objective lens
By designing objectives with first and second lens groups that meet specific conditions, the problem of aberration correction of objectives at long working distances and wide fields of view was solved, achieving high resolution and good aberration correction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- EVIDENT CORP
- Filing Date
- 2022-12-07
- Publication Date
- 2026-06-12
AI Technical Summary
While achieving high resolution and wide field of view, existing objectives struggle to balance long working distances and good aberration correction, especially with insufficient resolution at the periphery of the field of view.
An objective lens design consisting of a first lens group and a second lens group is adopted. The first lens group has positive refractive power and the second lens group has negative refractive power. The lens combination satisfies specific conditions to achieve effective light correction, including the use of a meniscus lens with its concave surface facing the object side and a conjoined lens.
It achieves a long working distance and wide field of view objective lens design, and can perform well in correcting aberrations, especially maintaining high resolution at the periphery of the field of view.
Smart Images
Figure CN116256878B_ABST
Abstract
Description
Technical Field
[0001] The disclosure in this specification relates to the objective lens. Background Technology
[0002] For objectives used in industrial applications such as wafer inspection, a high numerical aperture (NA) is required to achieve high resolution. In addition, a wide field of view is required to achieve high throughput, and a long working distance (WD) is required to increase transport speed while avoiding the risk of collision between the object being inspected and the objective.
[0003] Existing technical documents
[0004] Patent Document 1: Japanese Patent Application Publication No. 60-241009 Summary of the Invention
[0005] The problem that the invention aims to solve
[0006] For example, Patent Document 1 discloses a 100x objective lens with a field of view (NA) of 0.8 or higher, but such an objective lens has an excessively small actual field of view, making it difficult to achieve sufficient throughput. Furthermore, when attempting to achieve a wide field of view using this objective lens structure, it is particularly difficult to properly correct image plane curvature. As a result, it is difficult to achieve good resolution in the peripheral areas of the widest field of view.
[0007] One aspect of the present invention is to provide an objective lens that meets the specifications of long WD and wide field of view, and has good aberration correction performance up to the periphery of the field of view.
[0008] Methods for solving problems
[0009] An objective lens according to one aspect of the present invention comprises: a first lens group that converts diverging light from an object point into converging light and has positive refractive power; and a second lens group disposed on the image side of the first lens group and having negative refractive power. The first lens group includes a first lens at its position closest to the object side, the first lens being a meniscus lens with its concave surface facing the object side and having positive refractive power. The second lens group includes a pair of meniscus lens components with their concave surfaces facing each other. The objective lens includes three or more conjoined lenses at a position closer to the object side than the pair of meniscus lens components. The objective lens satisfies the following condition:
[0010] 2.6≤φ L1 / D L1 ≤16…(1)
[0011] 0.1≤|R 212 | / f≤3.5…(2),
[0012] Where, φ L1 D is the outer diameter of the first lens.L1 R is the thickness on the optical axis of the first lens. 212 is the radius of curvature of the surface closest to the image side of the first meniscus component, which is the object-side meniscus component in the pair of meniscus components, and f is the focal length of the objective lens.
[0013] Invention Effects
[0014] Based on the above method, it is possible to provide an objective lens that meets the specifications of long WD and wide field of view, and has good aberration correction performance up to the periphery of the field of view. Attached Figure Description
[0015] Figure 1 This is a cross-sectional view of objective lens 1 in Embodiment 1 of the present invention.
[0016] Figure 2 This is a cross-sectional view of the imaging lens 10.
[0017] Figure 3 This is an aberration diagram of an optical system consisting of objective lens 1 and imaging lens 10.
[0018] Figure 4 This is a cross-sectional view of objective lens 2 in Embodiment 2 of the present invention.
[0019] Figure 5 This is an aberration diagram of an optical system consisting of objective lens 2 and imaging lens 10.
[0020] Figure 6 This is a cross-sectional view of objective lens 3 in Embodiment 3 of the present invention.
[0021] Figure 7 This is an aberration diagram of an optical system consisting of objective lens 3 and imaging lens 10.
[0022] Figure 8 This is a cross-sectional view of objective lens 4 in Embodiment 4 of the present invention.
[0023] Figure 9 This is an aberration diagram of an optical system consisting of objective lens 4 and imaging lens 10.
[0024] Label Explanation
[0025] 1, 2, 3, 4: Objective lenses;
[0026] 10: Imaging lens;
[0027] G1: First lens group;
[0028] G2: Second lens group;
[0029] L1~L14, TL1~TL2: Lenses;
[0030] CL1~CL5, CTL1: Joint lens. Detailed Implementation
[0031] An objective lens according to one embodiment of this application will be described. The objective lens of this embodiment (hereinafter referred to as the objective lens) is an infinity-corrected microscope objective lens used in combination with an imaging lens.
[0032] The objective lens includes: a first lens group with positive refractive power that converts diverging light from an object point into converging light; and a second lens group with negative refractive power disposed on the image side of the first lens group. The image-side lens component of the first lens group is the object-side lens component that functions by converting diverging light from the object point into converging light and emitting that converging light. That is, when there are multiple lens surfaces in the objective lens that emit converging light, the object-side lens surface among these lens surfaces is the image-side lens surface of the first lens group. The boundary between the first lens group and the second lens group can be determined by the features described above.
[0033] Furthermore, in this specification, the term "lens component," whether referring to a single lens or a combined lens, means a lens block whose only two surfaces—the object-side surface and the image-side surface—are in contact with air through which light rays from the object point pass. That is, one single lens is one lens component, and one combined lens is also one lens component. On the other hand, multiple single lenses or multiple combined lenses arranged with air gaps between them are not referred to as one lens component.
[0034] The first lens group converts divergent light from the object point into convergent light, which is then incident on the second lens group. The second lens group converts the convergent light from the first lens group into parallel light. Since the divergent light from the object point is temporarily converted into convergent light within the first lens group before being incident on the second lens group, the rim light height within the second lens group is lower than that within the first lens group. This allows for effective correction of Petzvar and other light within the second lens group, which has negative refractive power, resulting in good correction of image plane curvature across a wide field of view.
[0035] The first lens group includes a meniscus lens (hereinafter also referred to as the first lens) with positive refractive power and a concave surface facing the object side at the position closest to the object. To achieve an objective lens with high NA and long WD, the rim ray height at the point of incidence inevitably increases due to the divergence of light before it reaches the objective lens. Therefore, a lens with positive refractive power needs to be positioned closest to the object to suppress the divergence of the light beam. If the lens with positive refractive power positioned closest to the object is a meniscus lens with a concave surface facing the object, the main effect is to minimize spherical aberration and coma. In the case of an objective lens with a particularly long WD as shown in the embodiments described later, the rim ray height at the point of incidence is very high; therefore, without such a lens, it is difficult to achieve good overall aberration correction of the optical system. Therefore, a meniscus lens with positive refractive power and a concave surface facing the object is positioned closest to the object of the objective lens.
[0036] The second lens group comprises a pair of meniscus lens components with concave surfaces facing each other. Within the second lens group, which receives convergent light, there is a Gaussian group—a pair of meniscus lens components—with convex surfaces facing outwards and concave surfaces facing inwards. This reduces the height of peripheral rays on the facing concave surfaces. As a result, Pezvar and Fibonacci retardation can be effectively corrected on concave surfaces with negative refractive power, and image plane curvature can be significantly reduced.
[0037] The objective lens includes three or more conjoined lenses positioned closer to the object than the aforementioned pair of meniscus lens components. By including three or more conjoined lenses that combine lenses with different optical properties, chromatic aberration can be adequately corrected. In particular, conjoined lenses composed of a low-dispersion positive lens and a high-dispersion negative lens generally have an achromatic effect, known as chromatic correction. By placing three or more conjoined lenses with achromatic effect in a region greater than the rim light height—that is, in the region closer to the object than the pair of meniscus lens components—good chromatic correction can be achieved.
[0038] In addition, the objective lens is configured to satisfy the following conditional equations (1) and (2).
[0039] 2.6≤φ L1 / D L1 ≤16…(1)
[0040] 0.1≤|R 212 | / f≤3.5…(2).
[0041] Where, φ L1 It is the outer diameter of the first lens. D L1 R is the thickness along the optical axis of the first lens. 212It is the radius of curvature of the image-side surface of the object-side meniscus component (hereinafter also referred to as the first meniscus component) in a pair of meniscus lens components. f is the focal length of the objective lens. In addition, the outer diameter of the first lens is usually about 0.5 mm larger than the effective diameter of the image-side surface of the first lens.
[0042] Condition (1) is mainly used to effectively correct spherical aberration and coma in objectives with long WD. Due to the influence of long WD, divergent light incident at a large edge ray height cannot be significantly suppressed by the concave surface on the object side of the first lens, but by satisfying condition (1), it is mainly able to effectively correct spherical aberration and coma.
[0043] If φ L1 / D L1 Below the lower limit (2.6), the thickness of the first lens becomes too large, resulting in excessively high rim ray height within the first lens. Consequently, the rim ray height of the incident light on the image-side surface of the first lens and subsequent optical systems becomes excessive, making it difficult to minimize the generation of spherical aberration and coma. As a result, achieving good aberration correction for the entire optical system becomes difficult. On the other hand, if φ L1 / D L1 If the thickness exceeds the upper limit (16), the thickness becomes too thin relative to the outer diameter of the first lens, making it difficult to ensure the rigidity of the first lens. As a result, the manufacturing error of the surface shape becomes larger, making it difficult to achieve the desired aberration correction.
[0044] Condition (2) is mainly used to properly correct image plane curvature. By satisfying condition (2), the Pessava and the first meniscus lens component facing the image side can be properly corrected, and thus, the image plane curvature can be properly corrected as a whole in the optical system.
[0045] If |R 212 If | / f exceeds the upper limit (3.5), the radius of curvature of the concave surface of the first meniscus lens becomes too large. Therefore, it is impossible to adequately correct the Pessvar sum, making it difficult to properly correct image plane curvature across the entire optical system. In particular, in optical systems with a long WD, the ray height at the incident time point inevitably increases. Therefore, in areas close to the object, such as the first lens group included in the optical system, it is difficult to configure a strong concave surface that acts in the direction of increasing ray height, making Pessvar sum correction difficult. Therefore, in order to achieve adequate aberration correction with a long WD and a wide field of view, adequate Pessvar sum correction is required in the first meniscus lens. On the other hand, if |R 212 If | / f is below the lower limit (0.1), the first meniscus lens will overcorrect the Pezvar and Fibre. Therefore, it is difficult to achieve good correction of the overall image plane curvature of the optical system.
[0046] The objective lens constructed as described above can meet the specifications of long WD and wide field of view, and can effectively correct aberrations up to the periphery of the field of view.
[0047] Furthermore, the objective lens may also be configured to satisfy conditional (1-1) or conditional (1-2) below, instead of conditional (1). Additionally, the objective lens may also be configured to satisfy conditional (2-1) or conditional (2-2) below, instead of conditional (2).
[0048] 3.3≤φ L1 / D L1 ≤12…(1-1)
[0049] 3.8≤φ L1 / D L1 ≤8…(1-2)
[0050] 0.2≤|R 212 | / f≤1.7…(2-1)
[0051] 0.3≤|R 212 | / f≤1.2…(2-2).
[0052] The preferred structure of the objective lens will be described below.
[0053] The second lens group preferably comprises three conjoined lenses, one negative and one positive, arranged flanking a positive lens. By having an achromatic lens component consisting of three conjoined lenses, the space within the objective lens can be used effectively, and on-axis chromatic aberration correction can be performed efficiently. Furthermore, to maximize the effect of the achromatic lens component, it is preferable to place it in areas with high rim light height, but in such areas the lens diameter inevitably increases. As described above, by using an achromatic lens component consisting of three conjoined lenses, the rigidity of the lens component can be maintained relatively strongly even with an increased lens diameter.
[0054] The pair of meniscus lens components are preferably combined lenses. As described above, the pair of meniscus lens components mainly have the function of reducing patellar curvature and thus correcting image plane curvature. However, by making them combined lenses, in addition to correcting image plane curvature, they can also correct chromatic aberration. Therefore, they can primarily and effectively correct on-axis chromatic aberration.
[0055] In addition, the objective lens preferably satisfies at least one of the following conditions (3) to (5).
[0056] 0.5≤|R 211 | / f≤7…(3)
[0057] 18≤νdL≤31…(4)
[0058] 1.51≤ndH≤1.75…(5)
[0059] Among them, R 211 νdL is the radius of curvature of the object-side surface of the first meniscus lens component. νdL is the minimum Abbe number of at least one positive lens positioned further from the image-side surface than the object-side surface of the first meniscus lens component. ndH is the maximum refractive index of at least one negative lens included in the objective lens.
[0060] Condition (3) is mainly used to better correct the curvature of the image plane. As mentioned above, the first meniscus lens component with the convex side facing the object has a Pezval and correction effect, but in order to obtain a sufficient correction effect, it is preferable to sufficiently reduce the rim ray height on the concave surface of the first meniscus lens component on the image side.
[0061] |R 211 | / f does not exceed the upper limit (7), thereby preventing the radius of curvature of the convex surface on the object side of the first meniscus lens component from becoming too large. Therefore, by converging the incident light through this convex surface, the height of the edge rays on the concave surface on the image side can be sufficiently suppressed, thus effectively correcting image plane curvature. Furthermore, |R 211 | / f is not lower than the lower limit (0.5), thereby preventing the radius of curvature of the convex surface on the object side of the first meniscus lens component from becoming too small. This prevents excessive aberrations such as coma from occurring on the convex surface, enabling good aberration correction.
[0062] Condition (4) is primarily used to effectively correct on-axis chromatic aberration and magnification chromatic aberration. The principal ray of the off-axis beam intersects the optical axis within the objective lens; therefore, the height markings of the off-axis principal ray are reversed in both the object-side and image-side regions at this intersection. In this configuration, the positive lens positioned closer to the image-side region than the aforementioned intersection uses a highly dispersive glass material, thereby effectively correcting magnification chromatic aberration generated in the object-side region.
[0063] νdL does not exceed the upper limit (31), thereby, through the above-mentioned effects, the magnification chromatic aberration of the objective lens can be well corrected. In addition, νdL is not lower than the lower limit (18), thereby, the amount of on-axis chromatic aberration generated can be avoided from becoming too large, and the on-axis chromatic aberration can be well corrected as a whole in the objective lens.
[0064] Condition (5) is a condition used to properly correct spherical aberration and wavefront aberration. In order for a lens to have negative refractive power, at least one surface needs to be concave, and the thickness of the center of the lens is generally thinner than that of the periphery. Such a lens shape is prone to surface shape errors during manufacturing.
[0065] Since ndH does not exceed the upper limit (1.75), the refractive index of the negative lens will not become too large, and the influence of lens surface shape errors on wavefront aberrations can be minimized. Therefore, wavefront aberrations such as spherical aberration can be well corrected. In addition, low-refractive-index glass materials generally tend to have low dispersion. Therefore, by ensuring that ndH is not lower than the lower limit (1.51), the dispersion of the negative lens will not become too small, and chromatic aberration can be well corrected.
[0066] Furthermore, the objective lens may also be configured to satisfy conditional (3-1) or conditional (3-2) instead of conditional (3). Additionally, the objective lens may also be configured to satisfy conditional (4-1) or conditional (4-2) instead of conditional (4). Furthermore, the objective lens may also be configured to satisfy conditional (5-1) or conditional (5-2) instead of conditional (5).
[0067] 0.8≤|R 211 | / f≤4…(3-1)
[0068] 1.2≤|R 211 | / f≤2.5…(3-2)
[0069] 20≤νdL≤30…(4-1)
[0070] 24≤νdL≤29…(4-2)
[0071] 1.55≤ndH≤1.71…(5-1)
[0072] 1.61≤ndH≤1.66…(5-2).
[0073] The objective lens with the above-described structure has a medium magnification, more specifically, a magnification of 60x or less. That is, when the focal length of the objective lens is set to f, and the focal length of the imaging lens used in combination with the objective lens is set to ft, the relationship ft / f ≤ 60 is achieved.
[0074] Furthermore, the objective lens of the above structure is compact and achieves high NA and long WD. More specifically, it satisfies the following conditional expression.
[0075] 0.065≤d0 / L≤0.3…(6)
[0076] NA≥0.75…(7)
[0077] 40mm≤L≤75mm…(8)
[0078] Where d0 is the distance along the optical axis from the specimen surface to the object-side surface of the objective lens. L is the distance along the optical axis from the specimen surface to the image-side surface of the objective lens. NA is the numerical aperture of the objective lens on the object side. That is, d0 is approximately equal to WD, and L is approximately equal to the sum of WD and the total length of the objective lens (more precisely, the total length of the optical system from the first lens group to the second lens group, as described later).
[0079] In particular, by satisfying condition (6), it is possible to balance a long WD and a compact structure. When d0 / L is below the lower limit, the WD is too short or the objective lens is too large. On the other hand, when d0 / L exceeds the upper limit, the restrictions on the number and shape of lenses become too great, making it difficult to correct aberrations.
[0080] The following is a detailed description of the embodiments of the above-mentioned objective lens.
[0081] [Example 1]
[0082] Figure 1 This is a cross-sectional view of objective lens 1 in this embodiment. Objective lens 1 is a microscope objective lens, comprising a first lens group G1 with positive refractive power that converts diverging light from an object point into converging light, and a second lens group G2 with negative refractive power disposed at a position closer to the image side than the first lens group G1.
[0083] The first lens group G1 consists of a meniscus lens L1 with a concave surface facing the object side and having positive refractive power, a meniscus lens L2 with a concave surface facing the object side, a conjoint lens CL1, and a conjoint lens CL2 arranged sequentially from the object side.
[0084] The joining lens CL1 consists of two joining lenses, namely a lens L3, which is a biconvex lens, arranged sequentially from the object side, and a lens L4, which is a meniscus lens with its concave surface facing the object side. The joining lens CL2 consists of two joining lenses, namely a lens L5, which is a meniscus lens with its concave surface facing the image side, arranged sequentially from the object side, and a lens L6, which is a biconvex lens.
[0085] The second lens group G2 consists of conjoint lenses CL3, CL4, and CL5 arranged sequentially from the object side. Conjoint lenses CL4 and CL5 are a pair of meniscus lens components with their concave surfaces facing each other. Objective lens 1 contains three conjoint lenses (conjoint lens CL1, conjoint lens CL2, and conjoint lens CL3) positioned closer to the object side than the pair of meniscus lens components.
[0086] The combined lens CL3 consists of three combined lenses, arranged sequentially from the object side: lens L7 (a biconvex lens), lens L8 (a biconcave lens), and lens L9 (a biconvex lens). In other words, the combined lens CL3 is a positive-negative-positive combination of three combined lenses, with positive lenses (lens L7 and lens L9) positioned on either side of a negative lens (lens L8).
[0087] The joining lens CL4 consists of two joining lenses, namely a lens L10 (a biconvex lens) and a lens L11 (a biconcave lens) arranged sequentially from the object side. The joining lens CL5 consists of two joining lenses, namely a lens L12 (a biconcave lens) and a lens L13 (a biconvex lens) arranged sequentially from the object side.
[0088] The various data for objective lens 1 are described below. Additionally, β is the magnification when objective lens 1 is combined with imaging lens 10. NA ob This is the numerical aperture on the object side of objective lens 1. f, f1, and f2 are the focal lengths of the objective lens, the first lens group G1, and the second lens group G2, respectively. Other parameters are as described above.
[0089] NA ob =0.77, β=50, f=3.6mm, f1=8.461mm, f2=-17.921mm, L=48.7mm, d0=4.04mm,
[0090] φ L1 =9.44mm, D L1 =2.262mm, R 211 =6.0569mm, R 212 =2.8444mm, νdL=28.43, ndH=1.65412.
[0091] The lens data for objective lens 1 is shown below. Furthermore, INF in the lens data represents infinity (∞).
[0092] Objective lens 1
[0093]
[0094]
[0095] Here, 's' represents the surface number, 'r' represents the radius of curvature (mm), 'd' represents the surface spacing (mm), 'nd' represents the refractive index relative to the 'd' line, and 'νd' represents the Abbe number. These designations remain the same in subsequent embodiments. Furthermore, surface number 's1' represents the specimen surface. Surface numbers 's2' and 's21' represent the object-side and image-side-side lens surfaces of objective lens 1, respectively. Additionally, for example, surface spacing 'd1' represents the distance along the optical axis from the surface represented by surface number 's1' to the surface represented by surface number 's2'. Furthermore, surface spacing 'd21' represents the distance along the optical axis (110 mm) from the surface represented by surface number 's21' to the imaging lens.
[0096] As shown below, objective lens 1 satisfies conditions (1) to (8).
[0097] (1)φ L1 / D L1 =4.173
[0098] (2)|R 212 | / f=0.790
[0099] (3)|R 211 | / f=1.682
[0100] (4)νdL=28.430(lens L13)
[0101] (5)ndH = 1.654 (lens L5, lens L11)
[0102] (6) d0 / L=0.083
[0103] (7) NA = 0.77
[0104] (8) L=48.7mm
[0105] Figure 2 This is a cross-sectional view of the imaging lens 10 used in conjunction with the objective lens 1. The imaging lens 10 is a microscope imaging lens that forms a magnified image of an object when combined with an infinity-corrected objective lens. The imaging lens 10 is a combined lens CTL1, which is composed of a lens TL1 as a biconvex lens and a lens TL2 as a meniscus lens disposed on the image side of the biconvex lens with its concave surface facing the object side. The imaging lens 10 is configured such that the distance on the optical axis from the lens surface (surface number s21) closest to the image side of the objective lens 1 to the lens surface (surface number s1) closest to the object side of the imaging lens 10 is 110 mm. Furthermore, the focal length of the imaging lens 10 is 180 mm.
[0106] The lens data for imaging lens 10 is shown below.
[0107] Imaging lens 10
[0108]
[0109] Figure 3 This is an aberration diagram of the optical system consisting of objective lens 1 and imaging lens 10, showing the aberrations in the image plane where the optical image is formed by objective lens 1 and imaging lens 10. Figure 3 (a) is a spherical aberration diagram. Figure 3 (b) is a graph representing the quantity that violates the sinusoidal condition. Figure 3 (c) is a scatter plot. Figure 3 Image (d) is a coma aberration diagram with an image height ratio of 70% (image height 9.27 mm). Furthermore, in the diagram, "M" represents the meridional component and "S" represents the sagittal component. For example... Figure 3 As shown, in this embodiment, aberrations are well corrected across a wide field of view.
[0110] [Example 2]
[0111] Figure 4 This is a cross-sectional view of objective lens 2 in this embodiment. Objective lens 2 is a microscope objective lens, comprising: a first lens group G1 having positive refractive power that converts diverging light from an object point into converging light; and a second lens group G2 having negative refractive power disposed at a position closer to the image side than the first lens group G1.
[0112] The first lens group G1 consists of a meniscus lens L1 with a concave surface facing the object side and having positive refractive power, a meniscus lens L2 with a concave surface facing the object side, a conjoint lens CL1, and a conjoint lens CL2 arranged sequentially from the object side.
[0113] The joining lens CL1 consists of two joining lenses, namely a lens L3, which is a biconvex lens, arranged sequentially from the object side, and a lens L4, which is a meniscus lens with its concave surface facing the object side. The joining lens CL2 consists of two joining lenses, namely a lens L5, which is a meniscus lens with its concave surface facing the image side, arranged sequentially from the object side, and a lens L6, which is a biconvex lens.
[0114] The second lens group G2 consists of conjoint lenses CL3, CL4, and CL5 arranged sequentially from the object side. Conjoint lenses CL4 and CL5 are a pair of meniscus lens components with their concave surfaces facing each other. Objective lens 2 contains three conjoint lenses (conjoint lens CL1, conjoint lens CL2, and conjoint lens CL3) positioned closer to the object side than the pair of meniscus lens components.
[0115] The combined lens CL3 consists of three combined lenses, arranged sequentially from the object side: lens L7 (a biconvex lens), lens L8 (a biconcave lens), and lens L9 (a biconvex lens). In other words, the combined lens CL3 is a positive-negative-positive combination of three combined lenses, with positive lenses (lens L7 and lens L9) positioned on either side of a negative lens (lens L8).
[0116] The joining lens CL4 consists of two joining lenses, namely a lens L10 (a biconvex lens) and a lens L11 (a biconcave lens) arranged sequentially from the object side. The joining lens CL5 consists of two joining lenses, namely a lens L12 (a biconcave lens) and a lens L13 (a biconvex lens) arranged sequentially from the object side.
[0117] The various data for objective lens 2 are shown below.
[0118] NA ob =0.8, β=50, f=3.6mm, f1=8.529mm, f2=-17.839mm, L=48.699mm,
[0119] d0 = 4.04 mm, φ L1 =9.9mm, D L1 =2.306mm, R 211 =6.0577mm, R 212 =2.8933mm, νdL=28.43,
[0120] ndH = 1.65412.
[0121] The lens data for objective lens 2 is shown below.
[0122] Objective lens 2
[0123]
[0124]
[0125] As shown below, objective lens 2 satisfies conditions (1) to (8).
[0126] (1)φ L1 / D L1 =4.293
[0127] (2)|R 212 | / f=0.804
[0128] (3)|R 211 | / f=1.683
[0129] (4)νdL=28.430(lens L13)
[0130] (5)ndH = 1.654 (lens L5, lens L11)
[0131] (6) d0 / L=0.083
[0132] (7) NA = 0.80
[0133] (8) L=48.699mm
[0134] Figure 5 It is an aberration diagram of the optical system consisting of objective lens 2 and imaging lens 10, which shows the aberrations in the image plane of the optical image formed by objective lens 2 and imaging lens 10. Figure 5 (a) is a spherical aberration diagram. Figure 5 (b) is a graph representing the quantity that violates the sinusoidal condition. Figure 5 Figure (c) is an astigmatic image. Figure 5(d) is a coma aberration image with an image height ratio of 70% (image height 9.27 mm). For example... Figure 5 As shown, in this embodiment, aberrations are well corrected across a wide field of view.
[0135] [Example 3]
[0136] Figure 6 This is a cross-sectional view of the objective lens 3 in this embodiment. The objective lens 3 is a microscope objective lens, comprising: a first lens group G1 having positive refractive power that converts diverging light from an object point into converging light; and a second lens group G2 having negative refractive power disposed at a position closer to the image side than the first lens group G1.
[0137] The first lens group G1 consists of a meniscus lens L1 with positive refractive power and concave surface facing the object side, a meniscus lens L2 with concave surface facing the object side, a conjoint lens CL1, and a conjoint lens CL2 arranged sequentially from the object side.
[0138] The joining lens CL1 consists of two joining lenses, namely a lens L3, which is a biconvex lens, arranged sequentially from the object side, and a lens L4, which is a meniscus lens with its concave surface facing the object side. The joining lens CL2 consists of two joining lenses, namely a lens L5, which is a meniscus lens with its concave surface facing the image side, arranged sequentially from the object side, and a lens L6, which is a biconvex lens.
[0139] The second lens group G2 consists of conjoint lenses CL3, CL4, and CL5 arranged sequentially from the object side. Conjoint lenses CL4 and CL5 are a pair of meniscus lens components with their concave surfaces facing each other. Objective lens 3 contains three conjoint lenses (conjoint lens CL1, conjoint lens CL2, and conjoint lens CL3) positioned closer to the object side than the pair of meniscus lens components.
[0140] The combined lens CL3 consists of three combined lenses, arranged sequentially from the object side: lens L7 (a biconvex lens), lens L8 (a biconcave lens), and lens L9 (a biconvex lens). In other words, the combined lens CL3 is a positive-negative-positive combination of three combined lenses, with positive lenses (lens L7 and lens L9) positioned on either side of a negative lens (lens L8).
[0141] The conjoined lens CL4 consists of two conjoined lenses, namely lens L10, which is a meniscus lens with its concave surface facing the image side, and lens L11, which is also a meniscus lens with its concave surface facing the image side, arranged sequentially from the object side. The conjoined lens CL5 consists of two conjoined lenses, namely lens L12, which is a biconcave lens, and lens L13, which is a biconvex lens, arranged sequentially from the object side.
[0142] The various data for objective lens 3 are shown below.
[0143] NA ob =0.82, β=50, f=3.6mm, f1=8.643mm, f2=-17.573mm, L=49.299mm,
[0144] d0 = 3.733 mm, φ L1 =9.76mm, D L1 =2.306mm, R 211 =6.337mm, R 212 =3.0206mm, νdL=29.84,
[0145] ndH = 1.65412.
[0146] The lens data for objective lens 3 is shown below.
[0147] Objective lens 3
[0148]
[0149]
[0150] As shown below, objective lens 3 satisfies conditions (1) to (8). (1) φ L1 / D L1 =4.232
[0151] (2)|R 212 | / f=0.839
[0152] (3)|R 211 | / f=1.760
[0153] (4)νdL=29.840(lens L13)
[0154] (5)ndH = 1.654 (lens L5, lens L11)
[0155] (6) d0 / L=0.076
[0156] (7) NA = 0.82
[0157] (8) L=49.299mm
[0158] Figure 7 It is an aberration diagram of the optical system consisting of objective lens 3 and imaging lens 10, representing the aberrations in the image plane of the optical image formed by objective lens 3 and imaging lens 10. Figure 7 (a) is a spherical aberration diagram. Figure 7 (b) is a graph representing the quantity that violates the sinusoidal condition. Figure 7 (c) is a scatter plot. Figure 7 (d) is a coma aberration diagram with an image height ratio of 70% (image height 9.27 mm). For example... Figure 7 As shown, in this embodiment, aberrations are well corrected across a wide field of view.
[0159] [Example 4]
[0160] Figure 8 This is a cross-sectional view of the objective lens 4 in this embodiment. The objective lens 4 is a microscope objective lens, comprising: a first lens group G1 having positive refractive power that converts diverging light from an object point into converging light; and a second lens group G2 having negative refractive power disposed at a position closer to the image side than the first lens group G1.
[0161] The first lens group G1 consists of a meniscus lens L1 with positive refractive power and concave surface facing the object side, a meniscus lens L2 with concave surface facing the object side, a conjoint lens CL1, and a conjoint lens CL2 arranged sequentially from the object side.
[0162] The joining lens CL1 consists of two joining lenses, namely a lens L3, which is a biconvex lens, arranged sequentially from the object side, and a lens L4, which is a meniscus lens with its concave surface facing the object side. The joining lens CL2 consists of two joining lenses, namely a lens L5, which is a meniscus lens with its concave surface facing the image side, arranged sequentially from the object side, and a lens L6, which is a biconvex lens.
[0163] The second lens group G2 consists of a conjoining lens CL3, a conjoining lens CL4, a conjoining lens CL5, and a lens L14 acting as a biconvex lens, arranged sequentially from the object side. Conjoining lenses CL4 and CL5 are a pair of meniscus lenses with their concave surfaces facing each other. Objective lens 4 contains three conjoining lenses (conjoining lens CL1, conjoining lens CL2, and conjoining lens CL3) positioned closer to the object side than the pair of meniscus lenses.
[0164] The combined lens CL3 consists of three combined lenses, arranged sequentially from the object side: lens L7 (a biconvex lens), lens L8 (a biconcave lens), and lens L9 (a biconvex lens). In other words, the combined lens CL3 is a positive-negative-positive combination of three combined lenses, with positive lenses (lens L7 and lens L9) positioned on either side of a negative lens (lens L8).
[0165] The conjoined lens CL4 consists of two conjoined lenses, namely lens L10, which is a meniscus lens with its concave surface facing the image side, and lens L11, which is also a meniscus lens with its concave surface facing the image side, arranged sequentially from the object side. The conjoined lens CL5 consists of two conjoined lenses, namely lens L12, which is a biconcave lens, and lens L13, which is a biconvex lens, arranged sequentially from the object side.
[0166] The various data for objective lens 4 are shown below.
[0167] NA ob =0.8, β=50, f=3.6mm, f1=8.824mm, f2=-17.901mm, L=53.001mm,
[0168] d0 = 3.905 mm, φ L1 =9.74mm, D L1 =2.359mm, R 211 =6.1484mm, R 212 =3.0222mm, νdL=25.42, ndH=1.673.
[0169] The lens data for objective lens 4 is shown below.
[0170] Objective lens 4
[0171]
[0172] As shown below, objective lens 4 satisfies conditions (1) to (8).
[0173] (1)φ L1 / D L1 =4.129
[0174] (2)|R 212 | / f=0.840
[0175] (3)|R 211 | / f=1.708
[0176] (4)νdL=25.420(lens L14)
[0177] (5)ndH = 1.673 (lens L5)
[0178] (6) d0 / L=0.074
[0179] (7) NA = 0.80
[0180] (8) L=53.001mm
[0181] Figure 9It is an aberration diagram of the optical system consisting of objective lens 4 and imaging lens 10, which shows the aberrations in the image plane of the optical image formed by objective lens 4 and imaging lens 10. Figure 9 (a) is a spherical aberration diagram. Figure 9 (b) is a graph representing the quantity that violates the sinusoidal condition. Figure 9 (c) is a scatter plot. Figure 9 (d) is a coma aberration diagram with an image height ratio of 70% (image height 9.27 mm). For example... Figure 9 As shown, in this embodiment, aberrations are well corrected across a wide field of view.
Claims
1. An objective lens, characterized in that, include: The first lens group converts divergent light from the object point into convergent light and has positive refractive power; as well as The second lens group is positioned closer to the image side than the first lens group and has negative refractive power. The first lens group includes a first lens at the position closest to the object side. The first lens is a meniscus lens with positive refractive power and a concave surface facing the object side. The second lens group comprises a pair of meniscus lenses with concave surfaces facing each other. The objective lens comprises three conjoined lenses located on the image side of the first lens and on the object side of the pair of meniscus components. The objective lens satisfies the following condition: 2.6 < Φ L1 / D L1 ≤ 16 … (1) 0.1≤|R 212 | / f≤3.5 …(2), wherein Φ L1 is an outer diameter of the first lens, D L1 is a thickness on an optical axis of the first lens, R 212 is a radius of curvature of a surface of the first meniscus lens component of the pair of meniscus lens components that is the meniscus lens component on the object side, and f is a focal length of the objective lens.
2. The objective lens according to claim 1, characterized in that, The second lens group comprises three combined lenses, one negative and one positive, with a positive lens positioned on either side of a negative lens.
3. The objective lens according to claim 1 or 2, characterized in that, The objective lens satisfies the following condition: 0.5≤ |R 211 | / f≤7 …(3), wherein R 211 is the radius of curvature of the face of the first meniscus lens element closest to the object side.
4. The objective lens according to claim 1 or 2, characterized in that, The pair of meniscus lenses are respectively composed of conjoined lenses.
5. The objective lens according to claim 3, characterized in that, The pair of meniscus lenses are respectively composed of conjoined lenses.
6. The objective lens according to claim 1 or 2, characterized in that, The objective lens satisfies the following condition: 18≤νdL≤31 …(4) Wherein, νdL is the minimum Abbe number of at least one positive lens disposed at a position further from the image side than the surface closest to the image side of the first meniscus lens component.
7. The objective lens according to claim 3, characterized in that, The objective lens satisfies the following condition: 18≤νdL≤31 …(4) Wherein, νdL is the minimum Abbe number of at least one positive lens disposed at a position further from the image side than the surface closest to the image side of the first meniscus lens component.
8. The objective lens according to claim 5, characterized in that, The objective lens satisfies the following condition: 18≤νdL≤31 …(4) Wherein, νdL is the minimum Abbe number of at least one positive lens disposed at a position further from the image side than the surface closest to the image side of the first meniscus lens component.
9. The objective lens according to claim 1 or 2, characterized in that, The objective lens satisfies the following condition: 1.51≤ndH≤1.75 …(5) Wherein, ndH is the maximum refractive index of at least one negative lens included in the objective lens.
10. The objective lens according to claim 3, characterized in that, The objective lens satisfies the following condition: 1.51≤ndH≤1.75 …(5) Wherein, ndH is the maximum refractive index of at least one negative lens included in the objective lens.
11. The objective lens according to claim 5, characterized in that, The objective lens satisfies the following condition: 1.51≤ndH≤1.75 …(5) Wherein, ndH is the maximum refractive index of at least one negative lens included in the objective lens.
12. An objective lens, characterized in that, have: The first lens group converts divergent light from the object point into convergent light and has positive refractive power; and The second lens group is positioned closer to the image side than the first lens group and has negative refractive power. The first lens group includes a first lens at the position closest to the object side. The first lens is a meniscus lens with positive refractive power and a concave surface facing the object side. The second lens group comprises a pair of meniscus lenses with concave surfaces facing each other. The second lens group also includes a combined lens consisting of three single lenses, one negative and one positive, flanked by two positive lenses. The objective lens satisfies the following condition: 2.6≤Φ L1 / D L1 ≤16 …(1) 0.1≤|R 212 | / f≤3.5 …(2), Where, Φ L1 D is the outer diameter of the first lens. L1 R is the thickness on the optical axis of the first lens. 212 is the radius of curvature of the surface closest to the image side of the first meniscus component, which is the object-side meniscus component in the pair of meniscus components, and f is the focal length of the objective lens.
13. The objective lens according to claim 12, characterized in that, The objective lens satisfies the following condition: 0.5≤|R 211 | / f≤7 …(3), Among them, R 211 It is the radius of curvature of the surface of the first meniscus lens component closest to the object.
14. The objective lens according to claim 12 or 13, characterized in that, The pair of meniscus lenses are respectively composed of conjoined lenses.
15. The objective lens according to claim 12 or 13, characterized in that, The objective lens satisfies the following condition: 18≤νdL≤31 …(4) Wherein, νdL is the minimum Abbe number of at least one positive lens disposed at a position further from the image side than the surface closest to the image side of the first meniscus lens component.
16. The objective lens according to claim 12 or 13, characterized in that, The objective lens satisfies the following condition: 1.51≤ndH≤1.75 …(5) Wherein, ndH is the maximum refractive index of at least one negative lens included in the objective lens.