0066] In a specific embodiment, the optical system satisfies the conditional formula: F2 / F234 < 7.5, where F2 is the focal length of the second lens, and F234 is the focal length of the second lens group. When the optical system satisfies the above conditional formula, the negative refractive power of the second lens is part of the overall negative refractive power of the second lens group. Therefore, by controlling the negative refractive power borne by the second lens within a reasonable range, it is beneficial for the second lens group to balance the spherical aberration generated by the front lens group, provide reasonable and controllable negative refractive power for the zoom lens, further improve the imaging quality, and also help to shorten the overall length of the system. When F2 / F234 ≥ 7.5, the negative refractive power borne by the second lens is too small, directly resulting in the weakening of the negative refractive power of the second lens group, which is not conducive to correcting the aberration generated by the front and rear lens groups.

[0067] In a specific embodiment, the optical system satisfies the conditional formula: 4 < F1 / F567 < 13, where F1 is the focal length of the first lens group, and F567 is the focal length of the third lens group. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the focal length of the first lens group to the focal length of the third lens group, it is beneficial to obtain a wider zoom range. In addition, by reasonably controlling the positive refractive power borne by the first lens group and the third lens, and cooperating with the negative refractive power contributed by the second lens group, and moving the position of the lens group by means of the action of the cam, different focal lengths in three zoom states are jointly achieved, thereby achieving the required zoom characteristics.

[0068] In a specific embodiment, the optical system satisfies the conditional formula: 1.9 < F1 / Fc < 6, where F1 is the focal length of the first lens group, and Fc is the focal length of the optical system at the telephoto end. When the optical system satisfies the above conditional formula, reasonably configuring the ratio of the focal length of the first lens group to the focal length at the telephoto end is beneficial to obtain a wider zoom range in the telephoto direction. At the same time, by assigning an appropriate refractive power to the first lens group, it is beneficial to correct distortion and spherical aberration, and further improve the resolution of the system. When F1 / Fc ≥ 6, the focal length at the telephoto end is too small, which is not conducive to achieving the telephoto characteristics, and will also reduce the zoom ratio, ultimately resulting in a weakened market competitiveness.

[0069] In a specific embodiment, the optical system satisfies the conditional formula: g3 / (g1 + g2) < 2, where g1 is the distance from the object side surface of the first lens to the image side surface of the first lens on the optical axis, g2 is the distance from the object side surface of the second lens to the image side surface of the fourth lens on the optical axis, and g3 is the distance from the object side surface of the fifth lens to the image side surface of the seventh lens on the optical axis. When the optical system satisfies the above conditional formula, by reasonably configuring the total thickness of the three lens groups, it is beneficial to shorten the total length of the optical system, and control the thickness and spacing of the lenses in each lens group within a reasonable range. On the one hand, it saves materials, and on the other hand, it can ensure good processability. When g3 / (g1 + g2) ≥ 2, it is easy to cause uneven distribution of the thickness and air gap of the lenses in each lens group of the optical system, increasing the assembly difficulty.

[0070] In a specific embodiment, the optical system satisfies the conditional formula: 2 < R14 / F7 < 12, where R14 is the radius of curvature of the image side surface of the seventh lens at the optical axis, and F7 is the focal length of the seventh lens. When the optical system satisfies the above conditional formula, by controlling the ratio of the radius of curvature of the image side surface of the seventh lens at the optical axis to the effective focal length of the seventh lens, it helps the surface shape of the seventh lens to be easily processed and balance the aberration generated by the front lens group. When R14 / F7 ≤ 2, the positive refractive power borne by the seventh lens is too large, which easily causes excessive deflection of the off-axis field light, and then it cannot reasonably transition to the image plane, finally resulting in a reduction in the overall imaging quality. When R14 / F7 ≥ 12, the surface shape of the image side surface of the seventh lens is too flat, the ability to deflect light is weakened, and the ability to balance and correct aberration is weakened, which is not conducive to ensuring good imaging quality.

[0071] First Embodiment

[0072] Please refer to Figure 1a - Figure 1f , the optical system of this embodiment sequentially includes, from the object side to the image side along the optical axis direction:

[0073] Prism E, which has an incident surface A1, a reflecting surface A2, and an exit surface A3. It can be understood that when the light from the object to be photographed enters Prism E through the incident surface A1, it can be totally reflected by the reflecting surface A2 and turned to the exit surface A3 to exit along the direction of the optical axis.

[0074] The first lens L1, which has a positive refractive power. The object side surface S1 of the first lens L1 is convex near the optical axis, and the image side surface S2 is concave near the optical axis; the object side surface S1 of the first lens L1 is convex at the circumference, and the image side surface S2 is concave at the circumference.

[0075] The second lens L2, which has a negative refractive power. The object side surface S3 of the second lens L2 is convex near the optical axis, and the image side surface S4 is concave near the optical axis; the object side surface S3 of the second lens L2 is convex at the circumference, and the image side surface S4 is concave at the circumference.

[0076] The third lens L3 has a positive refractive power. The object side S5 of the third lens L3 is concave near the optical axis, and the image side S6 is convex near the optical axis; the object side S5 of the third lens L3 is convex at the circumference, and the image side S6 is convex at the circumference.

[0077] The fourth lens L4 has a negative refractive power. The object side S7 of the fourth lens is concave near the optical axis, and the image side S8 is concave near the optical axis; the object side S7 of the fourth lens L4 is concave at the circumference, and the image side S8 is convex at the circumference.

[0078] The fifth lens L5 has a positive refractive power. The object side S9 of the fifth lens L5 is convex near the optical axis, and the image side S10 is convex near the optical axis; the object side S9 of the fifth lens L5 is convex at the circumference, and the image side S10 is concave at the circumference.

[0079] The sixth lens L6 has a negative refractive power. The object side S11 of the sixth lens is concave near the optical axis, and the image side S12 is concave near the optical axis; the object side S11 of the sixth lens L6 is convex at the circumference, and the image side S12 is concave at the circumference.

[0080] The seventh lens L7 has a positive refractive power. The object side S13 of the seventh lens L7 is convex near the optical axis, and the image side S14 is concave near the optical axis; the object side S13 of the seventh lens L7 is concave at the circumference, and the image side S14 is convex at the circumference.

[0081] The materials of the above-mentioned first lens L1 to seventh lens L7 are plastic or glass. The material of at least one of the first lens L1 to seventh lens L7 is plastic.

[0082] In addition, the optical system further includes a diaphragm STO, an infrared filter L8, and an image plane S17. The diaphragm STO is disposed between the fourth lens L4 and the fifth lens L5 for controlling the amount of incident light. In other embodiments, the diaphragm STO can also be disposed between other adjacent two lenses, or on other lenses. The infrared filter L8 is disposed on the image side of the seventh lens L7, and it includes an object side S15 and an image side S16. The infrared filter L8 is used to filter out infrared light so that the light incident on the image plane S17 is visible light, and the wavelength of the visible light is 380nm - 780nm. The material of the infrared filter L8 is glass and can be coated with a film on the glass. The image plane S17 is the plane where the image of the light of the object to be photographed is formed after passing through the optical system. The prism E can be a right prism.

[0083] Tables 1a(1) - 1a(2) show the tables of the characteristics of the optical system of this embodiment, and the units of the Y radius, thickness, and focal length are all millimeters (mm).

[0084] Table 1a(1)

[0085]

[0086] Table 1a(2)

[0087] Variable distance D1 D2 D3 f (mm) FNO FOV (°) Short - focus position -0.3441 -5.3239 -7.2270 15.4 3.27 29.5 Mid - focus position -1.2762 -3.1307 -8.4798 18.6 3.86 24.3 Long - focus position -1.4479 -0.4121 -11.0350 24.3 5.04 18.6

[0088] Among them, f is the focal length of the optical system, FNO is the f-number of the optical system, FOV is the field of view angle of the optical system, and TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface of the optical system. The positive and negative of the thickness value only represent the direction.

[0089] In this embodiment, the object side surface and the image side surface of any one of the third lens L3 to the seventh lens L7 are aspherical surfaces. The surface shape x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0090]

[0091] Among them, x is the sagitta, the distance from the vertex of the aspherical surface when the aspherical surface is along the optical axis at a position with a height of h; c is the paraxial curvature of the aspherical surface, c = 1 / R (that is, the paraxial curvature c is the reciprocal of the Y radius R in Table 1a(1) above); k is the conic coefficient; Ai is the correction coefficient of the i-th order of the aspherical surface. Table 1b gives the high-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 of each aspherical mirror surface S1 - S14 in the first embodiment.

[0092] Table 1b

[0093]

[0094] Figure 1a Shows a schematic structural diagram of the optical system of the first embodiment at the short focal length end. Figure 1b Shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the first embodiment at the short focal length end. Among them, the longitudinal spherical aberration curve represents the deviation of the convergence points of light rays of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the sagittal image plane; the distortion curve represents the distortion magnitude values corresponding to different field of view angles. According to Figure 1b It can be seen that the optical system given in the first embodiment can achieve good imaging quality.

[0095] Figure 1c Shows a schematic structural diagram of the optical system of the first embodiment at the middle focal length end. Figure 1dThe longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the first embodiment at the middle focal end are shown. Among them, the longitudinal spherical aberration curve represents the deviation of the convergence points of light rays of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the sagittal image plane; the distortion curve represents the distortion magnitude values corresponding to different field angles. According to Figure 1d it can be known that the optical system given in the first embodiment can achieve good imaging quality.

[0096] Figure 1e The schematic structural diagram of the optical system of the first embodiment at the long focal end is shown. Figure 1f The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the first embodiment at the long focal end are shown. Among them, the longitudinal spherical aberration curve represents the deviation of the convergence points of light rays of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the sagittal image plane; the distortion curve represents the distortion magnitude values corresponding to different field angles. According to Figure 1f it can be known that the optical system given in the first embodiment can achieve good imaging quality.

[0097] Second embodiment

[0098] Please refer to Figure 2a - Figure 2f , the optical system of this embodiment sequentially includes, from the object side to the image side along the optical axis direction:

[0099] Prism E, which has an incident surface A1, a reflecting surface A2, and an exit surface A3. It can be understood that when light rays from the object to be photographed enter Prism E through the incident surface A1, they can be totally reflected by the reflecting surface A2 and turned to the exit surface A3 to be emitted along the direction of the optical axis.

[0100] The first lens L1, which has a positive refractive power. The object side surface S1 of the first lens L1 is convex near the optical axis, and the image side surface S2 is concave near the optical axis; the object side surface S1 of the first lens L1 is convex at the circumference, and the image side surface S2 is concave at the circumference.

[0101] The second lens L2, which has a negative refractive power. The object side surface S3 of the second lens L2 is convex near the optical axis, and the image side surface S4 is concave near the optical axis; the object side surface S3 of the second lens L2 is convex at the circumference, and the image side surface S4 is concave at the circumference.

[0102] The third lens L3, which has a positive refractive power. The object side surface S5 of the third lens L3 is concave near the optical axis, and the image side surface S6 is convex near the optical axis; the object side surface S5 of the third lens L3 is convex at the circumference, and the image side surface S6 is concave at the circumference.

[0103] The fourth lens L4 has a negative refractive power. The object side surface S7 of the fourth lens L4 is concave near the optical axis, and the image side surface S8 is concave near the optical axis; the object side surface S7 of the fourth lens L4 is concave at the circumference, and the image side surface S8 is convex at the circumference.

[0104] The fifth lens L5 has a positive refractive power. The object side surface S9 of the fifth lens L5 is convex near the optical axis, and the image side surface S10 is convex near the optical axis; the object side surface S9 of the fifth lens L5 is convex at the circumference, and the image side surface S10 is concave at the circumference.

[0105] The sixth lens L6 has a negative refractive power. The object side surface S11 of the sixth lens is concave near the optical axis, and the image side surface S12 is concave near the optical axis; the object side surface S11 of the sixth lens L6 is convex at the circumference, and the image side surface S12 is concave at the circumference.

[0106] The seventh lens L7 has a positive refractive power. The object side surface S13 of the seventh lens L7 is convex near the optical axis, and the image side surface S14 is concave near the optical axis; the object side surface S13 of the seventh lens L7 is concave at the circumference, and the image side surface S14 is convex at the circumference.

[0107] The other structures of the second embodiment are the same as those of the first embodiment, and can be referred to.

[0108] Tables 2a(1) - 2a(2) show the tables of the characteristics of the optical system of this embodiment. The units of the Y radius, thickness, and focal length are all millimeters (mm).

[0109] Table 2a(1)

[0110]

[0111]

[0112] Table 2a(2)

[0113] Variable distance D1 D2 D3 f (mm) FNO FOV (°) Short - focus position -0.0500 -5.6105 -9.1817 16 3.79 28.3 Mid - focus position -1.1000 -3.2195 -10.5077 19.2 4.15 23.5 Long - focus position -1.4491 -0.0500 -13.3481 25.5 5 17.7

[0114] Among them, the meanings of the parameters in Tables 2a(1) - 2a(2) are the same as those of the parameters in the first embodiment.

[0115] Table 2b gives the high-order term coefficients of the aspherical mirror surfaces that can be used in the second embodiment. Among them, the aspherical surface types can be defined by the formulas given in the first embodiment.

[0116] Table 2b

[0117]

[0118]

[0119] Figure 2a The schematic structural diagram of the optical system of the second embodiment at the short focal end is shown. Figure 2b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the second embodiment at the short focal end are shown. According to Figure 2b it can be seen that the optical system given in the second embodiment can achieve good imaging quality.

[0120] Figure 2c The schematic structural diagram of the optical system of the second embodiment at the middle focal end is shown. Figure 2d The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the second embodiment at the middle focal end are shown. According to Figure 2d it can be seen that the optical system given in the second embodiment can achieve good imaging quality.

[0121] Figure 2e The schematic structural diagram of the optical system of the second embodiment at the long focal end is shown. Figure 2f The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the second embodiment at the long focal end are shown. According to Figure 2f it can be seen that the optical system given in the second embodiment can achieve good imaging quality.

[0122] The third embodiment

[0123] Please refer to Figure 3a - Figure 3f , the optical system of this embodiment sequentially includes, from the object side to the image side along the optical axis direction:

[0124] Prism E, which has an incident surface A1, a reflecting surface A2 and an exit surface A3. It can be understood that when the light from the object to be photographed enters Prism E through the incident surface A1, it can be totally reflected by the reflecting surface A2 and turned to the exit surface A3 and exit along the direction of the optical axis.

[0125] The first lens L1, which has a positive refractive power. The object side surface S1 of the first lens L1 is convex near the optical axis, and the image side surface S2 is convex near the optical axis; the object side surface S1 of the first lens L1 is convex at the circumference, and the image side surface S2 is convex at the circumference.

[0126] The second lens L2, which has a negative refractive power. The object side surface S3 of the second lens L2 is convex near the optical axis, and the image side surface S4 is concave near the optical axis; the object side surface S3 of the second lens L2 is convex at the circumference, and the image side surface S4 is concave at the circumference.

[0127] The third lens L3, which has a positive refractive power. The object side surface S1 of the third lens L3 is concave near the optical axis, and the image side surface S2 is convex near the optical axis; the object side surface S5 of the third lens L3 is convex at the circumference, and the image side surface S6 is concave at the circumference.

[0128] The fourth lens L4 has a negative refractive power. The object side surface S7 of the fourth lens L4 is concave near the optical axis, and the image side surface S8 is concave near the optical axis; the object side surface S7 of the fourth lens L4 is concave at the circumference, and the image side surface S8 is convex at the circumference.

[0129] The fifth lens L5 has a positive refractive power. The object side surface S9 of the fifth lens L5 is convex near the optical axis, and the image side surface S10 is convex near the optical axis; the object side surface S9 of the fifth lens L5 is convex at the circumference, and the image side surface S10 is concave at the circumference.

[0130] The sixth lens L6 has a negative refractive power. The object side surface S11 of the sixth lens is concave near the optical axis, and the image side surface S12 is concave near the optical axis; the object side surface S11 of the sixth lens L6 is convex at the circumference, and the image side surface S12 is concave at the circumference.

[0131] The seventh lens L7 has a positive refractive power. The object side surface S13 of the seventh lens L7 is convex near the optical axis, and the image side surface S14 is concave near the optical axis; the object side surface S13 of the seventh lens L7 is concave at the circumference, and the image side surface S14 is convex at the circumference.

[0132] The other structures of the third embodiment are the same as those of the first embodiment, and can be referred to.

[0133] Tables 3a(1)-3a(2) show the tables of the characteristics of the optical system of this embodiment. The units of the Y radius, thickness, and focal length are all millimeters (mm).

[0134] Table 3a(1)

[0135]

[0136]

[0137] Table 3a(2)

[0138] Variable distance D1 D2 D3 f (mm) FNO FOV (°) Short - focus position -0.0997 -5.3805 -7.5445 -14.4 3.11 31.5 Mid - focus position -1.2100 -2.7548 -9.0445 -17.9 3.68 25.3 Long - focus position -1.4478 -0.2136 -11.3633 -22.8 4.83 19.8

[0139] Among them, the meanings of the parameters in Tables 3a(1)-3a(2) are the same as those of the parameters in the first embodiment.

[0140] Table 3b gives the high-order term coefficients of the aspherical mirror surfaces that can be used in the third embodiment. Among them, the aspherical surface types can be defined by the formulas given in the first embodiment.

[0141] Table 3b

[0142]

[0143]

[0144] Figure 3a The schematic structural diagram of the optical system according to the third embodiment at the short focal end is shown. Figure 3b The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system according to the third embodiment at the short focal end are shown. According to Figure 3b it can be known that the optical system given in the third embodiment can achieve good imaging quality.

[0145] Figure 3c The schematic structural diagram of the optical system according to the third embodiment at the middle focal end is shown. Figure 3d The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system according to the third embodiment at the middle focal end are shown. According to Figure 3d it can be known that the optical system given in the third embodiment can achieve good imaging quality.

[0146] Figure 3e The schematic structural diagram of the optical system according to the third embodiment at the long focal end is shown. Figure 3f The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system according to the third embodiment at the long focal end are shown. According to Figure 3f it can be known that the optical system given in the third embodiment can achieve good imaging quality.

[0147] Fourth embodiment,

[0148] Please refer to Figure 4a - Figure 4f , the optical system of this embodiment sequentially includes, from the object side to the image side along the optical axis direction:

[0149] Prism E, which has an incident surface A1, a reflection surface A2, and an exit surface A3. It can be understood that when the light from the object to be photographed enters Prism E through the incident surface A1, it can be totally reflected by the reflection surface A2 and turned to the exit surface A3 to exit along the direction of the optical axis.

[0150] The first lens L1, which has a positive refractive power. The object side surface S1 of the first lens L1 is concave near the optical axis, and the image side surface S2 is convex near the optical axis; the object side surface S1 of the first lens L1 is concave at the circumference, and the image side surface S2 is convex at the circumference.

[0151] The second lens L2, which has a negative refractive power. The object side surface S3 of the second lens L2 is convex near the optical axis, and the image side surface S4 is concave near the optical axis; the object side surface S3 of the second lens L2 is convex at the circumference, and the image side surface S4 is concave at the circumference.

[0152] The third lens L3, which has a positive refractive power. The object side surface S1 of the third lens L3 is concave near the optical axis, and the image side surface S2 is convex near the optical axis; the object side surface S5 of the third lens L3 is convex at the circumference, and the image side surface S6 is concave at the circumference.

[0153] The fourth lens L4 has a negative refractive power. The object side surface S7 of the fourth lens L4 is concave near the optical axis, and the image side surface S8 is concave near the optical axis. The object side surface S7 of the fourth lens L4 is concave at the circumference, and the image side surface S8 is convex at the circumference.

[0154] The fifth lens L5 has a positive refractive power. The object side surface S9 of the fifth lens L5 is convex near the optical axis, and the image side surface S10 is convex near the optical axis. The object side surface S9 of the fifth lens L5 is convex at the circumference, and the image side surface S10 is concave at the circumference.

[0155] The sixth lens L6 has a negative refractive power. The object side surface S11 of the sixth lens is concave near the optical axis, and the image side surface S12 is concave near the optical axis. The object side surface S11 of the sixth lens L6 is convex at the circumference, and the image side surface S12 is concave at the circumference.

[0156] The seventh lens L7 has a positive refractive power. The object side surface S13 of the seventh lens L7 is convex near the optical axis, and the image side surface S14 is concave near the optical axis. The object side surface S13 of the seventh lens L7 is concave at the circumference, and the image side surface S14 is convex at the circumference.

[0157] The other structures of the fourth embodiment are the same as those of the first embodiment, and can be referred to.

[0158] Tables 4a(1) - 4a(2) show the tables of the characteristics of the optical system of this embodiment. The units of the Y radius, thickness, and focal length are all millimeters (mm).

[0159] Table 4a(1)

[0160]

[0161]

[0162] Table 4a(2)

[0163] Variable distance D1 D2 D3 f (mm) FNO FOV (°) Short - focus position -0.0500 -5.2665 -7.2839 13.2 3.37 34.3 Mid - focus position -1.2100 -2.5568 -8.8186 16.5 3.73 27.3 Long - focus position -1.4478 -0.0500 -11.1027 21.2 4.52 21.2

[0164] Among them, the meanings of the parameters in Tables 4a(1) - 4a(2) are the same as those of the parameters in the first embodiment.

[0165] Table 4b gives the higher-order term coefficients that can be used for each aspherical mirror surface in the fourth embodiment. Among them, each aspherical surface type can be defined by the formula given in the first embodiment.

[0166] Table 4b

[0167]

[0168]

[0169] Figure 4a The structural schematic diagram of the optical system of the fourth embodiment at the short focal end is shown. Figure 4b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fourth embodiment at the short focal end are shown. According to Figure 4b it can be seen that the optical system given in the fourth embodiment can achieve good imaging quality.

[0170] Figure 4c The structural schematic diagram of the optical system of the fourth embodiment at the middle focal end is shown. Figure 4d The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fourth embodiment at the middle focal end are shown. According to Figure 4d it can be seen that the optical system given in the fourth embodiment can achieve good imaging quality.

[0171] Figure 4e The structural schematic diagram of the optical system of the fourth embodiment at the long focal end is shown. Figure 4f The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fourth embodiment at the long focal end are shown. According to Figure 4f it can be seen that the optical system given in the fourth embodiment can achieve good imaging quality.

[0172] The fifth embodiment

[0173] Please refer to Figure 5a - Figure 5f , the optical system of this embodiment sequentially includes, from the object side to the image side along the optical axis direction:

[0174] Prism E, which has an incident surface A1, a reflection surface A2 and an exit surface A3. It can be understood that when the light from the object to be photographed enters Prism E through the incident surface A1, it can be totally reflected by the reflection surface A2 and turned to the exit surface A3 to exit along the direction of the optical axis.

[0175] The first lens L1, which has a positive refractive power. The object side surface S1 of the first lens L1 is concave near the optical axis, and the image side surface S2 is convex near the optical axis; the object side surface S1 of the first lens L1 is concave at the circumference, and the image side surface S2 is convex at the circumference.

[0176] The second lens L2, which has a negative refractive power. The object side surface S3 of the second lens L2 is convex near the optical axis, and the image side surface S4 is concave near the optical axis; the object side surface S3 of the second lens L2 is convex at the circumference, and the image side surface S4 is concave at the circumference.

[0177] The third lens L3, which has a positive refractive power. The object side surface S5 of the third lens L3 is concave near the optical axis, and the image side surface S6 is convex near the optical axis; the object side surface S5 of the third lens L3 is convex at the circumference, and the image side surface S6 is concave at the circumference.

[0178] The fourth lens L4 has a negative refractive power. The object side S7 of the fourth lens L4 is concave near the optical axis, and the image side S8 is concave near the optical axis. The object side S7 of the fourth lens L4 is concave at the circumference, and the image side S8 is convex at the circumference.

[0179] The fifth lens L5 has a positive refractive power. The object side S9 of the fifth lens L5 is convex near the optical axis, and the image side S10 is convex near the optical axis. The object side S9 of the fifth lens L5 is convex at the circumference, and the image side S10 is concave at the circumference.

[0180] The sixth lens L6 has a negative refractive power. The object side S11 of the sixth lens is concave near the optical axis, and the image side S12 is concave near the optical axis. The object side S11 of the sixth lens L6 is convex at the circumference, and the image side S12 is concave at the circumference.

[0181] The seventh lens L7 has a positive refractive power. The object side S13 of the seventh lens L7 is convex near the optical axis, and the image side S14 is concave near the optical axis. The object side S13 of the seventh lens L7 is concave at the circumference, and the image side S14 is convex at the circumference.

[0182] The other structures of the fifth embodiment are the same as those of the first embodiment, and can be referred to.

[0183] Tables 5a(1)-5a(2) show the tables of the characteristics of the optical system of this embodiment. The units of the Y radius, thickness, and focal length are all millimeters (mm).

[0184] Table 5a(1)

[0185]

[0186]

[0187] Table 5a(2)

[0188] Variable distance D1 D2 D3 f (mm) FNO FOV (°) Short - focus position -0.1055 -5.4875 -7.8443 14.6 3.29 31.1 Mid - focus position -1.2100 -2.8630 -9.3443 18.1 3.61 25 Long - focus position -1.4478 -0.3264 -11.6631 23.1 4.45 19.6

[0189] Among them, the meanings of the parameters in Tables 5a(1)-5a(2) are the same as those of the parameters in the first embodiment.

[0190] Table 5b gives the high-order term coefficients of the aspherical mirrors that can be used in the fifth embodiment. Among them, the aspherical surface types can be defined by the formulas given in the first embodiment.

[0191] Table 5b

[0192]

[0193]

[0194] Figure 5a The structural schematic diagram of the optical system of the fifth embodiment at the short focal end is shown. Figure 5b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fifth embodiment at the short focal end are shown. According to Figure 5b it can be known that the optical system given in the fifth embodiment can achieve good imaging quality.

[0195] Figure 5c The structural schematic diagram of the optical system of the fifth embodiment at the middle focal end is shown. Figure 5d The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fifth embodiment at the middle focal end are shown. According to Figure 5d it can be known that the optical system given in the fifth embodiment can achieve good imaging quality.

[0196] Figure 5e The structural schematic diagram of the optical system of the fifth embodiment at the long focal end is shown. Figure 5f The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fifth embodiment at the long focal end are shown. According to Figure 5f it can be known that the optical system given in the fifth embodiment can achieve good imaging quality.

[0197] Sixth embodiment,

[0198] Please refer to Figure 6a - Figure 6f , the optical system of this embodiment sequentially includes, from the object side to the image side along the optical axis direction:

[0199] Prism E, which has an incident surface A1, a reflecting surface A2 and an exit surface A3. It can be understood that when the light from the object to be photographed enters Prism E through the incident surface A1, it can be totally reflected by the reflecting surface A2 and turned to the exit surface A3 to exit along the direction of the optical axis.

[0200] The first lens L1, which has a positive refractive power. The object side surface S1 of the first lens L1 is convex near the optical axis, and the image side surface S2 is convex near the optical axis; the object side surface S1 of the first lens L1 is convex at the circumference, and the image side surface S2 is convex at the circumference.

[0201] The second lens L2, which has a negative refractive power. The object side surface S3 of the second lens L2 is convex near the optical axis, and the image side surface S4 is concave near the optical axis; the object side surface S3 of the second lens L2 is convex at the circumference, and the image side surface S4 is concave at the circumference.

[0202] The third lens L3, which has a positive refractive power. The object side surface S1 of the third lens L3 is convex near the optical axis, and the image side surface S2 is convex near the optical axis; the object side surface S5 of the third lens L3 is convex at the circumference, and the image side surface S6 is concave at the circumference.

[0203] The fourth lens L4 has a negative refractive power. The object side S7 of the fourth lens L4 is concave near the optical axis, and the image side S8 is concave near the optical axis. The object side S7 of the fourth lens L4 is concave at the circumference, and the image side S8 is convex at the circumference.

[0204] The fifth lens L5 has a positive refractive power. The object side S9 of the fifth lens L5 is convex near the optical axis, and the image side S10 is convex near the optical axis. The object side S9 of the fifth lens L5 is convex at the circumference, and the image side S10 is concave at the circumference.

[0205] The sixth lens L6 has a negative refractive power. The object side S11 of the sixth lens is concave near the optical axis, and the image side S12 is concave near the optical axis. The object side S11 of the sixth lens L6 is convex at the circumference, and the image side S12 is concave at the circumference.

[0206] The seventh lens L7 has a positive refractive power. The object side S13 of the seventh lens L7 is convex near the optical axis, and the image side S14 is concave near the optical axis. The object side S13 of the seventh lens L7 is convex at the circumference, and the image side S14 is concave at the circumference.

[0207] The other structures of the sixth embodiment are the same as those of the first embodiment, and can be referred to.

[0208] Tables 6a(1) - 6a(2) show the tables of the characteristics of the optical system of this embodiment. The units of the Y radius, thickness, and focal length are all millimeters (mm).

[0209] Table 6a(1)

[0210]

[0211]

[0212] Table 6a(2)

[0213] Variable distance D1 D2 D3 f (mm) FNO FOV (°) Short - focus position -0.1170 -5.2486 -8.3714 16.2 3.11 28.1 Mid - focus position -1.1478 -2.7993 -9.7699 19.8 3.68 22.9 Long - focus position -1.4461 -0.5996 -11.6913 24.2 4.83 18.7

[0214] Among them, the meanings of the parameters in Tables 6a(1) - 6a(2) are the same as those of the parameters in the first embodiment.

[0215] Table 6b gives the higher-order term coefficients of the aspherical mirror surfaces that can be used in the sixth embodiment. Among them, the aspherical surface types can be defined by the formulas given in the first embodiment.

[0216] Table 6b

[0217]

[0218]

[0219] Figure 6a The structural schematic diagram of the optical system of the sixth embodiment at the short focal end is shown. Figure 6b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the sixth embodiment at the short focal end are shown. According to Figure 6b it can be seen that the optical system given in the sixth embodiment can achieve good imaging quality.

[0220] Figure 6c The structural schematic diagram of the optical system of the sixth embodiment at the middle focal end is shown. Figure 6d The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the sixth embodiment at the middle focal end are shown. According to Figure 6d it can be seen that the optical system given in the sixth embodiment can achieve good imaging quality.

[0221] Figure 6e The structural schematic diagram of the optical system of the sixth embodiment at the long focal end is shown. Figure 6f The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the sixth embodiment at the long focal end are shown. According to Figure 6f it can be seen that the optical system given in the sixth embodiment can achieve good imaging quality.

[0222] Table 7 shows the values of Fc / Fd, FOVc / ImgH, TTL / (ATg2 - ATg3), (R3 + R4) / (R7 + R8), F2 / F234, F1 / F567, F1 / Fc, g3 / (g1 + g2), R14 / F7 of the optical systems of the first to sixth embodiments.

[0223] Table 7

[0224]

[0225]

[0226] As can be seen from Table 7, each embodiment satisfies the following conditional expressions: Fc / Fd > 1.45, 4 deg / mm < FOVc / ImgH < 5.5 deg / mm, 40 < TTL / (ATg2 - ATg3) < 95, 2 < (R3 + R4) / (R7 + R8) < 8.5, F2 / F234 < 7.5, 4 < F1 / F567 < 13, 1.9 < F1 / Fc < 6, g3 / (g1 + g2) < 2, 2 < R14 / F7 < 12.

[0227] The technical features of the above embodiments can be combined arbitrarily. For the sake of brief description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0228] The above embodiments merely illustrate several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the appended claims.

Claims

1. An optical system, characterized in that, it has a total of seven lenses with refractive power, and successively includes from the object side to the image side along the optical axis: a prism; a first lens group with positive refractive power, the number of lenses with refractive power in the first lens group is one, and the first lens group includes a first lens; a second lens group with negative refractive power, the number of lenses with refractive power in the second lens group is three, the second lens group includes a second lens, a third lens and a fourth lens, the second lens has negative refractive power, the third lens has positive refractive power, and the fourth lens has negative refractive power; a third lens group with positive refractive power, the number of lenses with refractive power in the third lens group is three, the third lens group includes a fifth lens, a sixth lens and a seventh lens, the fifth lens has positive refractive power, the sixth lens has negative refractive power, and the seventh lens has positive refractive power; the distances between the first lens group, the second lens group and the third lens group are adjustable so that the optical system is in the telephoto end, the mid - focal end and the short - focal end, and the focal lengths of the optical system at the telephoto end, the mid - focal end and the short - focal end are different; the optical system satisfies the conditional formula: 2.16 ≤ F2 / F234 < 7.5; wherein, F2 is the focal length of the second lens, and F234 is the focal length of the second lens group.

2. The optical system according to claim 1, characterized in that, the optical system satisfies the conditional formula: 1.60 ≥ Fc / Fd > 1.45, where Fc is the focal length of the optical system at the telephoto end, and Fd is the focal length of the optical system at the short - focal end.

3. The optical system according to claim 1, characterized in that, the optical system satisfies the conditional formula: 4deg / mm < FOVc / ImgH < 5.5deg / mm, where FOVc is the maximum field of view angle of the optical system at the telephoto end, and ImgH is half of the diagonal length of the effective imaging area of the imaging surface.

4. The optical system according to claim 1, characterized in that, the optical system satisfies the conditional formula: 40 < TTL / (ATg2 - ATg3) < 95, where TTL is the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis, ATg2 is the sum of the air spaces on the optical axis between adjacent lenses in the second lens group, and ATg3 is the sum of the air spaces on the optical axis between adjacent lenses in the third lens group.

5. The optical system according to claim 1, characterized in that, the optical system satisfies the conditional formula: 2 < (R3 + R4) / (R7 + R8) < 8.5, where R3 is the curvature radius of the object side surface of the second lens on the optical axis, R4 is the curvature radius of the image side surface of the second lens on the optical axis, R7 is the curvature radius of the object side surface of the fourth lens on the optical axis, and R8 is the curvature radius of the image side surface of the fourth lens on the optical axis.

6. The optical system according to claim 1, characterized in that, The optical system satisfies the conditional formula: 4 < F1 / F567 < 13, where F1 is the focal length of the first lens group and F567 is the focal length of the third lens group.

7. The optical system according to claim 1, wherein, the optical system satisfies the conditional formula: 1.9 < F1 / Fc < 6, where F1 is the focal length of the first lens group and Fc is the focal length of the optical system at the telephoto end.

8. The optical system according to claim 1, wherein, the optical system satisfies the conditional formula: 1.18 ≤ g3 / (g1 + g2) < 2, where g1 is the distance on the optical axis from the object side surface of the first lens to the image side surface of the first lens, g2 is the distance on the optical axis from the object side surface of the second lens to the image side surface of the fourth lens, and g3 is the distance on the optical axis from the object side surface of the fifth lens to the image side surface of the seventh lens.

9. The optical system according to claim 1, wherein, the optical system satisfies the conditional formula: 2 < R14 / F7 < 12, where R14 is the radius of curvature at the optical axis of the image side surface of the seventh lens and F7 is the focal length of the seventh lens.

10. An imaging module, wherein, it includes a lens barrel, an electronic photosensitive element, and the optical system according to any one of claims 1 to 9, and the first lens to the seventh lens of the optical system are installed in the lens barrel.

11. An electronic device, wherein, it includes a housing and the imaging module according to claim 10, and the imaging module is disposed in the housing.

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