CN118311760A - 2-Fold micro objective lens with large numerical aperture and wide view field - Google Patents
2-Fold micro objective lens with large numerical aperture and wide view field Download PDFInfo
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- CN118311760A CN118311760A CN202410389728.1A CN202410389728A CN118311760A CN 118311760 A CN118311760 A CN 118311760A CN 202410389728 A CN202410389728 A CN 202410389728A CN 118311760 A CN118311760 A CN 118311760A
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- 238000003384 imaging method Methods 0.000 description 8
- 238000005259 measurement Methods 0.000 description 5
- 238000005286 illumination Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000005452 bending Methods 0.000 description 2
- 210000001747 pupil Anatomy 0.000 description 2
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Abstract
The invention discloses a 2-time micro-objective lens with a large numerical aperture and a wide view field, which is applied to a visible light wave band of 430-720nm, and comprises a first group of lens groups G1 with positive refractive power, a second group of lens groups G2 with negative refractive power and a third group of lens groups G3 with positive refractive power, wherein the first group of lens groups G1 with positive refractive power, the second group of lens groups G2 with negative refractive power and the third group of lens groups G3 with positive refractive power are distributed in sequence from an object space to an image space; wherein the diaphragm of the microscope objective is positioned on the right side of the third lens group G3 and is arranged close to the image side. The microscope objective has the visual field number of less than or equal to 35mm and the maximum numerical aperture of less than or equal to 0.11, has flat field and apochromatic performance, and solves the problem that the existing low-power microscope objective is difficult to have the optical performances of wide visual field, high resolution, flat field, apochromatic performance and the like in design.
Description
Technical Field
The invention relates to the technical field of low-power micro-objective imaging, in particular to a 2-power micro-objective with a large numerical aperture and a wide view field.
Background
Compared with a high-power objective lens, the low-power micro-objective lens has a larger visual field range and a longer working distance, so that the high-power micro-objective lens has the advantage that a large-range image sample can be observed in one amplification, and the measurement of the sample size, the analysis of a large-size image and the like are easier. Therefore, low power micro objective lens is widely used in industry, biology, material science and other fields. However, with the increasing demand for low magnification micro objective lens with wide field of view and high resolution, besides increasing the difficulty of lens design, the problems of apochromatic aberration and pupil aberration are also caused. Therefore, a low magnification micro objective lens which has a wide field of view and high resolution and can realize apochromatic aberration in a flat field is needed.
Disclosure of Invention
The invention aims to: the invention aims to provide a 2-time micro objective lens which has a wide field of view and high resolution and can realize flat field apochromatic aberration.
The technical scheme is as follows: in order to achieve the above objective, the 2-fold micro objective lens with large numerical aperture and wide field of view of the present invention is applied in the visible light band of 430-720nm, and comprises a first group of lens groups G1 with positive refractive power, a second group of lens groups G2 with negative refractive power and a third group of lens groups G3 with positive refractive power, which are distributed from the object side to the image side in sequence; wherein, the diaphragm of the micro objective lens is positioned on the right side of the third lens group G3 and is arranged close to the image side; the number of the field of view of the microscope objective is less than or equal to 35mm, the maximum numerical aperture is less than or equal to 0.11, and the microscope objective has flat field and apochromatic performance.
Wherein, the working distance (the distance from the object side of the microscope object to the center of the R1 surface of the L1 lens) of the microscope objective is 35-37mm, and the focal length is 100mm.
Wherein the following relationship is satisfied between the focal length f1 of the first lens group G1, the focal length f2 of the second lens group G2, the focal length f3 of the third lens group G3, and the 2-fold micro objective lens focal length f:
0.3≤|f1/f|≤0.85；
0.1≤|f2/f|≤0.5；
0.05≤|f3/f|≤0.6。
the first lens group G1 includes a first lens L1, and the first lens L1 is a biconvex lens with positive focal power.
Wherein the d-ray refractive index n1 and the abbe number v1 of the first lens L1 satisfy the following relationships, respectively: n1 is more than or equal to 1.8 and less than or equal to 2, v1 is more than or equal to 20 and less than or equal to 30.
The second lens group G2 includes a second lens L2, and the second lens L2 is a biconcave lens with negative focal power.
Wherein the d-ray refractive index n2 and abbe number v2 of the second lens L2 satisfy the following relationships, respectively: n2 is more than or equal to 1.6 and less than or equal to 1.8, v2 is more than or equal to 25 and less than or equal to 35.
The third lens group G3 includes a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8, where the third lens L3, the fourth lens L4, and the eighth lens L8 are all biconvex lenses, the seventh lens L7 is a biconcave lens, and the fifth lens L5 and the sixth lens L6 form a biconcave lens; the third lens L3, the fourth lens L4, the fifth lens L5, and the eighth lens L8 are positive focal power lenses, and the sixth lens L6 and the seventh lens L7 are negative focal power lenses.
Wherein the d-ray refractive index and abbe number of the third lens L3 are n3 and v3, respectively, the d-ray refractive index and abbe number of the fourth lens L4 are n4 and v4, respectively, the d-ray refractive index and abbe number of the fifth lens L5 are n5 and v5, respectively, the d-ray refractive index and abbe number of the sixth lens L6 are n6 and v6, respectively, the d-ray refractive index and abbe number of the seventh lens L7 are n7 and v7, respectively, the d-ray refractive index and abbe number of the eighth lens L8 are n8 and v8, respectively, and the following relationships are satisfied:
1.8≤n1≤2,20≤v1≤30；
1.6≤n2≤1.8,25≤v2≤35；
1.4≤n3≤1.6,77≤v3≤87；
1.6≤n4≤1.8,40≤v4≤50；
1.4≤n5≤1.6,77≤v5≤87；
1.6≤n6≤1.8,28≤v6≤38；
1.6≤n7≤1.8,28≤v7≤38；
1.8≤n8≤2,20≤v8≤30。
the beneficial effects are that: the invention has the following advantages: 1. according to the invention, through optimizing the relation between each lens group and the focal length f of the 2 times micro objective lens, the refractive power of the micro objective lens on visible light is ensured to be moderate, so that when imaging is performed under the conditions that NA is less than or equal to 0.11 and the number of fields of view is less than or equal to 35, not only can the curvature of field and the curvature of image surface be corrected, but also the illumination uniformity and telecentricity of the fields of view can be maintained;
2. The 2-fold micro objective lens has a large numerical aperture and a wide view field, can observe a larger sample area when in use, has higher resolution, and can meet various microscopic observation requirements;
3. according to the invention, the apochromatic function of the microscope objective is realized by matching the refractive index and the Abbe number of each lens material, so that the imaging quality is improved.
Drawings
FIG. 1 is a schematic diagram of a 2-fold micro objective lens structure;
FIG. 2 is a graph of field curvature and distortion of a 2-fold micromirror objective;
FIG. 3 is a graph of transfer function of a 2-fold microobjective;
FIG. 4 is a dot column diagram of a 2-fold microobjective;
FIG. 5 is a longitudinal chromatic aberration diagram of a 2-fold microobjective.
Detailed Description
The technical scheme of the present invention will be described in detail with reference to the following examples and the accompanying drawings.
The numerical aperture of the objective lens is used for measuring the light collecting capacity, and the larger the numerical aperture is, the more light rays are collected by the objective lens, and the higher the resolution is. For the image space with the same size, the objective lens with low multiple corresponds to the large object space field, and the objective lens with high multiple corresponds to the small object space field. Number of fields = field of view of the objective lens.
As shown in fig. 1, the 2-fold micro objective lens with large numerical aperture and wide field of view according to the present invention includes a first group lens group G1 with positive refractive power, a second group lens group G2 with negative refractive power, and a third group lens group G3 with positive refractive power, which are sequentially distributed from an object side to an image side. Wherein the diaphragm of the microscope objective is positioned on the right side of the third lens group G3 and is close to the image side.
Wherein the following relationship is satisfied between a focal length f1 of the first lens group G1, a focal length f2 of the second lens group G2, a focal length f3 of the third lens group G3, and a focal length f of the micro objective lens:
0.3≤|f1/f|≤0.85；
0.1≤|f2/f|≤0.5；
0.05≤|f3/f|≤0.6。
Specifically, the first lens group G1 includes a first lens L1. The first lens L1 is a biconvex lens, and its d-ray refractive index n1 and abbe number v1 satisfy the following relationships, respectively: n1 is more than or equal to 1.8 and less than or equal to 2, v1 is more than or equal to 20 and less than or equal to 30.
The second lens group G2 includes a second lens L2. The second lens L2 is a biconcave lens, and its d-light (587 nm) refractive index n2 and abbe number v2 satisfy the following relationships, respectively: n2 is more than or equal to 1.6 and less than or equal to 1.8, v2 is more than or equal to 25 and less than or equal to 35.
The third lens group G3 includes a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8. The third lens L3, the fourth lens L4 and the eighth lens L8 are all biconvex lenses, the seventh lens L7 is a biconcave lens, and the fifth lens L5 and the sixth lens L6 form a biconcave negative lens. The third lens L3, the fourth lens L4, the fifth lens L5, and the eighth lens L8 are positive focal power lenses, and the sixth lens L6 and the seventh lens L7 are negative focal power lenses.
The d-ray refractive index and abbe number of the third lens L3 are n3 and v3, respectively, the d-ray refractive index and abbe number of the fourth lens L4 are n4 and v4, respectively, the d-ray refractive index and abbe number of the fifth lens L5 are n5 and v5, respectively, the d-ray refractive index and abbe number of the sixth lens L6 are n6 and v6, respectively, the d-ray refractive index and abbe number of the seventh lens L7 are n7 and v7, respectively, the d-ray refractive index and abbe number of the eighth lens L8 are n8 and v8, respectively, and the following relationships are satisfied:
1.8≤n1≤2,20≤v1≤30；
1.6≤n2≤1.8,25≤v2≤35；
1.4≤n3≤1.6,77≤v3≤87；
1.6≤n4≤1.8,40≤v4≤50；
1.4≤n5≤1.6,77≤v5≤87；
1.6≤n6≤1.8,28≤v6≤38；
1.6≤n7≤1.8,28≤v7≤38；
1.8≤n8≤2,20≤v8≤30。
In an optical system requiring high-precision imaging, such as a microscope objective, the focal length configuration of each lens group has a critical influence on the imaging quality of the whole system, specifically: in the relationship satisfied between the focal lengths of the three lens groups and the focal length f of the microscope objective lens, if |f1/f| <0.3, |f2/f| <0.1, |f3/f| <0.05, that is, the focal length setting of each lens group is too short, the refractive power of the first lens group G1, the second lens group G2, or the 3 rd lens group G3 becomes too strong, the light beam is excessively converged when passing through these lens groups, resulting in an increase in field curvature occurring at the time of imaging, and bending of the image surface also occurs, which affects the accuracy of imaging, especially when high-precision measurement is performed, the field curvature and the image surface curvature may introduce errors. If the focal length of each lens group is too long, the refractive power of the first lens group G1, the second lens group G2 or the 3 rd lens group G3 becomes too weak, telecentricity of the object (i.e. the vergence change when the light beam reaches the image plane in the whole view field range) is difficult to maintain, so that illumination uniformity in the view field is reduced, and as applied to high-precision measurement technologies such as interferometry, the illumination uniformity can affect the uniformity of interference fringes, thereby seriously affecting the measurement accuracy.
In order to ensure that the 2 times micro-objective lens can realize high-precision imaging and measurement under the condition that NA is less than or equal to 0.11 (high resolution) and the number of fields of view is 35 (wide field of view), the correlation between each lens group and the focal length f of the micro-objective lens needs to be optimized, so that the moderate refractive power of the micro-objective lens is ensured, field curvature and image surface bending are avoided, and the illumination uniformity and telecentricity of the fields of view are maintained; meanwhile, the refractive index and the Abbe number of the lens are required to be distributed in the limited range, and the apochromatic function of the microscope objective is realized through matching of the refractive index and the Abbe number.
In this embodiment, the design schemes with better parameters such as curvature, thickness, interval, material and the like of each lens surface of the 2-fold micro objective lens are listed, and specifically shown in table 1:
table 1:2 times of microscope objective lens parameters
In this example, the 2-fold micro objective lens designed based on the above lens parameters has optical properties as shown in table 2:
Table 2:2 times of micro objective parameters
| 2 Times of micro objective parameters | Index (I) |
| Focal length f [ mm ] | 100 |
| Maximum numerical aperture | 0.11 |
| Maximum number of fields of view | 35 |
| Working distance [ mm ] | ＞36 |
| Distortion [% ] | ＜0.2 |
| Telecentricity [ ° ] | <0.3 |
。
As shown in fig. 2-5, the optical performance test curves of the 2-fold microobjective lens designed in this example are shown.
As can be seen from FIG. 2, the field curvature range of the microscope objective is + -13.8 μm, which is smaller than + -60 μm of the flat field design standard, so that the flat field function is realized, and the distortion is less than 0.2%, and is well corrected.
As can be seen from fig. 3 and 4, the diameter of the dispersed spot of the microscope objective lens is within the Airy spot, and reaches the diffraction limit. Meanwhile, the 2-fold micro objective lens is compared with the existing Sanfeng 2X standard objective lens, the numerical aperture NA of the invention reaches 0.11, and the other side is 0.055. The performance of the 2-fold micro objective reaches the diffraction limit under the condition that NA is less than or equal to 0.11, which proves that the micro objective has high resolution.
As can be seen from FIG. 5, the longitudinal aberration of the microscope objective is-0.012 mm-0.016 mm, which is less than + -0.024 mm, which indicates that the pupil aberration and chromatic aberration of the objective are well corrected, and the apochromatic function is realized by selecting, optimizing and matching the refractive index and Abbe number of the lens.
Claims (9)
1. The 2-fold micro objective lens with a large numerical aperture and a wide field of view is applied to a visible light wave band of 430-720nm, and is characterized by comprising a first group of lens groups G1 with positive refractive power, a second group of lens groups G2 with negative refractive power and a third group of lens groups G3 with positive refractive power, wherein the first group of lens groups G1 with positive refractive power, the second group of lens groups G2 with negative refractive power and the third group of lens groups G3 with positive refractive power are distributed in sequence from an object space to an image space; wherein, the diaphragm of the micro objective lens is positioned on the right side of the third lens group G3 and is arranged close to the image side; the number of the field of view of the microscope objective is less than or equal to 35mm, the maximum numerical aperture is less than or equal to 0.11, and the microscope objective has flat field and apochromatic performance.
2. 2-Fold microobjective with large numerical aperture and wide field of view according to claim 1, characterized in that the working distance of the microobjective is 35-37mm and the focal length is 100mm.
3. The 2-fold micro objective lens with a large numerical aperture and a wide field of view according to claim 1, wherein the following relationship is satisfied between a focal length f1 of the first lens group G1, a focal length f2 of the second lens group G2, a focal length f3 of the third lens group G3, and a 2-fold micro objective lens focal length f:
0.3≤|f1/f|≤0.85；
0.1≤|f2/f|≤0.5；
0.05≤|f3/f|≤0.6。
4. 2-fold micro objective with large numerical aperture and wide field of view according to claim 1, characterized in that the first lens group G1 comprises a first lens L1, the first lens L1 being a biconvex lens of positive power.
5. 2-Fold microobjective with large numerical aperture and wide field of view according to claim 4, characterized in that the d-ray refractive index n1 and abbe number v1 of the first lens L1 satisfy the following relations respectively: n1 is more than or equal to 1.8 and less than or equal to 2, v1 is more than or equal to 20 and less than or equal to 30.
6. The 2 x microobjective lens of claim 1 having a large numerical aperture and a wide field of view, wherein the second lens group G2 comprises a second lens L2, the second lens L2 being a biconcave lens of negative power.
7. The 2 x microobjective lens having a large numerical aperture and a wide field of view as in claim 6 wherein the d-ray refractive index n2 and abbe number v2 of the second lens L2 satisfy the following relationships: n2 is more than or equal to 1.6 and less than or equal to 1.8, v2 is more than or equal to 25 and less than or equal to 35.
8. The 2-fold micro objective lens with a large numerical aperture and a wide field of view according to claim 1, wherein the third lens group G3 comprises a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8, wherein the third lens L3, the fourth lens L4, and the eighth lens L8 are all biconvex lenses, the seventh lens L7 is biconcave, and the fifth lens L5 and the sixth lens L6 constitute biconcave negative lenses; the third lens L3, the fourth lens L4, the fifth lens L5, and the eighth lens L8 are positive focal power lenses, and the sixth lens L6 and the seventh lens L7 are negative focal power lenses.
9. The 2-fold micro objective lens with a large numerical aperture and a wide field of view according to claim 8, wherein the d-ray refractive index and abbe number of the third lens L3 are n3 and v3, respectively, the d-ray refractive index and abbe number of the fourth lens L4 are n4 and v4, respectively, the d-ray refractive index and abbe number of the fifth lens L5 are n5 and v5, respectively, the d-ray refractive index and abbe number of the sixth lens L6 are n6 and v6, respectively, the d-ray refractive index and abbe number of the seventh lens L7 are n7 and v7, respectively, the d-ray refractive index and abbe number of the eighth lens L8 are n8 and v8, respectively, and the following relations are satisfied:
1.8≤n1≤2,20≤v1≤30；
1.6≤n2≤1.8,25≤v2≤35；
1.4≤n3≤1.6,77≤v3≤87；
1.6≤n4≤1.8,40≤v4≤50；
1.4≤n5≤1.6,77≤v5≤87；
1.6≤n6≤1.8,28≤v6≤38；
1.6≤n7≤1.8,28≤v7≤38；
1.8≤n8≤2,20≤v8≤30。
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