A phase contrast objective lens for microscope

Abstract

The present invention relates to the field of optical imaging technology, and discloses a microscope phase contrast objective lens, comprising a first lens group with positive refractive power, a second lens group with positive refractive power, an object plane and a cover glass, wherein the first lens group is located below the second lens group, and the absolute value of the refractive power of the first lens group is greater than the absolute value of the refractive power of the second lens group. The present invention is arranged by setting the first lens group and the second lens group in the phase contrast objective optical system, and by limiting the focal length, refractive index, Abbe number and thickness of the first lens group and the second lens group, so that the field curvature, distortion and aberration sensitivity of the phase contrast objective optical system are further improved, thereby ensuring the optical performance of the phase contrast objective optical system, so that the objective optical system has the characteristics of small magnification, large numerical aperture, high resolution performance, small chromatic aberration under a large field of view, small number of lenses, and short total length of the objective optical system.

Description

Technical Field

[0001] The invention relates to the technical field of optical imaging, in particular to a microscope phase contrast objective lens. Background Art

[0002] With the rapid development of the biological industry in recent years, there is an increasing demand for observing transparent slices. The observation requirements are met by using the phase contrast method of the microscope. Generally speaking, due to the long working distance required for medical detection, in order to observe more details on the microscope, a large numerical aperture and transparent slices, a phase contrast plate is also required, which means that the back focus of the lens or lens group needs to converge on the phase plate. For such a phase contrast objective optical system, it is difficult to compensate for axial aberrations, chromatic aberrations of magnification, and field curvature. The aberrations of objectives with large field numbers and small magnifications are even more difficult to control.

[0003] A Chinese patent discloses a microscope objective (authorization announcement number CN101271191A), which describes a 10x phase contrast objective with a field of view number of 20, and the longitudinal chromatic aberration defined by the focus position deviation between the spectral lines C'-e and F'-e is 1.5 times the depth of focus, where C' is 643.847nm, F' is 479.991nm and e is 546.074nm, and the depth of focus range is defined by λ / NA² (λ is wavelength, NA is numerical aperture). However, the magnification is not small enough, the field of view number is not large enough, and the longitudinal chromatic aberration is large and only the C' line 643.847nm to the F' line 479.991nm is considered.

[0004] There is also a patent that discloses a microscope objective (authorization announcement number KR10-1850999). The patent technology describes a 50x phase contrast objective composed of 17 lenses, but the magnification used is not small enough, the number of lenses is large, the cost of the lens material is high, and the total length of the objective optical system is too long. Summary of the invention

[0005] The object of the present invention is to provide a microscope phase contrast objective lens to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A phase contrast objective lens for a microscope comprises a first lens group with positive refractive power, a second lens group with positive refractive power, an object plane and a cover glass, wherein the first lens group is located below the second lens group, the absolute value of the refractive power of the first lens group is greater than the absolute value of the refractive power of the second lens group, the first lens group is composed of a first lens with positive refractive power, a second lens with negative refractive power, a third lens with negative refractive power, a fourth lens with positive refractive power, a fifth lens with negative refractive power, a sixth lens with negative refractive power and a seventh lens with positive refractive power from bottom to top; the second lens group is composed of a first phase plate glass, a second phase plate glass and an eighth lens with positive refractive power from bottom to top, and the first phase plate glass is located directly above the seventh lens.

[0008] The aperture and resolution of the phase contrast objective optical system meet the following conditions:

[0009] 0.5<|f*NA / D0|<0.8

[0010] Wherein, f is the focal length of the phase contrast objective optical system; NA is the object-side numerical aperture of the phase contrast objective optical system; D0 is the distance from the cover glass to the optical axis of the first lens of the phase contrast objective optical system closest to the object plane;

[0011] The focal distances of the first lens group and the second lens group satisfy the following conditions:

[0012] 0.5 <f / f1<2.50; 1.0<f / f2<3.00; 0.5<f2 / f1<2.0;

[0013] Among them, f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, and f is the focal length of the phase contrast objective optical system.

[0014] As a further solution of the present invention: the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the phase plate glass 1, the phase plate glass 2 and the eighth lens need to meet the following conditions:

[0015] -0.7 <f11 / f1<1.7; -1.5<f12 / f1<0.9; -1.8<f13 / f1<0.6;

[0016] 0.4 <f14 / f1<2.8; -9.1<f15 / f1<-5.0; -2.9<f16 / f1<-0.5;

[0017] 0.5 <f17 / f1<2.9; 0.2<f23 / f11<2.6;

[0018] Among them, f1 is the focal length of the first lens group, f11 is the focal length of the first lens, f12 is the focal length of the second lens, f13 is the focal length of the third lens, f14 is the focal length of the fourth lens, f15 is the focal length of the fifth lens, f16 is the focal length of the sixth lens, f17 is the focal length of the seventh lens, and f23 is the focal length of the eighth lens.

[0019] As a further solution of the present invention: the refractive indexes of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the phase plate glass 1, the phase plate glass 2, and the eighth lens satisfy the following conditions:

[0020] 1.78 <N11<1.90; 1.43<N12<1.55; 1.68<N13<1.80;

[0021] 1.40 <N14<1.50; 1.40<N15<1.50; 1.69<N16<1.81;

[0022] 1.40 <N17<1.50; 1.45<N21<1.58; 1.45<N22<1.58;

[0023] 1.68 <N23<1.80;

[0024] Among them, N11 is the refractive index of the first lens, N12 is the refractive index of the second lens, N13 is the refractive index of the third lens, N14 is the refractive index of the fourth lens, N15 is the refractive index of the fifth lens, N16 is the refractive index of the sixth lens, N17 is the refractive index of the seventh lens, N21 is the refractive index of phase plate glass one, N22 is the refractive index of phase plate glass two, and N23 is the refractive index of the eighth lens.

[0025] As a further solution of the present invention: the Abbe numbers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the phase plate glass 1, the phase plate glass 2, and the eighth lens meet the following conditions:

[0026] V11≤50; V12≤98; V13≤40; V14≤98; V15≤98;

[0027] V16≤40; V17≤95; V21≤70; V23≤70; V23≤40;

[0028] Among them, V11 is the Abbe number of the first lens, V12 is the Abbe number of the second lens, V13 is the Abbe number of the third lens, V14 is the Abbe number of the fourth lens, V15 is the Abbe number of the fifth lens, V16 is the Abbe number of the sixth lens, V17 is the Abbe number of the seventh lens, V21 is the Abbe number of phase plate glass one, V22 is the Abbe number of phase plate glass two, and V23 is the Abbe number of the eighth lens.

[0029] As a further solution of the present invention: the thickness of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the phase plate glass 1, the phase plate glass 2, and the eighth lens on the optical axis meets the following conditions:

[0030] 5.15 <T1 / T2<5.35; 0.01<T11 / T1<0.19; 0.01<T12 / T1<0.15;

[0031] 0.01 <T13 / T1<0.15; 0.01<T14 / T1<0.19; 0.02<T15 / T1<0.22;

[0032] 0.01 <T16 / T1<0.15; 0.01<T17 / T1<0.20; 0.03<T21 / T2<0.23;

[0033] 0.03 <T22 / T2<0.23; 0.43<T23 / T2<0.63;

[0034] Wherein, T1 is the length of the first lens group on the optical axis, T2 is the length of the second lens group on the optical axis, T11 is the thickness of the first lens on the optical axis, T12 is the thickness of the second lens on the optical axis, T13 is the thickness of the third lens on the optical axis, T14 is the thickness of the fourth lens on the optical axis, T15 is the thickness of the fifth lens on the optical axis, T16 is the thickness of the sixth lens on the optical axis, T17 is the thickness of the seventh lens on the optical axis, T21 is the thickness of the phase plate glass 1 on the optical axis, T22 is the thickness of the phase plate glass 2 on the optical axis, and T23 is the thickness of the eighth lens on the optical axis.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention arranges the first lens group and the second lens group in the phase contrast objective optical system so that the first lens group has positive refractive power and the second lens group has positive refractive power, so that the objective optical system has good optical performance, and limits the focal distance, refractive index, Abbe number and thickness of the first lens group and the second lens group so that the field curvature, distortion and aberration sensitivity of the phase contrast objective optical system are further improved, thereby ensuring the optical performance of the phase contrast objective optical system, so that the objective optical system has the characteristics of small magnification, large numerical aperture, high resolution performance, small chromatic aberration under a large field of view, small number of lenses and short total length of the objective optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 1 is a lens composition diagram of a phase contrast objective optical system according to a first embodiment of the present invention;

[0038] Figure 2 is a spherical aberration diagram of the phase contrast objective optical system of the first embodiment of the present invention;

[0039] Figure 3 A field curvature diagram of the phase contrast objective optical system of the first embodiment of the present invention;

[0040] Figure 4 is a distortion diagram of the phase contrast objective optical system of the first embodiment of the present invention;

[0041] Figure 5 is a modulation transfer function diagram of the phase contrast objective optical system of the first embodiment of the present invention;

[0042] Figure 6 A lens composition diagram of a phase contrast objective optical system according to a second embodiment of the present invention;

[0043] Figure 7 is a spherical aberration diagram of the phase contrast objective optical system of the second embodiment of the present invention;

[0044] Figure 8 A field curvature diagram of a phase contrast objective optical system according to a second embodiment of the present invention;

[0045] Fig. 9 is a distortion diagram of the phase contrast objective optical system of the second embodiment of the present invention;

[0046] Fig.10 is a modulation transfer function diagram of the phase contrast objective optical system of the second embodiment of the present invention;

[0047] Fig.11 1 is a lens composition diagram of a phase contrast objective optical system according to a third embodiment of the present invention;

[0048] Fig.12 is a spherical aberration diagram of the phase contrast objective optical system of the third embodiment of the present invention;

[0049] Fig.13 A field curvature diagram of a phase contrast objective optical system according to Embodiment 3 of the present invention;

[0050] Fig.14 is a distortion diagram of the phase contrast objective optical system of the third embodiment of the present invention;

[0051] Fig.15 This is a modulation transfer function diagram of the phase contrast objective optical system of the third embodiment of the present invention.

[0052] In the figure: 601, first lens holder; 602, second lens holder; 603, third and fourth cemented lens holder; 604, fifth, sixth and seventh cemented lens holder; 605, phase plate glass cemented lens holder; 606, eighth lens holder; 700, object plane; 701, cover glass; 81, first lens group; 711, first lens; 7111, first surface of first lens; 7112, second surface of first lens; 712, second lens; 7121, first surface of second lens; 7122, second surface of second lens; 713, third lens; 7131, first surface of third lens; 7132, second surface of third lens; 714, fourth lens; 7141, first surface of fourth lens; 7142, The second surface of the fourth lens; 715, the fifth lens; 7151, the first surface of the fifth lens; 7152, the second surface of the fifth lens; 716, the sixth lens; 7161, the first surface of the sixth lens; 7162, the second surface of the sixth lens; 717, the seventh lens; 7171, the first surface of the seventh lens; 7172, the second surface of the seventh lens; 82, the second lens group; 721, phase plate glass one; 7211, the first surface of phase plate glass one; 7212, the second surface of phase plate glass one; 722, phase plate glass two; 7221, the first surface of phase plate glass two; 7222, the second surface of phase plate glass two; 723, the eighth lens; 7231, the first surface of the eighth lens; 7232, the second surface of the eighth lens. DETAILED DESCRIPTION

[0053] See also Figures 1 to 15In an embodiment of the present invention, a microscope phase contrast objective lens comprises a first lens group 81 with positive refractive power, a second lens group 82 with positive refractive power, an object plane 700 and a cover glass 701, wherein the first lens group 81 is located below the second lens group 82, the absolute value of the refractive power of the first lens group 81 is greater than the absolute value of the refractive power of the second lens group 82, and the first lens group 81 is composed of a first lens 711 with positive refractive power, a second lens 712 with negative refractive power, a third lens 713 with negative refractive power, a positive The second lens group 82 is composed of a fourth lens 714 with a refractive power, a fifth lens 715 with a negative refractive power, a sixth lens 716 with a negative refractive power and a seventh lens 717 with a positive refractive power; the second lens group 82 is composed of a phase plate glass 1 721, a phase plate glass 2 722 and an eighth lens 723 with a positive refractive power from bottom to top, and the phase plate glass 1 721 is located directly above the seventh lens 717, so that the microscope phase contrast objective optical system has a strong positive refractive power, thereby ensuring that the phase contrast objective has a larger magnification and high optical performance.

[0054] The aperture and resolution of the phase contrast objective optical system meet the following conditions:

[0055] 0.5<|f*NA / D0|<0.8

[0056] Thus, the phase contrast objective optical system has a larger numerical aperture and a stronger resolution, wherein f is the focal length of the phase contrast objective optical system; NA is the object-side numerical aperture of the phase contrast objective optical system; D0 is the distance from the cover glass 701 to the optical axis of the first lens 711 of the phase contrast objective optical system closest to the object plane 700;

[0057] The focal distances of the first lens group 81 and the second lens group 82 satisfy the following conditions:

[0058] 0.5 <f / f1<2.50; 1.0<f / f2<3.00; 0.5<f2 / f1<2.0;

[0059] Thereby, the phase contrast objective optical system has a large numerical aperture, a large field of view, and better optical performance, and at the same time, the field curvature of the phase contrast objective optical system is corrected, the resolution capability of the phase contrast objective optical system is improved, and the distortion of the phase contrast objective optical system can be effectively compensated. Among them, f1 is the focal length of the first lens group 81, f2 is the focal length of the second lens group 82, and f is the focal length of the phase contrast objective optical system.

[0060] Preferably, the focal lengths of the first lens 711, the second lens 712, the third lens 713, the fourth lens 714, the fifth lens 715, the sixth lens 716, the seventh lens 717, the phase plate glass 1 721, the phase plate glass 2 722 and the eighth lens 723 need to meet the following conditions:

[0061] -0.7 <f11 / f1<1.7; -1.5<f12 / f1<0.9; -1.8<f13 / f1<0.6;

[0062] 0.4 <f14 / f1<2.8; -9.1<f15 / f1<-5.0; -2.9<f16 / f1<-0.5;

[0063] 0.5 <f17 / f1<2.9; 0.2<f23 / f11<2.6;

[0064] Among them, f1 is the focal length of the first lens group 81, f11 is the focal length of the first lens 711, f12 is the focal length of the second lens 712, f13 is the focal length of the third lens 713, f14 is the focal length of the fourth lens 714, f15 is the focal length of the fifth lens 715, f16 is the focal length of the sixth lens 716, f17 is the focal length of the seventh lens 717, and f23 is the focal length of the eighth lens 723.

[0065] Preferably, the refractive indexes of the first lens 711, the second lens 712, the third lens 713, the fourth lens 714, the fifth lens 715, the sixth lens 716, the seventh lens 717, the phase plate glass 1 721, the phase plate glass 2 722, and the eighth lens 723 satisfy the following conditions:

[0066] 1.78 <N11<1.90; 1.43<N12<1.55; 1.68<N13<1.80;

[0067] 1.40 <N14<1.50; 1.40<N15<1.50; 1.69<N16<1.81;

[0068] 1.40 <N17<1.50; 1.45<N21<1.58; 1.45<N22<1.58;

[0069] 1.68 <N23<1.80;

[0070] Thereby reducing the longitudinal chromatic aberration of the phase contrast objective optical system, and further correcting the field curvature of the phase contrast objective optical system, wherein N11 is the refractive index of the first lens 711, N12 is the refractive index of the second lens 712, N13 is the refractive index of the third lens 713, N14 is the refractive index of the fourth lens 714, N15 is the refractive index of the fifth lens 715, N16 is the refractive index of the sixth lens 716, N17 is the refractive index of the seventh lens 717, N21 is the refractive index of the phase plate glass 1 721, N22 is the refractive index of the phase plate glass 2 722, and N23 is the refractive index of the eighth lens 723.

[0071] Preferably, the Abbe numbers of the first lens 711, the second lens 712, the third lens 713, the fourth lens 714, the fifth lens 715, the sixth lens 716, the seventh lens 717, the phase plate glass 1 721, the phase plate glass 2 722, and the eighth lens 723 meet the following conditions:

[0072] V11≤50; V12≤98; V13≤40; V14≤98; V15≤98;

[0073] V16≤40; V17≤95; V21≤70; V23≤70; V23≤40;

[0074] Thereby, the chromatic aberration of the phase contrast objective optical system is reduced so that the longitudinal chromatic aberration limited by the focus position deviation between the spectral lines Ce and ge is within 1.0 times of the focal depth, wherein C is 656.27nm, g is 435.84nm and e is 546.07nm, and the focal depth is λ / NA², wherein λ is the wavelength and NA is the numerical aperture, wherein V11 is the Abbe number of the first lens 711, V12 is the Abbe number of the second lens 712, V13 is the Abbe number of the third lens 713, V14 is the Abbe number of the fourth lens 714, V15 is the Abbe number of the fifth lens 715, V16 is the Abbe number of the sixth lens 716, V17 is the Abbe number of the seventh lens 717, V21 is the Abbe number of the phase plate glass 1 721, V22 is the Abbe number of the phase plate glass 2 722, and V23 is the Abbe number of the eighth lens 723.

[0075] Preferably, the thicknesses of the first lens 711, the second lens 712, the third lens 713, the fourth lens 714, the fifth lens 715, the sixth lens 716, the seventh lens 717, the phase plate glass 1 721, the phase plate glass 2 722, and the eighth lens 723 on the optical axis meet the following conditions:

[0076] 5.15 <T1 / T2<5.35; 0.01<T11 / T1<0.19; 0.01<T12 / T1<0.15;

[0077] 0.01 <T13 / T1<0.15; 0.01<T14 / T1<0.19; 0.02<T15 / T1<0.22;

[0078] 0.01 <T16 / T1<0.15; 0.01<T17 / T1<0.20; 0.03<T21 / T2<0.23;

[0079] 0.03 <T22 / T2<0.23; 0.43<T23 / T2<0.63;

[0080] Thereby, the eccentricity and coaxial sensitivity of the objective optical system are reduced, and the assembly yield of the objective optical system is improved, wherein T1 is the length of the first lens group 81 on the optical axis, T2 is the length of the second lens group 82 on the optical axis, T11 is the thickness of the first lens 711 on the optical axis, T12 is the thickness of the second lens 712 on the optical axis, T13 is the thickness of the third lens 713 on the optical axis, T14 is the thickness of the fourth lens 714 on the optical axis, T15 is the thickness of the fifth lens 715 on the optical axis, T16 is the thickness of the sixth lens 716 on the optical axis, T17 is the thickness of the seventh lens 717 on the optical axis, T21 is the thickness of the phase plate glass 1 721 on the optical axis, T22 is the thickness of the phase plate glass 2 722 on the optical axis, and T23 is the thickness of the eighth lens 723 on the optical axis.

[0081] In order to further elaborate the technical content of the invention, three embodiments are listed below to describe the objective optical system in detail.

[0082] Embodiment 1

[0083] like Figure 1 As shown, the microscope phase contrast objective lens of the first embodiment includes an object plane 700, a cover glass 701, a first lens group 81 and a second lens group 82, wherein the first lens group 81 includes a first lens 711 with positive refractive power, a second lens 712 with negative refractive power, a third lens 713 with negative refractive power, a fourth lens 714 with positive refractive power, a fifth lens 715 with positive refractive power, a sixth lens 716 with negative refractive power and a seventh lens 717 with positive refractive power; the surface of the first lens 711 facing the object side is a first lens first surface 7111, and the surface facing the image side is a first lens second surface 7112; the surface of the second lens 712 facing the object side is a second lens first surface 7121, and the surface facing the image side is a second lens The second surface 7122 of the third lens 713 is the first surface 7131 of the third lens facing the object side, and the surface facing the image side is the second surface 7132 of the third lens; the surface of the fourth lens 714 facing the object side is the first surface 7141 of the fourth lens, and the surface facing the image side is the second surface 7142 of the fourth lens; the surface of the fifth lens 715 facing the object side is the first surface 7151 of the fifth lens, and the surface facing the image side is the second surface 7152 of the fifth lens; the surface of the sixth lens 716 facing the object side is the first surface 7161 of the sixth lens, and the surface facing the image side is the second surface 7162 of the sixth lens; the surface of the seventh lens 717 facing the object side is the first surface 7171 of the seventh lens, and the surface facing the image side is the second surface 7172 of the seventh lens;

[0084] The second lens group 82 includes a phase plate glass 1 721, a phase plate glass 2 722 and an eighth lens 723 which are arranged in sequence from the object side to the image side, wherein the surface of the phase plate glass 1 721 facing the object side is the phase plate glass 1 first surface 7211, and the surface facing the image side is the phase plate glass 1 second surface 7212, the surface of the phase plate glass 2 722 facing the object side is the phase plate glass 2 first surface 7221, and the surface facing the image side is the phase plate glass 2 second surface 7222, and the eighth lens 723 has positive refractive power, and its surface facing the object side is the eighth lens first surface 7231, and the surface facing the image side is the eighth lens second surface 7232.

[0085] The first lens 711 is placed in the first lens holder 601 with the first lens second surface 7112 as the receiving surface, and the second lens 712 is placed in the second lens holder 602 with the second lens second surface 7122 as the receiving surface. The first lens holder 601 and the second lens holder 602 cooperate to ensure the interval between the first lens 711 and the second lens 712 on the optical axis. The third lens second surface 7132 of the third lens 713 is glued with the fourth lens first surface 7141 of the fourth lens 714. After the third lens 713 and the fourth lens 714 are glued, the third lens 713 and the fourth lens 714 are placed in the third and fourth glued lens holders 603 with the third lens first surface 7131 as the receiving surface. The second lens holder 602 cooperates with the third and fourth glued lens holders 603. , ensuring the interval between the second lens 712 and the third lens 713 on the optical axis; the fifth lens second surface 7152 of the fifth lens 715 is glued to the sixth lens first surface 7161 of the sixth lens 716, and the sixth lens second surface 7162 of the sixth lens 716 is glued to the seventh lens first surface 7171 of the seventh lens 717. After the fifth lens 715, the sixth lens 716 and the seventh lens 717 are glued, the seventh lens second surface 7172 of the seventh lens 717 is used as the receiving surface and is placed in the fifth, sixth and seventh glued lens holder 604; through the cooperation between the third and fourth glued lens holders 603 and the fifth, sixth and seventh glued lens holders 604, the interval between the fourth lens 714 and the fifth lens 715 on the optical axis is ensured.

[0086] The second surface 7212 of the phase plate glass 1 721 is glued to the first surface 7221 of the phase plate glass 2 722. After the phase plate glass 1 721 and the phase plate glass 2 722 are glued, the second surface 7222 of the phase plate glass 2 722 is used as a receiving surface and is placed in the phase plate glass glued lens holder 605. The fifth, sixth, and seventh glued lens holders 604 and the phase plate glass glued lens holder 605 are used to ensure the interval between the seventh lens 717 and the phase plate glass 1 721 on the optical axis. The eighth lens 723 is placed in the eighth lens holder 606 with the eighth lens second surface 7232 as a receiving surface. The eighth lens holder 606 is used to cooperate with the phase plate glass glued lens holder 605 to ensure the interval between the eighth lens 723 and the phase plate glass 2 722 on the optical axis.

[0087] In the phase contrast objective optical system of Example 1: the field of view is 25 mm, the longitudinal chromatic aberration defined by the focus position deviation between Ce is 0.77 times the focal depth, and the longitudinal chromatic aberration defined by the focus position deviation between ge is 0.72 times the focal depth, where C is 656.27 nm, g is 435.84 nm, e is 546.07 nm, and the focal depth is Λ / NA², where Λ is the wavelength and NA is the numerical aperture.

[0088] The focal length f11 of the first lens 711 is 18.14, the refractive index N11 is 1.84, the Abbe number V11 is 34.0, and the thickness T11 is 2.52.

[0089] The second lens 712 has a focal length f12 of -13.06, a refractive index N12 of 1.49, an Abbe number V12 of 95.0, and a thickness T12 of 1.00.

[0090] The third lens 713 has a focal length f13 of -21.02, a refractive index N13 of 1.74, an Abbe number V13 of 30.9, and a thickness T13 of 1.00.

[0091] The fourth lens 714 has a focal length f14 of 59.36, a refractive index N14 of 1.44, an Abbe number V14 of 94.9, and a thickness T14 of 2.65.

[0092] The fifth lens 715 has a focal length f15 of -299.69, a refractive index N15 of 1.44, an Abbe number V15 of 94.9, and a thickness T15 of 3.37.

[0093] The sixth lens 716 has a focal length f16 of -65.47, a refractive index N16 of 1.75, an Abbe number V16 of 32.1, and a thickness T16 of 1.00.

[0094] The seventh lens 717 has a focal length f17 of 63.98, a refractive index N17 of 1.44, an Abbe number V17 of 94.9, and a thickness T17 of 2.89.

[0095] The focal length f21 of the phase plate glass 721 is infinite, the refractive index N21 is 1.52, the Abbe number V21 is 64.2, and the thickness T21 is 0.70.

[0096] The focal length f22 of the second phase plate glass 722 is infinite, the refractive index N22 is 1.52, the Abbe number V22 is 64.2, and the thickness T22 is 0.70.

[0097] The eighth lens 723 has a focal length f23 of 26.06, a refractive index N23 of 1.74, an Abbe number V23 of 29.1, and a thickness T23 of 2.89.

[0098] Other optical parameters of the phase contrast objective optical system are shown in Table 1-1.

[0099]

[0100] Table 1-1

[0101] From the above, it can be known that in the phase contrast objective optical system of the first embodiment, f is the focal length of the phase contrast objective optical system, that is, f is 45.00; NA is the object-side numerical aperture of the objective optical system, that is, NA is 0.16; D0 is the distance from the cover glass 701 to the optical axis of the first lens 711 of the phase contrast objective optical system closest to the object plane 700, that is, D0 is 13.33, then |f*NA / D0| is 0.54, so that it can ensure the characteristics of small magnification, large numerical aperture, high resolution performance, and large field number.

[0102] The focal length of the first lens group 81 is the combined focal length of the first lens 711 to the seventh lens 717, that is, f1 is 37.85; the focal length of the second lens group 82 is the combined focal length of the phase plate glass 721 to the eighth lens 723, that is, f2 is 26.06; the focal length f of the entire optical system is 45.00, then f / f1 is 1.19, f / f2 is 1.73, f2 / f1 is 0.69, f11 / f1 is 0.48, f12 / f1 is -0.34, f13 / f1 is -0.55, f14 / f1 is 1.57, f15 / f1 is -7.91, f16 / f1 is -1.73, f17 / f1 is 1.69, and f23 / f11 is 1.44. The objective optical system within the focal length numerical range has a large positive refractive power, which enables the phase contrast objective to have a large numerical aperture. At the same time, the field curvature, distortion and aberration of the objective optical system are improved, thereby improving the resolution performance.

[0103] In this embodiment 1, the thickness of the first lens group 81, i.e., T1, is 28.72, and the thickness T2 of the second lens group 82 is 5.47; T1 / T2 is 5.25, T11 / T1 is 0.09, T12 / T1 is 0.03, T13 / T1 is 0.03, T14 / T1 is 0.09, T15 / T1 is 0.12, T16 / T1 is 0.03, T17 / T1 is 0.1, T21 / T2 is 0.13, T22 / T2 is 0.13, and T23 / T2 is 0.53.

[0104] Figures 2 to 5 The various aberration diagrams and MTF performance diagrams of the phase contrast objective optical system of the first embodiment are shown. The various aberrations presented therein represent the resolution capability. When the aberrations are relatively small, images with better quality can be observed.

[0105] Specifically, Figure 2is a spherical aberration diagram of the phase contrast objective optical system of the first embodiment of the present invention, as shown in Figure 2 As shown, the horizontal axis is the spherical aberration, the unit is mm, the vertical axis is the image height, the unit is mm, the solid line represents the d line, the dotted line represents the C line, the single-dot chain line represents the F line, and the double-dot chain line represents the g line. The spherical aberration of the phase contrast objective optical system is controlled within ±0.05mm, so that the central resolution of the phase contrast objective optical system is optimal.

[0106] Figure 3 is a field curvature diagram of the phase contrast objective optical system of the first embodiment of the present invention, such as Figure 3 As shown, the horizontal axis is the object plane movement, in mm, the vertical axis is the image height, in mm, the solid line represents the sagittal relative to each wavelength, and the dotted line represents the meridian relative to each wavelength. From the distribution of field curvature, it can be seen that the field curvature of the phase contrast objective optical system is controlled within ±0.05mm, making the central resolution of the phase contrast objective optical system optimal.

[0107] Figure 4 is a distortion diagram of the phase contrast objective optical system of the first embodiment of the present invention, as shown in Figure 4 As shown, the horizontal axis is the distortion, in %, and the vertical axis is the image height, in mm. From the distribution of distortion, it can be seen that the distortion of the phase contrast objective optical system is controlled within ±2%, making the central resolution of the phase contrast objective optical system optimal.

[0108] Figure 5 : is a diagram of the MTF (modulation transfer function) of the phase contrast objective optical system of the first embodiment of the present invention, such as Figure 5 As shown, the horizontal axis is the spatial frequency in cycles / mm, and the vertical axis is the modulation, i.e., MTF. The solid line represents the modulation (MTF) of the central image plane of the phase contrast objective optical system, and the dotted line represents the diffraction limit.

[0109] Embodiment 2

[0110] like Figure 6 As shown, the second embodiment also includes a first lens group 81, a second lens group 82, a third lens group 83, a first lens 711, a second lens 712, a third lens 713, a fourth lens 714, a fifth lens 715, a sixth lens 716, a seventh lens 717, a phase plate glass 1 721, a phase plate glass 2 722, and an eighth lens 723. The difference is that the material used for the first lens 711 and the optical parameters of each lens are different from those in the first embodiment.

[0111] Specifically, in the phase contrast objective optical system of the second embodiment, the field number is 25 mm, the longitudinal chromatic aberration defined by the focus position deviation between Ce is 0.77 times the focal depth, and the longitudinal chromatic aberration defined by the focus position deviation between ge is 0.71 times the focal depth, where C is 656.27 nm, g is 435.84 nm, and e is 546.07 nm. The focal depth is Λ / NA², where Λ is the wavelength and NA is the numerical aperture.

[0112] The focal length f11 of the first lens 711 is 17.96, the refractive index N11 is 1.75, the Abbe number V11 is 35.3, and the thickness T11 is 2.67.

[0113] The second lens 712 has a focal length f12 of -13.15, a refractive index N12 of 1.49, an Abbe number V12 of 95.0, and a thickness T12 of 1.14.

[0114] The third lens 713 has a focal length f13 of -20.22, a refractive index N13 of 1.73, an Abbe number V13 of 34.5, and a thickness T13 of 1.01.

[0115] The fourth lens 714 has a focal length f14 of 55.39, a refractive index N14 of 1.44, an Abbe number V14 of 94.9, and a thickness T14 of 2.72.

[0116] The fifth lens 715 has a focal length f15 of -200.58, a refractive index N15 of 1.44, an Abbe number V15 of 94.9, and a thickness T15 of 3.37.

[0117] The sixth lens 716 has a focal length f16 of -65.20, a refractive index N16 of 1.75, an Abbe number V16 of 30.9, and a thickness T16 of 1.00.

[0118] The seventh lens 717 has a focal length f17 of 64.20, a refractive index N17 of 1.44, an Abbe number V17 of 94.9, and a thickness T17 of 2.85.

[0119] The focal length f21 of the phase plate glass 721 is infinite, the refractive index N21 is 1.52, the Abbe number V21 is 64.2, and the thickness T21 is 0.70.

[0120] The focal length f22 of the second phase plate glass 722 is infinite, the refractive index N22 is 1.52, the Abbe number V22 is 64.2, and the thickness T22 is 0.70.

[0121] The eighth lens 723 has a focal length f23 of 25.99, a refractive index N23 of 1.75, an Abbe number V23 of 28.8, and a thickness

[0122] T23 is 2.88.

[0123] Other optical parameters of the phase contrast objective optical system are shown in Table 2-1

[0124]

[0125] Table 2-1

[0126] As can be seen from the above, in the phase contrast objective optical system of the second embodiment, f is the focal length of the phase contrast objective optical system, that is, f is 45.00; NA is the object-side numerical aperture of the objective optical system, that is, NA is 0.16; D0 is the distance from the cover glass 701 to the optical axis of the first lens 711 of the phase contrast objective optical system closest to the object plane 700, that is, D0 is 13.33, then |f*NA / D0| is 0.54, so that it can ensure the characteristics of small magnification, large numerical aperture, high resolution performance, and large field number.

[0127] The focal length of the first lens group 81 is the combined focal length of the first lens 711 to the seventh lens 717, that is, f1 is 37.78; the focal length of the second lens group 82 is the combined focal length of the phase plate glass 1 721 to the eighth lens 723, that is, f2 is 25.00; The focal length f of the entire optical system is 45.00, then f / f1 is 1.19, f / f2 is 1.73, f2 / f1 is 0.69, f11 / f1 is 0.48, f12 / f1 is -0.35, f13 / f1 is -0.54, f14 / f1 is 1.47, f15 / f1 is -5.31, f16 / f1 is -1.73, f17 / f1 is 1.70, f23 / f11 is 1.45, and the objective optical system within the focal length numerical range has a large positive refractive power, which enables the phase contrast objective to have a large numerical aperture. At the same time, the field curvature, distortion and aberration of the objective optical system are improved, thereby improving the resolution performance.

[0128] In the second embodiment, the thickness of the first lens group 81, i.e., T1, is 28.71, and the thickness T2 of the second lens group 82 is 5.48; T1 / T2 is 5.24, T11 / T1 is 0.09, T12 / T1 is 0.04, T13 / T1 is 0.04, T14 / T1 is 0.09, T15 / T1 is 0.12, T16 / T1 is 0.03, T17 / T1 is 0.1, T21 / T2 is 0.13, T22 / T2 is 0.13, and T23 / T2 is 0.53.

[0129] Specifically, Figure 7 is a spherical aberration diagram of the phase contrast objective optical system of the second embodiment of the present invention, as shown in Figure 7As shown, the horizontal axis is the spherical aberration, the unit is mm, the vertical axis is the image height, the unit is mm, the solid line represents the d line, the dotted line represents the C line, the single-dot chain line represents the F line, and the double-dot chain line represents the g line. The spherical aberration of the phase contrast objective optical system is controlled within ±0.05mm, so that the central resolution of the phase contrast objective optical system is optimal.

[0130] Figure 8 is a field curvature diagram of the phase contrast objective optical system of the second embodiment of the present invention, such as Figure 8 As shown, the horizontal axis is the object plane movement, in mm, the vertical axis is the image height, in mm, the solid line represents the sagittal relative to each wavelength, and the dotted line represents the meridian relative to each wavelength. From the distribution of field curvature, it can be seen that the field curvature of the phase contrast objective optical system is controlled within ±0.05mm, making the central resolution of the phase contrast objective optical system optimal.

[0131] Fig. 9 is a distortion diagram of the phase contrast objective optical system of the second embodiment of the present invention, as shown in Fig. 9 As shown, the horizontal axis is the distortion amount, in %, and the vertical axis is the image height, in mm. From the distribution of distortion, it can be seen that the distortion of the phase contrast objective optical system is controlled within ±2%, making the central resolution of the phase contrast objective optical system optimal.

[0132] Fig.10 is a diagram of the MTF (modulation transfer function) of the phase contrast objective optical system of the second embodiment of the present invention, as shown in FIG. Fig.10 As shown, the horizontal axis is the spatial frequency in cycles / mm, and the vertical axis is the modulation, i.e., MTF. The solid line represents the modulation (MTF) of the central image plane of the phase contrast objective optical system, and the dotted line represents the diffraction limit.

[0133] Embodiment 3

[0134] like Fig.11 As shown, the phase contrast objective optical system in the third embodiment also includes a first lens group 81, a second lens group 82, a third lens group 83, a first lens 711, a second lens 712, a third lens 713, a fourth lens 714, a fifth lens 715, a sixth lens 716, a seventh lens 717, a phase plate glass 1 721, a phase plate glass 2 722, and an eighth lens 723. The difference is that the material used for the first lens 711 and the optical parameters of each lens are slightly different from those in the second embodiment.

[0135] Specifically, in the phase contrast objective optical system of the second embodiment, the field number is 25 mm, the longitudinal chromatic aberration defined by the focus position deviation between Ce is 0.70 times the focal depth, and the longitudinal chromatic aberration defined by the focus position deviation between ge is 0.68 times the focal depth, where C is 656.27 nm, g is 435.84 nm, and e is 546.07 nm. The focal depth is Λ / NA², where Λ is the wavelength and NA is the numerical aperture.

[0136] The first lens 711 has a focal length f11 of 18.13, a refractive index N11 of 1.80, an Abbe number V11 of 33.9, and a thickness T11 of 2.58.

[0137] The second lens 712 has a focal length f12 of -13.53, a refractive index N12 of 1.49, an Abbe number V12 of 95.0, and a thickness T12 of 1.00.

[0138] The third lens 713 has a focal length f13 of -20.00, a refractive index N13 of 1.73, an Abbe number V13 of 32.9, and a thickness T13 of 1.00.

[0139] The fourth lens 714 has a focal length f14 of 57.22, a refractive index N14 of 1.44, an Abbe number V14 of 94.9, and a thickness T14 of 2.72.

[0140] The fifth lens 715 has a focal length f15 of -223.27, a refractive index N15 of 1.44, an Abbe number V15 of 94.9, and a thickness T15 of 3.38.

[0141] The sixth lens 716 has a focal length f16 of -65.04, a refractive index N16 of 1.75, an Abbe number V16 of 31.3, and a thickness T16 of 1.00.

[0142] The seventh lens 717 has a focal length f17 of 64.32, a refractive index N17 of 1.44, an Abbe number V17 of 94.9, and a thickness T17 of 2.85.

[0143] The focal length f21 of the phase plate glass 721 is infinite, the refractive index N21 is 1.52, the Abbe number V21 is 64.2, and the thickness T21 is 0.70.

[0144] The focal length f22 of the second phase plate glass 722 is infinite, the refractive index N22 is 1.52, the Abbe number V22 is 64.2, and the thickness T22 is 0.70.

[0145] The eighth lens 723 has a focal length f23 of 25.90, a refractive index N23 of 1.75, an Abbe number V23 of 28.6, and a thickness T23 of 2.88.

[0146] Other optical parameters of the phase contrast objective optical system are shown in Table 3-1

[0147]

[0148] Table 3-1

[0149] As can be seen from the above, in the phase contrast objective optical system of the third embodiment, f is the focal length of the phase contrast objective optical system, that is, f is 45.00; NA is the object-side numerical aperture of the objective optical system, that is, NA is 0.16; D0 is the distance on the optical axis from the cover glass to the lens surface of the phase contrast objective optical system closest to the object, that is, D0 is 13.33, then |f*NA / D0| is 0.54, so that it can ensure the characteristics of small magnification, large numerical aperture, high resolution performance, and large field number.

[0150] The focal length of the first lens group 81 is the combined focal length of the first lens 711 to the seventh lens 717, that is, f1 is 37.78; the focal length of the second lens group 82 is the combined focal length of the phase plate glass 1 721 to the eighth lens 723, that is, f2 is 25.90; The focal length f of the entire optical system is 45.00, then f / f1 is 1.19, f / f2 is 1.74, f2 / f1 is 0.69, f11 / f1 is 0.48, f12 / f1 is -0.36, f13 / f1 is -0.53, f14 / f1 is 1.52, f15 / f1 is -5.91, f16 / f1 is -1.72, f17 / f1 is 1.70, f23 / f11 is 1.43, and the objective optical system within the focal length numerical range has a large positive refractive power, which enables the phase contrast objective to have a large numerical aperture. At the same time, the field curvature, distortion and aberration of the objective optical system are improved, thereby improving the resolution performance.

[0151] In this embodiment three, the thickness of the first lens group 81, that is, T1, is 28.72, and the thickness T2 of the second lens group 82 is 5.47; T1 / T2 is 5.25, T11 / T1 is 0.09, T12 / T1 is 0.04, T13 / T1 is 0.04, T14 / T1 is 0.09, T15 / T1 is 0.12, T16 / T1 is 0.04, T17 / T1 is 0.1, T21 / T2 is 0.13, T22 / T2 is 0.13, and T23 / T2 is 0.53.

[0152] Specifically, Fig.12 is a spherical aberration diagram of the phase contrast objective optical system of the third embodiment of the present invention, as shown in Fig.12 As shown, the horizontal coordinate is the spherical aberration, the unit is mm, and the vertical coordinate is the image height, the unit is mm, such as Figure 7As shown, the solid line represents the d line, the dotted line represents the C line, the single-dot chain line represents the F line, and the double-dot chain line represents the g line. The spherical aberration of the phase contrast objective optical system is controlled within ±0.05 mm, so that the central resolution of the phase contrast objective optical system is optimal.

[0153] Fig.13 is a field curvature diagram of the phase contrast objective optical system of the third embodiment of the present invention, as shown in Fig.13 As shown, the horizontal axis is the object plane movement, unit is mm, and the vertical axis is the image height, unit is mm, such as Figure 8 As shown, the solid line represents the sagittal of the light with respect to each wavelength, and the dotted line represents the meridian with respect to each wavelength. From the distribution of field curvature, it can be seen that the field curvature of the phase contrast objective optical system is controlled within ±0.05mm, so that the central resolution of the phase contrast objective optical system is optimal.

[0154] Fig.14 is a distortion diagram of the phase contrast objective optical system of the third embodiment of the present invention, as shown in Fig.14 As shown, the abscissa is the distortion amount, in %, and the ordinate is the image height, in mm. From the distribution of distortion, it can be seen that the distortion of the phase contrast objective optical system is controlled within ±2%, so that the central resolution of the phase contrast objective optical system is optimal.

[0155] Fig.15 : is a diagram of the MTF (modulation transfer function) of the phase contrast objective optical system of the third embodiment of the present invention, as shown in FIG. Fig.15 As shown, the horizontal axis is the spatial frequency, the unit is cycles / mm, and the vertical axis is the modulation, that is, MTF, as shown Fig.15 As shown, the solid line represents the modulation (MTF) of the central image plane of the phase contrast objective optical system, and the dotted line represents the diffraction limit.

[0156] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A phase contrast objective lens for a microscope, comprising a first lens group (81) having positive refractive power, a second lens group (82) having positive refractive power, an object plane (700) and a cover glass (701), characterized in that: The first lens group (81) is located below the second lens group (82); the absolute value of the refractive power of the first lens group (81) is greater than the absolute value of the refractive power of the second lens group (82); the first lens group (81) is composed of, from bottom to top, a first lens (711) with positive refractive power, a second lens (712) with negative refractive power, a third lens (713) with negative refractive power, a fourth lens (714) with positive refractive power, a fifth lens (715) with negative refractive power, a sixth lens (716) with negative refractive power, and a seventh lens (717) with positive refractive power; the second lens group (82) is composed of, from bottom to top, a phase plate glass 1 (721), a phase plate glass 2 (722), and an eighth lens (723) with positive refractive power; the phase plate glass 1 (721) is located directly above the seventh lens (717), so that the microscope phase contrast objective optical system has a strong positive refractive power, thereby ensuring that the phase contrast objective has a greater magnification and high optical performance; The aperture and resolution of the phase contrast objective optical system meet the following conditions: 0.5<|f*NA / D0|<0.8 Wherein, f is the focal length of the phase contrast objective optical system; NA is the object-side numerical aperture of the phase contrast objective optical system; D0 is the distance from the cover glass (701) to the optical axis of the first lens (711) of the phase contrast objective optical system closest to the object plane (700); The focal lengths of the first lens group (81) and the second lens group (82) satisfy the following condition: 0.5 <f / f1<2.50;1.0<f / f2<3.00;0.5<f2 / f1<2.0; Wherein, f1 is the focal length of the first lens group (81), f2 is the focal length of the second lens group (82), and f is the focal length of the phase contrast objective optical system; The focal lengths of the first lens (711), the second lens (712), the third lens (713), the fourth lens (714), the fifth lens (715), the sixth lens (716), the seventh lens (717), the phase plate glass 1 (721), the phase plate glass 2 (722) and the eighth lens (723) must satisfy the following conditions: -0.7 <f11 / f1<1.7;-1.5<f12 / f1<0.9;-1.8<f13 / f1<0.6;0.4<f14 / f1<2.8;-9.1<f15 / f1<-5.0;-2.9<f16 / f1<-0.5;0.5<f17 / f1<2.9;0.2<f23 / f11<2.6; Wherein, f1 is the focal length of the first lens group (81), f11 is the focal length of the first lens (711), f12 is the focal length of the second lens (712), f13 is the focal length of the third lens (713), f14 is the focal length of the fourth lens (714), f15 is the focal length of the fifth lens (715), f16 is the focal length of the sixth lens (716), f17 is the focal length of the seventh lens (717), and f23 is the focal length of the eighth lens (723); The refractive indices of the first lens (711), the second lens (712), the third lens (713), the fourth lens (714), the fifth lens (715), the sixth lens (716), the seventh lens (717), the phase plate glass 1 (721), the phase plate glass 2 (722), and the eighth lens (723) satisfy the following conditions: 1.78 <N11<1.90;1.43<N12<1.55;1.68<N13<1.80;1.40<N14<1.50;1.40<N15<1.50;1.69<N16<1.81;1.40<N17<1.50;1.45<N21<1.58;1.45<N22<1.58;1.68<N23<1.80; Wherein, N11 is the refractive index of the first lens (711), N12 is the refractive index of the second lens (712), N13 is the refractive index of the third lens (713), N14 is the refractive index of the fourth lens (714), N15 is the refractive index of the fifth lens (715), N16 is the refractive index of the sixth lens (716), N17 is the refractive index of the seventh lens (717), N21 is the refractive index of the phase plate glass 1 (721), N22 is the refractive index of the phase plate glass 2 (722), and N23 is the refractive index of the eighth lens (723); The Abbe numbers of the first lens (711), the second lens (712), the third lens (713), the fourth lens (714), the fifth lens (715), the sixth lens (716), the seventh lens (717), the phase plate glass 1 (721), the phase plate glass 2 (722), and the eighth lens (723) satisfy the following conditions: V11≤50; V12≤98; V13≤40; V14≤98; V15≤98; V16≤40; V17≤95; V21≤70; V23≤70; V23≤40; Among them, V11 is the Abbe number of the first lens (711), V12 is the Abbe number of the second lens (712), V13 is the Abbe number of the third lens (713), V14 is the Abbe number of the fourth lens (714), V15 is the Abbe number of the fifth lens (715), V16 is the Abbe number of the sixth lens (716), V17 is the Abbe number of the seventh lens (717), V21 is the Abbe number of the phase plate glass 1 (721), V22 is the Abbe number of the phase plate glass 2 (722), and V23 is the Abbe number of the eighth lens (723).

2. A microscope phase contrast objective lens according to claim 1, characterized in that: The thicknesses of the first lens (711), the second lens (712), the third lens (713), the fourth lens (714), the fifth lens (715), the sixth lens (716), the seventh lens (717), the phase plate glass 1 (721), the phase plate glass 2 (722), and the eighth lens (723) on the optical axis meet the following conditions: 5.15 <T1 / T2<5.35;0.01<T11 / T1<0.19;0.01<T12 / T1<0.15;0.01<T13 / T1<0.15;0.01<T14 / T1<0.19;0.02<T15 / T1<0.22;0.01<T16 / T1<0.15;0.01<T17 / T1<0.20;0.03<T21 / T2<0.23;0.03<T22 / T2<0.23;0.43<T23 / T2<0.63; Wherein, T1 is the length of the first lens group (81) on the optical axis, T2 is the length of the second lens group (82) on the optical axis, T11 is the thickness of the first lens (711) on the optical axis, T12 is the thickness of the second lens (712) on the optical axis, T13 is the thickness of the third lens (713) on the optical axis, T14 is the thickness of the fourth lens (714) on the optical axis, T15 is the thickness of the fifth lens (715) on the optical axis, T16 is the thickness of the sixth lens (716) on the optical axis, T17 is the thickness of the seventh lens (717) on the optical axis, T21 is the thickness of the phase plate glass 1 (721) on the optical axis, T22 is the thickness of the phase plate glass 2 (722) on the optical axis, and T23 is the thickness of the eighth lens (723) on the optical axis.

Images