A collection objective lens and a flow cytometer

Abstract

The present invention discloses a collection lens and a flow cytometer, and relates to the field of lens imaging technology. The collection lens comprises: a plano-convex lens, a meniscus lens and a cemented lens arranged in sequence, and the principal optical axis of the plano-convex lens, the principal optical axis of the meniscus lens and the principal optical axis of the cemented lens are coaxial, the plane of the plano-convex lens is the light incident surface, and the concave surface of the meniscus lens is the light incident surface. The present invention solves the demand for large numerical aperture of the flow cytometer, and expands the application wavelength to 350nm-900nm.

Description

Technical Field

[0001] The invention relates to the technical field of objective lens imaging, and in particular to a collecting objective lens and a flow cytometer. Background Art

[0002] In a flow cytometer, the weak fluorescence signal emitted by the labeled cells (or particles) is collected by the collection lens, and then received by the photodetector through the beam transmission medium and the color separation system. The larger the numerical aperture (NA) of the collection lens, the stronger the fluorescence collection ability. For instrument performance, the stronger the fluorescence signal, the higher the sensitivity. Therefore, a collection lens with a large numerical aperture is very important for flow cytometers. Using water as the medium, the numerical aperture limit is 1.3.

[0003] In addition, with the expansion of ultraviolet fluorescein, commercial flow cytometers use near-ultraviolet lasers with excitation light of 355nm or even below. The inevitable absorption of glass materials in the ultraviolet band and the high requirements for imaging quality in a wide spectral range have posed new challenges to objective lens design.

[0004] In the U.S. invention patent with publication number "US6683314B2" and subject name "Fluorescence detector with reflection transfer branch for color extraction", two common Schott glasses, BK7 and SF8, are used to achieve a numerical aperture of at least 1.17. The lens consists of a total of seven lenses.

[0005] In the Chinese invention patent with publication number "CN106841014B" and subject name "Flow cytometer collection lens and optical system of dual-color laser flow cytometer", a collection lens consisting of six lenses with a numerical aperture of 1.2 was disclosed, using Chengdu Guangming's H-K9L and ZF6 materials; in the Chinese invention patent with publication number "CN111913292B" and subject name "A low-light collection lens system and flow cytometer", the collection lens disclosed consists of four groups of six lens materials with a numerical aperture of 1.2, and 5 kinds of Chinese glass library materials are used. The excessive use of glass materials leads to complex lenses and high costs.

[0006] Obviously, the common problem with the above patents is that the materials used have extremely low internal transmittance below 380nm. Taking a single lens (average thickness 5mm) as an example, the average transmittance at 380nm is 90%. The fluorescent signal passes through a lens composed of 6 pieces of glass material, and eventually 47% will be lost.

[0007] Microscope objectives with similar principles are visual optical systems, which generally only need to consider the wavelength range of 400-700nm, and the human eye has a greater tolerance for aberrations. The numerical aperture of large numerical aperture oil immersion microscope objectives can reach 1.4-1.5, which is characterized by high imaging resolution and high magnification, but the working distance and field of view are extremely small, which is even more inconsistent with the requirements of flow cytometers.

[0008] In a flow cytometer, multiple lasers are arranged vertically along the flow cell, and the required field of view is at least 400μm. At the same time, the wall thickness of the flow cell is generally at least 1mm, which is much thicker than the cover glass of a microscope. In order to effectively separate the images of different lasers in space so that they can be received by optical fibers or directly by detectors, and to avoid poor optical path stability due to high magnification, the magnification of the lens is generally between 10× and 20×.

[0009] The collection lenses mentioned above are not available on the market and need to be designed specifically. Summary of the invention

[0010] The technical problem to be solved by the present invention is to address the deficiencies of the prior art and specifically provide a collection objective lens and a flow cytometer, which are as follows:

[0011] 1) In the first aspect, the present invention provides a collection objective lens, and the specific technical solution is as follows:

[0012] It comprises: a plano-convex lens, a meniscus lens and a cemented lens which are arranged in sequence, wherein the principal optical axes of the plano-convex lens, the meniscus lens and the cemented lens are coaxial, the plane of the plano-convex lens is the light incident surface, and the concave surface of the meniscus lens is the light incident surface.

[0013] The beneficial effects of a collection objective lens provided by the present invention are as follows:

[0014] It solves the demand for large numerical aperture of flow cytometer and expands the application wavelength to 350nm~900nm.

[0015] Based on the above solution, a collecting objective lens of the present invention can also be improved as follows.

[0016] Further, the number of the meniscus lens is at least one;

[0017] When the number of the meniscus lenses is not less than two, all the meniscus lenses are sequentially arranged between the plano-convex lens and the cemented lens.

[0018] Furthermore, the cemented lens is a double cemented lens or a triple cemented lens. When the cemented lens is a double cemented lens, the number of the double cemented lenses is 2, and the outer surface of the positive lens of each double cemented lens is the light incident surface.

[0019] Furthermore, the effective aperture of the plano-convex lens is 5 mm to 7 mm, and the radius of curvature of the convex surface of the plano-convex lens is not greater than 5 mm.

[0020] Furthermore, the focal length of the collecting objective lens and the focal length of the cemented lens are constrained by a constraint relationship, and the constraint relationship is: 1 / 10<f / TTL<1 / 20, 5<f(G2) / f<7, f represents the focal length of the collecting objective lens, TTL represents the total optical length of the collecting objective lens, when the cemented lens is a triple cemented lens, f(G2) represents the focal length of the triple cemented lens, and when the cemented lens is a double cemented lens, f(G2) represents the focal length of the double cemented lens closest to the image plane.

[0021] Furthermore, the material of the plano-convex lens and the meniscus lens is N-BK7HTi material.

[0022] Furthermore, the negative lens in the cemented lens is made of F2HTi material.

[0023] 2) In the second aspect, the present invention also provides a flow cytometer, and the specific technical solution is as follows:

[0024] Includes any of the above-mentioned collection objectives.

[0025] Based on the above solution, the flow cytometer of the present invention can also be improved as follows.

[0026] Furthermore, an optical coupling gel layer prepared by using optical coupling gel is provided between the flow cell of the flow cytometer and the plano-convex lens.

[0027] Furthermore, the thickness of the optical coupling gel layer ranges from 0.08 mm to 0.15 mm, and the refractive index of the optical coupling gel ranges from 14.5 to 1.52. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0029] Figure 1 : A schematic diagram of the structure of the collecting objective lens in Example 1;

[0030] Figure 2 : A light path simulation diagram when the collection objective lens in Example 1 is applied to a flow cytometer;

[0031] Figure 3 As: the corresponding schematic diagram of the even-order aspheric expression;

[0032] Figure 4 is a diagram of image plane light spots of the collecting objective lens of Example 1;

[0033] Figure 5: A schematic diagram of the structure of the collecting objective lens in Example 2;

[0034] Figure 6 : A light path simulation diagram when the collection objective lens in Example 2 is applied to a flow cytometer;

[0035] Figure 7 : The image plane light spot diagram of the collecting objective lens of Example 2;

[0036] Figure 8 : A schematic diagram of the structure of the collecting objective lens in Example 3;

[0037] Fig. 9 : A light path simulation diagram when the collection objective lens in Example 3 is applied to a flow cytometer;

[0038] Fig.10 : The image plane light spot diagram of the collecting objective lens of Example 3;

[0039] Fig.11 : A schematic diagram of the structure of the collecting objective lens in Example 4;

[0040] Fig.12 : A light path simulation diagram when the collection objective lens in Example 4 is applied to a flow cytometer;

[0041] Fig.13 : The image plane light spot diagram of the collecting objective lens of Example 4. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0043] A collecting objective lens according to an embodiment of the present invention comprises: a plano-convex lens, a meniscus lens and a cemented lens arranged in sequence, wherein the principal optical axis of the plano-convex lens, the principal optical axis of the meniscus lens and the principal optical axis of the cemented lens are coaxial, the plane of the plano-convex lens is the light incident surface, and the concave surface of the meniscus lens is the light incident surface.

[0044] Optionally, in the above technical solution, the number of the meniscus lens is at least one;

[0045] When the number of the meniscus lenses is not less than two, all the meniscus lenses are sequentially arranged between the plano-convex lens and the cemented lens.

[0046] Optionally, in the above technical solution, the cemented lens is a double cemented lens or a triple cemented lens. When the cemented lens is a double cemented lens, the number of double cemented lenses is 2, and the outer surface of the positive lens of each double cemented lens is the light incident surface.

[0047] Optionally, in the above technical solution, the effective light aperture of the plano-convex lens is 5 mm to 7 mm, and the radius of curvature of the convex surface of the plano-convex lens is not greater than 5 mm.

[0048] Optionally, in the above technical solution, the focal length of the collecting objective lens and the focal length of the cemented lens are constrained by a constraint relationship, and the constraint relationship is: 1 / 10<f / TTL<1 / 20, 5<f(G2) / f<7, f represents the focal length of the collecting objective lens, TTL represents the total optical length of the collecting objective lens, when the cemented lens is a triple cemented lens, f(G2) represents the focal length of the triple cemented lens, and when the cemented lens is a double cemented lens, f(G2) represents the focal length of the double cemented lens closest to the image plane.

[0049] Optionally, in the above technical solution, the material of the plano-convex lens and the meniscus lens is N-BK7HTi material.

[0050] Optionally, in the above technical solution, the negative lens in the cemented lens is made of F2HTi material.

[0051] A flow cytometer according to an embodiment of the present invention comprises any one of the above-mentioned collection objective lenses.

[0052] Optionally, in the above technical solution, an optical coupling gel layer prepared by using optical coupling gel is provided between the flow cell of the flow cytometer and the plano-convex lens.

[0053] Optionally, in the above technical solution, the thickness of the optical coupling gel layer is in the range of 0.08 mm to 0.15 mm, and the refractive index of the optical coupling gel is in the range of 14.5 to 1.52.

[0054] The collection objective provided by the present invention solves the demand of flow cytometer for large numerical aperture and expands the application wavelength to 350nm~900nm. Specifically:

[0055] Cells or particles labeled with fluorescent substances are arranged one by one through the flow pool of the flow cytometer. When the cells or particles labeled with fluorescent substances are irradiated with laser of a specific wavelength, fluorescent signals and scattered light signals in the ultraviolet, visible or infrared ranges are stimulated. These weaker light signals are distributed within a 360° spatial solid angle. The collecting objective is installed close to one side of the light-transmitting area of ​​the flow pool to collect as many signals as possible.

[0056] In order to prevent the collected light signal from being lost, it is very necessary to couple the side wall of the flow cell and the collection objective lens using an optical coupling gel layer prepared by optical coupling gel. In the present invention, a plano-convex lens, a meniscus lens and two double-cemented lenses are combined using optical coupling gel to achieve design indicators of NA not less than 1.2, working distance greater than 1.5mm and lateral magnification greater than 10×. Under specific material design, the detection wavelength of flow cytometry is broadened from the conventional range of 500nm to 800nm ​​to 350nm to 900nm, wherein, within the wavelength range of 380 to 800nm, the root mean square diffuse light spot of 400μm full field of view can reach within 100μm.

[0057] The technical terms in the present invention are described as follows:

[0058] 1) Plano-convex lens is a type of convex lens, one side of which is flat and the other side is convex, which can be spherical or aspherical;

[0059] 2) The light-transmitting surface of the meniscus lens is concave on one side and convex on the other side. Both surfaces can be spherical or aspherical.

[0060] 3) Doublet lens refers to a lens that is glued together by a low-dispersion positive lens (i.e. convex lens) and a high-dispersion negative lens (i.e. concave lens). The curvature of the glued surface of the positive lens and the curvature of the glued surface of the negative lens in the same doublet lens are the same;

[0061] 4) A triplet lens is made of three lenses glued together, among which there is at least one high-dispersion negative lens and one low-dispersion positive lens. The curvature of the glued surface of all the positive lenses in the same triplet lens is the same as the curvature of the glued surface of the negative lenses.

[0062] The present invention is illustrated by the following examples.

[0063] Embodiment 1:

[0064] like Figure 1 As shown, the collecting objective lens 13 of Example 1 includes a plano-convex lens 131, a meniscus lens 132 and two double-cemented lenses, the meniscus lens 132 is a positive meniscus lens, the two double-cemented lenses are respectively recorded as a first double-cemented lens 133 and a second double-cemented lens 134, the plano-convex lens 131, the meniscus lens 132, the first double-cemented lens 133 and the second double-cemented lens 134 are arranged in sequence, and the main optical axis of the plano-convex lens 131, the main optical axis of the meniscus lens 132, the main optical axis of the first double-cemented lens 133 and the main optical axis of the second double-cemented lens 134 are located on the same axis.

[0065] Among them, the first double-cemented lens 133 is formed by gluing a positive lens 133a and a negative lens 133b, and the gluing surface is S8. The second double-cemented lens 134 is formed by gluing a positive lens 134a and a negative lens 134b, and the gluing surface is S13. Table 1 shows the parameters of the lenses included in the collecting objective lens 13 in Example 1.

[0066] Table 1:

[0067]

[0068] When the collecting lens 13 in Example 1 is applied to a flow cytometer, the optical path is as follows: Figure 2 As shown, the light emitted from the object plane 10 of the flow cytometer passes through the side wall 11 of the flow cell, further passes through the optical coupling gel layer 12, is collected by the collection lens 13 in Example 1, and is focused on the image plane 14. Specifically, the light emitted from the object plane 10 of the flow cytometer passes through S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, and S12 in sequence and is focused on the image plane 14.

[0069] Among them, the optical coupling gel layer 12 is obtained by completely filling the optical coupling gel in the gap less than 0.1 mm between the flow cell 11 and the collecting objective lens 13 in Example 1. The optical coupling gel has the characteristics of stable physical properties and low volatility, presents a paste or gel-like texture, has good optical transmittance in the near-ultraviolet to near-infrared band, and has a refractive index greater than or equal to 1.46.

[0070] In the present invention, the optical refractive index matching liquid preferably used has a refractive index of 1.52, which is greater than the refractive index of quartz, in order to reduce the height at which the edge light is incident on the lens, so as to obtain a better image quality result.

[0071] In Example 1, the aperture of the meniscus lens 14 is no more than 10 mm, and the material of the meniscus lens 14 is FK5HTi glass material. The transition temperature of FK5HTi glass material is relatively low, and it can be produced by molding. Compared with traditional processing methods, it can save a lot of costs in mass production.

[0072] Optionally, there are generally up to 2 to 5 laser emission signals vertically distributed on the object plane 10, and the distribution range is within the field of view of 0.4 mm. The magnification of the collecting objective lens is 11.8×, which is convenient for using common array sensors or optical fiber reception.

[0073] Optionally, in Example 1, the plano-convex lens 131 and the meniscus lens 132 both use low-dispersion crown glass; the positive lenses in the first double cemented lens 133 and the second double cemented lens 134 are made of calcium fluoride in order to better eliminate chromatic aberration in a wide spectral range, and other lens materials use "i-line" glass with good near-ultraviolet transmittance. The "i-line" glass has good internal transmittance when tested at a wavelength of 365nm (i-line) emitted by a high-pressure mercury lamp.

[0074] In Example 1, the material released by Schott in 2023 is used, wherein the plano-convex lens 131 uses N-BK7HTi material, the meniscus lens 132 uses FK5HTi material, and the material of the negative lens in the first double-cemented lens 133 and the second double-cemented lens 134 can be F2HTi material.

[0075] Optionally, in the embodiment, the S6 surface of the meniscus lens 132 is an even-order non-curved surface, Y is the radial distance from the optical axis, and the expression equation of the curved surface shape Z(Y) is:

[0076]

[0077] Where R is the radius of curvature, k is the cone constant, and A 2τ is the even-order aspheric coefficient. The sign of R is determined by whether the center of curvature of the lens surface is located to the left or right of the lens vertex. A positive R indicates that the center of curvature is located to the right of the lens vertex, and a negative R indicates that the center of curvature is located to the left of the lens vertex. Figure 3 shown.

[0078] In the embodiment, K is -1.556, A4 is -6.41×10-4, A6 is -1.66×10-5, and other aspheric coefficients are 0; the remaining surfaces are planes or spherical surfaces.

[0079] The final effect obtained in Example 1 is:

[0080] Only 6 lenses are used to achieve a numerical aperture of NA=1.2, and the image spot size within the 400μm field of view is less than 100μm. Figure 4 , specifically:

[0081] For the five object-space fields of view set, along the axial height (0mm, -0.085mm, -0.164mm, 0.085mm, 0.164mm), and the set wavelengths (0.405nm, 0.488nm, 0.561nm, 0.66nm, 0.78nm), the root mean square diffuse spot of the full field of view is 88.7μm, and 80% of the energy is within 95μm. The root mean square diffuse spot of the on-axis field of view reaches 69.6μm, and the aperture of the optical lens and the thickness of the glass material are minimized to the greatest extent. The designed total optical length is only 99.8mm, which will minimize the absorption of the optical material in the UV band and the sensitivity of the lens to the environment.

[0082] Embodiment 2:

[0083] like Figure 5 As shown, the numerical aperture of the collecting lens 23 in Example 2 is 1.2. Compared with Example 1, one more meniscus lens is used. The collecting lens 23 in Example 2 includes a plano-convex lens 231, two meniscus lenses and two double-cemented lenses. The two meniscus lenses are respectively recorded as a first meniscus lens 232 and a second meniscus lens 233, both of which are positive meniscus lenses. The two double-cemented lenses are respectively recorded as a first double-cemented lens 234 and a second double-cemented lens 235. The plano-convex lens 231, the first meniscus lens 232, the second meniscus lens 233, the first double-cemented lens 234 and The second double-cemented lens 235 is arranged in sequence, and the principal optical axis of the plano-convex lens 231, the principal optical axis of the first meniscus lens 232, the second meniscus lens 233, the principal optical axis of the first double-cemented lens 234 and the principal optical axis of the second double-cemented lens 235 are coaxial, wherein the first double-cemented lens 234 is formed by bonding a positive lens 234a and a negative lens 234b, and the bonding surface is S10, and the second double-cemented lens 235 is formed by bonding a positive lens 235a and a negative lens 235b, and the bonding surface is S13. Table 2 shows the parameters of the lenses included in the collecting objective 13 in Example 2.

[0084] Table 2:

[0085]

[0086]

[0087] When the collecting lens 23 in Example 2 is applied to a flow cytometer, the optical path is as follows: Figure 6As shown, the light emitted from the object plane 20 of the flow cytometer passes through the side wall 21 of the flow cell, further passes through the optical coupling gel layer 22, is collected by the collecting objective lens 23 in Example 2, and is focused on the image plane 24. Specifically, the light emitted from the object plane 20 passes through S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, and S14 in sequence and is focused on the image plane 24.

[0088] In Example 2, the material of the plano-convex lens 331, the first meniscus lens 332 and the second meniscus lens 333 are all N-BK7HTi material, the positive lens in the first double-cemented lens 234 and the second double-cemented lens 235 is made of calcium fluoride material, and the negative lens in the first double-cemented lens 234 and the second double-cemented lens 235 is made of F2HTi material.

[0089] The maximum aperture of all lenses in the collecting lens 23 of Example 2 is 11.3 mm. In Example 2, the designed total optical length of the collecting lens 23 is 135.9 mm, and the magnification of the collecting lens 23 is 12.4×. The final effect is that 7 lenses are used to achieve a numerical aperture of NA=1.2, and the root mean square diffuse light spot within the field of view of 400 μm is less than 100 μm. The image plane light spot diagram of Example 2 is shown in Figure 7 For the set 5 object fields of view, along the axial height (0mm, -0.085mm, 0.17mm, 0.085mm, 0.17mm), and the set wavelength (0.405nm, 0.488nm, 0.561nm, 0.66nm, 0.78nm), the RMS radius of the diffuse spot in the whole field of view is 86.8μm, of which 80% of the energy is circled within 100μm.

[0090] Embodiment 3:

[0091] like Figure 8As shown, the numerical aperture of the collecting objective lens 33 in Example 3 is 1.2. The collecting objective lens 33 in Example 3 includes a plano-convex lens 331, three meniscus lenses and a triplet lens 335. The three meniscus lenses are respectively denoted as a first meniscus lens 332, a second meniscus lens 333 and a third meniscus lens 334, all of which are positive meniscus lenses. The plano-convex lens 331, the first meniscus lens 332, the second meniscus lens 333, the third meniscus lens 334 and the triplet lens 335 are arranged in sequence, and the principal optical axis of the plano-convex lens 331, the principal optical axis of the first meniscus lens 332, the principal optical axis of the second meniscus lens 333, the principal optical axis of the third meniscus lens 334 and the principal optical axis of the triplet lens 335 are coaxial, wherein the triplet lens 335 is composed of two positive lenses and one negative lens glued together, the negative lens is located between the two positive lenses, the two positive lenses are respectively denoted as 335a and 335c, and the one negative lens is denoted as 335b. Table 3 shows the parameters of the lenses included in the collecting objective lens in Example 3.

[0092] Table 3:

[0093]

[0094]

[0095] When the collecting lens 33 in Example 3 is applied to a flow cytometer, the optical path is as follows: Fig. 9 As shown, the fluorescence emitted from the object plane 30 passes through the side wall 31 of the flow cell, further passes through the optical coupling gel layer 32, is collected by the collecting objective lens 33 in Example 3, and is focused on the image plane 16. Specifically, the fluorescence emitted from the object plane 30 passes through S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15 and S16 in sequence and is focused on the image plane 16.

[0096] In Example 3, the plano-convex lens 331, the first meniscus lens 332, the second meniscus lens 333 and the third meniscus lens 334 are all made of N-BK7HTi material, the positive lenses in the triplet lens 335, namely 335a and 335c, are made of calcium fluoride material, and the negative lens 335b in the triplet lens 335 is made of F2HTi material.

[0097] In Example 3, in order to achieve a maximum aperture of 10 mm for the glass lens, the total optical length of the collection lens of Example 3 is designed to be 122.7 mm, and the magnification of the collection lens 33 is 12.1×. The final effect is that 8 lenses are used to achieve a numerical aperture of NA=1.2, and the root mean square diffuse light spot is less than 100 μm in the field of view of 400 μm. The image plane light spot diagram of Example 3 is shown in FIG. Fig.10Specifically, for the set 5 object fields of view, along the axial height (0mm, -0.085mm, -0.17mm, 0.085mm, 0.17mm), and the set wavelength (0.405nm, 0.488nm, 0.561nm, 0.66nm, 0.78nm), the RMS radius of the diffuse light spot in the entire field of view is 91.2μm, and 80% of the energy is confined within 96μm.

[0098] It should be noted that all the lenses in Example 2 and Example 3 use ordinary spherical surfaces and only use three types of glass materials, which are very suitable for traditional cold processing and have a high cost performance.

[0099] Embodiment 4:

[0100] like Fig.11 As shown, the NA of the collecting lens of Embodiment 4 is 1.25, which is larger than the numerical aperture of the collecting lens in the above embodiments and is another preferred embodiment. The collecting lens 43 in Embodiment 4 includes a plano-convex lens, three meniscus lenses, and two double cemented lenses. The three meniscus lenses are respectively denoted as the first meniscus lens 432, the second meniscus lens 433, and the third meniscus lens 444, all of which are positive meniscus lenses. The two double-cemented lenses are respectively denoted as the first double-cemented lens 445 and the second double-cemented lens 446. The plano-convex lens 431, the first meniscus lens 432, the second meniscus lens 433, the third meniscus lens 444, the first double-cemented lens 445, and the second double-cemented lens 446 are arranged in sequence, and the principal optical axis of the plano-convex lens 431, the principal optical axis of the first meniscus lens 432, the principal optical axis of the second meniscus lens 433, the principal optical axis of the third meniscus lens 444, the principal optical axis of the first double-cemented lens 445, and the principal optical axis of the second double-cemented lens 446 are coaxial. Table 4 shows the parameters of the lenses included in the collecting objective in Example 4.

[0101] Table 4:

[0102]

[0103]

[0104] When the collecting lens in Example 4 is applied to a flow cytometer, the optical path is as follows: Fig.12 As shown, the fluorescence emitted from the object plane 40 passes through the side wall 41 of the flow cell, further passes through the optical refractive index matching liquid thin layer 42, is collected by the collecting objective lens 43 in Example 4, and is focused on the image plane 44. Specifically, after passing through S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15 and S16, it is focused on the image plane 44.

[0105] In Example 4, the plano-convex lens 431, the first meniscus lens 432, the second meniscus lens 433 and the third meniscus lens 444 are all made of N-BK7HTi material, the positive lens in the first double-cemented lens 445 and the second double-cemented lens 446 is made of calcium fluoride material, and the negative lens in the first double-cemented lens 445 and the second double-cemented lens 446 is made of F2HTi material;

[0106] In Example 4, the S13 surface is an even-order non-curved surface, and the expression equation is the same as the above equation 1, K is -0.95, A4 is -4.994×10 -5 The use of fewer high-order coefficients greatly reduces the difficulty of lens processing and inspection, and the remaining surfaces of the objective lens are plane or spherical.

[0107] Example 4 achieves a numerical aperture of NA=1.25, and the magnification of the collecting objective lens is 10.1×; and also achieves that the field of view within the range of 400μm is less than 100μm. The image plane light spot diagram of Example 4 is shown in Fig.13 Specifically, for the five object-space fields of view set, along the axial height (0mm, -0.105mm, -0.21mm, 0.105mm, 0.21mm), and the set wavelengths (0.405nm, 0.488nm, 0.561nm, 0.66nm, 0.78nm), the RMS radius of the diffuse spot in the whole field of view is 92.5μm, and 80% of the energy is enclosed within 109μm;

[0108] The NA1.25 objective lens in Example 4 has a collection efficiency at least 10% higher than that of the NA1.2 collection objective lens. Compared with the previous three examples, there are only one or two more glass lenses. Although this increases the complexity of the lens, it is meaningful for practical applications.

[0109] In Example 4, the following effects are achieved by using an optical refractive index matching liquid and combining and optimizing various lens materials and parameters:

[0110] 1) A numerical aperture of 1.2 or greater is achieved. This embodiment can collect fluorescence and scattered light within a range of at least 64.5°. Since the environment in which the flow cytometer generates fluorescence is in a liquid environment (the main component of the general liquid is water, and the refractive index n=1.333), according to the numerical aperture calculation formula (2), the numerical aperture in this embodiment is calculated to be 1.2;

[0111] NA=n0×sinθ.............(2)

[0112] Where NA represents the numerical aperture, n0 represents the refractive index, θ Represents the collection angle (half angle).

[0113] 2) The working distance is greater than 1 mm. In this embodiment, the working distance is about 1.6 mm. The working distance is the distance between the sample and the plane of the first plano-convex lens;

[0114] 3) Broaden the detection wavelength of flow cytometry to the range of 350nm to 900nm, where the root mean square diffuse spot of 400μm full field of view can be within 100μm within the wavelength range of 380 to 800nm;

[0115] The lens of the present invention is specifically used in flow cytometers, and may also be applicable to other application fields with a wide wavelength range and a large numerical aperture.

[0116] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A collection objective lens, characterized in that: Along the optical axis direction from the object side to the image side, it is composed of a plano-convex lens, four positive meniscus lenses and a triplet lens arranged in sequence, the four positive meniscus lenses are respectively recorded as a first positive meniscus lens, a second positive meniscus lens, a third positive meniscus lens and a fourth positive meniscus lens, wherein the plane of the plano-convex lens is a light incident surface, the concave surfaces of the first positive meniscus lens, the second positive meniscus lens, the third positive meniscus lens and the fourth positive meniscus lens are all light incident surfaces, and the triplet lens is composed of a positive lens, a negative lens and a positive lens glued in sequence along the optical axis direction from the object side to the image side; The effective aperture of the plano-convex lens is 5 mm to 7 mm, and the radius of curvature of the convex surface of the plano-convex lens is not greater than 5 mm; The focal length of the collecting objective lens and the focal length of the triplet lens are constrained by a constraint relationship, and the constraint relationship is: 1 / 20<f / TTL<1 / 10, 5<f(G2) / f<7, f represents the focal length of the collecting objective lens, TTL represents the total optical length of the collecting objective lens, and f(G2) represents the focal length of the triplet lens.

2. A collection objective lens according to claim 1, characterized in that: The material of the plano-convex lens and the meniscus lens is N-BK7HTi material.

3. A collection objective lens according to claim 2, characterized in that: The negative lens in the triplet lens is made of F2HTi material.

4. A flow cytometer, characterized in that: A collection objective lens comprising any one of claims 1 to 3.

5. A flow cytometer according to claim 4, characterized in that: An optical coupling gel layer prepared by using optical coupling gel is arranged between the flow cell of the flow cytometer and the plano-convex lens.

6. A flow cytometer according to claim 5, characterized in that: The thickness range of the optical coupling gel layer is: 0.08mm~0.15mm, and the refractive index of the optical coupling gel is 1.52.

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