CN108267845B - Athermalized large-aperture objective optical system - Google Patents
Athermalized large-aperture objective optical system Download PDFInfo
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- CN108267845B CN108267845B CN201810230469.2A CN201810230469A CN108267845B CN 108267845 B CN108267845 B CN 108267845B CN 201810230469 A CN201810230469 A CN 201810230469A CN 108267845 B CN108267845 B CN 108267845B
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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
- G02B13/005—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having spherical lenses only
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
- G02B7/021—Mountings, adjusting means, or light-tight connections, for optical elements for lenses for more than one lens
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
- G02B7/025—Mountings, adjusting means, or light-tight connections, for optical elements for lenses using glue
Abstract
An athermalized large-aperture objective optical system sequentially comprises, from an object plane to an image plane: the lens comprises a first lens group with negative focal power, a second lens group with positive focal power, a diaphragm, a third lens group with positive focal power and a fourth lens group with positive focal power. The invention adopts three groups of cemented lenses and a non-thermal-aberration design, can realize temperature compensation, effectively inhibit ghost images, and effectively correct aberrations such as spherical aberration and chromatic aberration while clearly imaging under a low-illumination condition.
Description
Technical Field
The invention relates to a technology in the field of optical devices, in particular to a athermalized large-aperture objective optical system.
Background
The existing large-aperture lens considers whether the imaging is clear under the condition of low illumination of a visible light wave band and also considers whether the imaging can be clear all the time when the temperature changes. The working temperature of most of the objective lenses is limited by the thermalization phenomenon, so that most of the objective lenses cannot be used in the environment with complicated temperature change. In addition, the large-aperture objective lens is more suitable for the case of poor lighting conditions, and if a brighter light source appears suddenly in the picture, the slight ghost image generated at this time is very obvious in the whole picture. In the prior art, almost all objective lenses have defects in ghost processing, and have obvious ghosts.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides an athermal large-aperture objective optical system, which adopts three groups of cemented lenses and an athermal design, can realize temperature compensation, effectively inhibit ghost images, and effectively correct aberrations such as spherical aberration and chromatic aberration while realizing clear imaging under a low-illumination condition.
The invention is realized by the following technical scheme:
the invention comprises the following components in sequence from an object plane to an image plane: the lens comprises a first lens group with negative focal power, a second lens group with positive focal power, a diaphragm, a third lens group with positive focal power and a fourth lens group with positive focal power.
The first lens group includes: the optical power of the lens is positive, the focal power of the lens is negative, the focal power of the lens is positive, the third lens and the focal power of the lens are negative, wherein: the third lens and the fourth lens are combined into a cemented lens, so that spherical aberration generated by the system can be effectively inhibited; the second lens uses a lens with negative focal power, controls the focal length range of the lens, and uses a material with negative temperature coefficient to improve the temperature compensation effect; meanwhile, the curvature radius of the second surface of the second lens is positive, so that the generation of ghost can be effectively avoided, and the possibility of generating ghost is reduced to a great extent.
The front surface of the first lens is preferably plated with a waterproof film.
The second lens group includes: a fifth lens of a biconvex structure with positive focal power and a sixth lens with negative focal power, wherein: the fifth lens is made of a material with a large refractive index, so that coma aberration caused by insufficient focal power can be effectively corrected, and ghost can be effectively inhibited and avoided by using a biconvex structure in the optical system; the sixth lens adopts a material with a negative temperature coefficient, and compensates for the deviation of the optimal imaging surface caused by temperature.
The diaphragm is a fixed independent diaphragm or is arranged on the second surface of the sixth lens.
The third lens group includes: the seventh lens with negative focal power and the eighth lens with positive focal power are combined into a cemented lens, and the two lenses are cemented by the two lenses with low Abbe number and high Abbe number, so that spherical aberration and chromatic aberration generated by other lenses are effectively inhibited, and the imaging quality is improved.
The fourth lens group includes: the optical power of the ninth lens is positive, the optical power of the tenth lens and the eleventh lens is negative after the ninth lens and the eleventh lens are bonded, and the optical power of the twelfth lens is positive, so that spherical aberration and chromatic aberration generated by the system are effectively inhibited.
The numerical aperture of the optical system is (0.98,1.03), the ratio of the effective focal length to the total optical length is (5.55,5.65), the ratio of the effective focal length to the optical back focal length is (6.84,7.08), the ratio of the half-image height to the total optical length is (0.091,0.094), and the half-field angle is (28 degrees, 28.5 degrees).
The effective light passing diameter of the front surface of the first lens in the first lens group is less than 35mm, and the focal length of the first lens is (24, 31); the second lens satisfies: a refractive index of (1.4,1.5), an Abbe number of (81, + ∞), a focal length of (-15, -10), and a temperature shift of (-infinity, -6) at 20 ℃ to 40 ℃; the third lens combined into the cemented lens satisfies: the refractive index is (1.7,1.8), the Abbe number is (49,54), and the fourth lens satisfies: the refractive index is (1.92,1.95), the abbe number is (17,24), and the absolute value of the focal length ratio of the third lens and the fourth lens is (0.9,1.3), and the absolute value of the refractive index of the glue and the lens is (50, 75).
The fifth lens in the second lens group satisfies: a refractive index of (1.90,1.95), an abbe number of (20,36), and a sixth lens satisfying: a refractive index of (1.4,1.65), an Abbe number of (63, + ∞), and a temperature shift amount at 20 ℃ to 40 ℃ of (- ∞ -2).
Technical effects
Compared with the prior art, the invention uses three groups of cemented lenses to maximally correct the spherical aberration and chromatic aberration of the optical system in a small space of 40mm x 40mm, thereby ensuring good imaging quality; several lenses with negative focal power and negative temperature coefficient are used, so that the optical system can form clear images under the conditions of high temperature and low temperature; by controlling the surface shape of the individual lens, the optical system is ensured to have no ghost image.
Drawings
FIG. 1 is a schematic view of an optical structure of example 1 of the present invention;
FIG. 2 is a diagram showing aberrations with respect to the d-line in example 1 of the present invention;
fig. 3 is a coma diagram with respect to d-line of embodiment 1 of the present invention;
FIGS. 4a and 4b are high temperature, low temperature MTFs for example 1 of the present invention;
FIG. 5 is a ghost simulation diagram according to embodiment 1 of the present invention;
FIG. 6 is a schematic view of the optical structure of embodiment 2 of the present invention;
FIG. 7 is a graph showing various aberrations with respect to the d-line in example 2 of the present invention;
fig. 8 is a coma diagram with respect to d-line of embodiment 2 of the present invention;
FIGS. 9a and 9b are high temperature, low temperature MTFs for example 2 of the present invention;
FIG. 10 is a ghost simulation diagram in accordance with embodiment 2 of the present invention;
in the figure: first to fourth lens groups A to D, first to twelfth lenses L1 to L12, first to twenty-second lens surfaces S1 to S22, a diaphragm STP, a cover glass DC, a filter lens IRCF, and an image plane IMG.
Detailed Description
Example 1
As shown in fig. 1, the present embodiment includes, in order from the object plane to the image plane: the lens comprises a first lens group A with negative focal power, a second lens group B with positive focal power, a third lens group C with positive focal power and a fourth lens group D with positive focal power.
The first lens group A includes: a first lens L1 with positive optical power, a second lens L2 with negative optical power, a third lens L3 with positive optical power, and a fourth lens L4 with negative optical power, wherein: the third lens L3 and the fourth lens L4 are combined into a cemented lens.
The second lens group B includes: a fifth lens L5 with positive optical power and a sixth lens L6 with negative optical power.
The stop STP in this embodiment is a fixed stop disposed on the second surface of the sixth lens L6.
The third lens group C includes: the seventh lens L7 with negative focal power and the eighth lens L8 with positive focal power are combined into a cemented lens.
The fourth lens group D includes: a ninth lens L9 having positive power, tenth and eleventh lenses L10 and L11 having negative power after the cemented, and a twelfth lens L12 having positive power.
In the optical system of the present embodiment, the numerical aperture satisfies: 1.03> Fno > 0.98; the focal length satisfies: 5.65> EFL/TTL >5.55, 7.08> EFL/BFL >6.84, wherein: EFL is the focal length of the optical system, BFL is the optical back focus of the optical system, TTL is the optical total length of the optical system; the size satisfies: 0.094> H/TTL >0.091 wherein: h is the half-image height of the optical system, and TTL is the total optical length of the optical system; the visual angle satisfies: 28.5 ° > HFOV >28 °, wherein: the HFOV is a half field angle of the optical system.
Parameters such as the refractive index Nd, the abbe number Vd, the focal length f, and the temperature shift α between 20 ℃ and 40 ℃ of each lens in the optical system of this embodiment are specifically as follows:
the numerical aperture Fno of the optical system is 1.025;
the effective light-passing diameter of the front surface S1 of the first lens L1 is
Having a focal length f1And satisfies the following conditions:
f1＝24.699；
the second lens L2 satisfies: nd (neodymium)2＝1.496，Vd2＝81.6，f2＝-11.7833，α2＝-6.2；
The third lens L3 and the fourth lens L4 which are combined into a cemented lens satisfy the following conditions: nd (neodymium)3＝1.7725，Vd3＝49.6，Nd4＝1.921，Vd4＝23.9，|f3/f4|＝0.939，|f34|＝73.7563；
The fifth lens L5 satisfies: vd5＝35.2；
The sixth lens L6 satisfies: nd (neodymium)6＝1.617，Vd6＝63.3，α6＝-2.3；
The seventh lens L7 and the eighth lens L8 combined into a cemented lens satisfy: nd (neodymium)8＝1.496，Vd8＝81.6，α8＝-6.2；
The ninth lens L9 satisfies: nd (neodymium)9＝1.91，Vd9＝35.2；
The tenth lens L10 and the eleventh lens L11 with negative focal power satisfy the following conditions: nd (neodymium)11＝1.496，Vd11＝81.6，α11＝-6.2；
The twelfth lens L12 satisfies: nd (neodymium)12＝1.91，Vd12＝35.2。
Table 1 shows the structural parameters of the optical system of the present embodiment
TABLE 1
| Surface numbering | Radius of curvature of surface | Thickness of | Refractive index of material | Abbe number of material |
| S1 | 25.965 | 3.06 | 1.804 | 39.6 |
| S2 | -80.22 | 0.11 | ||
| S3 | 238.251 | 0.85 | 1.496 | 81.6 |
| S4 | 5.709 | 4.09 | ||
| S5 | -7.609 | 4.75 | 1.7725 | 49.6 |
| S6 | -6.173 | 0.85 | 1.921 | 23.9 |
| S7 | -10.334 | 0.1 | ||
| S8 | 24.296 | 2.27 | 1.91 | 35.2 |
| S9 | -24.296 | 0.36 | ||
| S10 | -16.983 | 0.85 | 1.617 | 63.3 |
| STP | -39.343 | 6.16 | ||
| S12 | 39.178 | 0.75 | 1.922 | 20.8 |
| S13 | 8.967 | 3.27 | 1.496 | 81.6 |
| S14 | -16.009 | 0.1 | ||
| S15 | 10.243 | 2.46 | 1.91 | 35.2 |
| S16 | -30.867 | 0.5 | ||
| S17 | -28.419 | 0.75 | 1.752 | 25 |
| S18 | 16.677 | 0.75 | 1.496 | 81.6 |
| S19 | 6.057 | 0.64 | ||
| S20 | 9.106 | 2.33 | 1.91 | 35.2 |
| S21 | 31.373 | 0.43 | ||
| S22 | Infinite number of elements | 0.5 | 1.516 | 64.1 |
| S23 | Infinite number of elements | 1.52 | ||
| S24 | Infinite number of elements | 0.55 | 1.516 | 64.1 |
| S25 | Infinite number of |
1 | ||
| IMG | Infinite number of |
0 |
As shown in fig. 2, the aberration diagrams of the lens of example 1 with respect to the d-line (λ 587.56nm) are shown. S, M in the astigmatism diagram indicate aberrations corresponding to sagittal and meridional image planes, respectively
As shown in fig. 3, is a coma diagram of the lens of embodiment 1.
As shown in fig. 4a and 4b, MTF graphs at high and low temperatures of the lens of embodiment 1 are shown.
Fig. 5 is a ghost simulation diagram of the lens system according to embodiment 1.
Compared with the prior art, the optical system integrates the advantages of large aperture, no thermalization and no ghost image, and has good imaging quality.
Example 2
The difference between this embodiment and embodiment 1 is that the diaphragm STP in this embodiment is a fixed independent diaphragm.
The specific parameters are set as follows:
Fno＝0.985；
f1＝30.4656；
Nd2＝1.437，Vd2＝95.1，f2＝-13.2494，α2＝-6.3；
Nd3＝1.713，Vd3＝53.9，Nd4＝1.945，Vd4＝17.9，|f3/f4|＝1.288，|f34|＝54.2344；
Nd5＝1.921，Vd5＝23.9；
Nd6＝1.437，Vd6＝95.1，α6＝-6.3；
Nd8＝1.496，Vd8＝81.6，α8＝-6.2；
Nd9＝1.91，Vd9＝35.2；
Nd11＝1.496，Vd11＝81.6，α11＝-6.2；
Nd12＝1.91，Vd12＝35.2；
table 2 shows the structural parameters of the optical system of this embodiment
TABLE 2
As shown in fig. 7, the aberration diagrams of the lens of example 2 are each aberration diagrams with respect to the d-line (λ 587.56 nm). S, M in the astigmatism diagram indicate aberrations corresponding to sagittal and meridional image planes, respectively
As shown in fig. 8, is a coma aberration diagram of the lens of embodiment 2.
As shown in fig. 9a and 9b, MTF graphs at high and low temperatures of the lens of embodiment 2 are shown.
Fig. 10 is a ghost simulation diagram of the lens system according to embodiment 2.
Compared with the prior art, the optical system integrates the advantages of large aperture, no thermalization and no ghost image, and has good imaging quality.
The foregoing embodiments may be modified in many different ways by those skilled in the art without departing from the spirit and scope of the invention, which is defined by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims (6)
1. An athermalized large-aperture objective optical system, comprising in order from an object plane to an image plane: the optical power is the first lens group of negative, the focal power is the second lens group of positive, diaphragm, the focal power is the third lens group of positive, the focal power is the fourth lens group of positive, wherein: the first lens group includes: the optical system comprises three groups of cemented lenses, a second lens and a sixth lens, wherein the cemented lenses are made of materials with negative temperature coefficients, the radius of curvature of the second surface of the second lens is positive, the fifth lens is of a double convex structure with positive focal power, the sixth lens is of a negative focal power, and the sixth lens is made of materials with negative temperature coefficients;
the first lens group includes: the lens comprises a first lens with positive focal power, a second lens with negative focal power, a third lens with positive focal power and a fourth lens with negative focal power, wherein the third lens and the fourth lens are combined into a cemented lens;
the second lens group includes: a fifth lens with positive focal power and a sixth lens with negative focal power;
the third lens group includes: the seventh lens with negative focal power and the eighth lens with positive focal power are combined into a cemented lens;
the fourth lens group includes: the optical power of the optical lens assembly is positive, the optical power of the optical lens assembly is negative, the optical power of the optical lens assembly is positive, and the optical power of the optical lens assembly is positive;
the first lens element is a biconvex lens, the second lens element has a convex object-side surface and a concave image-side surface, the third lens element and the fourth lens element have concave object-side surfaces and convex image-side surfaces, the fifth lens element is a biconvex lens, the sixth lens element has a concave object-side surface and a convex image-side surface, the seventh lens element has a convex object-side surface and a concave image-side surface, the eighth lens element and the ninth lens element are biconvex lenses, the tenth lens element is a biconcave lens, the eleventh lens element and the twelfth lens element have convex object-side surfaces, and the image-side surfaces are concave surfaces;
the numerical aperture of the athermalized large-aperture objective lens is (0.98, 1.03).
2. The athermalized large-aperture objective optical system of claim 1, wherein said front surface of said first lens is coated with a water-resistant film.
3. The athermalized large-aperture objective optical system of claim 1, wherein said stop is a fixed separate stop or is disposed on the second surface of the sixth lens element.
4. The athermalized large-aperture objective optical system of claim 1, wherein the front surface of the first lens of said first lens group has an effective clear diameter of less than 35mm and a focal length of (24, 31); the second lens satisfies: a refractive index of (1.4,1.5), an Abbe number of (81, + ∞), a focal length of (-15, -10), and a temperature shift of (-infinity, -6) at 20 ℃ to 40 ℃; the third lens combined into the cemented lens satisfies: the refractive index is (1.7,1.8), the Abbe number is (49,54), and the fourth lens satisfies: the refractive index is (1.92,1.95), the abbe number is (17,24), and the absolute value of the focal length ratio of the third lens and the fourth lens is (0.9,1.3), and the absolute value of the refractive index of the glue and the lens is (50, 75).
5. The athermalized large-aperture objective optical system of claim 1, wherein the fifth lens of the second lens group satisfies: a refractive index of (1.90,1.95), an abbe number of (20,36), and a sixth lens satisfying: a refractive index of (1.4,1.65), an Abbe number of (63, + ∞), and a temperature shift amount at 20 ℃ to 40 ℃ of (- ∞ -2).
6. The athermalized large-aperture objective optical system according to any of claims 1 to 5, wherein the numerical aperture of the optical system is (0.98,1.03), the ratio of the effective focal length to the total optical length is (5.55,5.65), the ratio of the effective focal length to the optical back focus is (6.84,7.08), the ratio of the half-image height to the total optical length is (0.091,0.094), and the half field angle is (28 °,28.5 °).
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| CN110471243A (en) * | 2019-08-21 | 2019-11-19 | 宁波锦辉光学科技有限公司 | A kind of high brightness and resolution is big apart from automobile LOGO projection optical system |
| CN114326071B (en) * | 2021-12-14 | 2024-03-19 | 宁波永新光学股份有限公司 | 20-time large numerical aperture flat field apochromatic microscope objective lens |
| CN116009222B (en) * | 2023-02-27 | 2023-06-20 | 杭州光铭光电科技有限公司 | 4K double telecentric machine vision optical imaging system |
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Address after: 314000 No.188, Taojing Road, Gaozhao street, Xiuzhou District, Jiaxing City, Zhejiang Province Patentee after: Jiaxing Zhongrun Optical Technology Co.,Ltd. Address before: 314000 Room 2F201-6, Building 6, Jiaxing Photovoltaic Science Park, 1288 Kanghe Road, Xiuzhou District, Jiaxing City, Zhejiang Province Patentee before: JIAXING ZHONGRUN OPTICAL SCIENCE AND TECHNOLOGY Co.,Ltd. |