Long-working-distance diffraction limit microscope objective for optical tweezers and optical tweezers

Abstract

The invention discloses a long working distance diffraction limit microscope objective for optical tweezers and the optical tweezers, the microscope objective comprises five groups of lenses in sequence from object space to image space, the first lens group comprises a first lens and a second lens which are glued, the second lens group comprises a third lens and a fourth lens which are glued, the third lens group comprises a fifth lens and a sixth lens which are glued, and the fifth lens and the sixth lens are glued. The fourth lens group comprises a seventh lens and an eighth lens which are glued; the fifth lens group comprises a ninth lens and a tenth lens; the first to tenth lenses are respectively a biconcave lens, a meniscus lens of which the concave surface faces the image side, a meniscus lens of which the concave surface faces the image side, a biconvex lens, a biconvex lens, a meniscus lens of which the concave surface faces the object side, a biconvex lens, a biconcave lens and a biconvex single lens; and the concave surface of the meniscus lens faces the image side. The working distance of the microscope objective is long, focuses are converged outside the microscope when anti-parallel light beams enter the microscope, and the front focal length FFL is smaller than or equal to-6.345 mm.

Description

Technical Field

[0001] The invention relates to the field of visible light microscopy, and in particular to a long working distance diffraction-limited microscope objective lens and optical tweezers used for optical tweezers. Background Art

[0002] With the rapid development of modern microscopic optics, the resolution of super-resolution optical microscopy has reached the nanometer level, providing a powerful tool for the development of biology and other fields. However, for microscopic research, in addition to "seeing clearly", it is also necessary to be able to touch, and optical tweezers are the hands that can "touch" microscopic particles. It can clamp particles and control their movement and rotation. Optical tweezers are not ordinary "tweezers". Because they use light to manipulate particles, they have the characteristics of no mechanical contact and low damage. Moreover, as long as the appropriate absorption wavelength is selected, the thermal damage of optical tweezers to biological tissues can be almost ignored. Therefore, optical tweezers technology is very suitable for life sciences, colloid physics, chemistry, atomic physics and other fields, including large analysis or single cell mechanical property research, the interaction between DNA and protein molecules, the interaction between colloidal particles, the crystallization process control of crystals, laser capture or cooling of atoms, etc.

[0003] The microscope objective is one of the key components in optical tweezers, which is used to focus the laser beam and observe the manipulated particles. In optical tweezers, the microscope objective usually needs to work in a vacuum environment to reduce the influence of air on laser propagation and improve the performance and stability of the system. Microscope objectives with long working distances are conducive to the design and manufacture of vacuum chambers because they can provide more space to install windows, seals and other necessary vacuum system components. This makes the design and manufacture of vacuum chambers more flexible and also facilitates maintenance and upgrades. In addition, during the use of optical tweezers microscope objectives, there is a problem of reverse parallel light beams. If these reverse light beams converge inside the microscope after passing through the objective, they may cause damage to the lenses or other optical components of the microscope. Summary of the invention

[0004] The purpose of the present invention is to provide a long working distance diffraction-limited microscope objective and optical tweezers for optical tweezers, so as to solve the problem that the long working distance and the reverse parallel light beams converged inside the microscope will cause lens damage.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a long working distance diffraction-limited microscope objective lens for optical tweezers, the microscope objective lens including five lens groups from the object side to the image side, namely, a first lens group, a second lens group, a third lens group, a fourth lens group and a fifth lens group; Among them, the first lens group includes a first lens and a second lens that are cemented together, the second lens group includes a third lens and a fourth lens that are cemented together, the third lens group includes a fifth lens and a sixth lens that are cemented together, the fourth lens group includes a seventh lens and an eighth lens that are cemented together, and the fifth lens group includes a ninth lens and a tenth lens; The first lens is a biconcave lens, the second lens is a meniscus lens with the concave surface facing the image side, the third lens is a meniscus lens with the concave surface facing the image side, the fourth lens is a biconvex lens, the fifth lens is a biconvex lens, the sixth lens is a meniscus lens with the concave surface facing the object side, the seventh lens is a biconvex lens, the eighth lens is a biconcave lens, the ninth lens is a single biconvex lens, and the tenth lens is a meniscus lens with the concave surface facing the image side; The object-side imaging light beam sequentially passes through the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group, and finally converges on the image plane.

[0006] In the above solution, the first lens group satisfies: -4.36 < f1_2 / f < -1.36; where f1_2 is the combined focal length of the first lens group, and f is the combined focal length of the entire micro-optical objective; The second lens group satisfies: 1.86 < f3_4 / f < 5.64; where f3_4 is the combined focal length of the second lens group; The third lens group satisfies: 2.85 < f5_6 / f < 15.25; where f5_6 is the combined focal length of the third lens group; The fourth lens group satisfies: 4.11 < f7_8 / f < 20.68; where f7_8 is the combined focal length of the fourth lens group; The fifth lens group satisfies: 0.78 < f9_10 / f < 2.3; where f9_10 is the combined focal length of the fifth lens group.

[0007] In the above solution, the focal lengths of the first lens and the second lens are f1 and f2 respectively. The central curvature radius on the object side of the first lens is R1, the central curvature radius of the cemented surface is R2, and the central curvature radius on the image side of the second lens is R3, satisfying the following relational expressions: -25.46 ≤ NA * f1 ≤ -10.19; -0.81 ≤ f1 / f ≤ -2.52; 0.39 ≤ (R1 + R2) / (R1 - R2) ≤ 1.17; 22.5 ≤ NA * f2 ≤ 56.27; 2.20 ≤ f2 / f ≤ 5.30; -10.87 ≤ (R2 + R3) / (R2 - R3) ≤ -3.62; The focal lengths of the third lens and the fourth lens are f3 and f4 respectively. The central curvature radius on the object side of the third lens is R4, the central curvature radius of the cemented surface is R5, and the central curvature radius on the image side of the fourth lens is R6, satisfying the following relational expressions: -181.27≤NA*f3≤-72.5; -10.23≤f3 / f≤-6.54; 2.75≤(R4+R5) / (R4-R5)≤8.25; 21.11≤NA*f4≤52.8; 1.12≤f4 / f≤4.76; -0.24≤(R5+R6) / (R5-R6)≤-0.72; The focal lengths of the fifth lens and the sixth lens are f5 and f6 respectively, the central curvature radius of the object side of the fifth lens is R7, the central curvature radius of the cemented surface is R8, and the central curvature radius of the image side of the sixth lens is R9, satisfying the following relationship: 10.66≤NA*f5≤26.65; 0.88≤f5 / f≤4.35; 0.25≤(R7+R8) / (R7-R8)≤0.76; -29.99≤NA*f6≤11.96; -5.24≤f6 / f≤-0.42; -2.26≤(R8+R9) / (R8-R9)≤-0.75; The focal lengths of the seventh lens and the eighth lens are f7 and f8 respectively, the central curvature radius of the object side of the seventh lens is R10, the central curvature radius of the cemented surface is R11, and the central curvature radius of the image side of the eighth lens is R12, satisfying the following relationship: 13.71≤NA*f7≤34.28; 0.96≤f7 / f≤3.44; -0.05≤(R10+R11) / (R10-R11)≤-0.01; -14.44≤NA*f8≤-36.10; -4.3≤f8 / f≤-0.52; -0.79≤(R11+R12) / (R11-R12)≤-0.27; The focal lengths of the ninth lens and the tenth lens are f9 and f10 respectively, the central curvature radius of the ninth lens on the object side is R13, the central curvature radius of the image side is R14, the central curvature radius of the tenth lens on the object side is R15, and the central curvature radius of the tenth lens on the image side is R16, satisfying the following relationship: 21.42≤NA*f9≤53.54; 1.08≤f9 / f≤5.63; 0.003≤(R13+R14) / (R13-R14)≤0.01; 27.9≤NA*f10≤69.76; 1.57≤f10 / f≤6.42; -2.45≤(R15+R16) / (R15-R16)≤-0.82; Among them, the numerical aperture of the microscope objective is NA, and the focal length is f.

[0008] In the above scheme, after the reverse parallel light beam passes through the microscope objective lens, the image point converges outside the microscope objective lens, and the front focal length FFL is less than or equal to -6.345 mm.

[0009] In the above scheme, the distance from the vertex of the first surface of the first lens group to the last surface of the fifth lens group is less than or equal to 48.904 mm, the working distance is greater than or equal to 27.463 mm, and the ratio of the two is less than or equal to 1.78.

[0010] In the above solution, the axial thickness of the ninth lens is d9, which satisfies the following relationship: 0.1≤d9 / TTL≤0.25; the axial thickness of the tenth lens is d10, which satisfies the following relationship: 0.11≤d10 / TTL≤0.22; wherein TTL is the total optical length of the microscope objective.

[0011] In the above scheme, the microscope objective has a vertical axis chromatic aberration of less than or equal to 0.08um and an axial chromatic aberration of less than or equal to 1.1um within the wavelength range of 420nm to 780nm; its total optical length TTL is less than or equal to 76.367mm, and its numerical aperture NA is 0.45 to 0.65.

[0012] In the above solution, the microscope objective lens further includes a protection window, and the protection window is located between the fifth lens group and the image plane; The object-side imaging light beam passes through the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, and the protective window in sequence, and finally converges on the image plane.

[0013] In the above scheme, the medium between the protection window and the image plane is vacuum, and the medium between the other lens groups is air.

[0014] In a second aspect, the present invention provides an optical tweezers, comprising any one of the above-mentioned long working distance diffraction-limited microscope objective lenses for optical tweezers.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: The long working distance diffraction-limited microscope objective lens for optical tweezers of the present invention has excellent optical performance, a long working distance, and a focus outside the microscope when an anti-parallel light beam enters the microscope, and can be used as an optical tweezers microscope objective lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the optical system of the present invention; Figure 2 A schematic diagram of an anti-parallel light beam passing through the microscope objective lens of the present invention; Figure 3 for Figure 1 Transfer function curves of microscope objective lens at 2000lp / mm in each field of view; Figure 4for Figure 1 Schematic diagram of axial chromatic aberration of the optical system shown; Figure 5 for Figure 1 Schematic diagram of chromatic aberration of magnification of the optical system shown; Figure 6 for Figure 1 Schematic diagram of field curvature and distortion of the optical system shown.

[0017] In the figure, G1-first mirror group, G2-second mirror group, G3-third mirror group, G4-fourth mirror group, G5-fifth mirror group; L1-first lens, L2-second lens, L3-third lens, L4-fourth lens, L5-fifth lens, L6-sixth lens, L7-seventh lens, L8-eighth lens, L9-ninth lens, L10-tenth lens. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0019] The invention provides a long working distance diffraction-limited microscope objective lens for optical tweezers, which is used in the fields of laser optical tweezers and nanotechnology, and can realize flat-field apochromatism in the visible light band of 420-780 nm. The microscope objective lens includes: a first lens group, a second lens group, a third lens group, a fourth lens group, and a fifth lens group in sequence from the object plane to the image plane along the optical axis. It has excellent optical performance. In the 420-780 nm band, the vertical axis chromatic aberration is less than or equal to 0.08 um, and the axial chromatic aberration is less than or equal to 1.1 um; it also has a long working distance, the distance from the vertex of the first surface of the first lens group to the last surface of the fifth lens group is less than or equal to 48.904 mm, the working distance is greater than or equal to 27.463 mm, and the ratio of the two is less than or equal to 1.78. At the same time, when the reverse parallel light beam enters the microscope, the focus converges outside the microscope, and the front focal length FFL is less than or equal to -6.345 mm, which can prevent the opposite laser beam from converging inside the microscope after passing through the microscope, causing damage to the lens. The NA of the microscope objective lens is 0.45 to 0.65.

[0020] Example 1 The long working distance diffraction-limited microscope objective lens for optical tweezers of this embodiment is provided with five coaxial lens groups (ten lenses), which are composed of a first lens group, a second lens group, a third lens group, a fourth lens group, and a fifth lens group; the parallel light beam passes through the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group in sequence, and then passes through the protective window, and finally converges in the vacuum cavity (there is a vacuum between the protective window and the image point); after the reverse parallel light beam passes through the microscope objective lens, the image point converges outside the microscope objective lens, and the front focal length FFL is less than or equal to -6.345 mm.

[0021] The first lens group is composed of a double concave lens (first lens) and a meniscus lens (second lens) with the concave side facing the image side, the second lens group is composed of a meniscus lens (third lens) with the concave side facing the image side and a double convex lens (fourth lens), the third lens group is composed of a double convex lens (fifth lens) and a meniscus lens (sixth lens) with the concave side facing the object side, the fourth lens group is composed of a double convex lens (seventh lens) and a double concave lens (eighth lens), the fifth lens group includes a ninth lens and a tenth lens, the ninth lens is a double convex single lens, and the tenth lens is a meniscus lens with the concave side facing the image side.

[0022] The distance from the vertex of the first surface of the first lens group to the last surface of the fifth lens group is less than or equal to 48.904 mm, the working distance is greater than or equal to 27.463 mm, and the ratio of the two is less than or equal to 1.78.

[0023] The total optical length TTL of the microscope objective is less than or equal to 76.367mm. In the 420nm~780nm band, the vertical axis chromatic aberration is less than or equal to 0.08um, and the axial chromatic aberration is less than or equal to 1.1um, which has good chromatic aberration control ability. All five groups of lenses are spherical lenses, which are used to achieve flat-field apochromatism in the 420nm~780nm band.

[0024] Example 2 The long working distance diffraction-limited microscope objective lens used for optical tweezers in this embodiment is as follows: Figure 1 As shown, there are five groups of lenses from the object side to the image side, among which: The first lens group G1 includes a first lens L1 and a second lens L2, the second lens group G2 includes a third lens L3 and a fourth lens L4, the third lens group G3 includes a fifth lens L5 and a sixth lens L6, the fourth lens group G4 includes a seventh lens L7 and an eighth lens L8, and the fifth lens group G5 includes a ninth lens L9 and a tenth lens L10.

[0025] The object-side imaging light beam passes through the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the protective window in sequence, and finally converges on the image plane.

[0026] The long working distance diffraction-limited microscope objective lens for optical tweezers has a numerical aperture of NA, a focal length of f, a total optical length of TTL, and a front focal length of FFL.

[0027] Preferably, the first lens group is formed by gluing a first lens and a second lens, the focal lengths of the first lens and the second lens are f1 and f2 respectively, the central curvature radius of the object side of the first lens is R1, the central curvature radius of the gluing surface is R2, the central curvature radius of the image side of the second lens is R3, and the following relationship is satisfied: -25.46≤NA*f1≤-10.19; -0.81≤f1 / f≤-2.52; 0.39≤(R1+R2) / (R1-R2)≤1.17; 22.5≤NA*f2≤56.27; 2.20≤f2 / f≤5.30; -10.87≤(R2+R3) / (R2-R3)≤-3.62; Preferably, the second lens group is formed by cementing a third lens and a fourth lens, the focal lengths of the third lens and the fourth lens are f3 and f4 respectively, the central curvature radius of the object side of the third lens is R4, the central curvature radius of the cementing surface is R5, the central curvature radius of the image side of the fourth lens is R6, and the following relationship is satisfied: -181.27≤NA*f3≤-72.5; -10.23≤f3 / f≤-6.54; 2.75≤(R4+R5) / (R4-R5)≤8.25; 21.11≤NA*f4≤52.8; 1.12≤f4 / f≤4.76; -0.24≤(R5+R6) / (R5-R6)≤-0.72; Preferably, the third lens group is formed by cementing a fifth lens and a sixth lens, the focal lengths of the fifth lens and the sixth lens are f5 and f6 respectively, the central curvature radius of the object side of the fifth lens is R7, the central curvature radius of the cementing surface is R8, the central curvature radius of the image side of the sixth lens is R9, and the following relationship is satisfied: 10.66≤NA*f5≤26.65; 0.88≤f5 / f≤4.35; 0.25≤(R7+R8) / (R7-R8)≤0.76; -29.99≤NA*f6≤11.96; -5.24≤f6 / f≤-0.42; -2.26≤(R8+R9) / (R8-R9)≤-0.75; Preferably, the fourth lens group is formed by cementing a seventh lens and an eighth lens, the focal lengths of the seventh lens and the eighth lens are f7 and f8 respectively, the central curvature radius of the object side of the seventh lens is R10, the central curvature radius of the cementing surface is R11, the central curvature radius of the image side of the eighth lens is R12, and the following relationship is satisfied: 13.71≤NA*f7≤34.28; 0.96≤f7 / f≤3.44; -0.05≤(R10+R11) / (R10-R11)≤-0.01; -14.44≤NA*f8≤-36.10; -4.3≤f8 / f≤-0.52; -0.79≤(R11+R12) / (R11-R12)≤-0.27; Preferably, the fifth lens group consists of a ninth lens and a tenth lens, the focal lengths of the ninth lens and the tenth lens are f9 and f10 respectively, the central curvature radius of the object side of the ninth lens is R13, the central curvature radius of the image side is R14, the central curvature radius of the object side of the tenth lens is R15, the central curvature radius of the image side of the tenth lens is R16, and the following relationship is satisfied: 21.42≤NA*f9≤53.54; 1.08≤f9 / f≤5.63; 0.003≤(R13+R14) / (R13-R14)≤0.01; 27.9≤NA*f10≤69.76; 1.57≤f10 / f≤6.42; -2.45≤(R15+R16) / (R15-R16)≤-0.82.

[0028] Preferably, the materials of the five lens groups are all made of common glass materials.

[0029] Preferably, the medium between the protection window and the image plane is a vacuum, and the medium between the other lens groups is air.

[0030] Preferably, the distance from the vertex of the first surface of the first lens group to the last surface of the fifth lens group is less than or equal to 48.904 mm, the working distance is greater than or equal to 27.463 mm, and the ratio of the two is less than or equal to 1.78; Figure 2 As shown, when the reverse parallel light beam enters the microscope, the focus is gathered outside the microscope, and the front focal length FFL of the microscope objective is less than or equal to -6.345mm; in the 420nm~780nm band, the vertical axis chromatic aberration is less than or equal to 0.08um, and the axial chromatic aberration is less than or equal to 1.1um.

[0031] Example 3 like Figure 1 As shown, an embodiment of the present invention provides a long working distance diffraction-limited microscope objective lens for optical tweezers, which includes five groups of lenses from the object side to the image side, wherein: The first lens group G1 includes a first lens L1 and a second lens L2, the second lens group G2 includes a third lens L3 and a fourth lens L4, the third lens group G3 includes a fifth lens L5 and a sixth lens L6, the fourth lens group G4 includes a seventh lens L7 and an eighth lens L8, and the fifth lens group G5 includes a ninth lens L9 and a tenth lens L10. The object-side imaging light beam sequentially passes through the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the protective window, and finally converges on the focal plane.

[0032] For the focal length of the first lens group, -4.36 < f1_2 / f < -1.36, where f1_2 is the combined focal length of the first lens group and f is the combined focal length of the entire microscopic objective; within this range, spherical aberration and lateral chromatic aberration can be corrected well, and various other aberrations can be corrected simultaneously.

[0033] For the focal length of the second lens group, 1.86 < f3_4 / f < 5.64, where f3_4 is the combined focal length of the second lens group and f is the combined focal length of the entire microscopic objective; this can prevent the focal length of the second lens group from exceeding the upper limit, resulting in insufficient diopter of the second lens group, a bulky lens structure, and difficulty in comprehensively correcting various aberrations. It can also prevent the focal length of the second lens group from exceeding the lower limit, which would cause excessive field curvature and coma that are difficult to correct.

[0034] For the focal length of the third lens group, 2.85 < f5_6 / f < 15.25, where f5_6 is the combined focal length of the third lens group and f is the combined focal length of the entire microscopic objective; within this range, spherical aberration and axial chromatic aberration of the system can be corrected well.

[0035] For the focal length of the fourth lens group, 4.11 < f7_8 / f < 20.68, where f7_8 is the combined focal length of the fourth lens group and f is the combined focal length of the entire microscopic objective; through reasonable distribution of the optical power, the system has better imaging quality and lower sensitivity.

[0036] For the focal length of the fifth lens group, 0.78 < f9_10 / f < 2.3, where f9_10 is the combined focal length of the fifth lens group and f is the combined focal length of the entire microscopic objective; within this range, reasonably controlling the relationship between the shapes of the ninth and tenth lenses, the refractive index of the materials, and the focal length of the microscopic objective is beneficial to controlling the light path and enabling the light to transition smoothly.

[0037] In this embodiment, the object side of the first lens is concave and the image side is concave. The central curvature radius of the object side of the first lens is R1, and the central curvature radius of the image side is R2, and they satisfy the following relationship 0.39 ≤ (R1 + R2) / (R1 - R2) ≤ 1.17, which is beneficial to controlling the FFL of the system, so that after the reverse parallel light beam passes through the microscopic objective, the image point is located outside the microscopic objective.

[0038] In this embodiment, the first lens group includes at least two cemented lenses and at least one single lens with positive optical power, and satisfies the relationship: 2.20≤f2 / f≤5.30; wherein f2 is the focal length of a single lens with positive optical power of the first lens group. Within this range, spherical aberration and axial chromatic aberration can be better corrected, while other chromatic aberrations can be corrected at the same time.

[0039] In this embodiment, the object side of the ninth lens is convex, the image side is convex, the axial thickness of the ninth lens is d9, and the following relationship is satisfied: 0.1≤d9 / TTL≤0.25, which specifies the ratio of the axial thickness of the ninth lens L9 to the total optical length TTL of the microscope objective lens, which is beneficial to controlling the total optical length of the microscope objective lens.

[0040] In the present embodiment, the object side of the tenth lens is convex, the image side is concave, the axial thickness of the tenth lens is d10, and the following relationship is satisfied: 0.11≤d10 / TTL≤0.22, which specifies the ratio of the axial thickness of the tenth lens to the total optical length TTL of the microscope objective lens, which is beneficial to control the total optical length of the microscope objective lens.

[0041] In this embodiment, the total optical length TTL of the microscope objective is less than or equal to 76.367 mm. In this embodiment, the distance from the vertex of the first surface of the first lens group to the last surface of the fifth lens group is less than or equal to 48.904 mm, the working distance is greater than or equal to 27.463 mm, and the ratio of the two is less than or equal to 1.78.

[0042] In this embodiment, when the reverse parallel light beam enters the microscope, the focus is gathered outside the microscope, and the front focal length FFL is less than or equal to -6.345 mm.

[0043] In this embodiment, within the wavelength range of 420 nm to 780 nm, the vertical axis chromatic aberration of the microscope objective lens is less than or equal to 0.08 um, and the axial chromatic aberration is less than or equal to 1.1 um.

[0044] In this embodiment, the five lens groups are all made of commonly used glass materials from Chengdu Guangming.

[0045] In this embodiment, the medium between the protection window and the image plane is vacuum, and the medium between the other lens groups is air.

[0046] The long working distance diffraction-limited microscope objective lens for optical tweezers of the present invention will be described below with examples.

[0047] Table 1 shows the design data of the long working distance diffraction-limited microscope objective lens used for optical tweezers according to the embodiment of the present invention.

[0048] Table 1 Design data table of microscope objective

[0049] Figure 3 It is the transfer function curve of the microscope objective lens at each field of view at 2000lp / mm; Figure 4 Schematic diagram of axial chromatic aberration; Figure 5 Schematic diagram of magnification chromatic aberration; Figure 6 Schematic diagram of field curvature and distortion. It can be seen that the microscope objective has excellent optical performance.

[0050] In addition, the present invention also provides an optical tweezer, which includes the long working distance diffraction-limited microscope objective lens for optical tweezers described in any one of the above technical solutions.

[0051] In summary, the present invention provides a long working distance diffraction-limited microscope objective lens for optical tweezers, which has excellent optical performance, a long working distance, and a focus outside the microscope when the reverse parallel light beam is incident on the microscope, and can be used as an optical tweezers microscope objective lens.

[0052] It should be noted that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0053] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0054] It will be easily understood by those skilled in the art that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A long working distance diffraction-limited microscope objective lens for optical tweezers, characterized in that: The micro-optical objective lens includes five groups of lenses in sequence from the object side to the image side, namely the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group; Among them, the first lens group includes a cemented first lens and a second lens, the second lens group includes a cemented third lens and a fourth lens, the third lens group includes a cemented fifth lens and a sixth lens, the fourth lens group includes a cemented seventh lens and an eighth lens, and the fifth lens group includes a ninth lens and a tenth lens; The first lens is a double concave lens, the second lens is a meniscus lens with the concave surface facing the image side, the third lens is a meniscus lens with the concave surface facing the image side, the fourth lens is a double convex lens, the fifth lens is a double convex lens, the sixth lens is a meniscus lens with the concave surface facing the object side, the seventh lens is a double convex lens, the eighth lens is a double concave lens, the ninth lens is a single double convex lens, and the tenth lens is a meniscus lens with the concave surface facing the image side; The object-side imaging light beam passes through the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group in sequence, and finally converges on the image plane.

2. The long working distance diffraction-limited microscope objective lens for optical tweezers according to claim 1, characterized in that: The first lens group satisfies: -4.36 < f1_2 / f < -1.36; where f1_2 is the combined focal length of the first lens group, and f is the combined focal length of the entire micro-optical objective lens; The second lens group satisfies: 1.86 < f3_4 / f < 5.64; where f3_4 is the combined focal length of the second lens group; The third lens group satisfies: 2.85 < f5_6 / f < 15.25; where f5_6 is the combined focal length of the third lens group; The fourth lens group satisfies: 4.11 < f7_8 / f < 20.68; where f7_8 is the combined focal length of the fourth lens group; The fifth lens group satisfies: 0.78 < f9_10 / f < 2.3; where f9_10 is the combined focal length of the fifth lens group.

3. The long working distance diffraction-limited microscope objective lens for optical tweezers according to claim 1, characterized in that: The focal lengths of the first lens and the second lens are f1 and f2 respectively. The central curvature radius on the object side of the first lens is R1, the central curvature radius of the cemented surface is R2, and the central curvature radius on the image side of the second lens is R3, satisfying the following relational expressions: -25.46 ≤ NA * f1 ≤ -10.19; -0.81 ≤ f1 / f ≤ -2.52; 0.39 ≤ (R1 + R2) / (R1 - R2) ≤ 1.17; 22.5 ≤ NA * f2 ≤ 56.27; 2.20 ≤ f2 / f ≤ 5.30; -10.87 ≤ (R2 + R3) / (R2 - R3) ≤ -3.62; The focal lengths of the third lens and the fourth lens are f3 and f4 respectively. The central curvature radius on the object side of the third lens is R4, the central curvature radius of the cemented surface is R5, and the central curvature radius on the image side of the fourth lens is R6, satisfying the following relational expressions: -181.27 ≤ NA * f3 ≤ -72.5; -10.23 ≤ f3 / f ≤ -6.54; 2.75 ≤ (R4 + R5) / (R4 - R5) ≤ 8.25; 21.11 ≤ NA * f4 ≤ 52.8; 1.12 ≤ f4 / f ≤ 4.76; -0.24 ≤ (R5 + R6) / (R5 - R6) ≤ -0.72; The focal lengths of the fifth lens and the sixth lens are f5 and f6 respectively, the central curvature radius of the object side of the fifth lens is R7, the central curvature radius of the cemented surface is R8, and the central curvature radius of the image side of the sixth lens is R9, satisfying the following relationship: 10.66≤NA*f5≤26.65; 0.88≤f5 / f≤4.35; 0.25≤(R7+R8) / (R7-R8)≤0.76; -29.99≤NA*f6≤11.96; -5.24≤f6 / f≤-0.42; -2.26≤(R8+R9) / (R8-R9)≤-0.75; The focal lengths of the seventh lens and the eighth lens are f7 and f8 respectively, the central curvature radius of the object side of the seventh lens is R10, the central curvature radius of the cemented surface is R11, and the central curvature radius of the image side of the eighth lens is R12, satisfying the following relationship: 13.71≤NA*f7≤34.28; 0.96≤f7 / f≤3.44; -0.05≤(R10+R11) / (R10-R11)≤-0.01; -14.44≤NA*f8≤-36.10; -4.3≤f8 / f≤-0.52; -0.79≤(R11+R12) / (R11-R12)≤-0.27; The focal lengths of the ninth lens and the tenth lens are f9 and f10 respectively, the central curvature radius of the ninth lens on the object side is R13, the central curvature radius of the image side is R14, the central curvature radius of the tenth lens on the object side is R15, and the central curvature radius of the tenth lens on the image side is R16, satisfying the following relationship: 21.42≤NA*f9≤53.54; 1.08≤f9 / f≤5.63; 0.003≤(R13+R14) / (R13-R14)≤0.01; 27.9≤NA*f10≤69.76; 1.57≤f10 / f≤6.42; -2.45≤(R15+R16) / (R15-R16)≤-0.82; Among them, the numerical aperture of the microscope objective is NA, and the focal length is f.

4. The long working distance diffraction-limited microscope objective lens for optical tweezers according to claim 3, characterized in that: After the reverse parallel light beam passes through the microscope objective, the image point converges outside the microscope objective, and the front focal length FFL is less than or equal to -6.345mm.

5. The long working distance diffraction-limited microscope objective lens for optical tweezers according to claim 3, characterized in that: The distance from the vertex of the first surface of the first lens group to the last surface of the fifth lens group is less than or equal to 48.904 mm, the working distance is greater than or equal to 27.463 mm, and the ratio of the two is less than or equal to 1.

78.

6. The long working distance diffraction-limited microscope objective lens for optical tweezers according to claim 3, characterized in that: The axial thickness of the ninth lens is d9, which satisfies the following relationship: 0.1≤d9 / TTL≤0.25; the axial thickness of the tenth lens is d10, which satisfies the following relationship: 0.11≤d10 / TTL≤0.22; wherein TTL is the total optical length of the microscope objective lens.

7. The long working distance diffraction-limited microscope objective lens for optical tweezers according to claim 6, characterized in that: The microscope objective has a vertical axis chromatic aberration of less than or equal to 0.08um and an axial chromatic aberration of less than or equal to 1.1um within the wavelength range of 420nm to 780nm; Its total optical length TTL is less than or equal to 76.367 mm, and its numerical aperture NA is 0.45 to 0.

65.

8. The long working distance diffraction-limited microscope objective lens for optical tweezers according to claim 1, characterized in that: The microscope objective lens also includes a protection window, which is located between the fifth lens group and the image plane; The object-side imaging light beam passes through the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, and the protective window in sequence, and finally converges on the image plane.

9. The long working distance diffraction-limited microscope objective lens for optical tweezers according to claim 8, characterized in that: The medium between the protection window and the image plane is vacuum, and the medium between the other lens groups is air.

10. An optical tweezer, characterized in that: The optical tweezers include the long working distance diffraction-limited microscope objective lens for optical tweezers as claimed in any one of claims 1 to 9.

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