CN114815146A - Optical system, image capturing module, electronic equipment and carrier - Google Patents
Optical system, image capturing module, electronic equipment and carrier Download PDFInfo
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- CN114815146A CN114815146A CN202210236784.2A CN202210236784A CN114815146A CN 114815146 A CN114815146 A CN 114815146A CN 202210236784 A CN202210236784 A CN 202210236784A CN 114815146 A CN114815146 A CN 114815146A
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- 230000003287 optical effect Effects 0.000 title claims abstract description 243
- 238000003384 imaging method Methods 0.000 claims abstract description 45
- 230000014509 gene expression Effects 0.000 claims abstract description 33
- 238000012634 optical imaging Methods 0.000 abstract description 6
- 230000004075 alteration Effects 0.000 description 48
- 230000009286 beneficial effect Effects 0.000 description 13
- 201000009310 astigmatism Diseases 0.000 description 11
- 239000000463 material Substances 0.000 description 10
- 238000010586 diagram Methods 0.000 description 9
- 230000002349 favourable effect Effects 0.000 description 9
- 238000001746 injection moulding Methods 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 8
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- 239000011521 glass Substances 0.000 description 7
- 239000006185 dispersion Substances 0.000 description 6
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
- G02B13/002—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface
- G02B13/004—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface having four lenses
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B30/00—Camera modules comprising integrated lens units and imaging units, specially adapted for being embedded in other devices, e.g. mobile phones or vehicles
Abstract
The present disclosure provides an optical system, an image capturing module, an electronic apparatus, and a carrier, wherein the optical system includes a first lens element, a second lens element, a third lens element, and a fourth lens element sequentially disposed along an optical axis from an object side to an image side, the first lens element has a positive refractive power, the object side surface is convex at a paraxial region, the image side surface is convex at the paraxial region, the second lens element has a positive refractive power, the object side surface is concave at the paraxial region, the image side surface is convex at the paraxial region, the third lens element has a positive refractive power, the object side surface is concave at the paraxial region, the image side surface is convex at the paraxial region, the fourth lens element has a negative refractive power, the object side surface is convex at the paraxial region, and the image side surface is concave at the paraxial region; the effective focal length of the optical system is f, the distance from the object side surface of the first lens to the imaging surface on the optical axis is TTL, and the f and the TTL satisfy the conditional expression: f/TTL is more than 0.5 and less than 0.7. The design can effectively reduce the possibility of the angle of view change caused by temperature so as to improve the optical imaging quality of the optical system.
Description
Technical Field
The embodiment of the specification relates to the technical field of optical imaging, in particular to an optical system, an image capturing module, an electronic device and a carrier.
Background
In the related art, the angle of view of a lens in the market is easily changed due to the change of the external temperature, thereby affecting the optical imaging quality of the lens. Therefore, how to effectively reduce the influence of the angle of view change caused by the temperature influence of the lens is a problem to be solved.
Disclosure of Invention
Embodiments of the present disclosure provide an optical system, an image capturing module, an electronic apparatus, and a carrier, which can effectively reduce the possibility of a change in a field angle due to temperature, so as to improve the optical imaging quality of the optical system.
In a first aspect, embodiments herein provide an optical system; the optical system comprises a first lens element, a second lens element, a third lens element and a fourth lens element, which are disposed in order from an object side to an image side along an optical axis of the optical system, wherein the first lens element has positive refractive power, an object side surface of the first lens element is convex at a paraxial region, an image side surface of the first lens element is convex at the paraxial region, the second lens element has positive refractive power, an object side surface of the second lens element is concave at the paraxial region, an image side surface of the second lens element is convex at the paraxial region, the third lens element has positive refractive power, an object side surface of the third lens element is concave at the paraxial region, an image side surface of the third lens element is convex at the paraxial region, the fourth lens element has negative refractive power, an object side surface of the fourth lens element is convex at the paraxial region, and an image side surface of the fourth lens element is concave at the paraxial region; wherein, the effective focal length of the optical system is f, the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis is TTL, and f and TTL satisfy the conditional expression:
0.5＜f/TTL＜0.7。
based on the optical system in the embodiments of the present description, by designing the object-side surface of the third lens element to be concave at the paraxial region and the image-side surface of the third lens element to be convex at the paraxial region, i.e., designing the third lens element to have a meniscus structure, the field curvature and astigmatism of the optical system can be effectively corrected; by designing the fourth lens element with negative refractive power, the aberration of the optical system can be corrected and the incident angle of the chief ray can be adjusted, so that the chief ray can be better matched with the image sensor; by designing the refractive powers of the first lens element, the second lens element, the third lens element and the fourth lens element to be a combination of positive, negative and positive powers, the lens elements can bear more uniform incident deflection angles of light rays, so as to effectively correct aberrations of the optical system. When f/TTL is more than 0.5 and less than 0.7, the ratio of f to TTL is reasonably configured by controlling the f and the TTL through parameter design, so that the optical system has a compact structure, the internal overall layout of the optical systems such as lenses and the like is natural, and the miniaturization design of the optical system can be realized, through the configuration mode, the receiving imaging of weak spot spots can be realized by effectively utilizing the lenses with different refractive powers and focal lengths, meanwhile, the overall distortion rate of the optical system can be ensured to be smaller, the overall performance change in the range of-20 ℃ to 60 ℃ is smaller, and the temperature stability of the optical system can be effectively ensured; when f/TTL is less than or equal to 0.5, the structure of the optical system is looser, which is not beneficial to the miniaturization design and the aesthetic degree of the optical system; when f/TTL is more than or equal to 0.7, the tolerance of the optical system is sensitive, the assembly of the optical system is not facilitated, and the temperature stability of the optical system is not facilitated.
In some embodiments, the focal length of the first lens is f1, where f1 and f satisfy the following conditional expression:
1.0＜f1/f＜2.0。
based on the above embodiment, when 1.0 < f1/f < 2.0, the ratio of f1 to f is reasonably configured by controlling f1 and f through parameter design, so that the incident angle of the chief ray is reasonably distributed, which is beneficial to correcting the aberration of the optical system; when f1/f is less than or equal to 1.0, the deflection angle of the chief ray born by the first lens is too large, so that the tolerance of the first lens is sensitive, the requirement on the processing precision of the first lens is high, and the processing and the manufacturing of the first lens are not facilitated; when f1/f is greater than or equal to 2.0, the deflection angle of the chief ray borne by the first lens is too small, which is not favorable for the first lens to share the temperature stability of the optical system.
In some embodiments, the focal length of the second lens is f2, where f2 and f satisfy the following conditional expression:
1.5＜f2/f＜2.6。
based on the above embodiment, when f2/f is more than 1.5 and less than 2.6, the ratio of f2 to f is reasonably configured by controlling f2 and f through parameter design, and the focal power of the second lens is reasonably distributed, so that the compactness of the optical system is ensured, and the aberration of the optical system is favorably corrected; when f2/f is less than or equal to 1.5, the tolerance of the second lens is sensitive, so that the requirement on the processing precision of the second lens is high, and the processing and manufacturing of the second lens are not facilitated; if f2/f is equal to or greater than 2.6, the pressure on the rear third and fourth lenses to deflect the principal ray is large, which is not favorable for balancing the aberrations of the entire optical system.
In some embodiments, the focal length of the third lens is f3, where f3 and f satisfy the following conditional expression:
1.6＜f3/f＜2.8。
based on the above embodiment, when f3/f is more than 1.6 and less than 2.8, the ratio of f3 to f is reasonably configured by controlling f3 and f through parameter design, and the focal power of the third lens is reasonably distributed, so that the compactness of the optical system is ensured, and the aberration of the optical system is favorably corrected; when f3/f is less than or equal to 1.6, the tolerance of the third lens is sensitive, so that the requirement on the processing precision of the third lens is high, and the processing and manufacturing of the third lens are not facilitated; if f3/f is equal to or greater than 2.8, the pressure on the rear fourth lens to deflect the principal ray is large, which is disadvantageous in balancing the aberrations of the entire optical system.
In some embodiments, the focal length of the fourth lens is f4, where f4 and f satisfy the following conditional expression:
-5.0＜f4/f＜-2.0。
based on the above embodiment, when-5.0 < f4/f < -2.0, the ratio of f4 to f is reasonably configured by controlling f4 and f through parameter design, and the focal power of the fourth lens is reasonably distributed, so that the structural compactness of the optical system is ensured, and the aberration of the optical system can be well compensated; when f4/f is less than or equal to-5.0, the fourth lens has limited capability of balancing the aberration of the optical system, which is not favorable for the temperature stability of the optical system; when f4/f is greater than or equal to-2.0, the tolerance of the fourth lens is sensitive, which is not favorable for balancing the aberration of the whole optical system.
In some embodiments, the radius of curvature of the object-side surface of the first lens element at the paraxial region is R11, and the radius of curvature of the image-side surface of the first lens element at the paraxial region is R12, wherein R11 and R12 satisfy the following conditional expressions:
-1.5＜(R11-R12)/(R11+R12)＜-0.5。
based on the above embodiment, when-1.5 < (R11-R12)/(R11+ R12) < -0.5, the ratio of (R11-R12) to (R11+ R12) is reasonably configured by design control of parameters R11 and R12, at this time, the first lens has an attractive appearance, is easy to process and detect, can better suppress and balance the high-level aberration of the optical system, and has proper surface tolerance requirement, can better meet the index requirements of the optical system, and is beneficial to assembly of the first lens; when (R11-R12)/(R11+ R12) is less than or equal to-1.5 or (R11-R12)/(R11+ R12) is more than or equal to-0.5, the injection molding of the first lens is not facilitated, the tolerance of the first lens is sensitive, the assembly difficulty of the first lens is high, and the optical system is not facilitated to obtain excellent imaging quality and temperature stability.
In some embodiments, the radius of curvature of the object-side surface of the second lens element at the paraxial region is R21, and the radius of curvature of the image-side surface of the second lens element at the paraxial region is R22, wherein R21 and R22 satisfy the following conditional expressions:
0.2＜(R21-R22)/(R21+R22)＜0.6。
based on the above embodiment, when 0.2 < (R21-R22)/(R21+ R22) < 0.6, the ratio of (R21-R22) to (R21+ R22) is reasonably configured by design control of parameters R21 and R22, at this time, the second lens has an attractive appearance, is easy to process and detect, can better suppress and balance the high-level aberration of the optical system, and has proper surface tolerance requirements, can better meet the index requirements of the optical system, and is beneficial to assembly of the second lens; when (R21-R22)/(R21+ R22) is less than or equal to 0.2 or (R21-R22)/(R21+ R22) is more than or equal to 0.6, the injection molding of the second lens is not facilitated, the tolerance of the second lens is sensitive, the assembly difficulty of the second lens is high, and the optical system is not facilitated to obtain excellent imaging quality and temperature stability.
In some embodiments, the radius of curvature of the object-side surface of the third lens element at the paraxial region is R31, and the radius of curvature of the image-side surface of the third lens element at the paraxial region is R32, where R31 and R32 satisfy the following conditional expressions:
-0.1＜(R31-R32)/(R31+R32)＜-0.01。
based on the above embodiment, when-0.1 < (R31-R32)/(R31+ R32) < -0.01, the ratio of (R31-R32) to (R31+ R32) is reasonably configured by design control of parameters R31 and R32, at this time, the third lens has an attractive appearance, is easy to process and detect, can better suppress and balance the high-level aberration of the optical system, and has proper surface tolerance requirement, can better meet the index requirements of the optical system, and is beneficial to the assembly of the third lens; when the ratio of (R31-R32)/(R31+ R32) is less than or equal to-0.1 or the ratio of (R31-R32)/(R31+ R32) is more than or equal to-0.01, the injection molding of the third lens is not facilitated, the tolerance of the third lens is sensitive, the assembly difficulty of the third lens is high, and the optical system is not facilitated to obtain excellent imaging quality and temperature stability.
In some embodiments, the radius of curvature of the object-side surface of the fourth lens element at the paraxial region is R41, and the radius of curvature of the image-side surface of the fourth lens element at the paraxial region is R42, where R41 and R42 satisfy the following conditional expressions:
0.1＜(R41-R42)/(R41+R42)＜0.2。
based on the above embodiment, when 0.1 < (R41-R42)/(R41+ R42) < 0.2, the ratio of (R41-R42) to (R41+ R42) is reasonably configured by design control of parameters R41 and R42, at this time, the fourth lens has an attractive appearance, is easy to process and detect, can better suppress and balance the high-level aberration of the optical system, has proper surface tolerance requirement, can better meet the index requirements of the optical system, and is beneficial to the assembly of the fourth lens; when (R41-R42)/(R41+ R42) is less than or equal to 0.1 or (R41-R42)/(R41+ R42) is more than or equal to 0.2, the injection molding of the fourth lens is not facilitated, the tolerance of the fourth lens is sensitive, the assembly difficulty of the fourth lens is high, and the optical system is not facilitated to obtain excellent imaging quality and temperature stability.
In some of these embodiments, the first lens has a thickness n1 at the optical axis, where n1 satisfies the conditional expression:
-0.00001＜dn1/dt＜0.0。
based on the embodiment, when-0.00001 < dn1/dt < 0.0, the ratio of dn1 to dt is reasonably configured by controlling n1 through parameter design, and the temperature stability of the optical system in the range of-20 ℃ to 60 ℃ can be ensured; when dn1/dt is less than or equal to-0.00001, the temperature stability of the optical system in the range of-20 ℃ to 60 ℃ cannot be ensured; when dn1/dt ≧ 0.0, the present refractive materials cannot be realized at this time.
In a second aspect, an embodiment of the present disclosure provides an image capturing module, which includes an image sensor and the optical system described above, wherein the image sensor is disposed on an image side of the optical system.
Based on the image capturing module in the embodiment of the present specification, the image capturing module with the optical system satisfies the design of small volume and high pixel, and has good temperature stability within the range of-20 ℃ to 60 ℃, so that the image capturing module has good imaging quality.
In a third aspect, an embodiment of the present disclosure provides an electronic device, where the electronic device includes a mounting structure and the image capturing module described above, and the image capturing module is disposed on the mounting structure.
Based on the electronic equipment in the embodiment of the present specification, the electronic equipment with the image capturing module satisfies the design of small volume and high pixel, and meanwhile, the electronic equipment has good temperature stability within the range of-20 ℃ to 60 ℃, so that the electronic equipment has good imaging quality.
In a fourth aspect, an embodiment of the present disclosure provides a carrier, where the carrier includes a connection structure and the electronic device described above, and the electronic device is disposed on the connection structure.
Based on the carrier in the embodiment of the present specification, the carrier with the image capturing module satisfies the design of small volume and high pixel, and has good temperature stability within the range of-20 ℃ to 60 ℃, so that the carrier has good imaging quality.
Based on the optical system, the image capturing module, the electronic device and the carrier in the embodiments of the present disclosure, by designing the object-side surface of the third lens element to be concave at the paraxial region and the image-side surface of the third lens element to be convex at the paraxial region, i.e., designing the third lens element to be a meniscus structure, the field curvature and astigmatism of the optical system can be effectively corrected; by designing the fourth lens element with negative refractive power, the aberration of the optical system can be corrected and the incident angle of the chief ray can be adjusted, so that the chief ray can be better matched with the image sensor; by designing the refractive powers of the first lens element, the second lens element, the third lens element and the fourth lens element to be a combination of positive, negative and positive powers, the lens elements can bear more uniform incident deflection angles of light rays, so as to effectively correct aberrations of the optical system. When f/TTL is more than 0.5 and less than 0.7, the ratio of f to TTL is reasonably configured by controlling the f and the TTL through parameter design, so that the optical system has a compact structure, the internal overall layout of the optical systems such as lenses and the like is natural, and the miniaturization design of the optical system can be realized, through the configuration mode, the receiving imaging of weak spot spots can be realized by effectively utilizing the lenses with different refractive powers and focal lengths, meanwhile, the overall distortion rate of the optical system can be ensured to be smaller, the overall performance change in the range of-20 ℃ to 60 ℃ is smaller, and the temperature stability of the optical system can be effectively ensured; when f/TTL is less than or equal to 0.5, the structure of the optical system is looser, which is not beneficial to the miniaturization design and the aesthetic degree of the optical system; when f/TTL is more than or equal to 0.7, the tolerance of the optical system is sensitive, the assembly of the optical system is not facilitated, and the temperature stability of the optical system is not facilitated.
Drawings
In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic structural diagram of an optical system in a first embodiment of the present disclosure;
fig. 2 schematically shows MFT diagrams of an optical system at 1/4Ny, 1/2Ny, and Ny in a first embodiment of the present description;
FIG. 3 is a Through-Focus-MTF graph schematically showing the frequency of 43.0000p/mm in an optical system according to a first embodiment of the present disclosure;
fig. 4A to 4B schematically show an astigmatism graph and a distortion graph of an optical system provided in an embodiment of the present disclosure;
FIG. 5 is a graph schematically illustrating relative illuminance curves of an optical system in a first embodiment of the present disclosure;
fig. 6 is a schematic structural view of an optical system in a second embodiment of the present specification;
FIG. 7 is a MFT diagram of an optical system in example two of this specification at 1/4Ny, 1/2Ny, and Ny;
FIG. 8 is a Through-Focus-MTF graph schematically showing the frequency of 43.0000p/mm in the second embodiment of the present specification;
fig. 9A to 9B schematically show an astigmatism graph and a distortion graph of an optical system provided in a second embodiment of the present disclosure, respectively;
FIG. 10 is a graph schematically showing the relative illuminance of an optical system in example II of the present specification;
fig. 11 is a schematic structural diagram of an image capturing module in an embodiment of the present disclosure;
fig. 12 is a schematic structural diagram of an electronic apparatus in an embodiment of the present specification in a case where the electronic apparatus is a vehicle-mounted camera;
fig. 13 is a schematic structural view of a vehicle according to an embodiment of the present disclosure.
Reference numerals: 100. an optical system; 110. a first lens; 120. a second lens; 130. a third lens; 140. a fourth lens; 150. an optical filter; s1, the object side surface of the first lens; s2, an image side surface of the first lens; s3, the object side surface of the second lens; s4, an image side surface of the second lens; s5, the object side surface of the third lens; s6, an image side surface of the third lens; s7, the object side surface of the fourth lens; s8, an image side surface of the fourth lens element; s9, a first surface; s10, a second surface; s11, imaging surface; STO, stop; 200. an image capturing module; 210. an image sensor; 300. an electronic device; 310. a mounting structure; 400. a carrier is provided.
Detailed Description
The aberrations referred to in the embodiments of the present specification are explained first below; aberration (aberration) is a deviation between the result of non-paraxial ray tracing and the result of paraxial ray tracing in an optical lens group and an ideal condition of gaussian optics (first order approximation theory or paraxial ray). Aberrations fall into two broad categories: chromatic aberration and monochromatic aberration. The chromatic aberration is an aberration generated by different refractive indexes when light with different wavelengths passes through the lens, and can be divided into two types, namely, a position chromatic aberration and a magnification chromatic aberration. Chromatic aberration is a chromatic dispersion phenomenon, in which the speed or refractive index of light in a medium varies with the wavelength of light, the dispersion in which the refractive index of light decreases with increasing wavelength can be referred to as normal dispersion, and the dispersion in which the refractive index increases with increasing wavelength can be referred to as negative dispersion (or negative inverse dispersion). Monochromatic aberration is aberration that occurs even when monochromatic light is highly produced, and is divided into two categories, that is, "blurring" and "deforming" according to the effect produced; the former type includes spherical aberration (spherical aberration for short), astigmatism (astigmatism) and the like, and the latter type includes field curvature (field curvature for short), distortion (distortion) and the like. The aberration also includes coma aberration, which is a monochromatic conical light beam emitted from an off-axis object point outside the main axis to the optical lens group, and after being refracted by the optical lens group, the monochromatic conical light beam cannot be combined into a clear point at an ideal plane, but is combined into a comet-shaped light spot dragging a bright tail.
In the related art, the angle of view of a lens in the market is easily changed due to the change of the external temperature, thereby affecting the optical imaging quality of the lens. Therefore, how to effectively reduce the influence of the angle of view change caused by the temperature influence of the lens is a problem to be solved.
In order to solve the above technical problem, referring to fig. 1 to 10, a first aspect of the embodiments of the present disclosure provides an optical system 100 capable of effectively reducing a possibility of a change of a field angle due to temperature, so as to improve an optical imaging quality of the optical system 100.
As shown in fig. 1, the optical system 100 includes a first lens 110, a second lens 120, a third lens 130, and a fourth lens 140, which are disposed in order from an object side to an image side along an optical axis of the optical system 100.
The first lens element 110 with positive refractive power has a convex object-side surface S1 at a paraxial region of the first lens element 110 and a convex image-side surface S2 at a paraxial region of the first lens element 110;
the second lens element 120 with positive refractive power has a concave object-side surface S3 at a paraxial region thereof, and has a convex image-side surface S4 at a paraxial region thereof, the second lens element 120.
The third lens element 130 with positive refractive power has a concave object-side surface S5 at a paraxial region thereof and a convex image-side surface S6 at the paraxial region thereof.
The fourth lens element 140 with negative refractive power has a convex object-side surface S7 at a paraxial region thereof, and a concave image-side surface S8 at the paraxial region thereof, of the fourth lens element 140.
Further, the effective focal length of the optical system 100 is f, the distance from the object-side surface S1 of the first lens element 110 to the image plane S11 of the optical system 100 on the optical axis is TTL, and f and TTL satisfy the following conditional expression: f/TTL is more than 0.5 and less than 0.7. Specifically, the value of f/TTL can be 0.600 or 0.580.
In summary, by designing the object-side surface S5 of the third lens element 130 to be concave at the paraxial region and the image-side surface S6 of the third lens element 130 to be convex at the paraxial region, i.e., by designing the third lens element 130 to be meniscus-shaped, the curvature of field and astigmatism of the optical system 100 can be effectively corrected; by designing the fourth lens element 140 with negative refractive power, the aberration of the optical system 100 can be corrected, and the incident angle of the chief ray can be adjusted, so that the chief ray can be better matched with the image sensor 210; by designing the refractive powers of the first lens element 110, the second lens element 120, the third lens element 130 and the fourth lens element 140 to be a combination of positive, negative and positive, the lenses can bear more uniform incident angles of light rays, so as to effectively correct the aberration of the optical system 100. When f/TTL is more than 0.5 and less than 0.7, the ratio of f to TTL is reasonably configured by design control of parameters f and TTL, so that the structure of the optical system 100 is compact, the internal overall layout of the optical system 100 such as a lens is natural, and the miniaturization design of the optical system 100 can be realized, and by the configuration mode, the lens with different refractive power and focal length can be effectively utilized to realize the receiving imaging of weak spot spots, and meanwhile, the overall distortion rate of the optical system 100 can be ensured to be smaller, the overall performance change in the range of-20 ℃ to 60 ℃ is smaller, and the temperature stability performance of the optical system 100 can be effectively ensured; when f/TTL is less than or equal to 0.5, the structure of the optical system 100 is looser, which is not beneficial to the miniaturization design and the aesthetic degree of the optical system 100; when f/TTL is greater than or equal to 0.7, the tolerance of the optical system 100 is sensitive, which is not beneficial to the assembly of the optical system 100 and the temperature stability of the optical system 100.
Further, as shown in fig. 1, in some embodiments, the focal length of the first lens 110 is f1, where f1 and f satisfy the following conditional expression: f1/f is more than 1.0 and less than 2.0. Specifically, f1/f can be 1.613 or 1.703. In the design, when f1/f is more than 1.0 and less than 2.0, the ratio of f1 to f is reasonably configured by controlling f1 and f through parameter design, the incidence angle of the principal ray is reasonably distributed, and the aberration of the optical system 100 is favorably corrected; when f1/f is less than or equal to 1.0, the deflection angle of the chief ray borne by the first lens 110 is too large, so that the tolerance of the first lens 110 is sensitive, the requirement on the processing precision of the first lens 110 is high, and the processing and manufacturing of the first lens 110 are not facilitated; when f1/f is greater than or equal to 2.0, the deflection angle of the chief ray borne by the first lens 110 is too small, which is not favorable for the first lens 110 to share the temperature stability of the optical system 100.
Further, as shown in fig. 1, in some embodiments, the focal length of the second lens 120 is f2, where f2 and f satisfy the following conditional expression: f2/f is more than 1.5 and less than 2.6. Specifically, f2/f may take the value of 2.115 or 2.069. In the design, when f2/f is more than 1.5 and less than 2.6, the ratio of f2 to f is reasonably configured by controlling f2 and f through parameter design, and the focal power of the second lens 120 is reasonably distributed, so that the structural compactness of the optical system 100 is ensured, and the aberration of the optical system 100 is favorably corrected; when f2/f is less than or equal to 1.5, the tolerance of the second lens 120 is sensitive, so that the requirement on the processing precision of the second lens 120 is high, which is not favorable for the processing and manufacturing of the second lens 120; if f2/f is equal to or greater than 2.6, the pressure on the rear third lens element 130 and the rear fourth lens element 140 to deflect the principal rays is large, which is disadvantageous in balancing the aberrations of the entire optical system 100.
Further, as shown in fig. 1, in some embodiments, the focal length of the third lens 130 is f3, where f3 and f satisfy the following conditional expression: f3/f is more than 1.6 and less than 2.8. Specifically, f3/f can be 2.220 or 2.362. In the design, when f3/f is more than 1.6 and less than 2.8, the ratio of f3 to f is reasonably configured by controlling f3 and f through parameter design, and the focal power of the third lens 130 is reasonably distributed, so that the structural compactness of the optical system 100 is ensured, and the aberration of the optical system 100 is favorably corrected; when f3/f is less than or equal to 1.6, the tolerance of the third lens 130 is sensitive, so that the requirement on the machining precision of the third lens 130 is high, which is not beneficial to the machining and manufacturing of the third lens 130; if f3/f is equal to or greater than 2.8, the pressure on the rear fourth lens 140 to deflect the principal ray is large, which is not favorable for balancing the aberrations of the optical system 100 as a whole.
Further, as shown in fig. 1, in some embodiments, the focal length of the fourth lens 140 is f4, where f4 and f satisfy the following conditional expression: -5.0 < f4/f < -2.0. Specifically, f4/f can be-3.532 or-4.234. In the design, when f4/f is more than-5.0 and less than-2.0, the ratio of f4 to f is reasonably configured by controlling f4 and f through parameter design, and the focal power of the fourth lens 140 is reasonably distributed, so that the structural compactness of the optical system 100 is ensured, and the aberration of the optical system 100 can be well compensated; when f4/f is less than or equal to-5.0, the fourth lens 140 has limited ability to balance the aberration of the optical system 100, which is not favorable for the temperature stability of the optical system 100; when f4/f is ≧ 2.0, the tolerance of the fourth lens 140 is sensitive, which is detrimental to the balance of the aberrations of the optical system 100 as a whole.
Further, as shown in fig. 1, in some embodiments, the curvature radius of the object-side surface S1 of the first lens element 110 at the paraxial region is R11, and the curvature radius of the image-side surface S2 of the first lens element 110 at the paraxial region is R12, wherein R11 and R12 satisfy the following conditional expressions: -1.5 < (R11-R12)/(R11+ R12) < -0.5. Specifically, the value of (R11-R12)/(R11+ R12) may be-0.996 or-0.956. In the design, when-1.5 < (R11-R12)/(R11+ R12) < -0.5, the ratio of (R11-R12) and (R11+ R12) is reasonably configured by design control of parameters R11 and R12, at the moment, the first lens 110 has attractive appearance, is easy to process and detect, can better inhibit and balance high-level aberration of the optical system 100, has proper surface tolerance requirement of the first lens 110, can better meet various index requirements of the optical system 100, and is favorable for assembling the first lens 110; when the ratio of (R11-R12)/(R11+ R12) is less than or equal to-1.5 or the ratio of (R11-R12)/(R11+ R12) is greater than or equal to-0.5, the injection molding of the first lens 110 is not facilitated, the tolerance of the first lens 110 is sensitive, the assembly difficulty of the first lens 110 is high, and the optical system 100 is not facilitated to obtain excellent imaging quality and temperature stability.
Further, as shown in fig. 1, in some embodiments, the curvature radius of the object-side surface S3 of the second lens element 120 at the paraxial region is R21, and the curvature radius of the image-side surface S4 of the second lens element 120 at the paraxial region is R22, wherein R21 and R22 satisfy the following conditional expressions: 0.2 < (R21-R22)/(R21+ R22) < 0.6. Specifically, the value of (R21-R22)/(R21+ R22) may be 0.363 or 0.394. In the design, when 0.2 < (R21-R22)/(R21+ R22) < 0.6, the ratio of (R21-R22) to (R21+ R22) is reasonably configured by design control of parameters R21 and R22, at the moment, the second lens 120 has an attractive appearance, is easy to process and detect, can better inhibit and balance the high-level aberration of the optical system 100, has proper surface tolerance requirement of the second lens 120, can better meet various index requirements of the optical system 100, and is beneficial to the assembly of the second lens 120; when the ratio of (R21-R22)/(R21+ R22) is less than or equal to 0.2 or the ratio of (R21-R22)/(R21+ R22) is greater than or equal to 0.6, the injection molding of the second lens 120 is not facilitated, the tolerance of the second lens 120 is sensitive, the assembly difficulty of the second lens 120 is high, and the optical system 100 is not facilitated to obtain excellent imaging quality and temperature stability.
Further, as shown in fig. 1, in some embodiments, the radius of curvature of the object-side surface S5 of the third lens element 130 at the paraxial region is R31, and the radius of curvature of the image-side surface S6 of the third lens element 130 at the paraxial region is R32, wherein R31 and R32 satisfy the following conditional expressions: -0.1 < (R31-R32)/(R31+ R32) < -0.01. Specifically, the value of (R31-R32)/(R31+ R32) may be-0.033 or-0.037. In the design, when-0.1 < (R31-R32)/(R31+ R32) < -0.01, the ratio of (R31-R32) to (R31+ R32) is reasonably configured by design control of parameters R31 and R32, at the moment, the appearance of the third lens 130 is attractive, the processing and the detection are easy, the high-level aberration of the optical system 100 can be well inhibited and balanced, the face shape tolerance requirement of the third lens 130 is proper, the index requirements of the optical system 100 can be well met, and the assembly of the third lens 130 is facilitated; when the ratio of (R31-R32)/(R31+ R32) is less than or equal to-0.1 or the ratio of (R31-R32)/(R31+ R32) is greater than or equal to-0.01, the injection molding of the third lens 130 is not facilitated, the tolerance of the third lens 130 is sensitive, the assembling difficulty of the third lens 130 is high, and the optical system 100 is not facilitated to obtain excellent imaging quality and temperature stability.
Further, as shown in fig. 1, in some embodiments, the curvature radius of the object-side surface S7 of the fourth lens element 140 at the paraxial region is R41, and the curvature radius of the image-side surface S8 of the fourth lens element 140 at the paraxial region is R42, wherein R41 and R42 satisfy the following conditional expressions: 0.1 < (R41-R42)/(R41+ R42) < 0.2. Specifically, the value of (R41-R42)/(R41+ R42) may be 0.186 or 0.167. In the design, when 0.1 < (R41-R42)/(R41+ R42) < 0.2, the ratio of (R41-R42) to (R41+ R42) is reasonably configured by design control of parameters R41 and R42, at the moment, the appearance of the fourth lens 140 is attractive, the processing and the detection are easy, the high-level aberration of the optical system 100 can be well inhibited and balanced, the surface tolerance requirement of the fourth lens 140 is proper, various index requirements of the optical system 100 can be well met, and the assembly of the fourth lens 140 is facilitated; when the ratio of (R41-R42)/(R41+ R42) is less than or equal to 0.1 or the ratio of (R41-R42)/(R41+ R42) is greater than or equal to 0.2, the injection molding of the fourth lens 140 is not facilitated, the tolerance of the fourth lens 140 is sensitive, the assembling difficulty of the fourth lens 140 is high, and the optical system 100 is not facilitated to obtain excellent imaging quality and temperature stability.
Further, as shown in fig. 1, in some embodiments, the thickness of the first lens 110 at the optical axis is n1, where n1 satisfies the conditional expression: -0.00001 < dn1/dt < 0.0. Specifically, dn1/dt may take the value of-6.26E-6. In the design, when-0.00001 is larger than dn1/dt and smaller than 0.0, the ratio of dn1 to dt is reasonably configured by controlling n1 through parameter design, and the temperature stability of the optical system 100 within the range of-20 ℃ to 60 ℃ can be ensured; when dn1/dt is less than or equal to-0.00001, the temperature stability of the optical system 100 in the range of-20 ℃ to 60 ℃ cannot be ensured; when dn1/dt ≧ 0.0, the present refractive materials cannot be realized at this time.
Further, in order to reduce stray light in the optical system 100 to improve the imaging quality of the optical system 100, the optical system 100 further includes a stop STO, which may be an aperture stop STO or a field stop STO, wherein the aperture stop STO is adopted in the embodiments of the present specification. The stop STO is located between the object side of the optical system 100 and the image plane S11, and for example, the stop STO may be provided at any position between the object side of the optical system 100 and the object side surface S1 of the first lens 110, between any two of the first lens 110 to the fourth lens 140, and between the image side surface S8 of the fourth lens 140 and the image plane S11 of the optical system 100; to save costs, a stop STO can also be provided on the object-side or image-side surface of any lens. In the embodiment of the present disclosure, the stop STO is disposed on the object-side surface S1 of the first lens element 110, and in this design, the risk of generating ghost can be effectively reduced by the stop STO, so as to improve the imaging quality of the optical system 100.
Note that the object side surface of the lens refers to a surface of the lens facing the object side, and the image side surface of the lens refers to a surface of the lens facing the image side, for example, the object side surface S1 of the first lens 110 refers to a surface of the first lens 110 facing the (near) object side, and the image side surface S2 of the first lens 110 refers to a surface of the first lens 110 facing the (near) image side. The positive curvature radius of the object-side surface or the image-side surface of each lens on the optical axis indicates that the object-side surface or the image-side surface of the lens is convex toward the object surface, and the negative curvature radius of the object-side surface or the image-side surface of each lens on the optical axis indicates that the object-side surface or the image-side surface of the lens is convex toward the image surface.
Furthermore, in order to correct the aberration of the optical system 100 and improve the imaging quality of the optical system 100, at least one of the object-side surfaces or the image-side surfaces of the first lens element 110, the second lens element 120, the third lens element 130, and the fourth lens element 140 may be aspheric, for example, the object-side surface S1 of the first lens element 110 may be aspheric, and the object-side surface S3 of the second lens element 120 may also be aspheric. In the embodiment of the present specification, the object-side surface S1 of the first lens 110, the image-side surface S2 of the first lens 110, the object-side surface S3 of the second lens 120, the image-side surface S4 of the second lens 120, the object-side surface S5 of the third lens 130, the image-side surface S6 of the third lens 130, the object-side surface S7 of the fourth lens 140, and the image-side surface S8 of the fourth lens 140 are all aspheric. It should be noted that the above surface is an aspheric surface, and the entire surface of the lens may be an aspheric surface, or a part of the surface of the lens may be an aspheric surface, for example, a part of the first lens 110 at a paraxial region is an aspheric surface.
Further, to save the cost of the optical system 100, the first lens 110, the second lens 120, the third lens 130, and the fourth lens 140 may all be made of plastic materials. In the embodiment of the present disclosure, in order to improve the imaging quality of the optical system 100, the first lens 110 is made of a glass material, and all of the second lens 120, the third lens 130, and the fourth lens 140 are made of a plastic material, considering that the imaging quality of the optical system 100 is closely related to not only the coordination between the lenses in the optical system 100 but also the material of the lenses. By designing the material of the first lens 110 to be glass, the sensitivity of the optical system 100 to temperature can be effectively reduced by utilizing the characteristics of low thermal expansion coefficient of glass material and small change of refractive index with temperature.
Further, considering that a light beam emitted or reflected by a photographed object passes through the first lens 110, the second lens 120, the third lens 130, and the fourth lens 140 of the optical system 100 from the object side in sequence, reaches the imaging plane S11, and is imaged on the imaging plane S11, in order to ensure the imaging definition of the photographed object on the imaging plane S11, the optical system 100 may further include the optical filter 150, and the optical filter 150 may be disposed between the image side surface S8 of the fourth lens 140 and the imaging plane S11 of the optical system 100. The filter 150 includes a first surface S9 close to the object side and a second surface S10 close to the image side. Through the arrangement of the optical filter 150, the light beam passes through the optical filter 150 after passing through the fourth lens 140, so that the non-working waveband light beam in the light beam can be effectively filtered, that is, visible light can be filtered and only infrared light can be allowed to pass, or infrared light can be filtered and only visible light can be allowed to pass, and further, the imaging definition of the shot object on the imaging surface S11 is ensured.
Further, in consideration of the fact that the light beam emitted or reflected by the object passes through the first lens 110, the second lens 120, the third lens 130, and the fourth lens 140 of the optical system 100 from the object side in sequence to reach the imaging surface S11 and forms an image on the imaging surface S11, in order to protect the imaging photosensitive element (for example, the image sensor 210 below), the optical system 100 may further include a protective glass, and the protective glass is disposed between the image side surface S8 and the imaging surface S11 of the fourth lens 140. Wherein the protective glass comprises a third surface close to the object side and a fourth surface close to the image side. When the optical system 100 is also provided with the optical filter 150, the optical filter 150 is disposed on a side close to the image side surface S8 of the fourth lens element 140, and the protective glass is correspondingly disposed between the second surface S10 of the optical filter 150 and the image plane S11.
Based on the above description of the embodiments, more specific embodiments and drawings are set forth below for illustration.
Example one
Referring to fig. 1 to fig. 5, the optical system 100 includes a stop STO, a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a filter 150, and an image plane S11 sequentially disposed from an object side to an image side along an optical axis of the optical system 100.
The first lens element 110 with positive refractive power has a convex object-side surface S1 at a paraxial region of the first lens element 110, and has a convex image-side surface S2 at a paraxial region of the first lens element 110.
The second lens element 120 with positive refractive power has a concave object-side surface S3 at a paraxial region thereof, and has a convex image-side surface S4 at a paraxial region thereof, the second lens element 120.
The third lens element 130 with positive refractive power has a concave object-side surface S5 at a paraxial region thereof and a convex image-side surface S6 at the paraxial region thereof.
The fourth lens element 140 with negative refractive power has a convex object-side surface S7 at a paraxial region thereof, and a concave image-side surface S8 at the paraxial region thereof, of the fourth lens element 140.
By reasonably configuring the shape and positive and negative refractive power of each lens, setting the ratio of the effective focal length of each lens to the effective focal length of the optical system 100, and by controlling the curvature of the lenses, the thickness of the lenses, the spacing between the lenses, the aspheric coefficients of the lenses, and the materials of the lenses, the overall performance of the optical system 100 is optimized, so that the optical system 100 has excellent imaging quality and temperature stability.
In the first embodiment, the reference wavelength of the focal length of each lens is 632.8 nm. The relevant parameters of the optical system 100 are shown in table 1, wherein f in table 1 represents the effective focal length of the optical system 100, FNO represents the aperture value, and FOV represents the maximum field angle of the optical system 100, and it should be noted that the focal length, the radius of curvature, and the thickness are all in millimeters.
TABLE 1
In the first embodiment of the present specification, specific values of the parameters of the optical system 100 are substituted into corresponding conditional expressions to obtain table 2.
TABLE 2
The surfaces of the lenses of optical system 100 may be aspherical, for which the aspherical equation for the aspherical surface is:
z is the distance from a corresponding point on the aspheric surface to a plane tangent to the surface vertex, r is the distance from the corresponding point on the aspheric surface to the optical axis, c is the curvature of the aspheric surface vertex, k is a conical coefficient, Ai is a coefficient corresponding to the i-th high-order term in the aspheric surface type formula, and A4, A6, A8, A10, A12, A14 and A16 respectively represent aspheric coefficients of 4 th order, 6 th order, 8 th order, 10 th order, 12 th order, 14 th order and 16 th order corresponding orders. In the first embodiment of the present description, the object-side surface S1 of the first lens element 110, the image-side surface S2 of the first lens element 110, the object-side surface S3 of the second lens element 120, the image-side surface S4 of the second lens element 120, the object-side surface S5 of the third lens element 130, the image-side surface S6 of the third lens element 130, the object-side surface S7 of the fourth lens element 140, and the image-side surface S8 of the fourth lens element 140 are all aspheric surfaces, and the conic constant K and aspheric coefficient corresponding to the aspheric surface of each lens element are shown in table 3:
TABLE 3
Fig. 2 is an MFT diagram of the optical system 100 at 1/4Ny, 1/2Ny, and Ny in a first embodiment of the present disclosure, wherein an abscissa in the X-axis direction represents a half-image height in mm, and an ordinate in the Y-axis direction represents an MTF value. It can be seen from fig. 2 that the overall curve values are all high, and the curve values smoothly decrease with increasing half-image height, indicating that the MTF of each field of view of the optical system 100 in this embodiment one is good. (1/4Ny 43.0000p/mm, 1/2Ny 83.0000p/mm, Ny 166.0000p/mm)
Fig. 3 schematically shows a Through-Focus-MTF plot of the optical system 100 at a frequency of 43.0000p/mm in a first embodiment of the present description, wherein an abscissa in the X-axis direction represents a defocus distance in mm, and an ordinate in the Y-axis direction represents an MTF value. It can be seen from fig. 3 that the MTF peaks of the respective fields are substantially located at the imaging plane S11, and are substantially symmetrically distributed left and right with defocus, which indicates that the overall curvature of field tolerance of the optical system 100 is looser, which is beneficial for practical production assembly.
Fig. 4A is an astigmatism graph of the optical system 100 in the first embodiment of the present disclosure, where the abscissa along the X-axis represents the focus offset and the ordinate along the Y-axis represents the image height, which is expressed in mm, and the astigmatism curves include meridional field curvature and sagittal field curvature. The S curve in FIG. 4A represents sagittal curvature of field at a reference wavelength of 632.8nm, and the T curve represents meridional curvature of field at a reference wavelength of 632.8 nm. In the case of the reference wavelength of 632.8nm, it can be seen from fig. 4A that the image height is within 41.2mm, and the distortion is well compensated for less than 0.5% as a whole.
Fig. 4B is a distortion graph of the optical system 100 in the first embodiment of the present disclosure, where the distortion curve represents the magnitude of distortion corresponding to different angles of view, where the abscissa along the X-axis direction represents the distortion and the ordinate along the Y-axis direction represents the angle of view. In the case of the reference wavelength of 632.8nm, it can be seen from fig. 4B that the distortion is well corrected.
Fig. 5 is a graph of relative illuminance (ratio of illuminance of each field of view to illuminance of the central field of view) of the optical system 100 in the first embodiment of the present disclosure, in which the abscissa represents half-image height and the ordinate represents the ratio of illuminance of the central field of view. As can be seen from fig. 5, the relative illuminance curve of the optical system 100 is smooth as a whole, and has no recurrences, and the lowest point relative illuminance is better than 29.5%, and has a higher relative illuminance.
In the first embodiment, in the process of changing the ambient temperature from-20 ℃ to 60 ℃, the maximum variation of the focal length is 0.012mm, the maximum variation of the half-field angle ω is 0.096 °, the maximum variation of the optical distortion is 0.099%, and the maximum variation of the imaging height of an object with a height of 35cm at 40cm on the imaging surface S11 is 7 um.
Example two
Referring to fig. 6 to 10, the optical system 100 includes a stop STO, a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a filter 150, and an image plane S11 sequentially disposed from an object side to an image side along an optical axis of the optical system 100.
The first lens element 110 with positive refractive power has a convex object-side surface S1 at a paraxial region of the first lens element 110, and has a convex image-side surface S2 at a paraxial region of the first lens element 110.
The second lens element 120 with positive refractive power has a concave object-side surface S3 at a paraxial region thereof, and has a convex image-side surface S4 at a paraxial region thereof, the second lens element 120.
The third lens element 130 with positive refractive power has a concave object-side surface S5 at a paraxial region thereof and a convex image-side surface S6 at the paraxial region thereof.
The fourth lens element 140 with negative refractive power has a convex object-side surface S7 at a paraxial region thereof, and an image-side surface S8 of the fourth lens element 140 is concave at the paraxial region thereof.
By reasonably configuring the shape and positive and negative refractive power of each lens, setting the ratio of the effective focal length of each lens to the effective focal length of the optical system 100, and by controlling the curvature of the lenses, the thickness of the lenses, the spacing between the lenses, the aspheric coefficients of the lenses, and the materials of the lenses, the overall performance of the optical system 100 is optimized, so that the optical system 100 has excellent imaging quality and temperature stability.
In the second embodiment, the reference wavelength of the focal length of each lens is 632.8 nm. The relevant parameters of the optical system 100 are shown in table 4, wherein f in table 4 represents the effective focal length of the optical system 100, FNO represents the aperture value, and FOV represents the maximum field angle of the optical system 100, and it should be noted that the focal length, the radius of curvature, and the thickness are all in millimeters.
TABLE 4
In the second embodiment of the present specification, table 5 is obtained by substituting specific values of the parameters of the optical system 100 into corresponding conditional expressions.
TABLE 5
The surfaces of the lenses of optical system 100 may be aspherical, for which the aspherical equation for the aspherical surface is:
z is the distance from a corresponding point on the aspheric surface to a plane tangent to the surface vertex, r is the distance from the corresponding point on the aspheric surface to the optical axis, c is the curvature of the aspheric surface vertex, k is a conical coefficient, Ai is a coefficient corresponding to the i-th high-order term in the aspheric surface type formula, and A4, A6, A8, A10, A12, A14 and A16 respectively represent aspheric coefficients of 4 th order, 6 th order, 8 th order, 10 th order, 12 th order, 14 th order and 16 th order corresponding orders. In the second embodiment of the present specification, the object-side surface S1 of the first lens element 110, the image-side surface S2 of the first lens element 110, the object-side surface S3 of the second lens element 120, the image-side surface S4 of the second lens element 120, the object-side surface S5 of the third lens element 130, the image-side surface S6 of the third lens element 130, the object-side surface S7 of the fourth lens element 140, and the image-side surface S8 of the fourth lens element 140 are all aspheric surfaces, and the conic constant K and aspheric coefficient corresponding to the aspheric surfaces of the respective lens elements are shown in table 6:
TABLE 6
| Number of noodles | S1 | S2 | S3 | S4 |
| K | -4.61E+00 | -2.00E+02 | 2.31E+01 | 2.56E+00 |
| A4 | 1.62E-02 | -1.26E-01 | -1.97E-01 | -8.53E-02 |
| A6 | -3.10E-02 | -1.54E-01 | -2.80E-01 | -8.31E-03 |
| A8 | -5.81E-02 | -1.75E-01 | 6.97E-02 | 8.08E-02 |
| A10 | -2.73E-03 | 2.25E-01 | -3.16E-01 | -1.05E-01 |
| A12 | -9.11E-01 | 8.67E-02 | -1.19E+00 | 8.05E-02 |
| A14 | 3.32E+00 | -1.48E+00 | 5.02E-01 | 1.77E-01 |
| A16 | -3.90E+00 | 1.36E+00 | 1.90E+00 | -1.03E-01 |
| Number of noodles | S5 | S6 | S7 | S8 |
| K | -1.53E+00 | -8.58E-01 | -2.84E+00 | -3.09E+00 |
| A4 | -1.00E-01 | 5.76E-02 | -7.46E-02 | -5.98E-02 |
| A6 | 2.45E-02 | -5.27E-02 | 6.44E-03 | 1.97E-02 |
| A8 | 1.88E-01 | 6.30E-02 | 1.03E-02 | -7.16E-03 |
| A10 | 8.03E-02 | -1.15E-02 | -1.05E-02 | 1.62E-03 |
| A12 | -6.51E-02 | 1.04E-02 | 4.31E-03 | -1.83E-04 |
| A14 | -7.82E-02 | -1.95E-02 | -8.48E-04 | 3.72E-06 |
| A16 | 4.01E-02 | 1.03E-02 | 6.69E-05 | 6.04E-07 |
Fig. 7 is an MFT diagram of the optical system 100 in the second embodiment of the present disclosure at 1/4Ny, 1/2Ny, and Ny, where an abscissa in the X-axis direction represents a half-image height in mm, and an ordinate in the Y-axis direction represents an MTF value. It can be seen from fig. 7 that the overall curve values are all high, and the curve values smoothly decrease with increasing half-image height, indicating that the MTF of each field of view of the optical system 100 in this embodiment two is good. (1/4Ny 43.0000p/mm, 1/2Ny 83.0000p/mm, Ny 166.0000p/mm)
Fig. 8 schematically shows a Through-Focus-MTF plot at a frequency of 43.0000p/mm for the optical system 100 in example two of this specification, in which the abscissa in the X-axis direction represents the defocus distance in mm and the ordinate in the Y-axis direction represents the MTF value. It can be seen from fig. 8 that the MTF peaks of the respective fields are substantially located at the imaging plane S11, and are substantially symmetrically distributed left and right with defocus, which indicates that the overall curvature of field tolerance of the optical system 100 is looser, which is beneficial for practical production assembly.
Fig. 9A is an astigmatism graph of the optical system 100 in a second embodiment of the present specification, where an abscissa in the X-axis direction represents a focus offset amount and an ordinate in the Y-axis direction represents an image height in mm, and the astigmatism curves include meridional field curvature and sagittal field curvature. The S curve in FIG. 9A represents sagittal curvature of field at a reference wavelength of 632.8nm, and the T curve represents meridional curvature of field at a reference wavelength of 632.8 nm. In the case of the reference wavelength of 632.8nm, it can be seen from fig. 9A that the image height is within 41.2mm, and the distortion is well compensated for less than 0.5% as a whole.
Fig. 9B is a distortion graph of the optical system 100 in example two of the present specification, in which a distortion curve indicates a distortion magnitude value corresponding to different angles of view, where an abscissa in the X-axis direction indicates distortion, and an ordinate in the Y-axis direction indicates angles of view. In the case of the reference wavelength of 632.8nm, it can be seen from fig. 9B that the distortion is well corrected.
Fig. 10 is a graph of relative illuminance (ratio of illuminance of each field of view to illuminance of the central field of view) of the optical system 100 in example two of the present specification, in which the abscissa represents half-image height and the ordinate represents the ratio of illuminance of the central field of view. As can be seen from fig. 10, the relative illuminance curve of the optical system 100 is smooth as a whole, and has no recurrences, and the lowest point relative illuminance is better than 29.5%, and has a higher relative illuminance.
In the second embodiment, in the process of changing the ambient temperature from-20 ℃ to 60 ℃, the maximum variation of the focal length is 0.012mm, the maximum variation of the half-field angle ω is 0.089 °, the maximum variation of the optical distortion is 0.12%, and the maximum variation of the imaging height of an object with a height of 35cm at 40cm on the imaging surface S11 is 7.3 um.
A second aspect of the embodiment of the present disclosure provides an image capturing module 200, as shown in fig. 11, fig. 11 is a schematic structural diagram of the image capturing module 200 in the embodiment of the present disclosure. The image capturing module 200 includes an image sensor 210 and the optical system 100, wherein the image sensor 210 is disposed on the image side of the optical system 100. The optical system 100 is configured to receive a light beam emitted by a subject and project the light beam onto the image sensor 210, and the image sensor 210 is configured to convert an optical signal of the light beam into an image signal. In the design, the image capturing module 200 having the optical system 100 satisfies the design of small volume and high pixel, and the image capturing module 200 has good temperature stability within a range of-20 ℃ to 60 ℃, so that the image capturing module 200 has good imaging quality.
A third aspect of the embodiments of the present specification provides an electronic apparatus 300, and as shown in fig. 12, fig. 12 is a schematic structural diagram of the electronic apparatus 300 in the embodiments of the present specification when it is a vehicle-mounted camera. The electronic device 300 includes a mounting structure 310 and the image capturing module 200, wherein the image capturing module 200 is disposed on the mounting structure 310. The mounting structure 310 may be directly a housing of the electronic device 300, or may be an intermediate connection structure for fixing the image capturing module 200 on the housing of the electronic device 300, where details of the intermediate connection structure are not repeated, and a designer may reasonably design the image capturing device according to actual needs. The electronic device 300 may be, but is not limited to, a mobile phone, a video camera, a computer, or other devices having an image capturing function. As shown in fig. 12, the electronic apparatus 300 is an in-vehicle camera. In the design, the electronic device 300 with the image capturing module 200 satisfies the design of small volume and high pixel, and meanwhile, the electronic device 300 has good temperature stability within the range of-20 ℃ to 60 ℃, so that the electronic device 300 has good imaging quality.
A fourth aspect of the embodiments of the present disclosure provides a vehicle 400, as shown in fig. 13, and fig. 13 is a schematic structural view of the vehicle 400 in the embodiments of the present disclosure. The carrier 400 includes a connecting structure and the electronic apparatus 300, wherein the electronic apparatus 300 is disposed on the connecting structure (not shown). The connecting structure is used for carrying the electronic device 300, and the connecting structure may be a housing of the carrier 400 directly, or may be an intermediate connecting structure for fixing the electronic device 300 on the housing of the carrier 400, and the specific structure of the intermediate connecting structure is not described herein, and a designer may design the connecting structure reasonably according to actual needs. The vehicle 400 may be, but is not limited to, a vehicle, an aircraft, or other transportation equipment having a camera function. As shown in fig. 13, the vehicle 400 is an automobile. In the design, the carrier 400 with the image capturing module 200 satisfies the design of small volume and high pixel, and the carrier 400 has good temperature stability within a temperature range of-20 ℃ to 60 ℃, so that the carrier 400 has good imaging quality.
The same or similar reference numerals in the drawings of the present embodiment correspond to the same or similar components; in the description of the embodiments of the present specification, it should be understood that if there are terms "upper", "lower", "left", "right", etc. indicating orientations or positional relationships based on the orientations or positional relationships shown in the drawings, the terms are used for convenience of description of the embodiments of the present specification and for simplification of description, but do not indicate or imply that the devices or elements referred to must have specific orientations, be constructed and operated in specific orientations, and therefore, the terms describing the positional relationships in the drawings are used for illustrative purposes only and are not to be construed as limitations on the present patent, and specific meanings of the terms may be understood by those skilled in the art according to specific situations.
Claims (13)
1. An optical system comprising, in order from an object side to an image side along an optical axis of the optical system:
a first lens element with positive refractive power having a convex object-side surface at a paraxial region and a convex image-side surface at a paraxial region;
a second lens element with positive refractive power having a concave object-side surface at a paraxial region and a convex image-side surface at a paraxial region;
a third lens element with positive refractive power having a concave object-side surface at a paraxial region and a convex image-side surface at a paraxial region;
a fourth lens element with negative refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;
the effective focal length of the optical system is f, the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis is TTL, and the f and the TTL satisfy the conditional expression:
0.5＜f/TTL＜0.7。
2. the optical system of claim 1, wherein the optical system,
the focal length of the first lens is f1, wherein f1 and f satisfy the following conditional expression:
1.0＜f1/f＜2.0。
3. the optical system of claim 1, wherein the optical system,
the focal length of the second lens is f2, wherein f2 and f satisfy the following conditional expression:
1.5＜f2/f＜2.6。
4. the optical system of claim 1, wherein the optical system,
the focal length of the third lens is f3, wherein f3 and f satisfy the following conditional expression:
1.6＜f3/f＜2.8。
5. the optical system of claim 1, wherein the optical system,
the focal length of the fourth lens is f4, wherein f4 and f satisfy the following conditional expression:
-5.0＜f4/f＜-2.0。
6. the optical system of claim 1, wherein the optical system,
the curvature radius of the object-side surface of the first lens element at the paraxial region is R11, and the curvature radius of the image-side surface of the first lens element at the paraxial region is R12, wherein R11 and R12 satisfy the following conditional expressions:
-1.5＜(R11-R12)/(R11+R12)＜-0.5。
7. the optical system of claim 1, wherein the optical system,
the curvature radius of the object-side surface of the second lens element at the paraxial region is R21, and the curvature radius of the image-side surface of the second lens element at the paraxial region is R22, wherein R21 and R22 satisfy the following conditional expressions:
0.2＜(R21-R22)/(R21+R22)＜0.6。
8. the optical system of claim 1, wherein the optical system,
the radius of curvature of the object-side surface of the third lens element at the paraxial region is R31, and the radius of curvature of the image-side surface of the third lens element at the paraxial region is R32, wherein R31 and R32 satisfy the following conditional expressions:
-0.1＜(R31-R32)/(R31+R32)＜-0.01。
9. the optical system of claim 1, wherein the optical system,
the radius of curvature of the object-side surface of the fourth lens element at the paraxial region is R41, and the radius of curvature of the image-side surface of the fourth lens element at the paraxial region is R42, wherein R41 and R42 satisfy the following conditional expressions:
0.1＜(R41-R42)/(R41+R42)＜0.2。
10. the optical system of claim 1, wherein the optical system,
the first lens has a thickness n1 at the optical axis, wherein n1 satisfies the conditional expression:
-0.00001＜dn1/dt＜0.0。
11. an image capturing module comprises:
the optical system of any one of claims 1-10; and
an image sensor disposed on an image side of the optical system.
12. An electronic device, comprising:
a mounting structure; and
the image capturing module as claimed in claim 11, wherein the image capturing module is disposed on the mounting structure.
13. A carrier, comprising:
a connecting structure; and
the electronic device of claim 12, disposed on the connection structure.
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