A long working distance diffraction-limited microscope objective and optical tweezers for use

Abstract

This invention discloses a long working distance diffraction-limited microscope objective and optical tweezers for optical tweezers. The microscope objective comprises five lens groups from the object side to the image side. The first lens group includes cemented first and second lenses; the second lens group includes cemented third and fourth lenses; the third lens group includes cemented fifth and sixth lenses; the fourth lens group includes cemented seventh and eighth lenses; and the fifth lens group includes ninth and tenth lenses. The first to tenth lenses are respectively a biconcave lens, a meniscus lens with its concave surface facing the image side, a meniscus lens with its concave surface facing the image side, a biconvex lens, a biconvex lens, a meniscus lens with its concave surface facing the object side, a biconvex lens, a biconcave lens, a biconvex single lens, and a meniscus lens with its concave surface facing the image side. This microscope objective has a long working distance, and when a reverse parallel beam is incident on the microscope, the focal point converges outside the microscope, with a front focal length (FFL) less than or equal to -6.345 mm.

Description

Technical Field

[0001] This invention relates to the field of visible light microscopy, and more specifically to a long working distance diffraction-limited microscope objective and optical tweezers for use with optical tweezers. Background Technology

[0002] With the rapid development of modern microscopy, super-resolution optical microscopy has achieved nanometer-level resolution, providing a powerful tool for advancements in fields such as biology. However, for research at the microscopic scale, in addition to "seeing clearly," it is also necessary to be able to touch the microscopic particles. Optical tweezers are that "hand" that allows us to "touch" the microscopic particles. They can hold 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 is almost negligible. Therefore, optical tweezers technology is very suitable for life sciences, colloid physics, chemistry, atomic physics, and other fields, including the study of the mechanical properties of large-scale analysis or single cells, the interaction between DNA and protein molecules, the interaction between colloidal particles, the control of crystal crystallization processes, and laser trapping or cooling of atoms.

[0003] Microscope objectives are a key component of optical tweezers, used to focus laser beams and observe manipulated particles. In optical tweezers, microscope objectives typically operate in a vacuum environment to minimize the impact of air on laser propagation and improve system performance and stability. Long working distances of microscope objectives facilitate the design and fabrication of vacuum cavities, as they provide more space for installing windows, seals, and other necessary vacuum system components. This allows for greater flexibility in the design and fabrication of vacuum cavities, as well as easier maintenance and upgrades. Furthermore, optical tweezers microscope objectives present a problem of antiparallel beams during use. If these antiparallel beams converge inside the microscope after passing through the objective, they may damage the microscope's lenses or other optical components. Summary of the Invention

[0004] The purpose of this invention is to provide a long working distance diffraction-limited microscope objective and optical tweezers for optical tweezers, which solves the problem of lens damage caused by long working distance and the convergence of anti-parallel beams inside the microscope.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a long working distance diffraction-limited microscope objective for optical tweezers, the microscope objective comprising 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.

[0007] 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;

[0008] The first lens is a biconcave lens, the second lens is a meniscus lens with a concave surface facing the image side, the third lens is a meniscus lens with a 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 a 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 a concave surface facing the image side;

[0009] 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.

[0010] 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 microscopic objective lens;

[0011] 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;

[0012] 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;

[0013] 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;

[0014] 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.

[0015] 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:

[0016] -25.46 ≤ NA * f1 ≤ -10.19; -2.52 ≤ f1 / f ≤ -0.81; 0.39 ≤ (R1 + R2) / (R1 - R2) ≤ 1.17;

[0017] 22.5 ≤ NA * f2 ≤ 56.27; 2.20 ≤ f2 / f ≤ 5.30; -10.87 ≤ (R2 + R3) / (R2 - R3) ≤ -3.

[0018] The focal lengths of the third and fourth lenses are f3 and f4, respectively. The central radius of curvature of the object side of the third lens is R4, and the central radius of curvature of the cemented surface is R5. The central radius of curvature of the image side of the fourth lens is R6, satisfying the following relationship:

[0019] -181.27≤NA*f3≤-72.5; -10.23≤f3 / f≤-6.54; 2.75≤(R4+R5) / (R4-R5)≤8.25;

[0020] 21.11≤NA*f4≤52.8; 1.12≤f4 / f≤4.76; -0.72≤(R5+R6) / (R5-R6)≤-0.24;

[0021] The focal lengths of the fifth and sixth lenses are f5 and f6, respectively. The central radius of curvature of the fifth lens on the object side is R7, and the central radius of curvature of the cemented surface is R8. The central radius of curvature of the sixth lens on the image side is R9, satisfying the following relationship:

[0022] 10.66≤NA*f5≤26.65; 0.88≤f5 / f≤4.35; 0.25≤(R7+R8) / (R7-R8)≤0.76;

[0023] -29.99≤NA*f6≤11.96; -5.24≤f6 / f≤-0.42; -2.26≤(R8+R9) / (R8-R9)≤-0.75;

[0024] The seventh and eighth lenses have focal lengths of f7 and f8, respectively. The central radius of curvature of the seventh lens on the object side is R10, and the central radius of curvature of the cemented surface is R11. The central radius of curvature of the eighth lens on the image side is R12, satisfying the following relationship:

[0025] 13.71≤NA*f7≤34.28; 0.96≤f7 / f≤3.44; -0.05≤(R10+R11) / (R10-R11)≤-0.01;

[0026] -36.10≤NA*f8≤-14.44; -4.3≤f8 / f≤-0.52; -0.79≤(R11+R12) / (R11-R12)≤-0.27;

[0027] The focal lengths of the ninth and tenth lenses are f9 and f10, respectively. The central radius of curvature of the ninth lens on the object side is R13, and the central radius of curvature on the image side is R14. The central radius of curvature of the tenth lens on the object side is R15, and the central radius of curvature on the image side is R16. These conditions satisfy the following relationship:

[0028] 21.42≤NA*f9≤53.54; 1.08≤f9 / f≤5.63; 0.003≤(R13+R14) / (R13-R14)≤0.01;

[0029] 27.9≤NA*f10≤69.76; 1.57≤f10 / f≤6.42; -2.45≤(R15+R16) / (R15-R16)≤-0.82;

[0030] The numerical aperture of the microscope objective is NA, and the focal length is f.

[0031] In the above scheme, after the reverse parallel 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 -6.345 mm.

[0032] In the above scheme, the distance from the vertex of the first face of the first mirror group to the last face of the fifth mirror 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.

[0033] In the above scheme, the on-axis thickness of the ninth lens is d9, which satisfies the following relationship: 0.1≤d9 / TTL≤0.25; the on-axis thickness of the tenth lens is d10, which satisfies the following relationship: 0.11≤d10 / TTL≤0.22; where TTL is the total optical length of the microscope objective.

[0034] In the above scheme, the microscope objective has a transverse chromatic aberration of less than or equal to 0.08 μm and an axial chromatic aberration of less than or equal to 1.1 μm in the 420 nm to 780 nm wavelength range; 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.

[0035] In the above scheme, the microscope objective also includes a protective window, which is located between the fifth lens group and the image plane;

[0036] The object-side imaging beam passes sequentially through the first mirror group, the second mirror group, the third mirror group, the fourth mirror group, the fifth mirror group, and the protective window, and finally converges on the image plane.

[0037] In the above scheme, the medium between the protective window and the image plane is a vacuum, while the medium between the other lens groups is air.

[0038] In a second aspect, the present invention provides an optical tweezers comprising the long working distance diffraction-limited microscope objective for optical tweezers as described in any one of the above.

[0039] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0040] The long working distance diffraction-limited microscope objective for optical tweezers of the present invention has excellent optical performance. With a long working distance, the focal point of the reverse parallel beam incident on the microscope is focused outside the microscope, and it can be used as an optical tweezers microscope objective. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the optical system structure of the present invention;

[0042] Figure 2 A schematic diagram showing a reverse parallel beam of light passing through the microscope objective of this invention;

[0043] Figure 3 for Figure 1 Transfer function curves of microscope objectives at 2000 lp / mm in various fields of view;

[0044] Figure 4 for Figure 1 A schematic diagram of the axial chromatic aberration of the optical system shown.

[0045] Figure 5 for Figure 1 A schematic diagram of chromatic aberration at magnification in the optical system shown.

[0046] Figure 6 for Figure 1 A schematic diagram of the field curvature and distortion of the optical system shown.

[0047] In the diagram, G1 is the first lens group, G2 is the second lens group, G3 is the third lens group, G4 is the fourth lens group, and G5 is the fifth lens group; L1 is the first lens, L2 is the second lens, L3 is the third lens, L4 is the fourth lens, L5 is the fifth lens, L6 is the sixth lens, L7 is the seventh lens, L8 is the eighth lens, L9 is the ninth lens, and L10 is the tenth lens. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0049] This invention provides a long working distance diffraction-limited microscope objective for optical tweezers, applicable to the fields of laser optical tweezers and nanotechnology, capable of achieving flat-field apochromatic light in the 420–780 nm visible light band. The microscope objective comprises, sequentially from the object plane to the image plane along the optical axis, five lens groups. It exhibits excellent optical performance, with transverse chromatic aberration less than or equal to 0.08 μm and axial chromatic aberration less than or equal to 1.1 μm within the 420 nm–780 nm wavelength range. It also features a long working distance; the distance from the vertex of the first facet of the first lens group to the last facet of the fifth lens group is less than or equal to 48.904 mm, and the working distance is greater than or equal to 27.463 mm, with a ratio less than or equal to 1.78. Furthermore, when a counter-parallel beam is incident on the microscope, the focal point converges outside the microscope, with a front focal length (FFL) less than or equal to -6.345 mm, preventing the opposing laser beam from converging inside the microscope after passing through it and causing damage to the lenses. The NA of this microscope objective is 0.45–0.65.

[0050] Example 1

[0051] The long working distance diffraction-limited microscope objective for optical tweezers in this embodiment has five coaxial lens groups (ten lenses), consisting of a first lens group, a second lens group, a third lens group, a fourth lens group, and a fifth lens group. The parallel 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, then through the protective window, and finally converges in the vacuum cavity (the area between the protective window and the image point is a vacuum). After the antiparallel 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 -6.345 mm.

[0052] The first lens group consists of a biconcave lens (first lens) cemented together with a meniscus lens (second lens) with its concave surface facing the image side. The second lens group consists of a meniscus lens (third lens) with its concave surface facing the image side cemented together with a biconvex lens (fourth lens). The third lens group consists of a biconvex lens (fifth lens) cemented together with a meniscus lens (sixth lens) with its concave surface facing the object side cemented together. The fourth lens group consists of a biconvex lens (seventh lens) cemented together with a biconcave lens (eighth lens). The fifth lens group includes a ninth lens and a tenth lens, where the ninth lens is a biconvex single lens and the tenth lens is a meniscus lens with its concave surface facing the image side.

[0053] The distance from the vertex of the first face of the first mirror group to the last face of the fifth mirror 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.

[0054] The total optical length (TTL) of the microscope objectives is less than or equal to 76.367 mm. Within the 420 nm to 780 nm wavelength range, the transverse chromatic aberration is less than or equal to 0.08 μm, and the axial chromatic aberration is less than or equal to 1.1 μm, demonstrating excellent chromatic aberration control. All five lens groups are spherical lenses used to achieve field-plan apochromatic aberration control within the 420 nm to 780 nm wavelength range.

[0055] Example 2

[0056] The long working distance diffraction-limited microscope objective for optical tweezers in this embodiment, such as Figure 1 As shown, there are five groups of lenses from the object side to the image side, including:

[0057] The first lens group G1 includes the first lens L1 and the second lens L2; ​​the second lens group G2 includes the third lens L3 and the fourth lens L4; the third lens group G3 includes the fifth lens L5 and the sixth lens L6; the fourth lens group G4 includes the seventh lens L7 and the eighth lens L8; and the fifth lens group G5 includes the ninth lens L9 and the tenth lens L10.

[0058] The object-side imaging beam passes sequentially through the first mirror group G1, the second mirror group G2, the third mirror group G3, the fourth mirror group G4, the fifth mirror group G5, and the protection window, and finally converges on the image plane.

[0059] The long working distance diffraction-limited microscope objective 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.

[0060] Preferably, the first lens group is formed by cementing a first lens and a second lens together. The focal lengths of the first lens and the second lens are f1 and f2, respectively. The central radius of curvature on the object side of the first lens is R1, the central radius of curvature on the cemented surface is R2, and the central radius of curvature on the image side of the second lens is R3, and the following relationship is satisfied:

[0061] -25.46≤NA*f1≤-10.19; -2.52≤f1 / f≤-0.81; 0.39≤(R1+R2) / (R1-R2)≤1.17;

[0062] 22.5≤NA*f2≤56.27; 2.20≤f2 / f≤5.30; -10.87≤(R2+R3) / (R2-R3)≤-3.62;

[0063] Preferably, the second lens group is formed by cementing a third lens and a fourth lens together. The focal lengths of the third lens and the fourth lens are f3 and f4, respectively. The central radius of curvature of the object side of the third lens is R4, the central radius of curvature of the cemented surface is R5, and the central radius of curvature of the image side of the fourth lens is R6, and the following relationship is satisfied:

[0064] -181.27≤NA*f3≤-72.5; -10.23≤f3 / f≤-6.54; 2.75≤(R4+R5) / (R4-R5)≤8.25;

[0065] 21.11≤NA*f4≤52.8; 1.12≤f4 / f≤4.76; -0.72≤(R5+R6) / (R5-R6)≤-0.24;

[0066] Preferably, the third lens group is formed by cementing a fifth lens and a sixth lens together. The focal lengths of the fifth lens and the sixth lens are f5 and f6, respectively. The central radius of curvature of the fifth lens on the object side is R7, and the central radius of curvature of the cemented surface is R8. The central radius of curvature of the sixth lens on the image side is R9, and the following relationship is satisfied:

[0067] 10.66≤NA*f5≤26.65; 0.88≤f5 / f≤4.35; 0.25≤(R7+R8) / (R7-R8)≤0.76;

[0068] -29.99≤NA*f6≤11.96; -5.24≤f6 / f≤-0.42; -2.26≤(R8+R9) / (R8-R9)≤-0.75;

[0069] Preferably, the fourth lens group is formed by cementing a seventh lens and an eighth lens, with focal lengths of f7 and f8 respectively. The central radius of curvature of the seventh lens on the object side is R10, and the central radius of curvature of the cemented surface is R11. The central radius of curvature of the eighth lens on the image side is R12, and the following relationship is satisfied:

[0070] 13.71≤NA*f7≤34.28; 0.96≤f7 / f≤3.44; -0.05≤(R10+R11) / (R10-R11)≤-0.01;

[0071] -36.10≤NA*f8≤-14.44; -4.3≤f8 / f≤-0.52; -0.79≤(R11+R12) / (R11-R12)≤-0.27;

[0072] Preferably, the fifth lens group consists of a ninth lens and a tenth lens, with focal lengths of f9 and f10 respectively. The central radius of curvature of the ninth lens on the object side is R13, and on the image side it is R14. The central radius of curvature of the tenth lens on the object side is R15, and on the image side it is R16, and satisfies the following relationship:

[0073] 21.42 ≤ NA * f9 ≤ 53.54; 1.08 ≤ f9 / f ≤ 5.63; 0.003 ≤ (R13 + R14) / (R13 - R14) ≤ 0.01;

[0074] 27.9 ≤ NA * f10 ≤ 69.76; 1.57 ≤ f10 / f ≤ 6.42; -2.45 ≤ (R15 + R16) / (R15 - R16) ≤ -0.82.

[0075] Preferably, the five groups of lens materials are all selected as common glass materials.

[0076] Preferably, the medium between the protection window and the image plane is vacuum, and the media between the remaining lens groups are air.

[0077] 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; as Figure 2 shown, when the reverse parallel beam is incident on the microscope, the focus converges outside the microscope, and the front focal length FFL of the microscope objective is less than or equal to -6.345 mm; in the wavelength range of 420 nm to 780 nm, the lateral 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.

[0078] Embodiment 3

[0079] As Figure 1 shown, the embodiment of the present invention provides a long working distance diffraction-limited microscope objective for an optical tweezer, which includes five groups of lenses from the object side to the image side, where:

[0080] The first lens group G1 includes the first lens L1 and the second lens L2, the second lens group G2 includes the third lens L3 and the fourth lens L4, the third lens group G3 includes the fifth lens L5 and the sixth lens L6, the fourth lens group G4 includes the seventh lens L7 and the eighth lens L8, and the fifth lens group G5 includes the ninth lens L9 and the tenth lens L10. The object-side imaging 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 protection window, and finally converges on the focal plane.

[0081] For the focal length of the first lens group, -4.36 < f1_2 / f < -1.36, where f1_2: the combined focal length of the first lens group, f: the combined focal length of the microscope objective as a whole; within this range, spherical aberration and lateral chromatic aberration can be corrected well, and various other aberrations can be corrected at the same time.

[0082] 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 micro-optical 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 being less than the lower limit, which may cause excessive field curvature and coma that are difficult to correct.

[0083] 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 micro-optical objective; within this range, spherical aberration and axial chromatic aberration of the system can be better corrected.

[0084] 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 micro-optical objective; through reasonable distribution of the optical power, the system can have better imaging quality and lower sensitivity.

[0085] 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 micro-optical objective; within this range, reasonably controlling the relationship between the shape of the ninth and tenth lenses, the refractive index of the material, and the focal length of the micro-optical objective is beneficial to controlling the light path and enabling a smooth transition of the light.

[0086] 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 beam passes through the micro-optical objective, the image point is located outside the micro-optical objective.

[0087] In this embodiment, the first lens group includes at least two cemented lenses and at least one single lens with positive optical power, and they satisfy the relationship: 2.20 ≤ f2 / f ≤ 5.30; where f2 is the focal length of a single lens with positive optical power in the first lens group. Within this range, spherical aberration and axial chromatic aberration can be better corrected, and other chromatic aberrations can also be corrected.

[0088] In this embodiment, the object side of the ninth lens is convex and the image side is convex. The on-axis thickness of the ninth lens is d9, and it satisfies the following relationship: 0.1 ≤ d9 / TTL ≤ 0.25, which defines the ratio of the on-axis thickness of the ninth lens L9 to the overall optical length TTL of the micro-optical objective, and is beneficial to controlling the overall optical length of the micro-optical objective.

[0089] In this embodiment, the object side of the tenth lens is convex and the image side is concave. The axial thickness of the tenth lens is d10, which satisfies the following relationship: 0.11≤d10 / TTL≤0.22. This specifies the ratio of the axial thickness of the tenth lens to the total optical length TTL of the microscope objective, which is beneficial for controlling the total optical length of the microscope objective.

[0090] In this embodiment, the total optical length (TTL) of the microscope objective is less than or equal to 76.367 mm.

[0091] In this embodiment, the distance from the vertex of the first face of the first mirror group to the last face of the fifth mirror 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.

[0092] In this embodiment, when the reverse parallel beam is incident on the microscope, the focal point converges outside the microscope, and the front focal length (FFL) is less than or equal to -6.345 mm.

[0093] In this embodiment, the microscope objective has a transverse chromatic aberration of less than or equal to 0.08 μm and an axial chromatic aberration of less than or equal to 1.1 μm in the 420 nm to 780 nm wavelength range.

[0094] In this embodiment, the materials used for all five sets of lenses are glass materials commonly used in Chengdu Guangming.

[0095] In this embodiment, the medium between the protective window and the image plane is a vacuum, while the medium for the remaining lens groups is air.

[0096] The following examples will illustrate the long working distance diffraction-limited microscope objective for optical tweezers of the present invention.

[0097] Table 1 shows the design data for a long working distance diffraction-limited microscope objective for optical tweezers according to an embodiment of the present invention.

[0098] Table 1 Design data for microscope objectives

[0099]

[0100] Figure 3 The transfer function curves of the microscope objectives at 2000 lp / mm in various fields of view are shown. Figure 4 This is a schematic diagram of axial color difference; Figure 5 This is a diagram illustrating color difference at magnification. Figure 6 This diagram illustrates field curvature and distortion. It is evident that this microscope objective possesses excellent optical performance.

[0101] In addition, the present invention also provides an optical tweezers comprising the long working distance diffraction-limited microscope objective for optical tweezers described in any of the above technical solutions.

[0102] In summary, this invention provides a long working distance diffraction-limited microscope objective for optical tweezers, which has excellent optical performance, a long working distance, and a focal point that converges outside the microscope when the reverse parallel beam is incident on the microscope, and can be used as an optical tweezers microscope objective.

[0103] It should be noted that the sequence number of each step in the above embodiments does not imply 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 this application.

[0104] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this invention.

[0105] Those skilled in the art will readily understand that the above are merely 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 within the scope of protection of the present invention.

Claims

1. A long working distance, diffraction-limited, microscopic objective for optical tweezers, characterized in that, The microscopic objective comprises five lens groups from the object side to the image side, respectively, the first lens group, the second lens group, the third lens group, the fourth lens group and the fifth lens group; The first lens group comprises a first lens and a second lens which are cemented together, the second lens group comprises a third lens and a fourth lens which are cemented together, the third lens group comprises a fifth lens and a sixth lens which are cemented together, the fourth lens group comprises a seventh lens and an eighth lens which are cemented together, and the fifth lens group comprises a ninth lens and a tenth lens; The first lens is a biconcave lens, the second lens is a concave moon-shaped lens with the concave surface facing the image side, the third lens is a concave moon-shaped 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 concave moon-shaped 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 biconvex single lens, and the tenth lens is a concave moon-shaped 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 is finally converged on the image plane.

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

3. Long working distance, diffraction-limited microscope objective 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 of the first lens on the object side is R1, the central curvature radius of the cemented surface is R2, and the central curvature radius of the second lens on the image side is R3, which satisfy the following relationship: -25.46 ≤ NA*f1 ≤ -10.19; -2.52 ≤ f1 / f ≤ -0.81; 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 of the third lens on the object side is R4, the central curvature radius of the cemented surface is R5, and the central curvature radius of the fourth lens on the image side is R6, which satisfy the following relationship: -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; -0.72 ≤ (R5+R6) / (R5-R6) ≤ -0.24; 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, the central curvature radius of the image side of the sixth lens is R9, and the following relationships are 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; 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, the central curvature radius of the image side of the eighth lens is R12, and the following relationships are satisfied: 13.71≤NA*f7≤34.28; 0.96≤f7 / f≤3.44; -0.05≤(R10+R11) / (R10-R11)≤-0.01; -36.10≤NA*f8≤-14.44; -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 object side of the ninth lens is R13, the central curvature radius of the image side of the ninth lens 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 relationships are 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; Wherein, the numerical aperture of the microscope objective is NA, and the focal length is f.

4. Long working distance, diffraction-limited microscope objective for optical tweezers according to claim 3, characterized in that After the reverse parallel light 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. Long working distance, diffraction-limited microscope objective for optical tweezers according to claim 3, characterized in that The distance from the first face vertex of the first lens group to the last face of the fifth lens group is less than or equal to 48.904mm, the working distance is greater than or equal to 27.463mm, and the ratio of the two is less than or equal to 1.

78.

6. Long working distance, diffraction-limited microscope objective for optical tweezers according to claim 3, characterized in that The on-axis thickness of the ninth lens is d9, which satisfies the following relationship: 0.1≤d9 / TTL≤0.25; the on-axis 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.

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

65.

8. Long working distance, diffraction-limited microscope objective for optical tweezers according to claim 1, characterized in that The microscope objective further comprises a protective window between the fifth lens group and the image plane. The object imaging light beam sequentially passes through the first mirror group, the second mirror group, the third mirror group, the fourth mirror group, the fifth mirror group and a protective window, and finally converges on an image plane.

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

10. An optical tweezer, characterized by, The optical tweezer comprises the long working distance diffraction-limited microscopic objective for optical tweezers according to any one of claims 1 to 9.

Images