Microscope objective

Abstract

The present application relates to a microscope objective, comprising a first lens group (T1) with positive refractive power, a second lens group (T2) with positive refractive power and a third lens group (T3) with negative refractive power arranged in order along the optical axis from the object side to the image side, wherein the first lens group (T1) comprises at least one cemented lens group. The microscope objective of the present application has the advantages of large object field and large numerical aperture.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microscope, in particular to a microscope objective. BACKGROUND

[0002] With the increasing demand for observation resolution and imaging speed in the field of life science and industry, there is an increasing demand for microscope objective with larger field of view and larger aperture (NA). Therefore, in order to improve the performance of microscope objective and market competitiveness, large field of view and large numerical aperture have become the development trend of microscope objective. Of course, while realizing large field of view and large numerical aperture apochromatism, it is also necessary to ensure that the structure of the microscope objective has good processability, thereby playing an important role in the production of large field of view and large numerical aperture microscope objective. However, the existing technology usually uses 100X oil lens to observe samples, and the numerical aperture of such objective is 1.35 and the object field of view is 0.265mm. It can be seen that it still cannot meet the demand of large market and large numerical aperture. SUMMARY

[0003] The present application relates to the field of microscope, in particular to a microscope objective.

[0004] In order to achieve the above-mentioned purpose of the application, the present application provides a microscope objective, which comprises a first lens group with positive focal power, a second lens group with positive focal power and a third lens group with negative focal power arranged in order along the optical axis from the object side to the image side, and the first lens group comprises at least one cemented lens group.

[0005] According to one aspect of the present application, the first lens group is composed of a first optical element and a second optical element;

[0006] The second lens group is composed of a third cemented lens group, a fourth optical element and a fifth cemented lens group;

[0007] The third lens group is composed of a sixth optical element and a seventh optical element.

[0008] According to one aspect of the present application, the first optical element is a double cemented lens group with positive focal power;

[0009] The object side surface of the first optical element is a plane, and the image side surface is a hemispherical surface.

[0010] According to one aspect of the present application, the first optical element is composed of a plano-convex lens on the object side and a super-hemispherical lens on the image side.

[0011] According to one aspect of the present application, the second optical element is a lens with positive focal power;

[0012] The shape of the second optical element is a concave meniscus type with a concave object side surface.

[0013] According to an aspect of the present application, the third cemented lens group is composed of two positive lenses and one negative lens.

[0014] The two positive lenses are made of low dispersion material.

[0015] According to an aspect of the present application, when the fourth optical element is a double cemented lens group, it is composed of one positive lens and one negative lens.

[0016] According to an aspect of the present application, the fifth cemented lens group is composed of one positive lens and one negative lens.

[0017] According to an aspect of the present application, the sixth optical element and the seventh optical element have different positive and negative powers, and form a symmetric double Gauss structure.

[0018] According to an aspect of the present application, the sixth optical element is composed of one positive lens and one negative lens.

[0019] The seventh optical element is composed of a negative lens on the object side and a positive lens on the image side.

[0020] According to an aspect of the present application, the distance D from the object plane to the last surface of the microscope objective and the focal length fobj of the microscope objective satisfy the following relationship: 10 < D / fobj < 36.2.

[0021] The focal length fobj of the microscope objective satisfies the following condition: fobj > 1.7.

[0022] The object side numerical aperture NA of the microscope objective satisfies the following condition: 1 < NA ≤ 1.45.

[0023] According to an aspect of the present application, the highest projection height H2 of the central field edge light in the second lens group and the lowest projection height H1 of the central field edge light on the surface of the third lens group, and the projection height H3 of the central field edge light on the surface of the first lens of the second lens group satisfy the following relationship: 0.5 < |H2 / H3| < 1.5; 0.1 < |H1 / H2| < 0.8.

[0024] According to an aspect of the present application, the focal length fL1 of the first cemented lens of the first lens group and the radius value RL1 of the object side surface, and the focal length fobj of the microscope objective satisfy the following relationship: 1 < |fL1 / fobj|; |RL1 / fobj| = ∞.

[0025] According to one aspect of the present application, the combined focal length fT1 of the first lens group and the focal length fobj of the microscope objective satisfy the following relationship: 1<|fT1 / fobj|<5.

[0026] According to one aspect of the present application, the combined focal length fT2 of the second lens group and the focal length fobj of the microscope objective satisfy the following relationship: 1<|fT2 / fobj|<25.

[0027] According to one aspect of the present application, the combined focal length fT3 of the third lens group and the focal length fobj of the microscope objective satisfy the following relationship: 1<|fT3 / fobj|.

[0028] According to one aspect of the present application, the field of view is maximally 35 for bright field observation, and the wavelength range is 436-656 nm.

[0029] According to one aspect of the present application, the first lens group comprises a plano-convex lens and a meniscus lens, which group is used to rapidly increase the numerical aperture and to bear the pressure of increasing the numerical aperture angle for the following lens group.

[0030] According to one aspect of the present application, the second lens group comprises a three-cemented lens group, a single lens or a double-cemented lens group, and a double-cemented lens group, which group is mainly used to correct / eliminate chromatic aberration.

[0031] According to one aspect of the present application, the third lens group comprises a double-Gauss structure with one positive and one negative optical element, which group is mainly used to correct field curvature and increase the field of view. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 A structural diagram of a microscope objective according to the first embodiment of the present application is shown schematically;

[0033] Figure 2 A 0 field lateral aberration diagram of the microscope objective according to the first embodiment of the present application is shown schematically;

[0034] Figure 3 A 1 field lateral aberration diagram of the microscope objective according to the first embodiment of the present application is shown schematically;

[0035] Figure 4 A field curvature distortion diagram of the microscope objective according to the first embodiment of the present application is shown schematically;

[0036] Figure 5 A chromatic aberration curve diagram of the microscope objective according to the first embodiment of the present application is shown schematically;

[0037] Figure 6schematic representation of a microscope objective according to a second embodiment of the application;

[0038] Figure 7 schematic representation of a lateral aberration map for 0 field of a microscope objective according to a second embodiment of the application;

[0039] Figure 8 schematic representation of a lateral aberration map for 1 field of a microscope objective according to a second embodiment of the application;

[0040] Figure 9 schematic representation of a field curvature distortion map for a microscope objective according to a second embodiment of the application;

[0041] Figure 10 schematic representation of a chromatic aberration curve for a microscope objective according to a second embodiment of the application;

[0042] Figure 11 schematic representation of a microscope objective according to a third embodiment of the application;

[0043] Figure 12 schematic representation of a lateral aberration map for 0 field of a microscope objective according to a third embodiment of the application;

[0044] Figure 13 schematic representation of a lateral aberration map for 1 field of a microscope objective according to a third embodiment of the application;

[0045] Figure 14 schematic representation of a field curvature distortion map for a microscope objective according to a third embodiment of the application;

[0046] Figure 15 schematic representation of a chromatic aberration curve for a microscope objective according to a third embodiment of the application;

[0047] Figure 16 schematic representation of a microscope objective according to a fourth embodiment of the application;

[0048] Figure 17 schematic representation of a lateral aberration map for 0 field of a microscope objective according to a fourth embodiment of the application;

[0049] Figure 18 schematic representation of a lateral aberration map for 1 field of a microscope objective according to a fourth embodiment of the application;

[0050] Figure 19 schematic representation of a field curvature distortion map for a microscope objective according to a fourth embodiment of the application;

[0051] Figure 20 schematic representation of a chromatic aberration curve for a microscope objective according to a fourth embodiment of the application;

[0052] Figure 21 A structural diagram schematically showing a microscope objective according to a fifth embodiment of the present application;

[0053] Figure 22 A 0 field lateral aberration diagram schematically showing a microscope objective according to the fifth embodiment of the present application;

[0054] Figure 23 A 1 field lateral aberration diagram schematically showing a microscope objective according to the fifth embodiment of the present application;

[0055] Figure 24 A field curvature distortion diagram schematically showing a microscope objective according to the fifth embodiment of the present application;

[0056] Figure 25 A chromatic aberration curve diagram schematically showing a microscope objective according to the fifth embodiment of the present application. DETAILED DESCRIPTION

[0057] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0058] In the description of the embodiments of the present application, the terms "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" express the orientation or positional relationship shown in the relevant drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the above terms cannot be understood as a limitation of the present application.

[0059] The present application will be described in detail below in conjunction with the drawings and specific embodiments, which cannot be exhaustively described here, but the embodiments of the present application are not limited to the following embodiments.

[0060] Reference is made to Figure 1The microscope objective of the present application belongs to the category of infinity conjugate objective. When observing, the medium between the observed object and the microscope objective can be air or liquid. When the medium is air, the numerical aperture is less than 1, and when the medium is liquid, the numerical aperture can reach the maximum value. The microscope objective comprises, in order along the optical axis from the object side to the image side, a first optical element G1, a second optical element G2, a third cemented lens group G3, a fourth optical element G4, a fifth cemented lens group G5, a sixth optical element G6 and a seventh optical element G7. In the present application, the fourth optical element G4 is a lens or a double cemented lens group. Of course, in some embodiments in which the fourth optical element G4 is a lens, it can also be replaced by a double cemented lens group.

[0061] In the present application, the first optical element G1 is a double cemented lens group with positive focal power, the object side surface of which is a plane, and the image side surface of which is a semi-spherical surface (or close to a semi-spherical shape). Specifically, the first optical element G1 is composed of a plano-convex lens on the object side and a super-hemispherical lens on the image side. The second optical element G2 is a lens or a cemented lens group with positive focal power, and its shape is a meniscus type with a concave object side surface or a biconvex type. The third cemented lens group G3 is composed of two lenses with positive focal power and one lens with negative focal power, wherein the two lenses with positive focal power are made of low dispersion material. When the fourth optical element G4 is a double cemented lens group, it is composed of a lens with positive focal power and a lens with negative focal power. The fifth cemented lens group G5 is composed of a lens with positive focal power and a lens with negative focal power. The sixth optical element G6 and the seventh optical element G7 have different positive and negative focal powers (i.e. one positive and one negative), and form a double Gauss structure. For example, in some embodiments, the sixth optical element G6 has negative focal power, and the seventh optical element G7 has positive focal power. The sixth optical element G6 and the seventh optical element G7 can each be a lens, a cemented lens group or composed of a lens and a cemented lens group. Specifically, the sixth optical element G6 can be composed of a lens with positive focal power and a lens with negative focal power; the seventh optical element G7 can be composed of a negative focal power lens on the object side and a positive focal power lens on the image side. In addition, the focal powers of the fifth cemented lens group G5 and the sixth optical element G6 can also be changed accordingly.

[0062] In the present application, the first lens group T1 composed of the first optical element G1 and the second optical element G2 has positive power, and as described above, the first lens group T1 includes at least one lens with positive power and can be composed of one doublet lens group and one or more single lens groups. The second lens group T2 composed of the third lens group G3, the fourth optical element G4 and the fifth lens group G5 has positive power, and as described above, the second lens group T2 is composed of at least one optical element and can be a single lens or a cemented lens group, wherein the cemented lens group refers to a doublet lens group or a multi-lens cemented group. The third lens group T3 composed of the sixth optical element G6 and the seventh optical element G7 has negative power.

[0063] In the present application, the distance D from the object plane to the last surface of the microscope objective satisfies the following relationship with the focal length fobj of the microscope objective: 10 < D / fobj < 36.2. The focal length fobj of the microscope objective satisfies the following condition: fobj > 1.7. The numerical aperture NA of the microscope objective satisfies the following condition: 1 < NA < 1.45.

[0064] In the present application, the highest projection height H2 of the marginal ray of the central field of view in the second lens group T2 satisfies the following relationship with the lowest projection height H1 of the marginal ray of the central field of view on the lens surface in the third lens group T3 and the projection height H3 of the marginal ray of the central field of view on the first lens surface of the second lens group T2: 0.5 < |H2 / H3| < 1.5; 0.1 < |H1 / H2| < 0.8. Among them, the ray height reaches the maximum value between the first lens surface and the last lens surface of the second lens group T2.

[0065] In the present application, the focal length fL1 of the first cemented lens of the first lens group T1 and the radius value RL1 of the object side surface satisfy the following relationship with the focal length fobj of the microscope objective: 1 < |fL1 / fobj|; |RL1 / fobj| = ∞.

[0066] In the present application, the combined focal length fT1 of the first lens group T1 and the focal length fobj of the microscope objective satisfy the following relationship: 1 < |fT1 / fobj| < 5. The combined focal length fT2 of the second lens group T2 and the focal length fobj of the microscope objective satisfy the following relationship: 1 < |fT2 / fobj| < 25. The combined focal length fT3 of the third lens group T3 and the focal length fobj of the microscope objective satisfy the following relationship: 1 < |fT3 / fobj|.

[0067] In summary, the microscope objective of the present application comprises three lens groups, the first lens group T1 is composed of one doublet and one or more single lenses, which is used to increase the numerical aperture on the object side. The second lens group T2 is composed of at least one doublet and single lenses, which is used to correct chromatic aberration. The third lens group T3 is composed of double Gauss structure, which is used to achieve the effect of flat field and increase the field of view. Thus, the field number of the microscope objective of the present application can reach 35 at most, the numerical aperture can reach 1.4 at most, and the field of view can reach 0.625 mm at most. Moreover, the working distance of the microscope objective can reach more than 0.15 mm, of course, it also includes the working distance between 0 mm and 0.15 mm, and the working distance is the distance from the cover glass to the edge of the first lens group of the objective. The number of lenses is 13-14, which is the most cost-effective, and can be applied to bright field observation, the field number can reach 35 at most, and the numerical aperture can reach 1.4 at most. The complex chromatic aberration is achieved in the wavelength range of 436-656 nm. Of course, the lens can be increased to further improve the performance.

[0068] The microscope objective of the present application is described in detail in the following five groups of embodiments, and S1, S2, …, SN represent the surfaces of each lens, and the cemented surface in the cemented lens group is marked as one surface. In the following embodiments, the first lens group T1 is mainly responsible for providing optical power and reducing the numerical aperture for the rear part, the second lens group T2 is mainly used for correcting chromatic aberration, and the third lens group T3 is mainly used for correcting field curvature and increasing the field of view. The large field of view and large numerical aperture complex chromatic aberration microscope objective of the present application, in some embodiments, the working wavelength range of the microscope objective can be 436-1000 nm, the complex chromatic aberration effect is best in the spectral wavelength range of 436-656 nm, and the field of view range is 30.

[0069] The parameters of each embodiment which meet the above relationship are shown in Table 1 as follows:

[0070]

[0071] Table 1

[0072] First embodiment

[0073] Referring to Figure 1 In this embodiment, the microscope objective has a total of 14 lenses, the first surface of the first lens on the object side is S1, and the surface of the last lens is S21.

[0074] The first optical element G1 is a cemented lens group with positive power and a plano-convex shape. The first lens L1 close to the object side is a plano-convex lens, and the second lens L2 far from the object side is a super-hemisphere lens. The second optical element G2 is a single lens, i.e., the third lens L3, with positive power and a meniscus shape. The object side is concave. The third cemented lens group G3 is composed of two positive-power lenses and one negative-power lens, i.e., the fourth lens L4, the fifth lens L5 and the sixth lens L6. The two positive-power lenses can be made of the same material or different materials, and are both low-dispersion materials. The fourth optical element G4 is a double cemented lens group. The seventh lens L7 close to the object side has positive power, and the eighth lens L8 far from the object side has negative power. In the fifth cemented lens group G5, the ninth lens L9 close to the object side has positive power, and the tenth lens L10 far from the object side has negative power. The sixth optical element G6 is a double cemented lens group. The eleventh lens L11 close to the object side has negative power, and the twelfth lens L12 far from the object side has positive power. The seventh optical element G7 is a double cemented lens group. The thirteenth lens L13 close to the object side has negative power, and the fourteenth lens L14 far from the object side has positive power. The sixth optical element G6 and the seventh optical element G7 form two symmetrical double cemented groups, i.e., a double Gauss structure.

[0075] In the embodiment, the system focal length is 3 mm, the working distance is 0.15 mm, the numerical aperture is 1.35, and the lens thickness and radius of the microscope objective are shown in Table 2.

[0076]

[0077]

[0078] Table 2

[0079] Wherein, the radius refers to the curvature radius of the surface, and the thickness refers to the axial distance from the current surface to the next surface. For example, the thickness of the surface S1 is the distance from S1 to S2, which can be the axial thickness of the medium or lens, or the axial air gap therebetween.

[0080] Figure 2 is the 0 field transverse aberration diagram of the microscope objective of the first embodiment, wherein the abscissa PY and PX represent the normalized entrance pupil size, the ordinate represents the transverse aberration, the scale is ±5 microns, the Y direction is the meridional direction, and the X direction is the sagittal direction. As shown in the figure, the aberration is well balanced, and the imaging performance is good.

[0081] Figure 3 is the 1 field transverse aberration diagram of the microscope objective of the first embodiment, and the scale is ±5 microns. As shown in the figure, the curve is close to the abscissa, and the imaging performance is good.

[0082] Figure 4 This is a field curvature distortion diagram of the microscope objective lens according to the first embodiment. The left image is the field curvature diagram, where the vertical axis represents the field of view and the horizontal axis represents the field curvature, with units of μm. The axial difference between the optimal focusing point at the edge of the field of view and the optimal focusing point at the center of the field of view is less than 2λ / NA. 2 The theoretical values ​​meet the requirement of full-field sharpness and a field-plan objective. In the figure, the vertical axis represents the normalized field of view; the horizontal axis represents the field curvature, with a maximum value of 5 μm and a minimum value of -5 μm. The right figure is a distortion diagram, where the vertical axis represents the field of view and the horizontal axis represents the distortion (percentage). As shown in the figure, the full-field distortion is less than 2%. The vertical axis in the figure represents the normalized field of view, and the horizontal axis represents the distortion, with a maximum of 2% and a minimum of -2%.

[0083] Figure 5 This is a chromatic aberration curve of the microscope objective lens according to the first embodiment. The chromatic aberration correction is good across the entire wavelength, and the difference between any two curves at any field of view is less than λ / NA. 2 .

[0084] The large field-of-view plan immersion microscope objective of this embodiment has a large object-side field of view (0.5 mm), a large numerical aperture (NA = 1.35), and a field of view greater than 0.58 mm. In some preferred embodiments, the numerical aperture can be greater than 1.4 mm.

[0085] Second implementation method

[0086] See Figure 6 In this embodiment, the microscope objective has a total of 13 lenses, with the first surface of the first lens on the objective side being S1 and the surface of the last lens being S20.

[0087] The first optical element G1 is a cemented lens group with positive power and a plano-convex shape, the first lens L1 close to the object side is a plano-convex lens, and the second lens L2 away from the object side is a super-hemisphere lens; the second optical element G2 is a single lens, i.e., the third lens L3, with positive power and a meniscus shape, and the object side is concave; the third cemented lens group G3 is composed of two positive-power lenses and one negative-power lens, i.e., the fourth lens L4, the fifth lens L5 and the sixth lens L6; the materials of the two positive-power lenses can be the same or different, and are both low-dispersion materials; the fourth optical element G4 is a single lens, i.e., the seventh lens L7; in the fifth cemented lens group G5, the eighth lens L8 close to the object side has negative power, and the ninth lens L9 close to the image side has positive power; the sixth optical element G6 is a double cemented lens group with negative power, the tenth lens L10 close to the object side has positive power, and the eleventh lens L11 close to the image side has negative power; the seventh optical element G7 is a double cemented lens group with positive power, the twelfth lens L12 close to the object side has negative power, and the thirteenth lens L13 close to the image side has positive power. The sixth optical element G6 and the seventh optical element G7 form two symmetrical double cemented groups, i.e., a double Gauss structure.

[0088] In the embodiment, the system focal length is 3 mm, the working distance is 0.15 mm, the numerical aperture is 1.4, and the lens thickness and radius of the microscope objective are shown in Table 3 as follows:

[0089] Surface Radius (mm) Thickness (mm) Nd Vd S20 5.637 3.3 1.85 23.8 S19 9.875 1 1.61 45.2 S18 3.527 2.8 S17 -3.757 2.5 1.88 40.8 S16 90.853 5 1.60 83.4 S15 -6.735 0.15 S14 -80.256 5.5 1.43 95 S13 -8.651 1.5 1.61 45.2 S12 -24.587 0.15 S11 37.886 3 1.43 95 S10 -37.886 0.15 S9 17.695 6 1.43 95 S8 -13.587 1.2 1.61 44.3 S7 13.587 7.35 1.43 95 S6 -16.178 0.15 S5 7.958 3.9 1.43 95 S4 18.663 0.15 S3 4.268 5 1.88 40.8 S2 2.324 0.5 1.52 32.2 S1 Infinity 0.15

[0090] Table 3

[0091] Wherein, the radius refers to the curvature radius of the surface, and the thickness refers to the axial distance from the current surface to the next surface, for example, the thickness of the surface S1 is the distance from S1 to S2, which can be the axial thickness of the medium or the lens, or the axial air gap therebetween.

[0092] Figure 7 is the 0 field transverse aberration diagram of the microscope objective of the second embodiment, wherein the abscissa PY and PX represent the normalized entrance pupil size, the ordinate represents the transverse aberration, the scale is ±5 microns, the Y direction is the meridional direction, and the X direction is the sagittal direction, and it can be seen from the diagram that the aberration is well balanced and has good imaging performance.

[0093] Figure 8 is the 1 field transverse aberration diagram of the microscope objective of the second embodiment, and the scale is ±5 microns, and it can be seen from the diagram that the curve is close to the abscissa, and has good imaging performance.

[0094] Figure 9is the field curvature distortion diagram of the microscope objective of the second embodiment, the left figure is the field curvature diagram, the vertical coordinate represents the field of view, and the horizontal coordinate represents the field curvature, with units of μm. The axial difference between the best focus point of the edge field of view and the best focus point of the central field of view is less than 2λ / NA 2 , the theoretical value meets the requirement of clear full field of view, reaching the requirement of flat field objective. The vertical coordinate in the figure is the normalized field of view; the horizontal coordinate represents the field curvature, with a maximum value of 5 μm and a minimum value of -5 μm. The right figure is the distortion diagram, the vertical coordinate represents the field of view, and the horizontal coordinate represents the distortion (percentage). As can be seen from the figure, the distortion of the full field of view is less than 2%. The vertical coordinate in the figure is the normalized field of view, and the horizontal coordinate represents the distortion, with a maximum value of 2% and a minimum value of -2%.

[0095] Figure 10 is the chromatic aberration curve diagram of the microscope objective of the second embodiment. The full-wavelength curve chromatic aberration correction is good, and the difference between any two curves at each field of view is less than λ / NA 2 .

[0096] The large field of view flat field immersion microscope objective of the present embodiment has a large object-side field of view (0.5 mm) and a large numerical aperture (NA = 1.4). The field of view can be greater than 0.58 mm, and in some better embodiments, the numerical aperture can be greater than 1.4.

[0097] Third embodiment

[0098] Referring to Figure 11 , in the present embodiment, the microscope objective has a total of 13 lenses. The first surface of the first lens on the object side is S1, and the surface of the last lens is S20.

[0099] The first optical element G1 is a cemented lens group with positive optical power and a plano-convex shape. The first lens L1 near the object side is a plano-convex lens, and the second lens L2 away from the object side is a super-hemisphere lens. The second optical element G2 is a single lens, i.e., the third lens L3, with positive optical power and a meniscus shape, and the object-side surface is concave. The third cemented lens group G3 is a three-cemented lens group composed of two positive-power lenses and one negative-power lens, which are the fourth lens L4, the fifth lens L5, and the sixth lens L6, respectively. The materials of the two positive-power lenses can be the same or different, and both are low-dispersion materials. The fourth optical element G4 is a single lens, i.e., the seventh lens L7. In the fifth cemented lens group G5, the eighth lens L8 on the object side has negative optical power, and the ninth lens L9 on the image side has positive optical power. The sixth optical element G6 is a double-cemented lens group, with the tenth lens L10 on the object side having positive optical power and the eleventh lens L11 on the image side having negative optical power. The seventh optical element G7 is a double-cemented lens group, with the twelfth lens L12 on the object side having negative optical power and the thirteenth lens L13 on the image side having positive optical power. The sixth optical element G6 and the seventh optical element G7 form two symmetrical double-cemented groups, i.e., a double-Gauss structure.

[0100] In the embodiment, the system focal length f = 1.8 mm, the working distance is 0.15 mm, the numerical aperture is 1.3, and the lens thickness and radius of the microscope objective are as shown in Table 4:

[0101]

[0102]

[0103] Table 4

[0104] Wherein, the radius refers to the radius of curvature of the surface, and the thickness refers to the axial distance from the current surface to the next surface, for example, the thickness of the surface S1 is the distance from S1 to S2, which can be the axial thickness of the medium or lens, or the axial air gap therebetween.

[0105] Figure 12 is the 0 field lateral aberration graph of the microscope objective of the third embodiment, wherein the abscissa PY, PX represents the normalized entrance pupil size, the ordinate represents the lateral aberration, the scale is ± 5 microns, the Y direction is the meridional direction, and the X direction is the sagittal direction, and it can be seen from the graph that the aberration is well balanced and has good imaging performance.

[0106] Figure 13 is the 1 field lateral aberration graph of the microscope objective of the third embodiment, and the scale is ± 5 microns, and it can be seen from the graph that the curve is close to the abscissa, and has good imaging performance.

[0107] Figure 14 is the field curvature distortion graph of the microscope objective of the third embodiment, the left graph is the field curvature graph, the ordinate represents the field of view, and the abscissa represents the field curvature, with units of microns. The axial difference between the best focus point of the edge field of view and the best focus point of the center field of view is less than 2λ / NA 2 , the theoretical value meets the clear full field of view, and meets the flat field objective requirement. The ordinate in the graph is the normalized field of view; the abscissa represents the field curvature, the maximum value is 2 microns, and the minimum value is -2 microns. The right graph is a distortion graph, the ordinate represents the field of view, and the abscissa represents the distortion (percentage). It can be seen from the graph that the full field of view distortion is less than 1%. The ordinate in the graph is the normalized field of view, and the abscissa represents the distortion, the maximum is 1%, and the minimum is -1%.

[0108] Figure 15 is the chromatic aberration curve graph of the microscope objective of the third embodiment, the full wavelength curve chromatic aberration correction is good, and the difference between any two curves at each field of view is less than λ / NA 2 .

[0109] The large field flat field immersion microscope objective of the present embodiment has a large object field (0.5mm), a large numerical aperture (NA=1.3), and a field of view greater than 0.58mm, and in some preferred embodiments the numerical aperture can be greater than 1.4.

[0110] Fourth embodiment

[0111] Reference Figure 16 In the present embodiment, the microscope objective has a total of 14 lenses, and the first surface of the first lens on the object side is S1, and the surface of the last lens is S21.

[0112] The first optical element G1 is a cemented lens group with positive refractive power and a plano-convex shape. The first lens L1 near the object side is a plano-convex lens, and the second lens L2 away from the object side is a super-hemisphere lens. The second optical element G2 is a single lens, i.e., the third lens L3, with positive refractive power and a meniscus shape, and the object side is concave. The third cemented lens group G3 is composed of two positive refractive power lenses and one negative refractive power lens, which are the fourth lens L4, the fifth lens L5, and the sixth lens L6, respectively. The materials of the two positive refractive power lenses can be the same or different, and both are low dispersion materials. The fourth optical element G4 is a double cemented lens group, with the seventh lens L7 on the object side having negative refractive power and the eighth lens L8 on the image side having positive refractive power. In the fifth cemented lens group G5, the ninth lens L9 on the object side has negative refractive power and the tenth lens L10 on the image side has positive refractive power. The sixth optical element G6 is a double cemented lens group, with the eleventh lens L11 on the object side having positive refractive power and the twelfth lens L12 on the image side having negative refractive power. The seventh optical element G7 is a double cemented lens group, with the thirteenth lens L13 on the object side having negative refractive power and the fourteenth lens L14 on the image side having positive refractive power. The sixth optical element G6 and the seventh optical element G7 form two symmetrical double cemented groups, i.e., a double Gauss structure.

[0113] In the present embodiment, the system focal length f=1.8mm, the working distance is 0.15mm, the numerical aperture is 1.36, and the lens thickness and radius of the microscope objective are shown in Table 5:

[0114]

[0115]

[0116] Table 5

[0117] Wherein, the radius refers to the radius of curvature of the surface, and the thickness refers to the axial distance from the current surface to the next surface, for example, the thickness of surface S1 is the distance from S1 to S2, which can be the axial thickness of the medium or lens, or the axial air gap between them.

[0118] Figure 17 is a lateral aberration map of the microscope objective of the fourth embodiment at 0 field, wherein the abscissa PY, PX represents normalized entrance pupil size, the ordinate represents lateral aberration, the scale is ±5 microns, the Y direction is the meridional direction, and the X direction is the sagittal direction. As shown in the figure, the aberration is well balanced, and the imaging performance is good.

[0119] Figure 18 is a lateral aberration map of the microscope objective of the fourth embodiment at 1 field, and the scale is ±5 microns. As shown in the figure, the curve is close to the abscissa, and the imaging performance is good.

[0120] Figure 19 is a field curvature distortion map of the microscope objective of the fourth embodiment. The left figure is a field curvature map, wherein the ordinate represents field, and the abscissa represents field curvature, with units of microns. The axial difference between the best focus point of the edge field and the best focus point of the center field is less than 2λ / NA 2 , and the theoretical value satisfies clear full field, meeting the requirements of flat field objective. The ordinate in the figure is normalized field; the abscissa represents field curvature, with a maximum value of 2 microns and a minimum value of -2 microns. The right figure is a distortion map, wherein the ordinate represents field, and the abscissa represents distortion (percentage). As shown in the figure, the distortion of the full field is less than 1%. The ordinate in the figure is normalized field, and the abscissa represents distortion, with a maximum value of 1% and a minimum value of -1%.

[0121] Figure 20 is a chromatic aberration curve of the microscope objective of the fourth embodiment. The full wavelength curve chromatic aberration correction is good, and the difference between any two curves at each field is less than λ / NA 2 .

[0122] The numerical aperture of the large field flat field immersion microscope objective of the embodiment is large (NA = 1.36), and in some better embodiments, the numerical aperture can be greater than 1.4.

[0123] Fifth Embodiment

[0124] Reference Figure 21 In the embodiment, the microscope objective has a total of 14 lenses, the first surface of the first lens on the object side is S1, and the surface of the last lens is S21.

[0125] The first optical element G1 is a cemented lens group with positive power and a plano-convex shape, the first lens L1 close to the object side is a plano-convex lens, and the second lens L2 away from the object side is a super-hemisphere lens; the second optical element G2 is a single lens, i.e., the third lens L3, with positive power and a meniscus shape, and the object side is concave; the third cemented lens group G3 is composed of two positive-power lenses and one negative-power lens, i.e., the fourth lens L4, the fifth lens L5 and the sixth lens L6; the materials of the two positive-power lenses can be the same or different, and are both low-dispersion materials; the fourth optical element G4 is a double cemented lens group, the seventh lens L7 close to the object side has negative power, and the eighth lens L8 away from the object side has positive power; in the fifth cemented lens group G5, the ninth lens L9 close to the object side has negative power, and the tenth lens L10 away from the object side has positive power; the sixth optical element G6 is a double cemented lens group, the eleventh lens L11 close to the object side has positive power, and the twelfth lens L12 away from the object side has negative power; the seventh optical element G7 is a double cemented lens group, the thirteenth lens L13 close to the object side has negative power, and the fourteenth lens L14 away from the object side has positive power. The sixth optical element G6 and the seventh optical element G7 form two symmetrical double cemented groups, i.e., a double-Gauss structure.

[0126] In the embodiment, the system focal length f is 4.5 mm, the working distance is 0.15 mm, the numerical aperture is 1.21, and the lens thickness and radius of the microscope objective are shown in Table 6 as follows:

[0127] Surface Radius (mm) Thickness (mm) Nd Vd S21 7.215 5 1.74 32.3 S20 5.516 1 1.76 52.3 S19 3.256 4.3 S18 -3.154 1.5 1.88 40.8 S17 -17.356 5.4 1.43 95 S16 -6.868 0.15 S15 -35.214 4 1.43 95 S14 -7.689 2 1.61 44.3 S13 -18.775 0.15 S12 26.365 4.5 1.43 95 S11 -14.215 1.5 1.61 44.3 S10 -12.326 0.15 S9 -26.117 4 1.43 95 S8 19.623 1.5 1.61 44.3 S7 -18.366 4 1.43 95 S6 11.787 0.15 S5 -19.733 2.8 1.43 95 S4 10.454 0.15 S3 4.512 4.8 1.88 40.8 S2 4.357 1 1.52 32.2 S1 Infinity 0.15

[0128] Table 6

[0129] Wherein, the radius refers to the curvature radius of the surface, and the thickness refers to the axial distance from the current surface to the next surface, for example, the thickness of the surface S1 is the distance from S1 to S2, which can be the axial thickness of the medium or the lens, or the axial air gap therebetween.

[0130] Figure 22 is the 0 field transverse aberration diagram of the microscope objective of the fifth embodiment, wherein the abscissa PY and PX represent the normalized entrance pupil size, the ordinate represents the transverse aberration, the scale is ±5 microns, the Y direction is the meridional direction, and the X direction is the sagittal direction. As shown in the figure, the aberration is balanced well, and the imaging performance is good.

[0131] Figure 23 is the 1 field transverse aberration diagram of the microscope objective of the fifth embodiment, and the scale is ±5 microns. As shown in the figure, the curve is close to the abscissa, and the imaging performance is good.

[0132] Figure 24is the field curvature distortion diagram of the microscope objective of the fifth embodiment, the left graph is the field curvature diagram, the vertical coordinate represents the field of view, and the horizontal coordinate represents the field curvature, with units of μm. The axial difference between the best focus point of the edge field of view and the best focus point of the center field of view is less than 2λ / NA 2 , the theoretical value meets the requirement of clear full field of view, and reaches the requirement of flat field objective. The vertical coordinate in the graph is the normalized field of view; the horizontal coordinate represents the field curvature, with a maximum value of 2μm and a minimum value of -2μm. The right graph is the distortion diagram, the vertical coordinate represents the field of view, and the horizontal coordinate represents the distortion (percentage). As can be seen from the graph, the distortion of the full field of view is less than 1%. The vertical coordinate in the graph is the normalized field of view, and the horizontal coordinate represents the distortion, with a maximum value of 1% and a minimum value of -1%.

[0133] Figure 25 is the chromatic aberration curve diagram of the microscope objective of the fifth embodiment. The full wavelength curve chromatic aberration correction is good, and the difference between any two curves at each field of view is less than λ / NA 2 .

[0134] The large field of view flat field immersion microscope objective of the present embodiment has a large object field of view (object field of view = 0.625mm). In some better embodiments, the object field of view can be greater than 0.65mm.

[0135] The above only describes one embodiment of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A microscope objective comprising, in order from the object side to the image side along the optical axis, a first lens group (Tl) having positive refractive power, a second lens group (T2) having positive refractive power, and a third lens group (T3) having negative refractive power, characterized in that, The first lens group (T1) comprises at least one cemented lens group; The combined focal length fT2 of the second lens group (T2) and the focal length fobj of the microscope objective satisfy the following relationship: 10.3≤|fT2 / fobj|<25; The first lens group (T1) is composed of a first optical element (G1) and a second optical element (G2); the second lens group (T2) is composed of a third cemented lens group (G3), a fourth optical element (G4) and a fifth cemented lens group (G5); and the third lens group (T3) is composed of a sixth optical element (G6) and a seventh optical element (G7); The second optical element (G2) is a lens with positive focal power; The second optical element (G2) is in the shape of a meniscus with a concave object side; The third cemented lens group (G3) is composed of two lenses with positive focal power and one lens with negative focal power; When the fourth optical element (G4) is a double cemented lens group, it is composed of one lens with positive focal power and one lens with negative focal power; The fifth cemented lens group (G5) is composed of one lens with positive focal power and one lens with negative focal power.

2. The microscope objective according to claim 1, characterized in that The first optical element (G1) is a double cemented lens group with positive focal power; The object side of the first optical element (G1) is a plane, and the image side is a hemisphere.

3. The microscope objective according to claim 2, characterized in that The first optical element (G1) is composed of a plano-convex lens on the object side and a hyper-hemisphere lens on the image side.

4. The microscope objective according to claim 1, characterized in that The two lenses with positive focal power in the third cemented lens group (G3) are made of low dispersion material.

5. The microscope objective according to claim 1, characterized in that The sixth optical element (G6) and the seventh optical element (G7) have different positive and negative focal powers and form a symmetric double Gauss structure.

6. The microscope objective according to claim 1, characterized in that The sixth optical element (G6) is composed of one lens with positive focal power and one lens with negative focal power; The seventh optical element (G7) is composed of a negative focal power lens on the object side and a positive focal power lens on the image side.

7. The microscope objective according to claim 1, characterized in that The distance D from the object plane to the last surface of the microscope objective and the focal length fobj of the microscope objective satisfy the following relationship: 10<D / fobj<36.2; The focal length fobj of the microscope objective satisfies the following condition: fobj>1.7; The numerical aperture NA of the microscope objective satisfies the following condition: 1<NA≤1.

45.

8. The microscope objective according to claim 1, characterized in that The highest projection height H2 of the central field edge light in the second lens group (T2) and the lowest projection height H1 of the central field edge light on the lens surface in the third lens group (T3), and the projection height H3 of the central field edge light on the first lens surface of the second lens group (T2) satisfy the following relationship: 0.5<|H2 / H3|<1.5; 0.1<|H1 / H2|<0.

8.

9. The microscope objective according to claim 1, characterized in that The focal length fL1 of the first cemented lens of the first lens group (T1) and the radius value RL1 of the object side, and the focal length fobj of the microscope objective satisfy the following relationship: 1<|fL1 / fobj|; |RL1 / fobj|=∞.

10. The microscope objective according to claim 1, characterized in that The combined focal length fT1 of the first lens group (T1) and the focal length fobj of the microscope objective satisfy the following relationship: 1<|fT1 / fobj|<5.

11. The microscope objective according to claim 1, characterized in that The combined focal length fT3 of the third lens group (T3) and the focal length fobj of the microscope objective satisfy the following relationship: 1<|fT3 / fobj|.

12. The microscope objective according to claim 1, characterized in that Applied to bright field observation, the maximum field number is 35, and the application wave band is 436-656nm.

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