Infrared microscope objective lens

Abstract

The utility model discloses an infrared microscope objective lens, which comprises a lens cone, an internal component arranged in the lens cone and a locking piece for fixing the internal component in the lens cone, the internal assembly sequentially comprises a first lens, a first spacer, a second lens, a third lens, a fourth lens, a second spacer, a fifth lens, a third spacer, a sixth lens, a fourth spacer and a seventh lens from the image side to the object side along the optical axis. The locking piece is arranged on the image side of the first lens; a diaphragm is arranged at a contraction part in the second spacer; wherein the object side surface of the second lens is glued with the image side surface of the third lens, the object side surface of the third lens is glued with the image side surface of the fourth lens, and the second lens, the third lens and the fourth lens form a triple glued lens with negative focal power. The device has strict field curvature constraint and distortion constraint, has high object space resolution, has a near-infrared working wave band, and can accurately and clearly detect the defects of silicon-based chips, wafers and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of optical imaging, in particular to an infrared microscope objective lens. Background Art

[0002] Most of the microscope objective lenses on the market now are suitable for the visible light band. Because silicon has low visible light transmittance, the effect will be greatly reduced when these lenses are used to detect silicon-based chips and wafers widely used in the semiconductor manufacturing industry.

[0003] Considering the high infrared transmittance of silicon, the use of infrared microscope lenses can be effectively used to detect silicon-based chips and wafers, revealing their internal structures and defects, such as cracks, foreign matter, dislocations, etc. Therefore, a high-resolution infrared microscope objective lens with good reliability is urgently needed. Summary of the invention

[0004] The purpose of the present application is to provide an infrared microscope objective lens, which is used to solve the problem that current microscope objective lenses are mostly suitable for visible light bands, and there are no microscope objective lenses suitable for infrared light bands, and therefore cannot be used in the inspection process of silicon-based chips and wafers in the semiconductor manufacturing industry.

[0005] In order to solve the above technical problems, the utility model provides an infrared microscope objective lens, including a lens barrel, an internal component arranged in the lens barrel, and a locking member for fixing the internal component in the lens barrel;

[0006] The internal components include, in order from the image side to the object side along the optical axis: a first lens, a first spacer, a second lens, a third lens, a fourth lens, a second spacer, a fifth lens, a third spacer, a sixth lens, a fourth spacer and a seventh lens; the locking member is arranged on the image side of the first lens; a contracted portion in the second spacer is an aperture stop;

[0007] The object side surface of the second lens is glued to the image side surface of the third lens, and the object side surface of the third lens is glued to the image side surface of the fourth lens. The second lens, the third lens and the fourth lens form a triplet lens with negative optical power.

[0008] In one embodiment of the present application, the effective focal length of the infrared microscope objective is f, the focal length of the triplet lens is fTB, and the infrared microscope objective satisfies: |fTB / f|>10.

[0009] In one embodiment of the present application, the inner diameter of the locking member is d1, the curvature radius of the image side of the first lens is R3, the effective focal length of the first lens is f1, and the locking member and the first lens satisfy: 0.80 <f1 / (d1+R3)<1.20。

[0010] In one embodiment of the present application, the inner diameter of the image side plane of the second spacer is d3m, the outer diameter of the image side plane of the second spacer is D3, and the second spacer satisfies: 0.09<(D3-d3m) / D3<0.15.

[0011] In one embodiment of the present application, the inner diameter of the aperture is d3, the angle between the inner inclined surface on the image side of the second spacer and the axial direction is θ3, the radius of curvature of the image side surface of the fourth lens is R7, and the infrared microscope objective satisfies: 2.95<100×d3×tan(θ3) / R7<3.50.

[0012] In one embodiment of the present application, the inner diameter of the object side plane of the second spacer is d3s, the inner diameter of the aperture is d3, the distance from the object side plane of the second spacer to the aperture is h3', the radius of curvature of the image side surface of the fifth lens is R10, and the infrared microscope objective satisfies: 0.50<500×(d3s-d3) / (h3'×R10)<1.20.

[0013] In one embodiment of the present application, the distance between the object side plane of the second spacer and the image side plane of the fourth spacer is EP24, the center thickness of the fifth lens on the optical axis is CT5, the center thickness of the sixth lens on the optical axis is CT6, and the infrared microscope objective lens satisfies: 1.0 <EP24 / (CT5+CT6)<1.7。

[0014] In one embodiment of the present application, the curvature radius of the image side surface of the sixth lens is R12, the inner diameter of the third spacer is d4, the outer diameter of the third spacer is D4, and the sixth lens and the third spacer satisfy: 0.50<R12 / (D4-d4)<1.00.

[0015] In one embodiment of the present application, the radius of curvature of the image side surface of the seventh lens is R14, the inner diameter of the object side plane of the fourth spacer is d5s, the inner diameter of the image side plane of the fourth spacer is d5m, the height of the inner inclined surface on the object side of the fourth spacer is h5', and the infrared microscope objective satisfies: 8.0<R14×h5' / (d5m-d5s)<13.0.

[0016] In one embodiment of the present application, the axial distance from the image side of the first lens to the object side of the last lens is TD, the maximum height of the lens barrel is H, the sum of the axial thickness of all lenses is ∑CT, the sum of the heights of all spacers is ∑h, and the infrared microscope objective satisfies: 1.2<(TD / ∑CT)×(∑h / H)<2.5.

[0017] Compared with the prior art, one or more embodiments of the above scheme may have the following advantages or beneficial effects:

[0018] The infrared microscope objective lens provided by the embodiment of the utility model is applied, and the internal components are arranged in the lens barrel, and the mutual distance between the lenses is controlled by the spacer, wherein the maximum height of the lens barrel is controlled by controlling the on-axis distance from the object side of the first lens to the image side of the last lens, thereby controlling the overall length of the lens and improving the space utilization. By reasonably setting the thickness of the spacer, the distribution of the overall structure of the lens is controlled, the difference of the structure is reduced, and the stability and product reliability in high temperature and high humidity environments are improved. On the basis of ensuring accurate imaging, the object resolution is improved as much as possible; it is used in the infrared light band and can be applied to the detection process of silicon-based chips and wafers in the semiconductor manufacturing industry. The utility model has strict field curvature constraints and distortion constraints, and has high resolution in the object space. The working band is near infrared, and defects of silicon-based chips, wafers, etc. can be accurately and clearly detected.

[0019] Other features and advantages of the utility model will be described in the following description, and partly become apparent from the description, or understood by implementing the utility model. The purpose and other advantages of the utility model can be realized and obtained by the structures specifically pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0021] Figure 1 Shown is a schematic diagram of the structural composition of the infrared microscope objective lens described in an embodiment of the present application.

[0022] Figure 2 Shown is a schematic diagram of the lens structure of the infrared microscope objective lens with size markings in an embodiment of the present application.

[0023] Figure 3 Shown is a schematic diagram of the structure and optical path from the image plane to the object plane of the infrared microscope objective lens described in an embodiment of the present application.

[0024] Figure 4 Shown is a schematic diagram of the structure of a spacer in an infrared microscope objective lens according to an embodiment of the present application.

[0025] Logo Description:

[0026] 21 is a locking piece, 22 is a first spacer, 23 is a second spacer, 24 is a third spacer, 25 is a fourth spacer, 26 is a lens barrel, L1 is a first lens, L2 is a second lens, L3 is a third lens, L4 is a fourth lens, L5 is a fifth lens, L6 is a sixth lens, and L7 is a seventh lens. DETAILED DESCRIPTION

[0027] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that as long as there is no conflict, the various embodiments of the present invention and the various features in the embodiments can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0028] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application, and thus the drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.

[0029] The following embodiments of the present application provide an infrared microscope objective lens, which is used to solve the problem that current microscope objective lenses are mostly suitable for visible light bands, and there are no microscope objective lenses suitable for infrared light bands, and therefore cannot be used in the inspection process of silicon-based chips and wafers in the semiconductor manufacturing industry.

[0030] The principle and implementation of an infrared microscope objective lens of this embodiment will be described in detail below in conjunction with the accompanying drawings so that those skilled in the art can understand the infrared microscope objective lens of this embodiment without creative work.

[0031] refer to Figure 1-Figure 3 As shown, this embodiment provides an infrared microscope objective lens, including a lens barrel 26, an internal component and a locking piece 21, wherein the internal component is sleeved in the lens barrel 26, and the locking piece 21 cooperates with the lens barrel 26 to fix the internal component inside the lens barrel 26.

[0032] The internal components specifically include a lens part and a spacer part, the lens part includes seven lenses, and the spacer part includes four spacers. Further, the internal components include: a first lens L1, a first spacer 22, a second lens L2, a third lens L3, a fourth lens L4, a second spacer 23, a fifth lens L5, a third spacer 24, a sixth lens L6, a fourth spacer 25 and a seventh lens L7 in order from the image side to the object side along the optical axis. That is, the first spacer 22 is arranged between the first lens L1 and the second lens L2 to control the distance between the first lens L1 and the second lens L2; ​​the second spacer 23 is arranged between the fourth lens L4 and the fifth lens L5 to control the distance between the fourth lens L4 and the fifth lens L5; the third spacer 24 is arranged between the fifth lens L5 and the sixth lens L6 to control the distance between the fifth lens L5 and the sixth lens L6; the fourth spacer 25 is arranged between the sixth lens L6 and the seventh lens L7 to control the distance between the sixth lens L6 and the seventh lens L7. The locking member 21 is disposed on the image side of the first lens L1 and is detachably locked with the lens barrel 26. A contraction in the second spacer 23 realizes the lens diaphragm function. The above parts are fixed by the lens barrel 26 and the locking member 21.

[0033] like Figure 4 As shown, the spacer and the locking member 21 can be set to an annular shape, wherein the inner side of the annular spacer can be provided with an inclined surface based on the demand, and the inner and outer diameters and height of the annular spacer are set based on the objective lens design requirements, and the lens spacing requirements involved. The outer side of the annular locking member 21 is provided with an external thread, and the corresponding position inside the object side end of the lens barrel 26 is provided with an internal thread. The lens barrel 26 is connected to the locking member 21 by screw thread, and the lens barrel 26 and the locking member 21 can also be fastened based on other reasonable detachable methods, and no fixed restrictions are imposed on them here.

[0034] Furthermore, the inner side surface of the second spacer 23 can be formed by splicing two or more annular inclined surfaces with different inclination angles, and the splicing point of each two annular inclined surfaces is a contraction point, and a contraction point of the second spacer 23 is used as the aperture of the infrared microscope objective lens, realizing the function of the objective lens aperture. The aperture position of the second spacer 23 can be set based on actual conditions.

[0035] This embodiment also makes the following settings for the lens part, specifically setting the object side surface of the second lens L2 to be glued with the image side surface of the third lens L3, and the object side surface of the third lens L3 to be glued with the image side surface of the fourth lens L4, that is, the second lens L2, the third lens L3 and the fourth lens L4 are glued to form a triplet lens with negative optical power. At the same time, the effective focal length f of the triplet lens and the infrared microscope objective lens must also satisfy |fTB / f|>10, where fTB is the focal length fTB of the triplet lens. This setting can effectively reduce the optical power and tolerance sensitivity of the triplet lens.

[0036] In the infrared microscope objective lens of this embodiment, the locking member 21 and the first lens L1 also need to satisfy: 0.80 < f1 / (d1 + R3) < 1.20, where d1 is the inner diameter of the locking member, R3 is the curvature radius of the image side surface of the first lens, and f1 is the effective focal length of the first lens. This setting realizes the reasonable control of the curvature radius of the object side surface of the first lens and the focal length of the first lens, adjusts the beam contraction angle, and thus improves the imaging quality of the infrared microscope objective lens. The inner diameter of the locking member can also be adjusted according to the parameters of the first lens, reducing the entry of stray light and preventing the blocking of signal light. In addition, the outer diameters of the subsequent assembled spacer and lens can also be controlled to limit the overall size of the lens.

[0037] In the infrared microscope objective lens of this embodiment, the second spacer also needs to satisfy: 0.09 < (D3 - d3m) / D3 < 0.15, where d3m is the inner diameter of the image side plane of the second spacer and D3 is the outer diameter of the image side plane of the second spacer. This setting can control the bearing width between the third lens L3 and the first spacer 22, improving the structural strength of the first spacer 22 and the reliability of fixing the triplet lens.

[0038] The infrared microscope objective lens of this embodiment also needs to satisfy: 2.95 < 100×d3×tan(θ3) / R7 < 3.50, where d3 is the inner diameter of the aperture stop, θ3 is the angle between the inner inclined surface of the image side of the second spacer and the axis direction, and R7 is the curvature radius of the image side surface of the fourth lens; the inner inclined surface of the image side of the second spacer is the distance from the edge point of the inner diameter of the image side of the second spacer to the aperture stop. The above setting controls the entry of stray light through the inner diameter of the aperture stop and the size of the inner inclined surface of the image side of the second spacer, thereby improving the imaging clarity of the infrared microscope objective lens; at the same time, the inclined surface inclination angle is set according to the curvature radius of the image side surface of the third lens L3 and the inner diameter of the aperture stop, preventing the inner inclined surface of the image side of the second spacer from interfering with the transmission of signal light.

[0039] The infrared microscope objective lens of this embodiment also needs to satisfy: 0.50 < 500×(d3s - d3) / (h3'×R10) < 1.20, where d3s is the inner diameter of the object side plane of the second spacer, d3 is the inner diameter of the aperture stop, h3' is the distance from the object side plane of the second spacer to the aperture stop, and R10 is the curvature radius of the image side surface of the fifth lens. The above setting controls the entry of stray light through the inner diameter of the aperture stop and the distance from the object side plane of the second spacer to the aperture stop plane, thereby improving the imaging clarity of the infrared microscope objective lens. And the inner diameter of the object side plane of the second spacer and the inner diameter of the aperture stop are set according to the curvature radius of the image side of the fifth lens and the distance from the object side plane of the second spacer to the aperture stop plane, further controlling the size of the second spacer to prevent the inner inclined surface of the object side of the second spacer from interfering with the transmission of signal light.

[0040] The infrared microscope objective lens in this embodiment also needs to satisfy: 1.0 < EP24 / (CT5 + CT6) < 1.7, where EP24 is the distance between the object side plane of the second spacer and the image side plane of the fourth spacer, CT5 is the central thickness of the fifth lens on the optical axis, and CT6 is the central thickness of the sixth lens on the optical axis. The above settings improve the processability of the lens by adjusting the central thicknesses of the fifth lens and the sixth lens. Designing the distance between the second spacer 23 and the fourth spacer 25 within a reasonable range is beneficial for the second spacer 23 and the fourth spacer 25 to block the stray light caused by the divergent light emitted from the image side of the fifth lens and the sixth lens, thereby improving the image quality of the infrared microscope objective lens and ensuring assembly stability at the same time.

[0041] In the infrared microscope objective lens of this embodiment, the sixth lens L6 and the third spacer 24 also need to satisfy: 0.50 < R12 / (D4 - d4) < 1.00, where R12 is the curvature radius of the image side surface of the sixth lens, d4 is the inner diameter of the third spacer, and D4 is the outer diameter of the third spacer. The above settings improve the structural strength of the third spacer 24 by reasonably controlling the curvature radius of the object side of the sixth lens and the inner and outer diameter values of the third spacer. While optimizing the component stability, the third spacer 24 intercepts the excess non-imaging stray light without interfering with the signal light, thereby improving the imaging quality of the infrared microscope objective lens.

[0042] The infrared microscope objective lens in this embodiment also needs to satisfy: 8.0 < R14×h5' / (d5m - d5s) < 13.0, where R14 is the curvature radius of the image side surface of the seventh lens, d5s is the inner diameter of the object side plane of the fourth spacer, d5m is the inner diameter of the image side plane of the fourth spacer, and h5’ is the height of the inner inclined surface on the object side of the fourth spacer. The above settings set the inner diameter of the object side surface, the inner diameter of the image side surface, and the height of the inner inclined surface on the object side of the fourth spacer through the curvature radius of the image side surface of the seventh lens, which can control the entry of stray light. While improving the imaging clarity of the infrared microscope objective lens, it can also prevent the inner wall of the inner inclined surface on the object side of the fourth spacer from interfering with the transmission of the signal light.

[0043] The infrared microscope objective lens in this embodiment also needs to satisfy: 1.2 < (TD / ∑CT)×(∑h / H) < 2.5, where TD is the axial distance from the image side surface of the first lens to the object side surface of the last lens, H is the maximum height of the lens barrel, ∑CT is the sum of the axial thicknesses of all lenses, and ∑h is the sum of the heights of all spacers. The above settings control the maximum height of the lens barrel by controlling the axial distance from the object side surface of the first lens to the image side surface of the last lens, thereby controlling the overall length of the lens and improving the space utilization rate. By reasonably setting the thickness of the spacers to control the distribution of the overall structure of the lens and reducing the structural differences, the stability in high-temperature and high-humidity environments is improved, and the product reliability is also enhanced at the same time.

[0044] In this embodiment, the overall trend of the aperture of the lens in the objective lens part of the infrared microscope can be set to be higher on the left and lower on the right (that is, higher on the image side and lower on the object side along the optical axis direction). This makes it easier to manufacture the structural components of the lens, and the lens barrel can also adopt a simple and useful "one-end installation" method.

[0045] In addition to the above settings for each spacer and lens, the following settings are also made for each lens: The first lens L1 has a positive optical power. The image side of the first lens L1 is set to be convex, and the object side of the first lens L1 is set to be flat. The main function of the first lens L1 is to absorb light and converge the light, so that the light can be smoothly transmitted to the image plane. The second lens L2 has a positive optical power and is set as a biconvex lens. The third lens L3 has a negative optical power and is set as a biconcave lens. The fourth lens L4 has a positive optical power and is set as a biconvex lens or the image side is set to be convex and the object side is set to be flat. The purpose of the triplet lens is to correct the chromatic aberration of the entire system and improve the assemblability of the infrared microscope objective lens.

[0046] The fifth lens L5 has a positive optical power and can be set as a biconvex lens. The sixth lens L6 has a positive optical power. The image side of the sixth lens L6 can be set to be convex, and the object side of the sixth lens L6 can be set to be concave, that is, the sixth lens L6 can be set as a convex-concave meniscus lens. The seventh lens L7 has a positive optical power. The image side of the seventh lens L7 can be set to be convex, and the object side of the seventh lens L7 can be set to be concave. The seventh lens L7 can also be set as a positive meniscus lens; that is, the seventh lens L7 can be set as a convex-concave meniscus lens. The design purpose of the above three lenses is to smoothly transmit the light received by the object side to the triplet lens.

[0047] Preferably, the above seven lenses are all spherical glass lenses. A flat glass serving as a chip protection glass is also provided on the image side of the infrared microscope objective lens.

[0048] In this embodiment, the infrared microscope objective lens also needs to satisfy 0.3 < NA < 0.62, where NA is the numerical aperture of the infrared microscope objective lens. According to the formula σ = 0.5 * λ / NA (σ represents the resolution and λ represents the system wavelength), setting a relatively large numerical value for the numerical aperture NA of the infrared microscope objective lens can ensure that the infrared microscope objective lens has a sufficiently high resolution. For example, in this application, a 10-fold larger NA flat-field infrared microscope objective lens can be obtained by setting the specific numerical value of the numerical aperture NA of the infrared microscope objective lens.

[0049] In this embodiment, the infrared microscope objective lens also needs to satisfy 3 < TD / f < 5, where f is the effective focal length of the infrared microscope objective lens, and TD is the axial distance from the image side of the first lens to the object side of the seventh lens. The setting of 3 < TD / f < 5 in this embodiment can avoid an overly large lens length and obtain a larger focal length while minimizing the lens aperture as much as possible, resulting in better performance of the infrared microscope objective lens.

[0050] In this embodiment, the infrared microscope objective lens also needs to satisfy 1.5 < TD / ∑AT < 2.5, where TD is the axial distance from the image side of the first lens to the object side of the seventh lens, and ∑AT is the sum of the air gaps on the optical axis between all any two adjacent lenses. The setting of 1.5 < TD / ∑AT < 2.5 in this embodiment can ensure the processing and assembly characteristics of the infrared microscope objective lens, and avoid problems such as interference between the front and rear lenses during the assembly process, difficult forming due to too thin lenses, and easy deformation during assembly caused by too small gaps.

[0051] In this embodiment, the seventh lens in the infrared microscope objective lens also needs to satisfy 5 < f7 / R15 < 10, where f7 is the effective focal length of the seventh lens, and R15 is the curvature radius of the object side of the seventh lens. The above setting can limit the curvature radius of the object side of the seventh lens within a reasonable range, slow down the deflection of light in the seventh lens and thus reduce the sensitivity of the seventh lens. At the same time, the above setting can also reduce the spherical aberration generated by the seventh lens.

[0052] The working wavelength band of the infrared microscope objective lens in this embodiment is 1300nm - 1320nm. The infrared microscope objective lens in this embodiment can directly image on the chip without the need to configure an eyepiece. Therefore, the full-field distortion of the infrared microscope objective lens in this embodiment can be set to not be greater than 0.5%, and at the same time, the full-field field curvature of the infrared microscope objective lens is set to not be greater than 1μm.

[0053] Reference Figure 3 As shown (the spacer is not shown), when the infrared microscope objective lens in this embodiment is actually used, the observed sample is located at S16. After the light on the sample enters the lens, it is imaged on S0 on the left side of the lens. The infrared microscope objective lens operates in the near-infrared wavelength band (the designed wavelength range is 1300nm - 1320nm).

[0054] While ensuring accurate imaging (as small as possible field curvature and distortion), the infrared microscope objective lens in this embodiment improves the object space resolution as much as possible (the larger the NA, the higher the object space resolution). The higher the object space resolution, the smaller the object that can be seen clearly.

[0055] Those skilled in the art should understand that, without departing from the technical solution claimed in the present application, the number of lenses constituting the infrared microscope objective lens can be changed to obtain the various results and advantages described in this specification. For example, although seven lenses are described as an example in the embodiment, the infrared microscope objective lens is not limited to including seven lenses, and the infrared microscope objective lens may also include other numbers of lenses if necessary.

[0056] A specific design example of the infrared microscope objective lens applicable to the above embodiment is further described below with reference to the above category schematic diagram. In this example, the infrared microscope objective lens is a 10-fold large NA flat-field infrared microscope objective lens.

[0057] A specific example of a specific infrared microscope objective lens can also be referenced for the lens structure diagram Figure 1 and Figure 2 The infrared microscope objective lens includes, from the image side to the object side along the optical axis, a protective glass L0, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture STO, a fifth lens L5, a sixth lens L6, a seventh lens L7 and an observation sample S16.

[0058] The object side surface S1 of the protective glass L0 is a plane, and the image side surface S2 is a plane;

[0059] The first lens L1 has positive refractive power, its object side surface S3 is convex, and its image side surface S4 is flat;

[0060] The second lens L2 has positive refractive power, and its object-side surface S5 is convex, and its image-side surface S6 is convex;

[0061] The third lens L3 has negative refractive power, and its object-side surface S6 is concave, and its image-side surface S7 is concave;

[0062] The fourth lens L4 has positive refractive power, and its object-side surface S7 is convex, and its image-side surface S8 is convex;

[0063] The fifth lens L5 has positive refractive power, and its object-side surface S10 is convex, and its image-side surface S11 is convex;

[0064] The sixth lens L6 has positive refractive power, an object-side surface S12 thereof is convex, and an image-side surface S13 thereof is concave;

[0065] The seventh lens L7 has negative refractive power, its object-side surface S14 is convex, and its image-side surface S15 is concave;

[0066] The surface of the aperture STO is S9, and the light passes through the surfaces from S15 to S1 in sequence and is finally imaged on the image plane S0, and S0 and S1 coincide.

[0067] refer to Figure 2As shown, D0 represents the outer diameter of the lens barrel; d0 represents the inner diameter of the lens barrel on the object side; H represents the maximum height of the lens barrel; d1 represents the inner diameter of the locking piece; h1 represents the height of the locking piece; d2 represents the inner diameter of the first spacer; D2 represents the outer diameter of the first spacer; h2 represents the height of the first spacer; d3s represents the inner diameter of the object side plane of the second spacer; d3m represents the inner diameter of the image side plane of the second spacer; D3 represents the outer diameter of the image side plane of the second spacer; d3 represents the inner diameter of the aperture; h3' represents the distance from the object side plane of the second spacer to the aperture; h3 represents the height of the second spacer; θ3 represents the angle between the inner inclined surface of the image side of the second spacer and the axial direction; d4 represents the inner diameter of the third spacer; D4 represents the outer diameter of the third spacer; h4 represents the height of the third spacer; d5s represents the inner diameter of the object side plane of the fourth spacer; d5m represents the inner diameter of the image side plane of the fourth spacer; h5' represents the height of the inner inclined surface of the object side of the fourth spacer; h5 represents the height of the fourth spacer.

[0068] As shown in Table 1, it is a basic parameter table of the lens part of an infrared microscope objective lens of a specific example, wherein the units of the curvature radius, thickness, and focal length are all millimeters (mm).

[0069]

[0070] Table 1

[0071] The main value parameters in the specific example are as follows: the parfocal length of the infrared microscope objective is 81.4mm, the effective focal length f of the infrared microscope objective is 20mm, the object height of the infrared microscope objective is 0.43mm, the image height of the infrared microscope objective is 4.3mm, the numerical aperture NA of the infrared microscope objective is 0.62, the working distance of the infrared microscope objective is 3mm, the full field distortion of the infrared microscope objective is <0.5%, and the full field curvature of the infrared microscope objective is less than 1μm.

[0072] As shown in Table 2, it is a basic parameter table of the lens barrel and spacers in a specific example of an infrared microscope objective.

[0073]

[0074]

[0075] Table 2

[0076] The specific values ​​of some calculation parameters in the above table are:

[0077] The effective focal length f1 of the first lens is 96 mm, the radius of curvature R7 of the image side surface of the fourth lens is 18.94 mm, the radius of curvature R10 of the image side surface of the fifth lens is 123.01 mm, the distance EP24 between the object side plane of the second spacer and the image side plane of the fourth spacer is 8.53 mm, the central thickness CT5 of the fifth lens on the optical axis is 3.61 mm, the central thickness CT6 of the sixth lens on the optical axis is 3.4 mm, the radius of curvature R12 of the image side surface of the sixth lens is 31.04 mm, the radius of curvature R14 of the image side surface of the seventh lens is 8.87 mm, the on-axis distance TD from the image side surface of the first lens to the object side surface of the last lens is 78.36 mm, the sum ∑CT of the on-axis thicknesses of all lenses is 37.49 mm, the sum ∑h of the heights of all spacers is 62.30 mm, and the radius of curvature R3 of the image side surface of the first lens is 62.76 mm.

[0078] The infrared microscope objective lens in the specific example further satisfies:

[0079] |fTB / f| = 17.35, where fTB is the focal length of the triplet lens and f is the effective focal length of the infrared microscope objective lens.

[0080] NA = 0.62, where NA is the numerical aperture of the infrared microscope objective lens, satisfying the requirement of 0.3 < NA < 0.62.

[0081] TD / f = 3.92, where f is the effective focal length of the infrared microscope objective lens and TD is the on-axis distance from the image side surface of the first lens to the object side surface of the seventh lens.

[0082] TD / ∑AT = 1.92, where TD is the on-axis distance from the image side surface of the first lens to the object side surface of the seventh lens and ∑AT is the sum of the air gaps on the optical axis between all any two adjacent lenses.

[0083] f7 / R15 = 7.71, where f7 is the effective focal length of the seventh lens and R15 is the radius of curvature of the object side surface of the seventh lens.

[0084] On the basis of ensuring accurate imaging, the infrared microscope objective lens in the specific example can improve the object space resolution as much as possible and is applicable to the working wavelength band of near-infrared light.

[0085] The infrared microscope objective provided by the embodiment of the utility model sets the internal components in the lens barrel, and controls the mutual distance between the lenses by the designed spacers, wherein the maximum height of the lens barrel is controlled by controlling the on-axis distance from the object side of the first lens to the image side of the last lens, thereby controlling the overall length of the lens and improving the space utilization. By reasonably setting the thickness of the spacer, the distribution of the overall structure of the lens is controlled, the structural differences are reduced, and the stability and product reliability in high temperature and high humidity environments are improved. On the basis of ensuring accurate imaging, the object resolution is improved as much as possible; it is used in the infrared light band and can be applied to the detection process of silicon-based chips and wafers in the semiconductor manufacturing industry. The utility model has strict field curvature constraints and distortion constraints, and has high resolution in the object space. The working band is near infrared, and defects of silicon-based chips, wafers, etc. can be accurately and clearly detected.

[0086] Although the embodiments disclosed in the present invention are as above, the above contents are only embodiments adopted for facilitating the understanding of the present invention, and are not intended to limit the present invention. Any technician in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention, but the protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. An infrared microscope objective lens, characterized in that: It comprises a lens barrel, an internal component arranged in the lens barrel, and a locking member for fixing the internal component in the lens barrel; The internal components include, in order from the image side to the object side along the optical axis: a first lens, a first spacer, a second lens, a third lens, a fourth lens, a second spacer, a fifth lens, a third spacer, a sixth lens, a fourth spacer and a seventh lens; the locking member is arranged on the image side of the first lens; a contracted portion in the second spacer is an aperture stop; The object side surface of the second lens is glued to the image side surface of the third lens, and the object side surface of the third lens is glued to the image side surface of the fourth lens. The second lens, the third lens and the fourth lens form a triplet lens with negative optical power.

2. The infrared microscope objective lens according to claim 1, characterized in that: The effective focal length of the infrared microscope objective is f, the focal length of the triplet lens is fTB, and the infrared microscope objective satisfies: |fTB / f|>10.

3. The infrared microscope objective lens according to claim 1, characterized in that: The inner diameter of the locking member is d1, the curvature radius of the image side of the first lens is R3, the effective focal length of the first lens is f1, and the locking member and the first lens satisfy: 0.80 <f1 / (d1+R3)<1.20。 4. The infrared microscope objective lens according to claim 1, characterized in that: The inner diameter of the image side plane of the second spacer is d3m, the outer diameter of the image side plane of the second spacer is D3, and the second spacer satisfies: 0.09<(D3-d3m) / D3<0.

15.

5. The infrared microscope objective lens according to claim 1, characterized in that: The inner diameter of the aperture is d3, the angle between the inner inclined surface on the image side of the second spacer and the axial direction is θ3, the radius of curvature of the image side surface of the fourth lens is R7, and the infrared microscope objective satisfies: 2.95<100×d3×tan(θ3) / R7<3.

50.

6. The infrared microscope objective lens according to claim 1, characterized in that: The inner diameter of the object side plane of the second spacer is d3s, the inner diameter of the aperture is d3, the distance from the object side plane of the second spacer to the aperture is h3', the radius of curvature of the image side of the fifth lens is R10, and the infrared microscope objective meets the following conditions: 0.50<500×(d3s-d3) / (h3'×R10)<1.

20.

7. The infrared microscope objective lens according to claim 1, characterized in that: The distance between the object side plane of the second spacer and the image side plane of the fourth spacer is EP24, the center thickness of the fifth lens on the optical axis is CT5, the center thickness of the sixth lens on the optical axis is CT6, and the infrared microscope objective lens satisfies: 1.0 <EP24 / (CT5+CT6)<1.7。 8. The infrared microscope objective lens according to claim 1, characterized in that: The curvature radius of the image side surface of the sixth lens is R12, the inner diameter of the third spacer is d4, the outer diameter of the third spacer is D4, and the sixth lens and the third spacer satisfy: 0.50<R12 / (D4-d4)<1.

00.

9. The infrared microscope objective lens according to claim 1, characterized in that: The curvature radius of the image side surface of the seventh lens is R14, the inner diameter of the object side plane of the fourth spacer is d5s, the inner diameter of the image side plane of the fourth spacer is d5m, the height of the inner inclined surface on the object side of the fourth spacer is h5', and the infrared microscope objective lens satisfies: 8.0<R14×h5' / (d5m-d5s)<13.

0.

10. The infrared microscope objective lens according to claim 1, characterized in that: The axial distance from the image side of the first lens to the object side of the last lens is TD, the maximum height of the lens barrel is H, the sum of the axial thickness of all lenses is ∑CT, the sum of the heights of all spacers is ∑h, and the infrared microscope objective satisfies: 1.2<(TD / ∑CT)×(∑h / H)<2.5.

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