CN113820834A

CN113820834A - 60-time microscope objective lens

Info

Publication number: CN113820834A
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: 2021-12-21
Anticipated expiration: 2041-11-09
Also published as: CN113820834B

Abstract

The invention provides a 60-time microscope objective lens which has the characteristics of high magnification and large numerical aperture, and the number of lenses is less, the processing difficulty is low, and the objective lens sequentially comprises the following components from an object plane to an image plane along an optical axis: first group, second group and third group, the second group contains 1 at least cemented lens, and the third group contains 1 at least cemented lens, satisfies the relational expression: 1.1< f1/f < 5.0; l 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 lens, and NA is the numerical aperture of the microscope objective lens.

Description

60-time microscope objective lens

Background

With the rapid development of the semiconductor industry and biomedicine in recent years, the precision required for observing a sample is higher and higher, the observation precision of a microscope is improved to meet the observation requirement, and because more details are observed on the microscope, a large magnification and a large numerical aperture are required, for such an objective optical system, correction of axial aberration and chromatic aberration of magnification is difficult, and the optical resolution performance is reduced due to the influence of aberration.

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

Disclosure of Invention

In view of the above problems, the present invention provides a 60-fold microscope objective lens, which has the characteristics of large magnification and large numerical aperture, and has fewer lenses and low processing difficulty.

The technical scheme is as follows: a60-fold microscope objective lens, characterized in that: include in proper order along the optical axis from the object plane to the image plane: first group, second group and third group, the second group contains 1 at least cemented lens, and the third group contains 1 at least cemented lens, satisfies the relational expression:

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 lens, and NA is the numerical aperture of the microscope objective lens.

Further, the microscope objective lens 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 side mirror surface.

Further, the first lens group at least includes four lenses, and the first lens group at least includes 2 lenticular lenses, and the lenticular lenses satisfy the following relation:

Vdf>78

wherein vdf is the full Abbe number of the biconvex lens of the first lens group.

Furthermore, the lenses of the first lens group at least include four convex surfaces facing the image space, and the lenses close to the object space in the first lens group are crescent lenses with concave surfaces facing the object space, and satisfy the relation:

7.5<fs/f<30

wherein fs: the single focal length of the lens close to the object space in the first lens group or the combined focal length of the cemented lens, 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 following relation:

Nms-Nps>0.13

Vdps-Vdms>20

wherein Nms is a refractive index of a negative lens element of the second lens group, Nps is a refractive index of a positive lens element of the second lens group, Vdms is an abbe number of a negative lens element of the second lens group, and Vdps is an abbe number of a positive lens element of the second lens group.

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

Further, the second lens group can move along the optical axis direction.

Further, the lenses close to the image side in the third lens group are biconcave lenses, and satisfy 1.2< R2/f <8, where R2 is the radius of curvature of the image side mirror surface of the third lens group.

Further, the third lens group includes a positive lens and a negative lens, and satisfies the following 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 abbe number of a negative lens of the third lens group, and Vdpt is the abbe number of a positive lens of the third lens group.

Further, the microscope objective lens satisfies the relation:

0.1<(hm/NA–f)/(d1+d2)<0.5

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

Compared with the prior art, the invention has the advantages that: the high-power microscope objective lens has larger positive refractive power, so that the microscope objective lens optical system has larger magnification and large numerical aperture, and simultaneously, the field curvature, distortion and aberration of the objective lens optical system are improved, thereby improving the resolution performance.

Drawings

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

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

FIG. 3 is a graph of MTF of a 60-fold microscope objective lens with a plate thickness of 0.17mm in an embodiment;

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

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 the detailed description is merely illustrative of exemplary embodiments of the present application and does not limit the scope of the present application in any way. Like reference numerals refer to like elements throughout the specification.

Referring to fig. 1, a 60-fold microscope objective according to the present invention sequentially includes, from an object plane to an image plane along an optical axis: first group, second group and third group, the second group contains 1 at least cemented lens, and the third group contains 1 at least cemented lens, satisfies the relational expression:

for the focal length of the first lens group, the given parameter limits 1.1< f1/f <5.0, where f 1: combined focal length of the first lens group, f: the integral combined focal length of the objective lens; the problems that the focal length of the first lens group exceeds the upper limit, the diopter of the first lens group is insufficient, the lens structure is overstaffed, various aberrations are difficult to comprehensively correct, and excessive spherical aberration and field curvature are difficult to correct due to the fact that the focal length of the first lens group exceeds the lower limit can be avoided;

for the focal length of the second lens group, the parameter constraint | f2/f | >18 is given, where f 2: the combined focal length of the second lens group, f: the integral combined focal length of the objective lens; therefore, the spherical aberration and the axial chromatic aberration of the optical system can be well corrected, particularly the 2-level spectral chromatic aberration;

for the focal length of the third lens group, the parameter limits given are 3.5< -f3/f <15, where f 3: the combined focal length of the third lens group, f: the integral combined focal length of the objective lens; the high-grade spherical aberration, the axial chromatic aberration and the field curvature can be conveniently corrected;

meanwhile, the microscope objective also meets the condition that NA is more than 0.65 and less than 0.95, so that the microscope objective optical system has a large numerical aperture, the large numerical aperture improves the resolution of the objective, the microscope imaging is clearer, and the observation effect is better.

According to the invention, the first lens group, the second lens group and the third lens group in the optical system are arranged, and the optical parameters of the lens groups are limited, so that the objective optical system has good optical performance, and has the characteristics of large magnification and large numerical aperture.

Further, in the present invention, the microscope objective lens 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, i.e. the working distance of the microscope objective lens, and R1 is the curvature radius of the first lens group close to the object side mirror surface.

In an embodiment of the present invention, the first lens group comprises at least four lenses, and the first lens group comprises at least 2 lenticular lenses, the lenticular lenses satisfy the following relation:

Vdf>78

vdf is the full abbe coefficient of the biconvex lens of the first lens group, so that the spherical aberration, chromatic aberration of magnification and 2-level chromatic aberration 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 lens close to the object space in the first lens group is a crescent lens with a concave surface facing the object space, and satisfies the following relation:

7.5<fs/f<30

wherein fs: the focal length of the single lens close to the object space in the first lens group or the combined focal length of the cemented lens, and f is the integral combined focal length of the microscope objective lens, so that spherical aberration, especially high-grade court and coma, can be corrected conveniently.

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

Nms-Nps>0.13

Vdps-Vdms>20

wherein, Nms is a refractive index of a negative lens of the second lens group, Nps is a refractive index of a positive lens of the second lens group, Vdms is an abbe number of a negative lens of the second lens group, and Vdps is an abbe number of a positive lens of the second lens group, so as to better correct spherical aberration and axial chromatic aberration of the system, especially 2-level spectral chromatic aberration.

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 space is a convex surface facing the object space, the spherical aberration and the axial chromatic aberration, especially the 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 present invention, the lenses close to the image side in the third lens group are biconcave lenses, and satisfy 1.2< R2/f <8, where R2 is the radius of curvature of the image side mirror surface of the third lens group, which can avoid generating excessive high-order spherical aberration and difficult correction of 2-order spectrum.

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 abbe number of a negative lens of the third lens group, and Vdpt is the abbe number of a positive lens of the third lens group, so that the spherical aberration and the axial chromatic aberration of the system, especially the 2-level spectral chromatic aberration, can be well corrected.

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 incident height of light in the first lens group, d1 is the minimum distance between the first lens group and the second lens group, d2 is the maximum distance between the second lens group and the third lens group, which can effectively correct spherical aberration and chromatic aberration of the system, and effectively balance additional aberration caused by different plate thicknesses when the lens groups move along the optical axis.

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

first lens group G1, comprising: a first lens 1 having positive refractive power, the object surface side of which is a concave surface and the opposite surface side of which is a convex surface;

a second lens 2 having negative refractive power, the object surface side of which is a concave surface and the opposite surface side of which is a convex surface;

a third lens 3 and a fourth lens 4 which are cemented, the third lens 3 having negative refractive power, the object surface side thereof being a convex surface, the opposite surface side thereof being a concave surface; the fourth lens 4 has positive focal power, and has a convex object surface side and a convex opposite surface side;

a fifth lens 5 and a sixth lens 6 which are cemented together, the fifth lens 5 having a negative refractive power, the object surface side thereof being a convex surface, the opposite surface side thereof being a concave surface; the sixth lens 6 has positive refractive power, and has a convex object surface side and a convex opposite surface side;

a second lens group G2, comprising: a seventh lens 7, an eighth lens 8, and a ninth lens 9 which are cemented, the seventh lens 7 having positive power, the object surface side being a convex surface, the opposite surface side being a convex surface; the eighth lens 8 has negative refractive power, and has a concave object surface side and a concave opposite surface side; the ninth lens 9 has positive refractive power, and has a convex object surface side and a convex opposite surface side.

Third lens group G3, comprising: a tenth lens 10 and an eleventh lens 11 which are cemented together, the tenth lens 10 having a positive power, the object surface side being a convex surface, the opposite surface side being a convex surface; the eleventh lens 11 has positive refractive power, and has a concave object surface side and a concave opposite surface side.

In this embodiment, the following are satisfied:

a first lens 1 having a refractive index nd of 1.6< nd <1.8 and an Abbe number vd of 50< vd < 70;

a second lens 2 having a refractive index nd of 1.6< nd <1.8 and an Abbe number vd of 40< vd < 60;

a third lens 3 having a refractive index nd of 1.4< nd <1.6 and an Abbe number vd of 40< vd < 60;

a fourth lens 4 having a refractive index nd of 1.4< nd <1.6 and an Abbe number vd of 90< vd < 100;

a fifth lens 5 having a refractive index nd of 1.7< nd <1.9, an Abbe number vd of 30< vd < 50;

a sixth lens 6 having a refractive index nd of 1.4< nd <1.5, and an Abbe number vd of 90< vd < 100;

a seventh lens 7 having a refractive index nd of 1.4< nd <1.6, an Abbe number vd of 90< vd < 100;

an eighth lens 8 having a refractive index nd of 1.6< nd <1.8, and an Abbe number vd of 40< vd < 60;

a ninth lens 9 having a refractive index nd of 1.5< nd <1.7, and an abbe number vd of 50< vd < 70;

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

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

In the microscope objective lens according to one embodiment of the present invention, the objective lens focal length f is 3.33mm, the objective numerical aperture NA is 0.85, and the objective lens is an infinite objective lens of 60 times, 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 plate thickness is measured; the working values are shown in table 3, where the interval (10) represents the distance between the surface S10 and the surface S11, and the interval (14) represents the distance between the surface S14 and the surface S15, when the plate thicknesses are 0.11mm, 0.17mm, and 0.23mm, respectively.

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

TABLE 3

It can be known from table 3 that the microscope objective lens of this embodiment has the compensation function, and the additional aberration that can balance different dull and stereotyped thicknesses and arouse when the second mirror group moves along the optical axis can be directed against the dull and stereotyped of different thickness, through the axial position of adjustment compensation objective lens, can remain good imaging state throughout, and the product application scope has been improved to the big amplitude.

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

In the MTF graphs of the transfer functions of the optical systems of fig. 2, 3 and 4, the horizontal axis represents the resolution in units of line pairs/millimeter (lp/mm), two lines, black and white, represent one line pair, and the number of line pairs that can be resolved per millimeter is the value of the resolution. The vertical axis represents the modulation Transfer function (mtf), which is a quantitative description of the resolution of the lens. We express the contrast in terms of Modulation. Assuming that the maximum luminance is Imax, the minimum luminance is Imin, and the modulation degree M is defined as: m ═ i (Imax-Imin)/(Imax + Imin). The modulation degree is between 0 and 1, and the larger the modulation degree, the larger the contrast is. When the maximum brightness and the minimum brightness are completely equal, the contrast disappears completely, and the modulation degree is equal to 0.

For a sine wave with an original modulation degree of M, if the modulation degree of an image reaching an image plane through a lens is M', the MTF function value is as follows: the MTF value is M 'or 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; whereas 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. The MTF function therefore represents the contrast of the lens at a certain spatial frequency.

The MTF curves show that the MTF values for a representative 0 field, 0.5 field and maximum field are already very close to the diffraction limit. The diffraction limit means that when an ideal object point is imaged by an optical system, due to the limitation of diffraction of light of physical optics, an ideal image point cannot be obtained, but a fraunhofer diffraction image is obtained, and the diffraction image is the diffraction limit, namely the maximum value, of the physical optics.

It can be seen that the present invention can approach the diffraction limit of physical optics over a wide range of the visible spectrum, over a substantial portion of the field of view.

Due to the increasing requirements of life science and industrial fields for observation resolution, the microscope objective tends to have a larger numerical aperture. The microscope lens of the invention is provided with large magnification and large numerical aperture for improving the performance of the microscope objective. The microscope objective optical system is ensured to have better processability while high magnification and large numerical aperture are realized, the number of lenses is small, and the processing difficulty is reduced; the microscope lens changes the working distance by moving the second lens group, observes samples covered by media with different thicknesses and refractive indexes, and enables the application of the microscope objective lens to be wider. The microscope objective with high magnification and large numerical aperture is put into production and plays an important role.

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 attributes 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. A60-fold microscope objective lens, characterized in that: include in proper order along the optical axis from the object plane to the image plane: first group, second group and third group, the second group contains 1 at least cemented lens, and the third group contains 1 at least cemented lens, satisfies the relational expression:

1.1<f1/f<5.0

|f2/f|>18

3.5<-f3/f<15

0.65<NA<0.95

2. The objective lens for 60 × microscope according to claim 1, wherein: the microscope objective satisfies:

1.2<-R1/d0<5.8

3. The objective lens for 60 × microscope according to claim 1, wherein: the first lens group at least comprises four lenses, the first lens group at least comprises 2 biconvex lenses, and the biconvex lenses satisfy the following relation:

Vdf>78

4. A 60-fold microscope objective lens according to claim 3, characterized in that: contain four convex surfaces towards the image space at least in the lens of first mirror group, and be close to the crescent lens of object space for the concave surface in the first mirror group, and satisfy the relational expression:

7.5<fs/f<30

wherein fs: the focal length of the single lens close to the object space in the first lens group or the combined focal length of the cemented lens, and f is the combined focal length of the whole microscope objective lens.

5. The objective lens for 60 × microscope according to claim 1, wherein: the second lens group comprises 1 biconcave lens and 1 biconvex lens, and satisfies the following relation:

Nms-Nps>0.13

Vdps-Vdms>20

6. The objective lens for 60 × microscope according to claim 5, wherein: the second lens group at least comprises 2 positive single lenses, and the lens surface of each positive single lens, which is close to the object space, is a convex surface facing the object space.

7. The objective lens for 60 × microscope according to claim 1, wherein: the second lens group can move along the optical axis direction.

8. The objective lens for 60 × microscope according to claim 1, wherein: the lenses close to the image space in the third lens group are biconcave lenses, and satisfy 1.2< R2/f <8, wherein R2 is the curvature radius of the lens close to the image space in the third lens group.

9. The objective lens for 60 × microscope according to claim 8, wherein: the third lens group comprises a positive lens and a negative lens, and satisfies the relation:

Npt-Nmt>0.08

Vdmt-Vdpt>16

10. The objective lens for 60 × microscope according to claim 7, wherein: the microscope objective satisfies the relation:

0.1<(hm/NA–f)/(d1+d2)<0.5