CN111929859B - Telephoto lens and mobile terminal - Google Patents
Telephoto lens and mobile terminal Download PDFInfo
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- CN111929859B CN111929859B CN202010998800.2A CN202010998800A CN111929859B CN 111929859 B CN111929859 B CN 111929859B CN 202010998800 A CN202010998800 A CN 202010998800A CN 111929859 B CN111929859 B CN 111929859B
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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
- G02B13/02—Telephoto objectives, i.e. systems of the type + - in which the distance from the front vertex to the image plane is less than the equivalent focal length
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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
- G02B13/0035—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 three lenses
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/02—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective
- G02B15/10—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective by adding a part, e.g. close-up attachment
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/02—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective
- G02B15/10—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective by adding a part, e.g. close-up attachment
- G02B15/12—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective by adding a part, e.g. close-up attachment by adding telescopic attachments
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Abstract
The invention provides a telephoto lens and a mobile terminal, wherein the telephoto lens sequentially comprises from an object side to an imaging surface along an optical axis: the lens comprises a first light-transmitting piece, a diaphragm, a first lens with positive focal power, a second lens with focal power, a third lens with focal power, a second light-transmitting piece and a filter. The object side surface of the first lens is a convex surface, and the image side surface of the second lens is a concave surface. The mobile terminal comprises a telephoto lens and an image sensor, wherein the image sensor is arranged on an imaging surface of the telephoto lens and used for receiving optical signals output by the telephoto lens and forming electric signals corresponding to the optical signals. Compared with the conventional telephoto lens, the telephoto lens and the mobile terminal provided by the invention have larger effective focal length, can meet the requirement of high-definition imaging of a remote object, have shorter total length, and can better meet the requirement of high-definition imaging of a current light and thin electronic product on a long scene.
Description
Technical Field
The invention relates to the technical field of optical lenses, in particular to a telephoto lens and a mobile terminal.
Background
In recent years, with the pursuit of imaging quality of portable electronic products, multiple cameras have become standard configurations of mobile phone products. In order to improve the imaging quality of a remote object, most flagships of mobile phone factories carry a long-focus optical lens, so that the scene can be clearly amplified when a long-distance scene is shot, and the shooting quality of mobile phones is improved.
In the existing multi-camera portable electronic products, the 35mm equivalent focal length ratio of most conventional telephoto lenses and wide-angle lenses is 3-5 times, and the zoom ratio can reach 3-5 times by combining and matching, so that the optical zoom multiple is smaller than that of the conventional zoom lens, and the increasingly improved high-definition imaging requirements of the portable electronic products of customers are difficult to meet.
Disclosure of Invention
The invention aims to provide a telephoto lens and a mobile terminal to solve the problems.
The embodiment of the invention achieves the aim through the following technical scheme.
In a first aspect, the present invention provides a telephoto lens, comprising, in order from an object side to an image plane along an optical axis: the lens comprises a first light-transmitting piece, a diaphragm, a lens group and a second light-transmitting piece; the lens group is composed of the following lenses along the optical axis from the object side to the imaging surface in sequence: the lens comprises a first lens with positive focal power, a second lens and a third lens, wherein the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a convex surface or a concave surface; the second lens with the focal power has a convex or concave object-side surface and a concave image-side surface; the third lens with the focal power has a convex or concave object-side surface and a convex or concave image-side surface; wherein the refractive index Nd of the material of the first light-transmitting member1>1.72 refractive index Nd of material of second light-transmitting member2>1.78; the telephoto lens satisfies the conditional expression: 4.0< TG2/(CT1+CT2+CT3) <7.5; where CT1 denotes the center thickness of the first lens, CT2 denotes the center thickness of the second lens, CT3 denotes the center thickness of the third lens, and TG2 denotes the length of the optical axis in the second light-transmitting member.
In a second aspect, the present invention provides a mobile terminal, which includes the telephoto lens according to the first aspect and an image sensor, where the image sensor is disposed on an imaging surface of the telephoto lens, and is configured to receive an optical signal output by the telephoto lens and form an electrical signal corresponding to the optical signal.
Compared with the prior art, the telephoto lens and the mobile terminal provided by the invention can realize higher optical zoom multiple, have shorter total length, and can better meet the high-definition imaging requirement of the current light and thin electronic product on the long shot.
Advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic structural diagram of a telephoto lens according to a first embodiment of the present invention;
FIG. 2 is a vertical axis chromatic aberration diagram of a telephoto lens according to a first embodiment of the present invention;
FIG. 3 is a through focus MTF graph of the telephoto lens according to the first embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a telephoto lens according to a second embodiment of the present invention;
FIG. 5 is a vertical axis chromatic aberration diagram of a telephoto lens according to a second embodiment of the present invention;
FIG. 6 is a through focus MTF graph of a telephoto lens according to a second embodiment of the present invention;
FIG. 7 is a schematic structural diagram of a telephoto lens according to a third embodiment of the present invention;
FIG. 8 is a vertical axis chromatic aberration diagram of a telephoto lens according to a third embodiment of the present invention;
FIG. 9 is a through focus MTF graph of a telephoto lens according to a third embodiment of the present invention;
FIG. 10 is a schematic structural diagram of a telephoto lens according to a fourth embodiment of the present invention;
FIG. 11 is a vertical axis chromatic aberration diagram of a telephoto lens according to a fourth embodiment of the present invention;
FIG. 12 is a through focus MTF graph of a telephoto lens according to a fourth embodiment of the present invention;
FIG. 13 is a schematic structural diagram of a telephoto lens according to a fifth embodiment of the present invention;
FIG. 14 is a top view of FIG. 13;
fig. 15 is a schematic structural diagram of a mobile terminal according to a sixth embodiment of the present invention.
Description of the main element symbols:
the following detailed description will further illustrate the invention in conjunction with the above-described figures.
Detailed Description
In order to make the objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. Several embodiments of the invention are presented in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
An embodiment of the present invention provides a telephoto lens, which sequentially includes, from an object side to an image plane along an optical axis: the lens comprises a first light-transmitting piece, a diaphragm, a lens group and a second light-transmitting piece; the lens group is composed of the following lenses along the optical axis from the object side to the imaging surface in sequence: the lens comprises a first lens with positive focal power, a second lens and a third lens, wherein the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a convex surface or a concave surface; the second lens with the focal power has a convex or concave object-side surface and a concave image-side surface; the third lens with the focal power has a convex or concave object-side surface and a convex or concave image-side surface; wherein the refractive index Nd of the material of the first light-transmitting member1>1.72 refractive index Nd of material of second light-transmitting member2>1.78; first printing opacity spare and second printing opacity spare all adopt the glass material of higher refracting index to make, can utilize the total reflection principle like this, reduce the energy loss of light in reflection process. The telephoto lens satisfies the conditional expression: 4.0< TG2/(CT1+CT2+CT3) <7.5; where CT1 denotes the center thickness of the first lens, CT2 denotes the center thickness of the second lens, CT3 denotes the center thickness of the third lens, and TG2 denotes the length of the optical axis in the second light-transmitting member. When the above conditional expressions are satisfied, the telephoto lens can have a larger focal length.
In one embodiment, the telephoto lens satisfies the conditional expression:
7＜f/IH＜15； （1）
where f denotes the focal length of the telephoto lens, and IH denotes the maximum actual image height of the telephoto lens. When the conditional expression (1) is satisfied, the telephoto lens can have a sufficiently large effective focal length, which is helpful for increasing the zoom ratio of the telephoto lens.
In one embodiment, the telephoto lens satisfies the conditional expression:
0.225< CT3-8/CT8-13<0.400； （2）
wherein, CT3-8Denotes a thickness on an optical axis from an object side surface of the first lens to an image side surface of the third lens, CT8-13A thickness of the image side surface of the third lens to the imaging plane on the optical axis is represented. When the condition (2) is satisfied, the length of the lens group can be reduced, the back focus of the whole lens is increased, and the structural design is facilitated.
In one embodiment, the telephoto lens satisfies the conditional expression:
0.20<CT1/CT4-7<0.82； （3）
wherein CT1 denotes the center thickness of the first lens, CT4-7Denotes a thickness on an optical axis from the image side surface of the first lens to the object side surface of the third lens. When the conditional expression (3) is satisfied, the defocus curve of the lens system can be effectively optimized, the peak value of the defocus curve of each field of view is concentrated, and when CT1/CT is adopted4-7When the value of (A) exceeds the lower limit, the defocusing curve of the field beyond 50% is difficult to optimize, the tolerance optimization is not facilitated, and the yield of the product is greatly influenced; when CT1/CT4-7When the value of (b) exceeds the upper limit, the length of the lens group is too long, which is not favorable for the structural design.
In one embodiment, the telephoto lens satisfies the conditional expression:
2<CT6-7/(1/R7 +1/R8) <17； （4）
wherein, CT6-7Denotes a thickness on an optical axis from an image side surface of the second lens to an object side surface of the third lens, R7Denotes a radius of curvature, R, of an object-side surface of the third lens8A radius of curvature of the image side surface of the third lens is indicated. When the conditional expression (4) is satisfied, it is advantageous to increase the image height of the telephoto lens and to realize an optical zoom of a sufficiently large magnification.
In one embodiment, the telephoto lens satisfies the conditional expression:
-2<( R3+R8)/( R3-R8) <4； （5）
wherein R is3Denotes a radius of curvature, R, of an object-side surface of the first lens8Showing a third lensThe radius of curvature of the image-side surface of (a). When (R)3+R8)/( R3-R8) When the value of (2) exceeds the upper limit, defocusing curves of each field of view are dispersed, and the imaging quality of the telephoto lens is influenced; when (R)3 +R8)/(R3-R8) When the value of (b) exceeds the lower limit, the optimization of the telephoto lens aberration is difficult, and the imaging quality of the telephoto lens is affected.
In one embodiment, the telephoto lens satisfies the conditional expression:
-0.2<φL2+φL3<-0.04； （6）
wherein phi isL2Denotes the power of the second lensL3The power of the third lens is indicated. When the conditional expression (6) is satisfied, the effective focal length of the whole telephoto lens is increased, so that the zoom ratio of the telephoto lens is increased.
In one embodiment, the telephoto lens satisfies the conditional expression:
-3<(φ7-φ5)/(φ8+φ6)<0； （7）
wherein phi is5Denotes an optical power of the object side surface of the second lens6Denotes an optical power of the image side surface of the second lens7Denotes an optical power of the object side surface of the third lens8Denotes an optical power of the image side surface of the third lens. When (phi)7φ5)/(φ8+φ6) When the value of (2) exceeds the upper limit, defocusing curves of each field of view are dispersed, and the imaging quality of the telephoto lens is influenced; when (phi)7-φ5)/(φ8+φ6) When the value of (b) exceeds the lower limit, the length of the lens group is increased, which is not favorable for the structural design.
In one embodiment, the telephoto lens satisfies the conditional expression:
-2<f1/f3<1； （8）
v1≥v3； （9）
wherein f is1Denotes the focal length of the first lens, f3Denotes the focal length, v, of the third lens1Expressing Abbe number of the first lens，v3The abbe number of the third lens is shown. When the above-described conditions (8) and (9) are satisfied, the tolerance optimization of the telephoto lens, particularly the optimization of the decentering sensitivities of the first lens and the third lens, is facilitated.
In one embodiment, the telephoto lens satisfies the conditional expression:
f >28mm； （10）
0.7< f/TTL <1.2； （11）
where TTL denotes the total optical length of the telephoto lens, and f denotes the focal length of the telephoto lens. When the conditional expressions (10) and (11) are satisfied, the total optical length of the lens can be shortened as much as possible on the premise that the lens has a sufficiently large focal length.
In one embodiment, the second lens is a glass spherical lens, and at least one of the first lens and the third lens is a glass aspherical lens. Aspheric surfaces allow the lens to obtain more control variables to correct aberrations.
In one embodiment, the first light-transmitting member is a first flat glass and the second light-transmitting member is a second flat glass; or the first light-transmitting piece is a first prism, and the second light-transmitting piece is a second prism.
In one embodiment, the first plate glass is disposed at the light inlet of the telephoto lens, and the second plate glass is disposed at the light outlet of the telephoto lens.
The aspheric surface shape of the telephoto lens in each embodiment of the invention satisfies the following equation:
wherein z represents the distance in the optical axis direction from the vertex of the curved surface, c represents the curvature of the vertex of the curved surface, k represents a conic coefficient, h represents the distance from the optical axis to the curved surface, and B, C, D, E, F, G, H represents the coefficients of the curved surface of fourth order, sixth order, eighth order, tenth order, twelfth order, fourteenth order, and sixteenth order, respectively.
Compared with the conventional telephoto lens, the telephoto lens provided by the invention can realize higher optical zoom factor. The optical zoom multiple is the ratio of the 35mm equivalent focal length of the telephoto lens to the 35mm equivalent focal length of the wide-angle lens. And the equivalent focal length of 35mm is 43.27/diagonal length of the target surface of the image sensor.
The equivalent focal length ratio of 35mm of the telephoto lens and the conventional wide-angle lens provided by the invention is more than 6.5 times, namely the telephoto lens provided by the invention is used in combination with the conventional wide-angle lens, so that the optical zooming of more than 6.5 times can be realized, the requirement of high-definition imaging of a long-distance object can be met, the total length is short, and the quality of long-range imaging of a portable electronic product can be better met.
The invention is further illustrated below in the following examples. In each of the following embodiments, the thickness and the radius of curvature of each lens in the telephoto lens are different, and specific differences can be referred to in the parameter tables in the embodiments.
First embodiment
As shown in fig. 1, which is a schematic structural diagram of a telephoto lens 1 according to a first embodiment of the present invention, sequentially including, from an object side to an image plane along an optical axis: the lens comprises a first flat glass G1, a diaphragm ST, a lens group L, a second flat glass G2 and a filter G3, wherein a first lens L1, a second lens L2 and a third lens L3 form the lens group L.
The first lens element L1 has positive refractive power, the object-side surface S3 of the first lens element is convex, the image-side surface S4 of the first lens element is convex, the first lens element L1 is made of glass, and both the object-side surface S3 and the image-side surface S4 of the first lens element are aspheric;
the second lens element L2 has negative power, the object-side surface S5 of the second lens element is concave, the image-side surface S6 of the second lens element is concave, and the second lens element L2 is a spherical glass lens element;
the third lens element L3 has positive power, the object-side surface S7 of the third lens element is convex, the image-side surface S8 of the third lens element is convex, and the third lens element L3 is a spherical glass lens element.
The relevant parameters of each lens in the telephoto lens 1 provided in the first embodiment of the present invention are shown in table 1.
TABLE 1
The aspherical parameters of the first lens L1 in this embodiment are shown in table 2.
TABLE 2
FIG. 2 is a vertical axis chromatic aberration curve of the telephoto lens 1, and it can be seen from the graph that the difference between each wavelength and the dominant wavelength (555 nm) is less than 1.5 μm, which indicates that the vertical axis chromatic aberration of the telephoto lens 1 is well corrected; fig. 3 is a defocus MTF curve of the telephoto lens 1, and it can be seen from the graph that the peak value of the defocus curve of each field is close to the central field, so that the influence of tolerance, especially eccentricity, on the imaging quality can be reduced, and the yield can be effectively improved.
Second embodiment
Fig. 4 is a structural diagram of a telephoto lens 2 according to the present embodiment. The telephoto lens 2 in the present embodiment is largely the same as the telephoto lens 1 in the first embodiment, except that: in the telephoto lens 2 of the present embodiment, the image-side surface S4 of the first lens is concave, the second lens L2 has positive power, the object-side surface S5 of the second lens is convex, the third lens L3 has negative power, the image-side surface S8 of the third lens is concave, and the curvature radius and material selection of each lens are different, and specific parameters of each lens are shown in table 3.
TABLE 3
The aspherical parameters of the first lens L1 of the present embodiment are shown in table 4.
TABLE 4
FIG. 5 is a vertical axis chromatic aberration curve of the telephoto lens 2, and it can be seen from the graph that the difference between each wavelength and the dominant wavelength (555 nm) is less than 1.0 μm, which indicates that the vertical axis chromatic aberration of the telephoto lens 2 is well corrected; fig. 6 is a defocus MTF curve of the telephoto lens 2, and it can be seen from the graph that the peak of the defocus curve of each field is close to the central field, so that the influence of tolerance, especially eccentricity, on the imaging quality can be reduced, and the yield can be effectively improved.
Third embodiment
Fig. 7 shows a structural diagram of a telephoto lens 3 according to the present embodiment. The telephoto lens 3 in the present embodiment is largely the same as the telephoto lens 1 in the first embodiment, except that: in the telephoto lens 3 of the present embodiment, the image-side surface S4 of the first lens is a concave surface, the object-side surface S3 of the first lens and the image-side surface S4 of the first lens are both spherical, the third lens L3 has negative power, the image-side surface S8 of the third lens is a concave surface, the object-side surface S7 of the third lens and the image-side surface S8 of the third lens are even aspheric surfaces, and the curvature radii and material choices of the lenses are different, and specific parameters related to each lens are shown in table 5.
TABLE 5
The aspherical parameters of the third lens L3 of the present embodiment are shown in table 6.
TABLE 6
FIG. 8 is a vertical axis chromatic aberration curve of the telephoto lens 3, and it can be seen from the graph that the difference between each wavelength and the dominant wavelength (555 nm) is less than 0.8 μm, which indicates that the vertical axis chromatic aberration of the telephoto lens 3 is well corrected; fig. 9 is a defocus MTF curve of the telephoto lens 3, and it can be seen from the graph that the peak of the defocus curve of each field is close to the central field, so that the influence of tolerance, especially eccentricity, on the imaging quality can be reduced, and the yield can be effectively improved.
Fourth embodiment
Fig. 10 shows a structural diagram of a telephoto lens 4 according to the present embodiment. The telephoto lens 4 in the present embodiment is largely the same as the telephoto lens 1 in the first embodiment, except that: in the telephoto lens 4 of the present embodiment, the image-side surface S4 of the first lens is a concave surface, the second lens L2 has positive power, the object-side surface S5 of the second lens is a convex surface, the third lens L3 has negative power, the image-side surface S8 of the third lens is a concave surface, the object-side surface S7 of the third lens and the image-side surface S8 of the third lens are even aspheric surfaces, and the curvature radii and material choices of the lenses are different, and specific parameters related to the lenses are shown in table 7.
TABLE 7
The aspherical surface parameters of each aspherical lens in this example are shown in table 8.
TABLE 8
FIG. 11 is a vertical axis chromatic aberration curve of the telephoto lens 4, and it can be seen from the graph that the difference between each wavelength and the dominant wavelength (555 nm) is less than 1.0 μm, which indicates that the vertical axis chromatic aberration of the telephoto lens 4 is well corrected; fig. 12 is a defocus MTF curve of the telephoto lens 4, and it can be seen from the graph that the peak of the defocus curve of each field is close to the central field, so that the influence of tolerance, especially eccentricity, on the imaging quality can be reduced, and the yield can be effectively improved.
Please refer to table 9, which shows the optical characteristics of the telephoto lens in the above four embodiments, including the total optical length TTL, the focal length f, the field angle 2 θ, the maximum actual image height IH, and the related values corresponding to each of the above conditional expressions.
TABLE 9
In summary, the focal length f of the telephoto lens provided by the present invention can reach 30mm, the diagonal length of the image sensor matched with the telephoto lens can reach 6.52mm, and the calculation method of the equivalent focal length of 35mm can be used to obtain: the equivalent focal length of 35mm is 43.27/the length of the diagonal line of the target surface of the image sensor is 43.27/6.52 and 30 is 199.1 mm. Therefore, the 35mm equivalent focal length of the telephoto lens provided by the invention can reach 199.1 mm. Generally, the 35mm equivalent focal length of a conventional wide-angle lens is usually 20-30 mm, and then after the telephoto lens provided by the invention is used in combination with the conventional wide-angle lens, the equivalent focal length ratio of the telephoto lens to the conventional wide-angle lens is more than 6.5 times, so that the optical zooming of more than 6.5 times can be realized, a better imaging effect can be brought to a distant view, and the high-definition imaging requirement of an electronic product is met.
Fifth embodiment
The total optical length (total optical path length) of the telephoto lens provided by any of the above embodiments of the invention exceeds 38mm, which is far beyond the thickness of the portable electronic device, and when the telephoto lens is used in the portable electronic device such as a mobile phone, the lens can be designed into a periscopic lens imaging system by using optical reflection surfaces such as a prism, and the periscopic lens is embedded in the mobile phone to meet the requirements of a light and thin electronic product.
Referring to fig. 13 and fig. 14, a telephoto lens 5 provided in this embodiment sequentially includes, from an object side to an image plane along an optical axis: a first prism P1, a diaphragm ST, a lens group L and a second prism P2; the first prism P1 is arranged at the light inlet of the telephoto lens, the second prism P2 is arranged at the light outlet of the telephoto lens, the first prism P1 turns the incident light to enter the telephoto lens, the second prism P2 turns the light twice to form the emergent light, and the incident light and the emergent light are in a non-coplanar perpendicular manner. Wherein the refractive index Nd of the material of the first prism P11>1.72, refractive index Nd of material of second prism P22>1.78. The lens group L can be connected with any one of the telephoto lensesThe lens sets of one embodiment are the same. That is, the lens group L formed by the first lens element L1, the second lens element L2 and the third lens element L3 may have the same structure as the lens group L of the first to fourth embodiments. Wherein, telephoto lens 5 satisfies the conditional expression: 4.0< TP2/(CT1+CT2+CT3) <7.5, CT1 denotes the center thickness of the first lens L1, CT2 denotes the center thickness of the second lens L2, CT3 denotes the center thickness of the third lens L3, and TP2 denotes the length of the optical axis in the second prism.
The first prism P1 includes a first prism entrance face 501, a first prism exit face 502, and a first prism reflection face 503. The entrance face 501 of the first prism is perpendicular to the exit face 502 of the first prism, and the reflection face 503 of the first prism is inclined with respect to both the entrance face 501 of the first prism and the exit face 502 of the first prism. For example, the first prism P1 may be an isosceles right-angle prism, i.e., the included angle between the reflection surface 503 of the first prism and the incidence surface 501 of the first prism is 45 °, and the included angle between the reflection surface 503 of the first prism and the exit surface 502 of the first prism is also 45 °. Therefore, the external light enters the incident surface 501 of the first prism P1, is turned by the reflecting surface 503 of the first prism to form an emergent light, and is emitted from the emergent surface 502 of the first prism; that is, the light ray enters the first prism P1 and then makes a 90 ° turn to enter the lens group L. In other embodiments, the angle between the reflective surface 503 of the first prism and the incident surface 501 of the first prism may be 30 °, 40 °, or any other suitable angle according to the desired optical path.
The second prism P2 may have the same or similar structure as the first prism P1, such as an isosceles right triangle; other configurations are possible, such as an isosceles trapezoid. If the second prism P2 is an isosceles trapezoid, the second prism P2 includes the incident surface 511 of the second prism, the exit surface 512 of the second prism, the first reflecting surface 513 of the second prism, and the second reflecting surface 514 of the second prism. The incident surface 511 of the second prism and the exit surface 512 of the second prism are coplanar, and the first reflecting surface 513 of the second prism and the second reflecting surface 514 of the second prism are inclined with respect to both the incident surface 511 of the second prism and the exit surface 512 of the second prism. For example, the angle between the first reflecting surface 513 of the second prism and the incident surface 511 of the second prism is 45 °, the angle between the second reflecting surface 514 of the second prism and the exit surface 512 of the second prism is 45 °, the angle between the first reflecting surface 513 of the second prism and the second reflecting surface 514 of the second prism is 90 °, so that the light emitted from the lens group L enters from the incident surface 511 of the second prism, passes through the first reflecting surface 513 of the second prism and the second reflecting surface 514 of the second prism to form an exit light, and exits from the exit surface 512 of the second prism, that is, the light entering the second prism P2 is reflected to the imaging surface.
The optical path of the telephoto lens 5 is redirected by the first prism P1 and the second prism P2, which can effectively reduce the thickness of the telephoto lens 5 in the optical axis direction of the lens group L.
In particular, the telephoto lens 5 satisfies the conditional expression: d1+ D2+ D3 = TG2, D1 represents the path length of the light from the incident surface 511 of the second prism to the first reflecting surface 513 of the second prism, D2 represents the path length of the light from the first reflecting surface 513 of the second prism to the second reflecting surface 514 of the second prism, D3 represents the path length of the light from the second reflecting surface 514 of the second prism to the exit surface 512 of the second prism, and TG2 represents the length of the optical axis on the second plate glass. In other words, the path length of the telephoto lens 1 in the first embodiment is equal to the path length of the telephoto lens 5 in the fifth embodiment. The second prism P2 has a higher refractive index, provides a longer optical path length, and not only refracts incident light for imaging, but also redirects the light so as to change the position of the image plane S13 and reduce the thickness of the lens in the direction of the optical axis of the lens group.
In the embodiment of the invention, the telephoto lens 5 is designed into a periscopic lens system (the incident light and the emergent light are vertical in different planes) by utilizing the reflecting optical surfaces of the two prisms so as to reduce the length of the incident light in the optical axis direction, namely the thickness of the portable electronic product, thereby meeting the light and thin requirements of the portable electronic product.
Sixth embodiment
Referring to fig. 15, the present embodiment provides a mobile terminal 6, including a telephoto lens (e.g., the telephoto lens 5) and an image sensor 610 in any of the above embodiments, where the image sensor 610 is disposed on an image plane of the telephoto lens 5, and is configured to receive an optical signal output by the telephoto lens 5 and form an electrical signal corresponding to the optical signal.
The image sensor 610 may be a CMOS (Complementary Metal Oxide Semiconductor) image sensor, and may also be a CCD (Charge Coupled Device) image sensor.
The total optical length TTL of the telephoto lens 5 provided by the invention can reach 39mm, which is far beyond the thickness of the mobile terminal 6, and the telephoto lens 5 is designed into a periscopic lens system by utilizing the prism reflection optical surface, so that the miniaturization requirement of the mobile terminal 6 can be met.
The mobile terminal 6 provided by this embodiment includes the telephoto lens 5 (which may also be the telephoto lens 1 or 2 or 3 or 4), and can achieve a higher optical zoom factor compared with a conventional telephoto lens, and can better meet high-definition imaging requirements of a light and thin electronic product.
The above examples only show some embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (13)
1. A telephoto lens comprising, in order from an object side to an image plane along an optical axis: the lens comprises a first light-transmitting piece, a diaphragm, a lens group and a second light-transmitting piece;
the lens group is composed of the following lenses along an optical axis from an object side to an imaging surface in sequence:
the lens comprises a first lens with positive focal power, wherein the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a convex surface or a concave surface;
the second lens is provided with a focal power, the object side surface of the second lens is a convex surface or a concave surface, and the image side surface of the second lens is a concave surface;
a third lens with a focal power, wherein the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a convex surface or a concave surface;
wherein the refractive index Nd of the material of the first light-transmitting member1>1.72 refractive index Nd of material of the second light-transmitting member2>1.78；
The telephoto lens satisfies the conditional expression:
4.0< TG2/(CT1+CT2+CT3) <7.5；
wherein CT1 denotes a center thickness of the first lens, CT2 denotes a center thickness of the second lens, CT3 denotes a center thickness of the third lens, and TG2 denotes a length of an optical axis in the second light-transmitting member;
the telephoto lens further satisfies the conditional expression: 2.425 ≤ CT6-7/( 1/R7 +1/R8) <17; and
f >28mm；
wherein, CT6-7Represents a thickness, R, of an image side surface of the second lens to an object side surface of the third lens on an optical axis7Denotes a radius of curvature, R, of an object-side surface of the third lens8A radius of curvature representing an image-side surface of the third lens; f denotes a focal length of the telephoto lens.
2. The telephoto lens according to claim 1, wherein the telephoto lens satisfies the conditional expression:
7<f/IH<15；
where f represents the focal length of the telephoto lens, and IH represents the maximum actual image height of the telephoto lens.
3. The telephoto lens according to claim 1, wherein the telephoto lens satisfies the conditional expression:
0.225< CT3-8/CT8-13<0.400；
wherein, CT3-8Represents a thickness on an optical axis from an object side surface of the first lens to an image side surface of the third lens, CT8-13Represents a thickness of an image-side surface of the third lens to an imaging plane on an optical axis.
4. The telephoto lens according to claim 1, wherein the telephoto lens satisfies the conditional expression:
0.2<CT1/CT4-7<0.82；
wherein CT1 denotes a center thickness of the first lens, CT4-7Represents a thickness on an optical axis from an image side surface of the first lens to an object side surface of the third lens.
5. The telephoto lens according to claim 1, wherein the telephoto lens satisfies the conditional expression:
-2< (R3 +R8)/(R3 -R8) <4；
wherein R is3Denotes a radius of curvature, R, of an object-side surface of the first lens8Represents a radius of curvature of an image-side surface of the third lens.
6. The telephoto lens according to claim 1, wherein the telephoto lens satisfies the conditional expression:
-0.20<φL2+φL3<-0.04；
wherein phi isL2Represents the power of the second lens, phiL3Represents the optical power of the third lens.
7. The telephoto lens according to claim 1, wherein the telephoto lens satisfies the conditional expression:
-3<(φ7-φ5)/(φ8+φ6)<0；
wherein phi is5Denotes an optical power of an object side surface of the second lens, phi6Represents an optical power of the image side surface of the second lens7Denotes an optical power of an object side surface of the third lens, phi8Representing the image-side surface of the third lensThe focal power.
8. The telephoto lens according to claim 1, wherein the telephoto lens satisfies the conditional expression:
-2<f1/f3<1；
v1≥v3；
wherein f is1Denotes the focal length of the first lens, f3Denotes the focal length, v, of the third lens1Represents the Abbe number, v, of the first lens3Represents an abbe number of the third lens.
9. The telephoto lens according to claim 1, wherein the telephoto lens satisfies the conditional expression:
0.7< f/TTL <1.2；
wherein TTL represents the total optical length of the telephoto lens.
10. The telephoto lens according to claim 1, wherein the second lens is a glass spherical lens, and at least one of the first lens and the third lens is a glass aspherical lens.
11. The telephoto lens according to claim 1, wherein the first light-transmitting member is a first plate glass, and the second light-transmitting member is a second plate glass; or, the first light-transmitting piece is a first prism, and the second light-transmitting piece is a second prism.
12. The telephoto lens according to claim 11, wherein the first prism is disposed at the light inlet of the telephoto lens, the second prism is disposed at the light outlet of the telephoto lens, the first prism turns the incident light to enter the lens group, the second prism turns the light multiple times to form the emergent light to enter the image plane, the incident light is perpendicular to the emergent light, and the second prism is an isosceles trapezoid prism.
13. A mobile terminal, comprising a telephoto lens according to any one of claims 1-12 and an image sensor disposed on an imaging surface of the telephoto lens, for receiving an optical signal output by the telephoto lens and forming an electrical signal corresponding to the optical signal.
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| JPH112760A (en) * | 1997-06-10 | 1999-01-06 | Nikon Corp | Inner focal system objective lens |
| JP3300671B2 (en) * | 1998-09-18 | 2002-07-08 | 旭光学工業株式会社 | Eyepiece system |
| JP4540389B2 (en) * | 2004-04-30 | 2010-09-08 | オリンパス株式会社 | Zoom lens and imaging device |
| US7312935B2 (en) * | 2005-06-15 | 2007-12-25 | Canon Kabushiki Kaisha | Optical system and optical apparatus having the same |
| CN103443686B (en) * | 2011-03-10 | 2015-10-14 | 富士胶片株式会社 | Variable magnification optical system and imaging device |
| CN109557643B (en) * | 2019-01-03 | 2020-06-23 | 江西联益光学有限公司 | Telephoto lens and mobile terminal |
| CN111061046B (en) * | 2019-10-29 | 2021-06-25 | 江西联创电子有限公司 | Infrared optical imaging lens and imaging device |
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