CN210348047U - Fixed focus lens - Google Patents
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- CN210348047U CN210348047U CN201921572590.XU CN201921572590U CN210348047U CN 210348047 U CN210348047 U CN 210348047U CN 201921572590 U CN201921572590 U CN 201921572590U CN 210348047 U CN210348047 U CN 210348047U
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Abstract
The utility model relates to a fixed focus lens, which comprises a first lens group (11) and a second lens group (12) which are arranged from an object side to an image side in sequence; in an object-to-image direction, the first lens group (11) includes: a first lens (111) having a negative power, a second lens (112) having a negative power, a third lens (113) having a positive power, and a fourth lens (114) having a positive power; in an object-to-image direction, the second lens group (12) includes: a fifth lens (121) having a negative power, a sixth lens (122) having a positive power, a seventh lens (123) having a negative power, an eighth lens (124) having a positive power, and a ninth lens (125) having a positive power. The utility model discloses each lens satisfies the collocation of above-mentioned focal power, and then can realize that this tight shot possess the ability to visible and near infrared spectrum synchronous imaging, can possess the burnt ratio in back of overlength.
Description
Technical Field
The utility model relates to an optics field especially relates to a tight shot.
Background
The existing infrared visible light confocal lens generally has the defects of low lens pixel, high and low temperature virtual focus, more noise points in a low-illumination environment and the like. In addition, in order to overcome the defects, most of the existing infrared and visible light confocal lenses need to adopt a plurality of lenses made of high-price anomalous dispersion and high-refractive index materials to realize confocal plane clear imaging. The lens has the defects of high design difficulty and high development cost, and is difficult to image infrared visible light with optimal resolution simultaneously.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a tight shot solves the poor problem of imaging quality.
To achieve the above objective, the present invention provides a fixed focus lens, which includes a first lens group and a second lens group sequentially arranged from an object side to an image side;
in an object-to-image-side direction, the first lens group includes: a first lens having a negative power, a second lens having a negative power, a third lens having a positive power, and a fourth lens having a positive power;
in an object-to-image direction, the second lens group includes: a fifth lens having a negative power, a sixth lens having a positive power, a seventh lens having a negative power, an eighth lens having a positive power, and a ninth lens having a positive power.
According to an aspect of the utility model, still include: a light splitter:
the first lens group, the second lens group and the optical splitter are arranged in sequence along the direction from the object side to the image side;
the beam splitter is a prism beam splitter.
According to an aspect of the present invention, the first lens group with the spacing distance between the second lens group is Lg, the total length of the prime lens is Lt, and then: Lg/Lt is more than 3 and less than 5.
According to an aspect of the present invention, the curvature radius of the object-side surface of the second lens element is R2a, and the curvature radius of the image-side surface of the first lens element is R1b, which satisfies: -2 < R2a/R1b < -1.
According to an aspect of the utility model, the focus of first battery of lens is fI, the focus of second battery of lens is fII, then satisfies: 3 < fI/fII < 11.
According to an aspect of the present invention, the focal length of the first lens group is fI, the focal length of the fourth lens group is f4, and then: 3 < fI/f4 < 10.
According to an aspect of the present invention, the focal length of the second lens group is fl, the focal length of the ninth lens group is f9, and then: 1 < f9/fII < 1.5.
According to an aspect of the present invention, the refractive index of the material of the fifth lens element to spectrum d line is Nd5, the refractive index of the material of the sixth lens element to spectrum d line is Nd6, which satisfies: 1.1 < (Nd5-1)/(Nd6-1) < 1.8.
According to an aspect of the present invention, the refractive index of the material of the seventh lens element to the spectral d-line is Nd7, and the refractive index of the material of the eighth lens element to the spectral d-line is Nd8, which satisfies 1.2 < (Nd7-1)/(Nd8-1) < 1.9.
According to an aspect of the invention, the third lens is a biconvex lens; and/or the presence of a gas in the gas,
the fifth lens is a biconcave lens; and/or the presence of a gas in the gas,
the seventh lens is a convex-concave lens.
According to an aspect of the utility model, still include: diaphragm: the first lens group, the diaphragm and the second lens group are arranged in sequence along the direction from the object side to the image side.
According to the utility model discloses a scheme makes its each lens satisfy the collocation of above-mentioned focal power, and then can realize that this tight shot possess the ability to visible and near infrared spectrum synchronous imaging, can possess the back focal ratio of overlength. Simultaneously, can make through the aforesaid setting the utility model discloses a fixed focus camera lens realizes the temperature compensation function under different ambient temperature, still has good resolution under big light ring state, reaches the effect of clear formation of image.
According to the utility model discloses a scheme, the proportional relation setting of the overall length of the spacing distance between first battery of lens and the second battery of lens and tight burnt camera lens is in above-mentioned within range, further is favorable to realizing the utility model discloses a tight ratio after the overlength of tight burnt camera lens can do the utility model discloses a back end structural design of tight burnt camera lens provides sufficient space.
According to the utility model discloses a scheme for the curvature radius's of two relative surfaces ratio between first lens and the second lens is in above-mentioned within range, and is right with improving the utility model discloses a tight shot assembles the efficiency of light favourable, and then can effectually reduce the volume of camera lens front end, not only can effectively reduce the penetrating of outside miscellaneous light, has guaranteed imaging quality, but also can effectively reduce the manufacturing cost of the utility model.
According to the utility model discloses a scheme, the focal power distribution satisfies above-mentioned condition between first battery of lens and the second battery of lens, makes the utility model discloses a lens quantity and volume distribution between the group of tight shot are more reasonable, have ensured that the focus of this tight shot is located reasonable position. Simultaneously, still be favorable to reducing the assembly tolerance of crowd's subassembly through above-mentioned setting, be favorable to improving the utility model discloses an assembly nature.
According to the utility model discloses a scheme has realized the optimal distribution to lens focal power in the first lens group, thereby makes the utility model discloses a fixed focus camera lens has reduced the overall length of first lens group when guaranteeing great angle of vision, has not only effectively improved the utility model discloses an efficiency of fixed focus camera lens transmission light has still effectively reduced the utility model discloses a manufacturing cost.
According to the utility model discloses a scheme has realized the optimal distribution to lens focal power in the second lens group, thereby makes the utility model discloses a tight shot has sufficient back burnt length, has promoted the utility model discloses a tight shot's back burnt ratio.
According to the utility model discloses a scheme can further promote the efficiency of camera lens second battery of lenses transmission light through setting up fifth lens into biconcave lens, is favorable to the correction of second lens group to the aberration.
Drawings
Fig. 1 schematically shows a structure of a fixed focus lens according to an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating a structure of a fixed focus lens according to an embodiment;
FIG. 3 is a schematic diagram illustrating an MTF curve of a visible spectrum of a fixed-focus lens according to an embodiment;
FIG. 4 is a schematic representation of an infrared spectrum MTF curve of a fixed-focus lens according to an embodiment;
fig. 5 is a view schematically showing a construction of a fixed focus lens according to a second embodiment;
FIG. 6 is a schematic diagram illustrating the visible spectrum MTF curve of a fixed-focus lens in the second embodiment;
FIG. 7 is a schematic diagram illustrating an infrared spectrum MTF curve of a fixed-focus lens according to a second embodiment;
FIG. 8 is a view schematically showing a construction of a fixed focus lens according to a third embodiment;
FIG. 9 is a schematic diagram illustrating MTF curves of the visible spectrum of a fixed-focus lens in the third embodiment;
FIG. 10 is a schematic representation of the MTF curve of the infrared spectrum of a fixed-focus lens in a third embodiment;
FIG. 11 is a view schematically showing a construction of a fixed focus lens according to a fourth embodiment;
FIG. 12 is a schematic diagram illustrating MTF curves of the visible spectrum of a fixed-focus lens in a fourth embodiment;
FIG. 13 is a schematic diagram illustrating an infrared spectrum MTF curve of a fixed-focus lens according to a fourth embodiment;
FIG. 14 is a view schematically showing a construction of a fixed focus lens according to a fifth embodiment;
FIG. 15 is a schematic diagram illustrating MTF curves of the visible spectrum of a fixed-focus lens in accordance with an embodiment V;
FIG. 16 is a schematic representation of the IR spectrum MTF curve of a fixed-focus lens in accordance with example V.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
In describing embodiments of the present invention, the terms "longitudinal," "lateral," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and other terms are used in an orientation or positional relationship shown in the associated drawings for convenience in describing the invention and for simplicity in description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be construed as limiting the invention.
The present invention will be described in detail with reference to the accompanying drawings and specific embodiments, which are not repeated herein, but the present invention is not limited to the following embodiments.
As shown in fig. 1, according to an embodiment of the present invention, a fixed focus lens includes a first lens group 11 and a second lens group 12 sequentially disposed from an object side to an image side. In this embodiment, in the object-to-image direction, the first lens group 11 includes: a first lens 111 having a negative power, a second lens 112 having a negative power, a third lens 113 having a positive power, and a fourth lens 114 having a positive power; in this embodiment, in the object-to-image direction, the second lens group 12 includes: a fifth lens 121 having a negative power, a sixth lens 122 having a positive power, a seventh lens 123 having a negative power, an eighth lens 124 having a positive power, and a ninth lens 125 having a positive power. Through the fixed-focus lens, all the lenses meet the matching of the focal power, so that the fixed-focus lens has the capability of synchronously imaging the visible spectrum and the near infrared spectrum and can have an ultra-long back focal ratio. Simultaneously, can make through the aforesaid setting the utility model discloses a fixed focus camera lens realizes the temperature compensation function under different ambient temperature, still has good resolution under big light ring state, reaches the effect of clear formation of image.
As shown in fig. 1, according to an embodiment of the present invention, the spacing distance between the first lens group 11 and the second lens group 12 is Lg, and the total length of the fixed focus lens is Lt, which satisfies: Lg/Lt is more than 3 and less than 5. In the present embodiment, the separation distance Lg between the first lens group 11 and the second lens group 12 is a distance between the vertex of the image side surface of the fourth lens 114 and the vertex of the object side surface of the fifth lens 121. The total length Lt of the prime lens refers to a distance between a vertex of the object side surface of the first lens 111 and a vertex of the imaging surface of the first imaging sensor a. Through the aforesaid setting, the proportional relation setting of the overall length of the spacing distance between first battery of lens 11 and the second battery of lens 12 and tight shot is in above-mentioned within range, further is favorable to realizing the utility model discloses a tight shot is than behind tight shot's overlength, can do the utility model discloses a tight shot's rear end structural design provides sufficient space.
As shown in fig. 1, according to an embodiment of the present invention, when the curvature radius of the object-side surface of the second lens element 112 is R2a, and the curvature radius of the image-side surface of the first lens element 111 is R1b, the following are satisfied: -2 < R2a/R1b < -1. Through setting up in the aforesaid for the curvature radius's of two relative surfaces ratio between first lens and the second lens is in above-mentioned within range, and is right and improve the utility model discloses a tight shot assembles the efficiency of light favourable, and then can effectually reduce the volume of camera lens front end, not only can effectively reduce penetrating of outside veiling glare, has guaranteed image quality, but also can effectively reduce the utility model discloses a manufacturing cost.
As shown in fig. 1, according to an embodiment of the present invention, the focal length of the first lens group 11 is fI, and the focal length of the second lens group 12 is fI, which satisfies: 3 < fI/fII < 11. Through the aforesaid setting, the focal power distribution satisfies above-mentioned condition between first battery of lens and the second battery of lens, makes the utility model discloses a lens quantity and volume distribution between the group of tight shot are more reasonable, have ensured that the focus of this tight shot is located reasonable position. Simultaneously, still be favorable to reducing the assembly tolerance of crowd's subassembly through above-mentioned setting, be favorable to improving the utility model discloses an assembly nature.
As shown in fig. 1, according to an embodiment of the present invention, the focal length of the first lens group 11 is fI, and the focal length of the fourth lens 114 is f4, which satisfies: 3 < fI/f4 < 10. Through the aforesaid setting, realized the optimal distribution to lens focal power in the first lens group, thereby make the utility model discloses a fixed focus camera lens has reduced the overall length of first lens group when guaranteeing great angle of vision, has not only effectively improved the utility model discloses an efficiency of fixed focus camera lens transmission light has still effectively reduced the utility model discloses a manufacturing cost.
As shown in fig. 1, according to an embodiment of the present invention, the focal length of the second lens group 12 is f ii, and the focal length of the ninth lens 125 is f9, which satisfies: 1 < f9/fII < 1.5. Through the aforesaid setting, realized the optimal distribution to lens focal power in the second lens group, thereby make the utility model discloses a tight shot has sufficient back burnt length, has promoted the utility model discloses a tight shot's back burnt accounts for than.
As shown in fig. 1, according to an embodiment of the present invention, the refractive index of the material of the fifth lens element 121 to the d-line of the spectrum is Nd5, and the refractive index of the material of the sixth lens element 122 to the d-line of the spectrum is Nd6, which satisfies the following conditions: 1.1 < (Nd5-1)/(Nd6-1) < 1.8. Note that the spectral d-line refers to green light in the spectrum. Through the aforesaid setting, optimize the collocation to the material of fifth lens and sixth lens to effectual correction the utility model discloses well tight shot's colour difference to be favorable to realizing the temperature compensation function of camera lens, and then to improving the utility model discloses an imaging quality is favorable.
As shown in FIG. 1, according to one embodiment of the present invention, the refractive index of the material of the seventh lens element 123 with respect to the d-line of the spectrum is Nd7, and the refractive index of the material of the eighth lens element 124 with respect to the d-line of the spectrum is Nd8, which satisfies 1.2 < (Nd7-1)/(Nd8-1) < 1.9. Through the aforesaid setting, optimize the collocation to the material of seventh lens and eighth lens, can further correct the utility model discloses a colour difference makes the utility model discloses can improve visible and near infrared spectrum homoenergetic clear imaging the utility model discloses an imaging quality.
As shown in fig. 1, according to an embodiment of the present invention, the third lens 113 is a biconvex lens. Through the arrangement, sufficient positive focal power can be provided for the first lens group, and meanwhile, chromatic aberration of the first lens group can be effectively corrected by matching the second lens, so that the imaging quality is favorably improved.
As shown in fig. 1, according to an embodiment of the present invention, the fifth lens 121 is a biconcave lens. The efficiency of lens second lens group transmission light can be further improved by setting the fifth lens into a biconcave lens, and the second lens group is favorable for correcting aberration.
As shown in fig. 1, according to an embodiment of the present invention, the seventh lens 123 is a convex-concave lens. Through the arrangement, the seventh lens in the shape is small in size, the lens space cannot be excessively occupied, the chromatic aberration of the second lens group can be effectively corrected by matching the eighth lens while the lens size is reduced, and the imaging quality is favorably improved.
As shown in fig. 1, according to an embodiment of the present invention, the fixed focus lens of the present invention further includes: and a diaphragm 13. In the present embodiment, the first lens group 11, the stop 13, and the second lens group 12 are disposed in order in the object-to-image direction, i.e., the stop 13 is located between the first lens group 11 and the second lens group 12.
As shown in fig. 2, according to an embodiment of the present invention, the fixed focus lens of the present invention further includes: a beam splitter 14. In the present embodiment, the first lens group 11, the second lens group 12, and the beam splitter 14 are disposed in order along the object-side to image-side direction, i.e., the beam splitter 14 is located at the object side of the second lens group 12. In the present embodiment, the beam splitter 14 is a prism beam splitter. In this embodiment, the beam splitter 14 is adopted, and the present invention is adopted, so that when the fixed focus lens captures an image, two imaging sensors, namely, a first imaging sensor a and a second imaging sensor B, can be correspondingly arranged. And then the images of the sensors A and B are synthesized, so that the images with wide spectral ranges can be synchronously obtained. When used for visible and near infrared spectral imaging, the imaging sensor is adjusted accordingly.
To explain the present invention in more detail, the present invention is exemplified.
According to the present invention, the numerical values of the embodiments of the fixed focus lens according to the above formulas are summarized as shown in table 1 below:
the first embodiment is as follows:
the present embodiment will be described based on the structure of the fixed focus lens shown in fig. 2. Referring to fig. 2, for convenience of description, the lens surfaces of the fixed focus lens of the present invention are numbered from the object side to the image side. Thus. S1 is an object-side surface of the first lens 111 close to the object side, and S2 is an image-side surface of the first lens 111 close to the image side; s3 is an object-side surface of the second lens element 112 close to the object side, S4 is a cemented surface of the second lens element 112 and the third lens element 113, and S5 is an image-side surface of the third lens element 113 close to the image side; s6 is an object-side surface of the fourth lens element 114, and S7 is an image-side surface of the fourth lens element 114, which is closer to the object side; s8 is a diaphragm; s9 is an object-side surface of the fifth lens element 121 close to the object side, S10 is a cemented surface of the fifth lens element 121 and the sixth lens element 122, and S11 is an image-side surface of the sixth lens element 122 close to the image side; s12 is an object-side surface of the seventh lens element 123, S13 is a cemented surface of the seventh lens element 123 and the eighth lens element 124, and S14 is an image-side surface of the eighth lens element 124, which is closer to the image side; s15 is an object-side surface of the ninth lens element 125, which is closer to the object side, and S16 is an image-side surface of the ninth lens element 125, which is closer to the image side; s17 is a side surface of the beam splitter 14 adjacent to the ninth lens 125, S18 is a side surface of the beam splitter 14 adjacent to the first imaging sensor a, and S19 is a side surface of the beam splitter 14 adjacent to the second imaging sensor B.
It should be noted that, the combined focal length of the first lens group 11 is fI, the combined focal length of the second lens group 12 is fI, the focal length of the first lens 111 is f1, the focal length of the second lens 112 is f2, the focal length of the third lens 113 is f3, the focal length of the fourth lens 114 is f4, the combined focal length of the fifth lens 121 and the sixth lens 122 is f56, the combined focal length of the seventh lens 123 and the eighth lens 124 is f78, and the focal length of the ninth lens 125 is f9, the parameters of the fixed focus lens system of the present invention are as follows:
fI＝121.159，fII＝33.155；
f1＝-32.638，f2＝-13.455，f3＝26.737，f4＝35.589，f56＝-81.431，f78＝84.019，f9＝38.904；
Lg＝27.67，Lt＝110.00；
the system parameters are: the focal length is 16.5mm, the field angle is 54.8 degrees, and the total length is 110.0 mm.
Table 2 below lists the relevant parameters of each lens in this example, including surface type, radius of curvature, thickness, refractive index of the material, and abbe number Vd of the lens, where Infinity represents Infinity:
TABLE 2
According to fig. 3 and fig. 4, the low frequency MTF value of the fixed focus lens in the visible band is not less than 80%, the medium frequency MTF value is not less than 60%, and the high frequency MTF value is not less than 40%; the low-frequency MTF value of the infrared band is not less than 70%, the medium-frequency MTF value is not less than 50%, and the high-frequency MTF value is not less than 40%. Furthermore, in the present embodiment, each aberration of the fixed focus lens can be well corrected, and has good temperature performance and low distortion characteristic, so the fixed focus lens of the present invention has good optical performance.
Example two:
the present embodiment will be described based on the structure of the fixed focus lens shown in fig. 5. Referring to fig. 5, for convenience of description, the lens surfaces of the fixed focus lens of the present invention are numbered from the object side to the image side. Thus. S1 is an object-side surface of the first lens 111 close to the object side, and S2 is an image-side surface of the first lens 111 close to the image side; s3 is an object-side surface of the second lens element 112, and S4 is an image-side surface of the second lens element 112; s5 is an object-side surface of the third lens 113 close to the object side, and S6 is an image-side surface of the third lens 113 close to the image side; s7 is an object-side surface of the fourth lens element 114, and S8 is an image-side surface of the fourth lens element 114, which is closer to the object side; s9 is a diaphragm; s10 is an object-side surface of the fifth lens element 121 close to the object side, and S11 is an image-side surface of the fifth lens element 121 close to the image side; s12 is an object-side surface of the sixth lens element 122, which is close to the object side; s13 is the image-side surface of the sixth lens element 122 close to the image side; s14 is an object-side surface of the seventh lens element 123 close to the object side, and S15 is a bonding surface between the seventh lens element 123 and the eighth lens element 124; s16 is the image-side surface of the eighth lens element 124 close to the image side; s17 is an object-side surface of the ninth lens element 125, which is closer to the object side, and S18 is an image-side surface of the ninth lens element 125, which is closer to the image side; s19 is a side surface of the beam splitter 14 adjacent to the ninth lens 125, S20 is a side surface of the beam splitter 14 adjacent to the first imaging sensor a, and S21 is a side surface of the beam splitter 14 adjacent to the second imaging sensor B.
It should be noted that, the combined focal length of the first lens group 11 is fI, the combined focal length of the second lens group 12 is fI, the focal length of the first lens 111 is f1, the focal length of the second lens 112 is f2, the focal length of the third lens 113 is f3, the focal length of the fourth lens 114 is f4, the combined focal length of the fifth lens 121 and the sixth lens 122 is f56, the combined focal length of the seventh lens 123 and the eighth lens 124 is f78, and the focal length of the ninth lens 125 is f9, the parameters of the fixed focus lens system of the present invention are as follows:
fI＝191.288，fII＝31.353；
f1＝-35.384，f2＝-14.681，f3＝31.116，f4＝37.997，f56＝-310.714，f78＝857.469，f9＝33.412；
Lg＝25.65，Lt＝107.50；
the system parameters are: the focal length is 15.6mm, the field angle is 50.4 degrees, and the total length is 107.5 mm.
Table 3 below lists the relevant parameters of each lens in this example, including surface type, radius of curvature, thickness, refractive index of the material, and abbe number Vd of the lens, where Infinity represents Infinity:
TABLE 3
According to fig. 6 and 7, the utility model discloses a tight shot low frequency MTF value at visible wave band is not less than 80%, intermediate frequency MTF value is not less than 60%, high frequency MTF value is not less than 40%; the low-frequency MTF value in the infrared band is not less than 70%, the medium-frequency MTF value is not less than 60%, and the high-frequency MTF value is not less than 40%. Furthermore, in the present embodiment, each aberration of the fixed focus lens can be well corrected, and has good temperature performance and low distortion characteristic, so the fixed focus lens of the present invention has good optical performance.
Example three:
this embodiment will be described based on the structure of the fixed focus lens shown in fig. 8. Referring to fig. 8, for convenience of description, the lens surfaces of the fixed focus lens of the present invention are numbered from the object side to the image side. Thus. S1 is an object-side surface of the first lens 111 close to the object side, and S2 is an image-side surface of the first lens 111 close to the image side; s3 is an object-side surface of the second lens element 112 close to the object side, S4 is a cemented surface of the second lens element 112 and the third lens element 113, and S5 is an image-side surface of the third lens element 113 close to the image side; s6 is an object-side surface of the fourth lens element 114, and S7 is an image-side surface of the fourth lens element 114, which is closer to the object side; s8 is a diaphragm; s9 is an object-side surface of the fifth lens element 121 close to the object side, and S10 is an image-side surface of the fifth lens element 121 close to the image side; s11 is an object-side surface of the sixth lens element 122, which is close to the object side; s12 is the image-side surface of the sixth lens element 122 close to the image side; s13 is an object-side surface of the seventh lens element 123, and S14 is an image-side surface of the seventh lens element 123; s15 is an object-side surface of the eighth lens element 124 close to the object side; s16 is the image-side surface of the eighth lens element 124 close to the image side; s17 is an object-side surface of the ninth lens element 125, which is closer to the object side, and S18 is an image-side surface of the ninth lens element 125, which is closer to the image side; s19 is a side surface of the beam splitter 14 adjacent to the ninth lens 125, S20 is a side surface of the beam splitter 14 adjacent to the first imaging sensor a, and S21 is a side surface of the beam splitter 14 adjacent to the second imaging sensor B.
It should be noted that, the combined focal length of the first lens group 11 is fI, the combined focal length of the second lens group 12 is fI, the focal length of the first lens 111 is f1, the focal length of the second lens 112 is f2, the focal length of the third lens 113 is f3, the focal length of the fourth lens 114 is f4, the combined focal length of the fifth lens 121 and the sixth lens 122 is f56, the combined focal length of the seventh lens 123 and the eighth lens 124 is f78, and the focal length of the ninth lens 125 is f9, the parameters of the fixed focus lens system of the present invention are as follows:
fI＝328.835，fII＝31.138
f1＝-30.538，f2＝-12.440，f3＝25.019，f4＝34.752，f56＝-134.365，f78＝112.510，f9＝38.401；
Lg＝25.26，Lt＝108.00；
the system parameters are: the focal length is 15.0mm, the field angle is 58.3 degrees, and the total length is 108.0 mm.
Table 4 below lists the relevant parameters of each lens in this example, including surface type, radius of curvature, thickness, refractive index of the material, and abbe number Vd of the lens, where Infinity represents Infinity:
TABLE 4
As can be seen from fig. 9 and 10, the low-frequency MTF value of the fixed-focus lens in the visible band of the present invention is not lower than 80%, the medium-frequency MTF value is not lower than 60%, and the high-frequency MTF value is not lower than 40%; the low-frequency MTF value in the infrared band is not less than 70%, the medium-frequency MTF value is not less than 50%, and the high-frequency MTF value is not less than 40%. Furthermore, in the present embodiment, each aberration of the fixed focus lens can be well corrected, and has good temperature performance and low distortion characteristic, so the fixed focus lens of the present invention has good optical performance.
Example four:
this embodiment will be described based on the structure of the fixed focus lens shown in fig. 11. Referring to fig. 11, for convenience of description, the lens surfaces of the fixed focus lens of the present invention are numbered from the object side to the image side. Thus. S1 is an object-side surface of the first lens 111 close to the object side, and S2 is an image-side surface of the first lens 111 close to the image side; s3 is an object-side surface of the second lens element 112 close to the object side; s4 is the image-side surface of the second lens element 112 close to the image side; the third lens 113 of S5 is close to the object-side surface of the object side; s6 is the image-side surface of the third lens element 113 close to the image side; s7 is an object-side surface of the fourth lens element 114, and S8 is an image-side surface of the fourth lens element 114, which is closer to the object side; s9 is a diaphragm; s10 is an object-side surface of the fifth lens element 121 close to the object side, and S11 is a bonding surface between the fifth lens element 121 and the sixth lens element 122; s12 is the image-side surface of the sixth lens element 122 close to the image side; s13 is an object-side surface of the seventh lens element 123 close to the object side; s14 is the image-side surface of the seventh lens element 123 close to the image side; s15 is an object-side surface of the eighth lens element 124 close to the object side; s16 is the image-side surface of the eighth lens element 124 close to the image side; s17 is an object-side surface of the ninth lens element 125, which is closer to the object side, and S18 is an image-side surface of the ninth lens element 125, which is closer to the image side; s19 is a side surface of the beam splitter 14 adjacent to the ninth lens 125, S20 is a side surface of the beam splitter 14 adjacent to the first imaging sensor a, and S21 is a side surface of the beam splitter 14 adjacent to the second imaging sensor B.
It should be noted that, the combined focal length of the first lens group 11 is fI, the combined focal length of the second lens group 12 is fI, the focal length of the first lens 111 is f1, the focal length of the second lens 112 is f2, the focal length of the third lens 113 is f3, the focal length of the fourth lens 114 is f4, the combined focal length of the fifth lens 121 and the sixth lens 122 is f56, the combined focal length of the seventh lens 123 and the eighth lens 124 is f78, and the focal length of the ninth lens 125 is f9, the parameters of the fixed focus lens system of the present invention are as follows:
fI＝343.999，fII＝32.446；
f1＝-36.960，f2＝-13.966，f3＝32.710，f4＝38.917，f56＝-628.564，f78＝147.230，f9＝42.846；
Lg＝24.93，Lt＝109.00；
the system parameters are: the focal length is 14.8mm, the field angle is 48.0 degrees, and the total length is 109.0 mm.
Table 5 below lists the relevant parameters of each lens in this example, including surface type, radius of curvature, thickness, refractive index of the material, and abbe number Vd of the lens, where Infinity represents Infinity:
TABLE 5
As can be seen from fig. 12 and 13, the low-frequency MTF value of the fixed-focus lens in the visible band of the present invention is not less than 85%, the medium-frequency MTF value is not less than 65%, and the high-frequency MTF value is not less than 50%; the low-frequency MTF value in the infrared band is not less than 75%, the medium-frequency MTF value is not less than 60%, and the high-frequency MTF value is not less than 50%. Furthermore, in the present embodiment, each aberration of the fixed focus lens can be well corrected, and has good temperature performance and low distortion characteristic, so the fixed focus lens of the present invention has good optical performance.
Example five:
the present embodiment will be described based on the structure of the fixed focus lens shown in fig. 14. Referring to fig. 14, for convenience of description, the lens surfaces of the fixed focus lens of the present invention are numbered from the object side to the image side. Thus. S1 is an object-side surface of the first lens 111 close to the object side, and S2 is an image-side surface of the first lens 111 close to the image side; s3 is an object-side surface of the second lens element 112 close to the object side; s4 is the image-side surface of the second lens element 112 close to the image side; the third lens 113 of S5 is close to the object-side surface of the object side; s6 is the image-side surface of the third lens element 113 close to the image side; s7 is an object-side surface of the fourth lens element 114, and S8 is an image-side surface of the fourth lens element 114, which is closer to the object side; s9 is a diaphragm; s10 is an object-side surface of the fifth lens element 121 close to the object side; s11 is the image-side surface of the fifth lens element 121 close to the image side; s12 is an object-side surface of the sixth lens element 122, which is close to the object side; s13 is the image-side surface of the sixth lens element 122 close to the image side; s14 is an object-side surface of the seventh lens element 123 close to the object side; s15 is the image-side surface of the seventh lens element 123 close to the image side; s16 is an object-side surface of the eighth lens element 124 close to the object side; s17 is the image-side surface of the eighth lens element 124 close to the image side; s18 is an object-side surface of the ninth lens element 125, which is closer to the object side, and S19 is an image-side surface of the ninth lens element 125, which is closer to the image side; s20 is a side surface of the beam splitter 14 adjacent to the ninth lens 125, S21 is a side surface of the beam splitter 14 adjacent to the first imaging sensor a, and S22 is a side surface of the beam splitter 14 adjacent to the second imaging sensor B.
It should be noted that, the combined focal length of the first lens group 11 is fI, the combined focal length of the second lens group 12 is fI, the focal length of the first lens 111 is f1, the focal length of the second lens 112 is f2, the focal length of the third lens 113 is f3, the focal length of the fourth lens 114 is f4, the combined focal length of the fifth lens 121 and the sixth lens 122 is f56, the combined focal length of the seventh lens 123 and the eighth lens 124 is f78, and the focal length of the ninth lens 125 is f9, the parameters of the fixed focus lens system of the present invention are as follows:
fI＝240.189，fII＝30.933；
f1＝-38.385，f2＝-13.375，f3＝31.684，f4＝37.826，f56＝-244.283，f78＝342.569，f9＝34.007；
Lg＝22.61，Lt＝108.00；
the system parameters are: the focal length is 14.0mm, the field angle is 51.0 degrees, and the total length is 108.0 mm.
Table 6 below lists the relevant parameters of each lens in this example, including surface type, radius of curvature, thickness, refractive index of the material, and abbe number Vd of the lens, where Infinity represents Infinity:
TABLE 6
As can be seen from fig. 12 and 13, the low-frequency MTF value of the fixed-focus lens in the visible band of the present invention is not less than 85%, the medium-frequency MTF value is not less than 60%, and the high-frequency MTF value is not less than 45%; the low-frequency MTF value in the infrared band is not less than 70%, the medium-frequency MTF value is not less than 60%, and the high-frequency MTF value is not less than 45%. Furthermore, in the present embodiment, each aberration of the fixed focus lens can be well corrected, and has good temperature performance and low distortion characteristic, so the fixed focus lens of the present invention has good optical performance.
The foregoing is merely exemplary of embodiments of the present invention and reference should be made to the apparatus and structures herein not described in detail as it is known in the art to practice the same in general equipment and general methods.
The above description is only one embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (11)
1. A prime lens is characterized by comprising a first lens group (11) and a second lens group (12) which are arranged in sequence from an object side to an image side;
in an object-to-image direction, the first lens group (11) includes: a first lens (111) having a negative power, a second lens (112) having a negative power, a third lens (113) having a positive power, and a fourth lens (114) having a positive power;
in an object-to-image direction, the second lens group (12) includes: a fifth lens (121) having a negative power, a sixth lens (122) having a positive power, a seventh lens (123) having a negative power, an eighth lens (124) having a positive power, and a ninth lens (125) having a positive power.
2. The prime lens according to claim 1, further comprising: spectrometer (14):
the first lens group (11), the second lens group (12) and the optical splitter (14) are arranged in sequence along the direction from the object side to the image side;
the light splitter (14) is a prism light splitter.
3. The prime lens according to claim 2, wherein a spacing distance between the first lens group (11) and the second lens group (12) is Lg, and a total length of the prime lens is Lt, then: Lg/Lt is more than 3 and less than 5.
4. The prime lens according to claim 3, wherein the radius of curvature of the object-side surface of the second lens (112) is R2a, and the radius of curvature of the image-side surface of the first lens (111) is R1b, such that: -2 < R2a/R1b < -1.
5. The prime lens according to claim 4, wherein the focal length of the first lens group (11) is fI, and the focal length of the second lens group (12) is fII, such that: 3 < fI/fII < 11.
6. The prime lens according to claim 4, wherein the focal length of the first lens group (11) is f, and the focal length of the fourth lens (114) is f4, such that: 3 < fI/f4 < 10.
7. The prime lens according to claim 4, wherein the focal length of the second lens group (12) is fII, and the focal length of the ninth lens (125) is f9, such that: 1 < f9/fII < 1.5.
8. The prime lens according to any one of claims 1 to 7, wherein the refractive index of the material of the fifth lens (121) to the d-line of the spectrum is Nd5, and the refractive index of the material of the sixth lens (122) to the d-line of the spectrum is Nd6, so that: 1.1 < (Nd5-1)/(Nd6-1) < 1.8.
9. The prime lens according to claim 8, wherein the refractive index of the material of the seventh lens element (123) to the d-line of the spectrum is Nd7, and the refractive index of the material of the eighth lens element (124) to the d-line of the spectrum is Nd8, so that 1.2 < (Nd7-1)/(Nd8-1) < 1.9 is satisfied.
10. The prime lens according to any one of claims 1 to 7 and 9, wherein the third lens (113) is a biconvex lens; and/or the presence of a gas in the gas,
the fifth lens (121) is a biconcave lens; and/or the presence of a gas in the gas,
the seventh lens (123) is a convex-concave lens.
11. The prime lens according to claim 1, further comprising: diaphragm (13): the first lens group (11), the diaphragm (13) and the second lens group (12) are arranged in sequence along the direction from the object side to the image side.
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| CN110471172A (en) * | 2019-09-20 | 2019-11-19 | 舜宇光学(中山)有限公司 | A kind of tight shot |
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