CN113820834B

CN113820834B - 60 times microscope objective

Info

Publication number: CN113820834B
Application number: CN202111322583.6A
Authority: CN
Inventors: 刘鹏
Original assignee: Zhangjiagang Zhonghe Automation Technology Co ltd
Current assignee: Zhangjiagang Zhonghe Automation Technology Co ltd
Priority date: 2021-11-09
Filing date: 2021-11-09
Publication date: 2024-01-12
Anticipated expiration: 2041-11-09
Also published as: CN113820834A

Abstract

The invention provides a 60-time microscope objective lens, which has the characteristics of high magnification and large numerical aperture, and has the advantages of less lens number and low processing difficulty, and comprises the following components in sequence from an object plane to an image plane along an optical axis: the lens system comprises a first lens group, a second lens group and a third lens group, wherein the second lens group comprises at least 1 cemented lens, the third lens group comprises at least 1 cemented lens, and the relation is satisfied: 1.1< f1/f <5.0; i f2/f >18;3.5< -f3/f <15;0.65< NA <0.95; wherein f1 is the combined focal length of the first lens group, f2 is the combined focal length of the second lens group, f3 is the combined focal length of the third lens group, f is the combined focal length of the whole microscope objective, and NA is the numerical aperture of the microscope objective.

Description

60 times microscope objective

Background

With the recent rapid development of semiconductor industry and biological medicine, the accuracy of observing samples is higher and higher, and the observation accuracy of a microscope is improved to meet the observation requirement, so that more details are observed on the microscope, a large magnification and a large numerical aperture are required, and the correction of axial aberration and chromatic aberration of magnification is difficult for such an objective optical system, and the optical resolution performance is reduced due to the influence of the aberration.

Some of the existing objectives with large magnification have problems of small numerical aperture, low resolution performance, large number of lenses and difficult processing.

Disclosure of Invention

In order to solve the problems, the invention provides a 60-time microscope objective lens which has the characteristics of large magnification and large numerical aperture, and has the advantages of less lens number and low processing difficulty.

The technical scheme is as follows: a 60 x microscope objective lens, characterized by: the optical axis comprises the following components in sequence from an object plane to an image plane: the lens system comprises a first lens group, a second lens group and a third lens group, wherein the second lens group comprises at least 1 cemented lens, the third lens group comprises at least 1 cemented lens, and the relation is satisfied:

1.1<f1/f<5.0

|f2/f|>18

3.5<-f3/f<15

0.65<NA<0.95

wherein f1 is the combined focal length of the first lens group, f2 is the combined focal length of the second lens group, f3 is the combined focal length of the third lens group, f is the combined focal length of the whole microscope objective, and NA is the numerical aperture of the microscope objective.

Further, the microscope objective satisfies:

1.2<-R1/d0<5.8

wherein d0 is the distance from the object plane to the object plane side mirror surface of the first lens group, and R1 is the curvature radius of the first lens group close to the object plane side mirror surface.

Further, the first lens group at least comprises four lenses, and the first lens group at least comprises 2 biconvex lenses, and the biconvex lenses satisfy the relation:

Vdf>78

where vdf is the full abbe number of the lenticular lens of the first lens group.

Further, the lenses of the first lens group at least include four convex surfaces facing the image space, and the lens of the first lens group close to the object space is a crescent lens with a concave surface facing the object space, and satisfies the relation:

7.5<fs/f<30

wherein, fs: and f is the combined focal length of the whole microscope objective lens.

Further, the second lens group includes 1 biconcave lens and 1 biconvex lens, and satisfies the relationship:

Nms-Nps>0.13

Vdps-Vdms>20

wherein Nms is the refractive index of one negative lens of the second lens group, nps is the refractive index of one positive lens of the second lens group, vdms is the dispersion coefficient of one negative lens of the second lens group, and Vdps is the dispersion coefficient of one positive lens of the second lens group.

Further, the second lens group at least comprises 2 positive single lenses, and the mirror surface of the positive single lens close to the object space is a convex surface facing the object space.

Further, the second lens group is movable in the optical axis direction.

Further, the lens of the third lens group close to the image side is a biconcave lens and satisfies 1.2< R2/f <8, wherein R2 is the curvature radius of the lens of the third lens group close to the image side.

Further, the third lens group includes a positive lens and a negative lens, and satisfies the relationship:

Npt-Nmt>0.08

Vdmt-Vdpt>16

wherein Nmt is the refractive index of one negative lens of the third lens group, npt is the refractive index of one positive lens of the third lens group, vdmt is the dispersion coefficient of one negative lens of the third lens group, vdpt is the dispersion coefficient of one positive lens of the third lens group.

Further, the microscope objective satisfies the relationship:

0.1<(hm/NA–f)/(d1+d2)<0.5

wherein hm is the maximum incidence height of the light in the first lens group, d1 is the minimum interval between the first lens group and the second lens group, and d2 is the maximum interval between the second lens group and the third lens group.

Compared with the prior art, the invention has the advantages that: as a high-magnification microscope objective lens, the high-magnification microscope objective lens has larger positive refractive power, has larger numerical aperture while having larger magnification, and improves field curvature, distortion and aberration of the objective lens optical system, thereby improving resolution performance.

Drawings

FIG. 1 is a schematic diagram of the composition of a 60-fold microscope objective of an embodiment;

FIG. 2 is a graph of the MTF of a 60-fold microscope objective at a plate thickness of 0.11 in an exemplary embodiment;

FIG. 3 is a graph of the MTF of a 60-fold microscope objective at a flat plate thickness of 0.17mm in an exemplary embodiment;

FIG. 4 is a graph of the MTF of a 60-fold microscope objective at a flat plate thickness of 0.23mm in an example.

Detailed Description

For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed description are merely illustrative of exemplary embodiments of the application and are not intended to limit the scope of the application in any way. Like reference numerals refer to like elements throughout the specification.

Referring to fig. 1, a 60-fold micromirror objective lens of the present invention sequentially comprises, from an object plane to an image plane along an optical axis: the lens system comprises a first lens group, a second lens group and a third lens group, wherein the second lens group comprises at least 1 cemented lens, the third lens group comprises at least 1 cemented lens, and the relation is satisfied:

for the focal length of the first lens group, the parameter limit given is 1.1< f1/f <5.0, where f1: a combined focal length of the first lens group, f: a combined focal length of the objective lens as a whole; the lens structure is bloated, various aberrations are difficult to comprehensively correct, and the fact that excessive spherical aberration and field curvature are generated and difficult to correct due to the fact that the focal length of the first lens group exceeds the upper limit can be avoided;

for the focal length of the second lens group, the parameter limit |f2/f| >18 is given, where f2: a combined focal length of the second lens group, f: a combined focal length of the objective lens as a whole; therefore, the spherical aberration and the axial chromatic aberration of the optical system, in particular to the 2-level spectral chromatic aberration, can be well corrected;

for the focal length of the third lens group, the parameter limit is given as 3.5< -f3/f <15, where f3: a combined focal length of the third lens group, f: a combined focal length of the objective lens as a whole; the high-grade spherical aberration, the axial chromatic aberration and the field curvature can be conveniently corrected;

meanwhile, the microscope objective also meets the requirement of 0.65< NA <0.95, so that the microscope objective optical system has a large numerical aperture, the resolution of the objective is improved by the large numerical aperture, and the microscope imaging is clearer and the observation effect is better.

The invention sets the first lens group, the second lens group and the third lens group in the optical system, and the objective optical system has good optical performance by limiting the optical parameters of the lens groups, so that the objective optical system has the characteristics of large magnification and large numerical aperture.

In addition, in the present invention, the microscope objective satisfies the relation:

1.2<-R1/d0<5.8

wherein d0 is the distance from the object plane to the object plane side mirror surface of the first lens group, namely the working distance of the microscope objective lens, R1 is the curvature radius of the first lens group close to the object plane side mirror surface, and the working distance of the objective lens can be longer through the lens combination and the design of each lens, so that the problems that the working distance is too short, the operation performance is poor, or excessive spherical aberration and chromatic aberration are generated, the lens structure is complex, and various aberrations are difficult to comprehensively correct are avoided.

In an embodiment of the present invention, the first lens group includes at least four lenses, and the first lens group includes at least 2 biconvex lenses, and the biconvex lenses satisfy the relationship:

Vdf>78

wherein vdf is the full dispersion coefficient of the biconvex lens of the first lens group, so that the spherical aberration, the chromatic aberration of magnification and the chromatic aberration of 2-level spectrum can be conveniently corrected.

In an embodiment of the present invention, the lenses of the first lens group at least include four convex surfaces facing the image space, and the lenses of the first lens group close to the object space are crescent lenses with concave surfaces facing the object space, and satisfy the relation:

7.5<fs/f<30

wherein, fs: and f is the combined focal length of the whole microscope objective lens, so that the spherical aberration, particularly the advanced court and the coma aberration, can be conveniently corrected.

In an embodiment of the present invention, the second lens group includes 1 biconcave lens and 1 biconvex lens, and satisfies the relationship:

Nms-Nps>0.13

Vdps-Vdms>20

wherein Nms is the refractive index of a negative lens of the second lens group, nps is the refractive index of a positive lens of the second lens group, vdms is the dispersion coefficient of a negative lens of the second lens group, and Vdps is the dispersion coefficient of a positive lens of the second lens group, so that the spherical aberration and the axial chromatic aberration, particularly the 2-level spectral chromatic aberration, of the system can be corrected well.

In the embodiment of the invention, the second lens group at least comprises 2 positive single lenses, the mirror surface of the positive single lens close to the object side is a convex surface facing the object side, so that spherical aberration and axial chromatic aberration, in particular to 2-level spectral chromatic aberration, can be well corrected, and other various aberrations can be corrected at the same time.

In the embodiment of the invention, the lens of the third lens group close to the image side is a biconcave lens and satisfies 1.2< R2/f <8, wherein R2 is the curvature radius of the lens of the third lens group close to the image side, so that excessive high-order spherical aberration and difficulty in correcting a 2-order spectrum can be avoided.

The third lens group comprises a positive lens and a negative lens, and satisfies the relation:

Npt-Nmt>0.08

Vdmt-Vdpt>16

wherein Nmt is the refractive index of a negative lens of the third lens group, npt is the refractive index of a positive lens of the third lens group, vdmt is the dispersion coefficient of a negative lens of the third lens group, vdpt is the dispersion coefficient of a positive lens of the third lens group, and the spherical aberration and the axial chromatic aberration, especially the 2-level spectral chromatic aberration, of the system can be corrected well.

In an embodiment of the invention, the microscope objective satisfies the relation:

0.1<(hm/NA–f)/(d1+d2)<0.5

wherein hm is the maximum incidence height of light rays in the first lens group, d1 is the minimum interval between the first lens group and the second lens group, d2 is the maximum interval between the second lens group and the third lens group, so that the spherical aberration and chromatic aberration of the system can be effectively corrected, and meanwhile, when the lens groups move along the optical axis, additional aberration caused by different flat plate thicknesses can be effectively balanced, and the second lens group can effectively exert the compensation function of the second lens group by the focal length of the first lens group and the third lens group and the spatial configuration thereof and the aberration environment where the moved second lens group is located.

In particular, in one embodiment of the invention, a microscope objective comprises:

the first lens group G1 includes: the first lens 1 has positive focal power, and the object plane side is a concave surface and the phase plane side is a convex surface;

the second lens 2 has negative focal power, and the object plane side is a concave surface and the phase plane side is a convex surface;

a third lens 3 and a fourth lens 4 which are glued, wherein the third lens 3 has negative focal power, the object plane side is a convex surface, and the phase plane side is a concave surface; the fourth lens 4 has positive optical power, and the object plane side thereof is a convex surface, and the phase plane side thereof is a convex surface;

a cemented fifth lens 5 and a sixth lens 6, the fifth lens 5 having negative optical power, the object plane side thereof being convex and the phase plane side thereof being concave; the sixth lens 6 has positive optical power, and its object plane side is a convex surface and its phase plane side is a convex surface;

the second lens group G2 includes: a cemented seventh lens 7, an eighth lens 8, and a ninth lens 9, the seventh lens 7 having positive optical power, the object plane side thereof being convex, the phase plane side thereof being convex; the eighth lens 8 has negative optical power, and the object plane side is a concave surface and the phase plane side is a concave surface; the ninth lens 9 has positive optical power, and its object plane side is a convex surface and its phase plane side is a convex surface.

The third lens group G3 includes: a tenth lens 10 and an eleventh lens 11 bonded together, the tenth lens 10 having positive optical power, the object plane side thereof being convex, and the phase plane side thereof being convex; the eleventh lens 11 has negative optical power, and has a concave object surface side and a concave phase surface side.

In this embodiment, the following is satisfied:

a first lens 1 having a refractive index nd of 1.6< nd <1.8 and a dispersion coefficient vd of 50< vd <70;

a second lens 2 having a refractive index nd of 1.6< nd <1.8 and a dispersion coefficient vd of 40< vd <60;

a third lens 3 having a refractive index nd of 1.4< nd <1.6 and a dispersion coefficient vd of 40< vd <60;

a fourth lens 4 having a refractive index nd of 1.4< nd <1.6 and a dispersion coefficient vd of 90< vd <100;

a fifth lens 5 having a refractive index nd of 1.7< nd <1.9 and a dispersion coefficient vd of 30< vd <50;

a sixth lens 6 having a refractive index nd of 1.4< nd <1.5 and a dispersion coefficient vd of 90< vd <100;

a seventh lens 7 having a refractive index nd of 1.4< nd <1.6 and a dispersion coefficient vd of 90< vd <100;

an eighth lens 8 having a refractive index nd of 1.6< nd <1.8 and a dispersion coefficient vd of 40< vd <60;

a ninth lens 9 having a refractive index nd of 1.5< nd <1.7 and a dispersion coefficient vd of 50< vd <70;

the tenth lens 10 has a refractive index nd of 1.7< nd <1.8 and an dispersion coefficient vd of 20< vd <30.

The eleventh lens 11 has a refractive index nd of 1.5< nd <1.7 and a dispersion vd number of 50< vd <60.

In the microscope objective lens according to one embodiment of the present invention, the focal length f=3.33 mm, the numerical aperture na=0.85, and the objective lens is an infinitely large 60-fold objective lens, and the optical parameters of the elements are shown in table 1.

TABLE 1

In this example, the characteristic parameters are shown in table 2.

(1)	f1/f	2.28
			(2)	\|f2/f\|	204.32
(3)	-R1/d0	2.79
			(4)	fs/f	15.08
(5)	-f3/f	7.00
			(6)	R2/f	2.65
(7)	(hm/NA-f)/(d1+d2)	0.25
			(8)	NA	0.85

TABLE 2

Performing optical theory simulation on the microscope objective lens in the embodiment, and respectively testing the performance of the lens when the thickness of the flat plate is measured; the working values are shown in Table 3 when the plate thicknesses are 0.11mm,0.17mm,0.23mm, respectively, where the spacing (10) represents the distance between the surface S10 and the surface S11, and the spacing (14) represents the distance between the surface S14 and the surface S15.

Thickness of flat plate	0.11	0.17	0.23
				Working distance d0	0.89	0.851	0.81
Interval (10)	1.50	1.84	2.19
				Interval (14)	22.05	21.71	21.37

TABLE 3 Table 3

As can be seen from table 3, the microscope objective of the present embodiment has a compensation function, and the second lens group can balance the additional aberration caused by different plate thicknesses when moving along the optical axis, and can maintain a good imaging state for plates with different thicknesses all the time by adjusting the axial position of the compensation objective, thereby greatly increasing the product application range.

Optical theory simulation is performed on the microscope objective lens in the above embodiment, fig. 2 is a graph of the transfer function MTF of the microscope objective lens in the specific embodiment at a plate thickness of 0.11mm, fig. 3 is a graph of the transfer function MTF of the microscope objective lens in the specific embodiment at a plate thickness of 0.17mm, and fig. 4 is a graph of the transfer function MTF of the microscope objective lens in the specific embodiment at a plate thickness of 0.23 mm.

In the transfer function MTF diagrams of the optical systems of fig. 2,3 and 4, the horizontal axis represents resolution, the unit is line pair/millimeter (1 p/mm), one line pair is calculated as one line pair, and the number of line pairs which can be distinguished per millimeter is the value of resolution. The vertical axis is the modulation transfer function MTF (Modulation Transfer Function), which is a quantitative description of the lens resolution. We use Modulation (Modulation) to represent the magnitude of the contrast. Let maximum luminance be Imax, minimum luminance be Imin, and modulation M be defined as: m= (Imax-Imin)/(imax+imin). The modulation degree is between 0 and 1, the larger the modulation degree means the larger the contrast. When the maximum brightness is completely equal to the minimum brightness, the contrast completely disappears, and the modulation degree at this time is equal to 0.

For a sine wave with an original modulation degree of M, if the modulation degree of an image reaching the image plane through the lens is M', the MTF function value is: MTF value = M' M.

It can be seen that the MTF value must be between 0 and 1, and the closer to 1, the better the performance of the lens. If the MTF value of the lens is equal to 1, the modulation degree of the lens output completely reflects the contrast of the input sine wave; and if the modulation degree of the input sine wave is 1, the modulation degree of the output image is exactly equal to the MTF value. Therefore, the MTF function represents the contrast of the lens at a certain spatial frequency.

The MTF curves can be seen that the MTF values for a representative 0 field, 0.5 field and maximum field have been very close to the diffraction limit. The diffraction limit means that when an ideal object point is imaged by an optical system, it is impossible to obtain an ideal image point due to the limitation of diffraction of light of physical optics, but a diffraction image of the diffraction image of the diffraction system is obtained, and the diffraction image is the diffraction limit of the physical optics, that is, the maximum value.

It can be seen that the present invention can be seen to approach the diffraction limit of physical optics over a wide range of the visible spectrum over a large majority of the field of view.

As the requirements of life sciences and industry for viewing resolution increase, the trend of microscope objectives is to have larger numerical apertures. The microscope lens of the invention sets a large magnification and a large numerical aperture for improving the performance of the microscope objective lens. The high magnification and the large numerical aperture are realized, and meanwhile, the microscope objective optical system is guaranteed to have better machinability, the number of lenses is small, and the machining difficulty is reduced; the microscope lens provided by the invention changes the working distance by moving the second lens group, and observes samples covered by media with different thicknesses and refractive indexes, so that the application of the microscope lens is wider. The microscope objective lens with high magnification and large numerical aperture has important function in production.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Claims

1. A 60 x microscope objective lens, characterized by: the optical axis comprises the following components in sequence from an object plane to an image plane: a first lens group, a second lens group and a third lens group,

the first lens group consists of a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, wherein the third lens and the fourth lens are cemented lenses, and the fifth lens and the sixth lens are cemented lenses;

the first lens has positive focal power, the object plane side of the first lens is a concave surface, and the phase plane side of the first lens is a convex surface;

the second lens has negative focal power, the object plane side of the second lens is a concave surface, and the phase plane side of the second lens is a convex surface;

the third lens has negative focal power, the object plane side of the third lens is a convex surface, and the phase plane side of the third lens is a concave surface; the fourth lens has positive focal power, the object plane side of the fourth lens is a convex surface, and the phase plane side of the fourth lens is a convex surface;

the fifth lens has negative focal power, the object plane side of the fifth lens is a convex surface, and the phase plane side of the fifth lens is a concave surface; the sixth lens has positive focal power, the object plane side of the sixth lens is a convex surface, and the phase plane side of the sixth lens is a convex surface;

the second lens group consists of a seventh lens, an eighth lens and a ninth lens, the seventh lens and the eighth lens are cemented lenses, the seventh lens has positive focal power, the object plane side of the seventh lens is a convex surface, and the phase plane side of the seventh lens is a convex surface; the eighth lens has negative focal power, the object plane side of the eighth lens is a concave surface, and the phase plane side of the eighth lens is a concave surface; the ninth lens has positive focal power, the object plane side of the ninth lens is a convex surface, and the phase plane side of the ninth lens is a convex surface;

the third lens group consists of a tenth lens and an eleventh lens, the tenth lens and the eleventh lens are cemented lenses, the tenth lens has positive focal power, the object plane side of the tenth lens is a convex surface, and the phase plane side of the tenth lens is a convex surface; the eleventh lens has negative focal power, the object plane side is a concave surface, and the phase plane side is a concave surface;

2.28≤f1/f<5.0

|f2/f|≥204.32

3.5<-f3/f≤7.0

0.65<NA<0.95

2. A 60 x microscope objective according to claim 1, characterized in that: the microscope objective satisfies the following conditions:

1.2<-R1/d0<5.8

3. A 60 x microscope objective according to claim 1, characterized in that: the fourth lens and the sixth lens satisfy the relation:

Vdf>78

wherein vdf is the dispersion coefficient.

4. A 60 x microscope objective according to claim 3, characterized in that: the first lens satisfies the relation:

7.5<fs/f<30

5. A 60 x microscope objective according to claim 1, characterized in that: the second lens group satisfies the relation:

Nms-Nps>0.13

Vdps-Vdms>20

wherein Nms is the refractive index of the eighth lens of the second lens group, nps is the refractive index of the seventh lens of the second lens group, vdms is the abbe number of the eighth lens of the second lens group, and Vdps is the abbe number of the seventh lens of the second lens group.

6. A 60 x microscope objective according to claim 1, characterized in that: the second lens group is movable in the optical axis direction.

7. A 60 x microscope objective according to claim 1, characterized in that: the eleventh lens of the third lens group satisfies 1.2< R2/f <8, wherein R2 is a radius of curvature of the eleventh lens of the third lens group.

8. A 60 x microscope objective according to claim 7, wherein: the third lens group satisfies the relation:

Npt-Nmt>0.08

Vdmt-Vdpt>16

where Nmt is the refractive index of the eleventh lens, npt is the refractive index of the tenth lens, vdmt is the abbe number of the eleventh lens, and Vdpt is the abbe number of the tenth lens.

9. A 60 x microscope objective according to claim 6, characterized in that: the microscope objective satisfies the relationship:

0.1<(hm/NA–f)/(d1+d2)<0.5