CN113219642A

CN113219642A - Phase contrast objective lens of microscope

Info

Publication number: CN113219642A
Application number: CN202110574617.4A
Authority: CN
Inventors: 方政; 林顺华; 段立新
Original assignee: Motic China Group Co Ltd
Current assignee: Motic China Group Co Ltd
Priority date: 2021-05-26
Filing date: 2021-05-26
Publication date: 2021-08-06

Abstract

The invention relates to the technical field of optical imaging, and discloses a microscope phase contrast objective lens which comprises a first lens group with positive refractive power, a second lens group with positive refractive power, an object surface and a cover glass, wherein the first lens group is positioned below the second lens group, and the absolute value of the refractive power of the first lens group is larger than that of the second lens group. According to the invention, the first lens group and the second lens group in the phase contrast objective optical system are arranged, and the focal distance, the refractive index, the Abbe number and the thickness of the first lens group and the second lens group are limited, so that the field curvature, the distortion and the aberration sensitivity of the phase contrast objective optical system are further improved, and the optical performance of the phase contrast objective optical system is ensured, 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 lens number and short total length of the objective optical system.

Description

Phase contrast objective lens of microscope

Technical Field

The invention relates to the technical field of optical imaging, in particular to a phase contrast objective of a microscope.

Background

With the rapid development of the biological industry in recent years, there is an increasing demand for observing transparent sections, and observation requirements are met by using a microscope phase contrast method, and generally speaking, since a long working distance is required for medical detection, a large number of details, a large numerical aperture and a large number of field curvatures are observed on a microscope, and a phase contrast plate is also required, which means that the back focuses of lenses or lens groups need to be converged on the phase plate.

Chinese patent discloses a microscope objective (grant publication No. CN 101271191A), which describes a phase contrast objective with a field number of 20 times, 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/NA (λ is wavelength, NA is numerical aperture). However, the magnification is not small enough, the number of fields of view is not large enough, and the longitudinal chromatic aberration is large and only the C 'line 643.847nm to the F' line 479.991nm are considered.

There is also a patent disclosing a microscope objective (granted publication No. KR 10-1850999) which describes a 50-fold phase contrast objective composed of 17 lenses, but using a magnification not small enough, a large number of lenses, a high cost of lens material, and a long total length of the objective optical system.

Disclosure of Invention

It is an object of the present invention to provide a phase contrast objective for a microscope that solves the problems set forth in the background above.

In order to achieve the purpose, the invention provides the following technical scheme:

a microscope phase contrast objective lens comprises a first lens group with positive refractive power, a second lens group with positive refractive power, an object surface and a cover glass, wherein the first lens group is positioned below the second lens group, the absolute value of the refractive power of the first lens group is larger than that of the refractive power of the second lens group, and the first lens group consists 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 in sequence 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 in sequence, and the first phase plate glass is located right above the seventh lens.

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

0.5<|f*NA/D0|<0.8

wherein f is the focal distance 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;

the focal distances of the first lens group and the second lens group meet the following conditions:

0.5<f/f1<2.50； 1.0<f/f2<3.00； 0.5<f2/f1<2.0；

where 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.

As a further scheme of the invention: the focal distances of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the first phase plate glass, the second phase plate glass and the eighth lens need to meet 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；

where f1 is a focal length of the first lens group, f11 is a focal length of the first lens, f12 is a focal length of the second lens, f13 is a focal length of the third lens, f14 is a focal length of the fourth lens, f15 is a focal length of the fifth lens, f16 is a focal length of the sixth lens, f17 is a focal length of the seventh lens, and f23 is a focal length of the eighth lens.

As a still further scheme of the invention: the refractive index of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the first phase plate glass, the second phase plate glass and the eighth lens meets 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 a refractive index of the first lens, N12 is a refractive index of the second lens, N13 is a refractive index of the third lens, N14 is a refractive index of the fourth lens, N15 is a refractive index of the fifth lens, N16 is a refractive index of the sixth lens, N17 is a refractive index of the seventh lens, N21 is a refractive index of the first phase plate glass, N22 is a refractive index of the second phase plate glass, and N23 is a refractive index of the eighth lens.

As a still further scheme of the 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 first phase plate glass, the second phase plate glass and the eighth lens meet the following conditions:

V11≤50； V12≤98； V13≤40； V14≤98； V15≤98；

V16≤40； V17≤95； V21≤70 ； V23≤70； V23≤40；

wherein 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 the first phase plate glass, V22 is the abbe number of the second phase plate glass, and V23 is the abbe number of the eighth lens.

As a still further scheme of the invention: the thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the first phase plate glass, the second phase plate glass and the eighth lens on the optical axis satisfy 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 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 group on the optical axis, T12 is the thickness of the second lens group on the optical axis, T13 is the thickness of the third lens group on the optical axis, T14 is the thickness of the fourth lens group on the optical axis, T15 is the thickness of the fifth lens group on the optical axis, T16 is the thickness of the sixth lens group on the optical axis, T17 is the thickness of the seventh lens group on the optical axis, T21 is the thickness of the first phase plate glass on the optical axis, T22 is the thickness of the second phase plate glass on the optical axis, and T23 is the thickness of the eighth lens group on the optical axis.

Compared with the prior art, the invention has the beneficial effects that:

the first lens group and the second lens group in the phase contrast objective optical system are arranged, so that the first lens group has positive refractive power, the second lens group has positive refractive power, the objective optical system has good optical performance, and the field curvature, distortion and aberration sensitivity of the phase contrast objective optical system are further improved by limiting the focal distance, the refractive index, the Abbe number and the thickness of the first lens group and the second lens group, so that the optical performance of the phase contrast objective optical system is ensured, and 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 lens number and short total length of the objective optical system.

Drawings

FIG. 1 is a lens configuration diagram of a phase contrast objective optical system according to a first embodiment of the present invention;

FIG. 2 is a spherical aberration diagram of an optical system of a phase contrast objective lens according to a first embodiment of the present invention;

FIG. 3 is a field curvature diagram of an optical system of a phase contrast objective lens according to a first embodiment of the present invention;

FIG. 4 is a distortion diagram of an optical system of a phase contrast objective lens according to a first embodiment of the present invention;

FIG. 5 is a diagram illustrating a modulation transfer function of a phase contrast objective optical system according to a first embodiment of the present invention;

FIG. 6 is a lens configuration diagram of a phase contrast objective optical system according to a second embodiment of the present invention;

FIG. 7 is a spherical aberration diagram of the phase contrast objective optical system according to the second embodiment of the present invention;

FIG. 8 is a field curvature diagram of a phase contrast objective optical system according to a second embodiment of the present invention;

FIG. 9 is a distortion diagram of an optical system of a phase contrast objective lens according to a second embodiment of the present invention;

FIG. 10 is a diagram illustrating a modulation transfer function of a phase contrast objective optical system according to a second embodiment of the present invention;

FIG. 11 is a lens configuration diagram of a phase contrast objective optical system according to a third embodiment of the present invention;

FIG. 12 is a spherical aberration diagram of an optical system of a phase contrast objective lens according to a third embodiment of the present invention;

fig. 13 is a field curvature diagram of a phase contrast objective optical system according to a third embodiment of the present invention;

FIG. 14 is a distortion diagram of an optical system of a phase contrast objective lens according to a third embodiment of the present invention;

fig. 15 is a modulation transfer function diagram of a phase contrast objective optical system according to a third embodiment of the present invention.

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

Detailed Description

Referring to fig. 1 to 15, in an embodiment of the present invention, a microscope phase contrast objective lens includes a first lens group 81 having a positive refractive power, a second lens group 82 having a positive refractive power, an object surface 700, and a cover glass 701, where the first lens group 81 is located below the second lens group 82, an absolute value of a refractive power of the first lens group 81 is greater than an absolute value of a refractive power of the second lens group 82, and the first lens group 81 is sequentially composed of, from bottom to top, a first lens 711 having a positive refractive power, a second lens 712 having a negative refractive power, a third lens 713 having a negative refractive power, a fourth lens 714 having a positive refractive power, a fifth lens 715 having a negative refractive power, a sixth lens 716 having a negative refractive power, and a seventh lens 717 having a positive refractive power; the second lens group 82 is composed of a first phase plate glass 721, a second phase plate glass 722 and an eighth lens 723 with positive refractive power from bottom to top in sequence, and the first phase plate glass 721 is positioned right above the seventh lens 717, so that the optical system of the microscope phase contrast objective lens has strong positive refractive power, and the phase contrast objective lens has larger magnification and high optical performance.

0.5<|f*NA/D0|<0.8

so that the phase contrast objective optical system has larger numerical aperture and stronger resolution, wherein f is the focal distance 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 on the optical axis from the cover glass 701 to the first lens 711 of the phase contrast objective optical system closest to the object plane 700;

the first lens group 81 and the second lens group 82 have a focal length satisfying the following condition:

0.5<f/f1<2.50； 1.0<f/f2<3.00； 0.5<f2/f1<2.0；

therefore, the phase contrast objective optical system has a large numerical aperture, a large field of view and better optical performance, and meanwhile, 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, wherein f1 is the focal distance of the first lens group 81, f2 is the focal distance of the second lens group 82, and f is the focal distance of the phase contrast objective optical system.

Preferably, the focal distances 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 first phase plate glass 721, the second phase plate glass 722 and the eighth lens 723 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；

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

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 first phase plate glass 721, the second phase plate glass 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；

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

Preferably, 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 first phase plate glass 721, the second phase plate glass 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；

thereby reducing chromatic aberration of the phase contrast objective optical system such that longitudinal chromatic aberration defined by a focus position deviation between spectral lines C-e and g-e is within 1.0 times a depth of focus, wherein C is 656.27nm, g is 435.84nm and e is 546.07nm, a depth of focus being λ/NA where λ is a wavelength and NA is a numerical aperture, wherein V11 is an abbe number of the first lens 711, V12 is an abbe number of the second lens 712, V13 is an abbe number of the third lens 713, V14 is an abbe number of the fourth lens 714, V15 is an abbe number of the fifth lens 715, V16 is an abbe number of the sixth lens 716, V17 is an abbe number of the seventh lens 717, V21 is an abbe number of the first phase plate glass, V22 is an abbe number of the second phase plate glass 722, and V23 is an abbe number of the eighth lens 723.

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 first phase plate glass 721, the second phase plate glass 722, and the eighth lens 723 on the optical axis satisfy 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；

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

In order to further elaborate the technical content of the invention, the objective optical system will be described in detail below by exemplifying three embodiments.

Example one

As shown in fig. 1, the microscope phase contrast objective lens of the first embodiment includes an object surface 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 having a positive refractive power, a second lens 712 having a negative refractive power, a third lens 713 having a negative refractive power, a fourth lens 714 having a positive refractive power, a fifth lens 715 having a positive refractive power, a sixth lens 716 having a negative refractive power, and a seventh lens 717 having a 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 second surface 7122; the surface of the third lens 713 facing the object side is a third lens first surface 7131, and the surface facing the image side is a third lens second surface 7132; the surface of the fourth lens 714 facing the object side is a fourth lens first surface 7141, and the surface facing the image side is a fourth lens second surface 7142; the surface of the fifth lens 715 facing the object side is a fifth lens first surface 7151, and the surface facing the image side is a fifth lens second surface 7152; the surface of the sixth lens 716 facing the object side is a sixth lens first surface 7161, and the surface facing the image side is a sixth lens second surface 7162; the object side surface of the seventh lens 717 is a seventh lens first surface 7171; the surface facing the image side is a seventh lens second surface 7172;

the second lens group 82 includes a first phase plate glass 721, a second phase plate glass 722 and an eighth lens 723, which are sequentially disposed from the object side to the image side, wherein a surface of the first phase plate glass 721 facing the object side is a first phase plate glass surface 7211, a surface facing the image side is a first phase plate glass second surface 7212, a surface of the second phase plate glass 722 facing the object side is a second phase plate glass first surface 7221, a surface facing the image side is a second phase plate glass second surface 7222, the eighth lens 723 has positive refractive power, a surface facing the object side is an eighth lens first surface 7231, and a surface facing the image side is an eighth lens second surface 7232.

The first lens 711 is placed in the first lens holder 601 with the first lens second face 7112 as a receiving face, and the second lens 712 is placed in the second lens holder 602 with the second lens second face 7122 as a receiving face, so that the space between the first lens 711 and the second lens 712 on the optical axis is ensured by the cooperation between the first lens holder 601 and the second lens holder 602; the third lens second face 7132 of the third lens 713 is glued with the fourth lens first face 7141 of the fourth lens 714, and after the third lens 713 is glued with the fourth lens 714, the third lens first face 7131 is taken as a bearing face and is placed in the third and fourth glued lens seat 603; the second lens 712 and the third lens 713 are ensured to be spaced on the optical axis by the cooperation of the second lens holder 602 and the third and fourth cemented lens holders 603; a fifth lens second face 7152 of the fifth lens 715 is glued with a sixth lens first face 7161 of the sixth lens 716, a sixth lens second face 7162 of the sixth lens 716 is glued with a seventh lens first face 7171 of the seventh lens 717, and after the fifth lens 715, the sixth lens 716 and the seventh lens 717 are glued, the seventh lens second face 7172 of the seventh lens 717 is taken as a bearing face and is placed in a fifth sixth seventh glued lens seat 604; the fourth lens 714 and the fifth lens 715 are spaced on the optical axis by the cooperation of the third and fourth cemented lens holder 603 and the fifth and sixth cemented lens holder 604.

A first and a second surface 7212 of the first phase plate glass 721 and a second and a first surface 7221 of the second phase plate glass 722 are glued, and after the first phase plate glass 721 and the second phase plate glass 722 are glued, the second phase plate glass 7222 of the second phase plate glass 722 is taken as a bearing surface and is placed in the phase plate glass cemented mirror seat 605; the seventh lens 717 and the first phase plate glass 721 are spaced on the optical axis by the fifth sixth seventh cemented lens mount 604 and the second phase plate glass cemented lens mount 605; the eighth lens second surface 7232 of the eighth lens 723 is a receiving surface, and is placed in the eighth lens holder 606, so that the optical axis interval between the eighth lens 723 and the second phase plate glass 722 is ensured by the cooperation between the eighth lens holder 606 and the phase plate glass cemented lens holder 605.

In the phase contrast objective optical system of the first embodiment: the field of view number is 25mm, the focus position deviation between C-e defines a longitudinal chromatic aberration that is 0.77 times the depth of focus, the focus position deviation between g-e defines a longitudinal chromatic aberration that is 0.72 times the depth of focus, where C is 656.27nm, g is 435.84nm, e is 546.07nm, the depth of focus is Λ/NA where Λ is the wavelength, and NA is the numerical aperture.

The first lens 711 has a focal length f11 of 18.14, a refractive index N11 of 1.84, an abbe number V11 of 34.0, and a thickness T11 of 2.52.

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.

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.

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.

The focal length f15 of the fifth lens 715 is-299.69, the refractive index N15 is 1.44, the Abbe number V15 is 94.9, and the thickness T15 is 3.37.

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.

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.

The focal length f21 of the first 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.

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.

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.

Other optical parameters of the phase contrast objective optical system are shown in table 1-1.

TABLE 1-1

From the above, it can be seen that: in the phase contrast objective optical system according to the first embodiment, f is a focal length of the phase contrast objective optical system, that is, f is 45.00; NA the object-side numerical aperture of the objective optical system, i.e. 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, i.e., D0 is 13.33, | f NA/D0| is 0.54, so that it can ensure the features of small magnification, large numerical aperture, high resolution performance, and large number of fields of view.

The focal length of the first lens group 81 is the combined focal length of the first lens 711 to the seventh lens 717, i.e., f1 is 37.85; the focal length of the second lens group 82 is the combined focal length of the first plate glass 721 to the eighth lens 723, i.e. f2 is 26.06; the focal length f of the whole 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 in the focal length numerical range has larger positive refractive power, so that the phase contrast objective has large numerical aperture, and simultaneously, the field curvature, distortion and aberration of the objective optical system are improved, thereby improving the resolution performance.

In this embodiment I, the thickness of the first lens group 81, T1, is 28.72, and the thickness of the second lens group 82, T2, 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, T23/T2 is 0.53.

Fig. 2 to 5 are graphs of various aberrations and MTF performance of the phase contrast objective optical system according to the first embodiment, which show various aberrations showing resolution capability, and an image with better quality can be observed when the aberrations are smaller.

Specifically, fig. 2 is a spherical aberration diagram of the phase contrast objective optical system according to the first embodiment of the present invention, and as shown in fig. 2, the abscissa represents a spherical aberration amount in mm, the ordinate represents an image height in mm, the solid line represents a d line, the broken line represents a C line, the one-dot chain line represents an F line, and the two-dot chain line represents a g line, and 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 optimized.

Fig. 3 is a field curvature diagram of the phase contrast objective optical system according to the first embodiment of the present invention, as shown in fig. 3, the abscissa represents the amount of object plane movement in mm, the ordinate represents the image height in mm, the solid line represents the sagittal vector of light with respect to each wavelength, and the broken line represents the meridional vector with respect to each wavelength. As can be seen from the distribution of the field curvature, the field curvature 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.

Fig. 4 is a distortion diagram of the phase contrast objective optical system according to the first embodiment of the present invention, as shown in fig. 4, the abscissa of the distortion diagram is the amount of distortion in units, and the ordinate of the distortion diagram is the image height in mm, and it can be seen from the distribution of the distortion 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 optimized

Fig. 5 is a MTF (modulation transfer function) graph of the phase contrast objective optical system according to the first embodiment of the present invention, as shown in fig. 5, the abscissa of the graph is spatial frequency and has units of cycles/mm, the ordinate is modulation, i.e., MTF, the solid line represents Modulation (MTF) of the central image plane of the phase contrast objective optical system, and the dotted line represents diffraction limit.

Example two

As shown in fig. 6, 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 first phase plate glass 721, a second phase plate glass 722, and an eighth lens 723, except that the first lens 711 is made of a material and optical parameters of the respective lenses are different from those of the first embodiment.

Specifically, in the phase contrast objective optical system of the second embodiment, the field of view number is 25mm, the focus position deviation between C-e defines a longitudinal chromatic aberration of 0.77 times the depth of focus, and the focus position deviation between g-e defines a longitudinal chromatic aberration of 0.71 times the depth of focus, where C is 656.27nm, g is 435.84nm, and e is 546.07 nm. The focal depth is Λ/NA, where Λ is the wavelength and NA is the numerical aperture.

The first lens 711 has a focal length f11 of 17.96, a refractive index N11 of 1.75, an abbe number V11 of 35.3, and a thickness T11 of 2.67.

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.

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.

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.

The focal length f15 of the fifth lens 715 is-200.58, the refractive index N15 is 1.44, the Abbe number V15 is 94.9, and the thickness T15 is 3.37.

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.

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.

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

T23 was 2.88.

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

TABLE 2-1

As can be seen from the above, in the phase contrast objective optical system according to the second embodiment, f is the focal length of the phase contrast objective optical system, i.e., f is 45.00; NA the object-side numerical aperture of the objective optical system, i.e. 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, i.e., D0 is 13.33, | f NA/D0| is 0.54, so that it can ensure the features of small magnification, large numerical aperture, high resolution performance, and large number of fields of view.

The focal length of the first lens group 81 is the combined focal length of the first lens 711 to the seventh lens 717, i.e., f1 is 37.78; the focal length of the second lens group 82 is the combined focal length of the first plate glass 721 to the eighth lens 723, i.e. f2 is 25.00; the focal length f of the whole 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, the objective optical system in the focal length numerical range has larger positive refractive power, so that the phase contrast objective lens has a larger numerical aperture, and simultaneously, the field curvature, distortion and aberration of the objective optical system are improved, thereby improving the resolution performance.

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, T23/T2 is 0.53.

Specifically, fig. 7 is a spherical aberration diagram of a phase contrast objective optical system according to a second embodiment of the present invention, and as shown in fig. 7, the abscissa represents a spherical aberration amount in mm, the ordinate represents an image height in mm, the solid line represents a d line, the broken line represents a C line, the one-dot chain line represents an F line, and the two-dot chain line represents a g line, and 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 optimized.

Fig. 8 is a field curvature diagram of a phase contrast objective optical system according to a second embodiment of the present invention, where the abscissa is the amount of object plane movement in mm, the ordinate is the image height in mm, the solid line represents the sagittal of light rays with respect to each wavelength, and the broken line represents the meridional with respect to each wavelength, as shown in fig. 8. As can be seen from the distribution of the field curvature, the field curvature 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.

Fig. 9 is a distortion diagram of the phase contrast objective optical system according to the second embodiment of the present invention, as shown in fig. 9, the abscissa of the distortion diagram is distortion amount in unit, and the ordinate of the distortion diagram is image height in mm. From the distribution of distortion, 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.

Fig. 10 is a MTF (modulation transfer function) graph of a phase contrast objective optical system according to a second embodiment of the present invention, where the abscissa is spatial frequency in cycles/mm, the ordinate is modulation, i.e., MTF, the solid line indicates the Modulation (MTF) of the central image plane of the phase contrast objective optical system, and the broken line indicates the diffraction limit, as shown in fig. 10.

EXAMPLE III

As shown in fig. 11, 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 first lens 721, a second lens 722, and an eighth lens 723, except that the first lens 711 is made of a material and optical parameters of the respective lenses are slightly different from those of the second embodiment.

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

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.

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.

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.

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.

The focal length f15 of the fifth lens 715 is-223.27, the refractive index N15 is 1.44, the Abbe number V15 is 94.9, and the thickness T15 is 3.38.

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.

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.

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.

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

TABLE 3-1

As can be seen from the above, in the phase contrast objective optical system according to the third embodiment, f is the focal length of the phase contrast objective optical system, i.e., f is 45.00; NA the object-side numerical aperture of the objective optical system, i.e. 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, i.e., D0 is 13.33, then if NA/D0 is 0.54, so that it can ensure the features of small magnification, large numerical aperture, high resolution performance, and large number of fields of view.

The focal length of the first lens group 81 is the combined focal length of the first lens 711 to the seventh lens 717, i.e., f1 is 37.78; the focal length of the second lens group 82 is the combined focal length of the first plate glass 721 to the eighth lens 723, i.e. f2 is 25.90; the focal length f of the whole 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, the objective optical system in the focal length numerical range has larger positive refractive power, so that the phase contrast objective lens has a larger numerical aperture, and simultaneously, the field curvature, distortion and aberration of the objective optical system are improved, thereby improving the resolution performance.

In the third embodiment, 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 0.04, 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, T23/T2 is 0.53.

Specifically, fig. 12 is a spherical aberration diagram of a phase contrast objective optical system according to a third embodiment of the present invention, in which, as shown in fig. 12, the abscissa represents the amount of spherical aberration in mm, and the ordinate represents the image height in mm, as shown in fig. 7, the solid line represents the d-line, the broken line represents the C-line, the one-dot chain line represents the F-line, and the two-dot chain line represents the g-line, and the spherical aberration of the phase contrast objective optical system is controlled to be within ± 0.05mm, so that the central resolution of the phase contrast objective optical system is optimized.

Fig. 13 is a field curvature diagram of an optical system of a phase contrast objective lens according to a third embodiment of the present invention, where, as shown in fig. 13, the abscissa represents the amount of object plane movement in mm, and the ordinate represents the image height in mm, as shown in fig. 8, the solid line represents the sagittal of light with respect to each wavelength, and the broken line represents the meridional with respect to each wavelength. As can be seen from the distribution of the field curvature, the field curvature 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.

Fig. 14 is a distortion diagram of a phase contrast objective optical system according to a third embodiment of the present invention, and as shown in fig. 14, the abscissa of the distortion diagram is the amount of distortion in units, and the ordinate of the distortion diagram is the image height in units of mm, and it can be seen from the distribution of the distortion 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.

Fig. 15 is a MTF (modulation transfer function) graph of a phase contrast objective optical system according to a third embodiment of the present invention, as shown in fig. 15, in which the abscissa represents spatial frequency in cycles/mm, the ordinate represents modulation, i.e., MTF, as shown in fig. 15, the solid line represents Modulation (MTF) of the central image plane of the phase contrast objective optical system, and the broken line represents diffraction limit.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention are equivalent to or changed within the technical scope of the present invention.

Claims

1. 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 surface (700) and a cover glass (701), wherein the first lens group (81) is positioned below the second lens group (82), the absolute value of the refractive power of the first lens group (81) is larger than that 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 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 in sequence from bottom to top; the second lens group (82) is composed of a first phase plate glass (721), a second phase plate glass (722) and an eighth lens (723) with positive refractive power from bottom to top in sequence, and the first phase plate glass (721) is positioned right above the seventh lens (717), so that the optical system of the microscope phase contrast objective lens has strong positive refractive power, and the phase contrast objective lens is ensured to have larger magnification and high optical performance;

0.5<|f*NA/D0|<0.8

wherein f is the focal distance 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 on the optical axis from the cover glass (701) to the first lens (711) of the phase contrast objective optical system closest to the object plane (700);

the first lens group (81) and the second lens group (82) have a focal distance satisfying the following condition:

0.5<f/f1<2.50； 1.0<f/f2<3.00； 0.5<f2/f1<2.0；

where 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.

2. A microscope phase contrast objective according to claim 1, characterized in that the focal distances 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 first phase plate glass (721), the second phase plate glass (722) and the eighth lens (723) satisfy the following condition:

-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；

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

3. A microscope phase contrast objective according to claim 1, characterized in that 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 first phase plate glass (721), the second phase plate glass (722) and the eighth lens (723) satisfy the following condition:

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 a refractive index of the first lens (711), N12 is a refractive index of the second lens (712), N13 is a refractive index of the third lens (713), N14 is a refractive index of the fourth lens (714), N15 is a refractive index of the fifth lens (715), N16 is a refractive index of the sixth lens (716), N17 is a refractive index of the seventh lens (717), N21 is a refractive index of the phase plate glass one (721), N22 is a refractive index of the phase plate glass two (722), and N23 is a refractive index of the eighth lens (723).

4. A microscope phase contrast objective according to claim 1, characterized in that 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 first phase plate glass (721), the second phase plate glass (722) and the eighth lens (723) satisfy the condition:

V11≤50； V12≤98； V13≤40； V14≤98； V15≤98；

V16≤40； V17≤95； V21≤70 ； V23≤70； V23≤40；

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 one (721), V22 is the abbe number of the phase plate glass two (722), and V23 is the abbe number of the eighth lens (723).

5. A microscope phase contrast objective 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 first phase plate glass (721), the second phase plate glass (722) and the eighth lens (723) on the optical axis satisfy the following condition:

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 a length of the first lens group (81) on the optical axis, T2 is a length of the second lens group (82) on the optical axis, T11 is a thickness of the first lens (711) on the optical axis, T12 is a thickness of the second lens (712) on the optical axis, T13 is a thickness of the third lens (713) on the optical axis, T14 is a thickness of the fourth lens (714) on the optical axis, T15 is a thickness of the fifth lens (715) on the optical axis, T16 is a thickness of the sixth lens (716) on the optical axis, T17 is a thickness of the seventh lens (717) on the optical axis, T21 is a thickness of the first phase plate glass (721) on the optical axis, T22 is a thickness of the second phase plate glass (722) on the optical axis, and T23 is a thickness of the eighth lens (723) on the optical axis.