Microscope objective

Abstract

The present application relates to a kind of microscope objective, successively include along optical axis from object side to image side: the first lens group (T1) of positive refractive power, the second lens group (T2) of positive refractive power, it is characterized in that, further include: the third lens group (T3) of negative or positive refractive power, the first lens group (T1) at least contains a positive refractive power lens;The second lens group (T2) at least contains a cemented lens group;The third lens group (T3) includes a positive refractive power lens group and a negative refractive power lens group.The microscope objective of the present application has long working distance, and uses near infrared band imaging, reduces the damage to sample, reduces the scattering of sample to light, lens uses low autofluorescence material, improves signal transmittance, reduces noise, while using lens group adjustable structure realizes thick sample observation.

Description

TECHNICAL FIELD

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

[0002] Due to the requirements of life science and industrial field for biological sample observation, it is required to be non-toxic and non-polluted, and to cause little damage to the sample. Moreover, when observing biological samples, it is required to observe the characteristics of tissues with certain thickness, that is, the objective lens is required to have high resolution and large focal depth. In addition, the biological liquid in which the biological sample and tissue are located has high light scattering, which causes problems such as insufficient energy, large noise and low signal-to-noise ratio, and the real topographic characteristics of the sample cannot be observed. Finally, the working distance of the objective lens is also required to be high, especially in the research of cell biology, the working distance of the lens is required to be long enough to meet the operation requirements of the staff on the cells. SUMMARY

[0003] In order to overcome the defects in the prior art, the present application provides a microscope objective, which has a long working distance and uses near-infrared band imaging to reduce damage to the sample, reduce light scattering of the sample, use low autofluorescence material, improve signal transmittance, reduce noise, and realize thick sample observation by using an adjustable lens group structure.

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

[0005] According to an aspect of the present application, in the direction from the object side to the image side along the optical axis,

[0006] The first lens group comprises a first lens group and a second lens group, and the first lens group is a cemented lens group or a plano-convex lens.

[0007] The second lens group comprises one or two lenses with positive focal power.

[0008] According to an aspect of the present application, in the direction from the object side to the image side along the optical axis,

[0009] The rear surface of the first lens group is curved towards the object plane.

[0010] The lens of the second lens group is a meniscus lens, a plano-convex lens or a biconvex lens.

[0011] According to an aspect of the present application, the cemented lens group of the second lens group is a double cemented lens group composed of two lenses or a triple cemented lens group composed of three lenses;

[0012] According to an aspect of the present application, the third lens group has a negative power, and the lens group close to the object side has a positive power;

[0013] According to an aspect of the present application, the two lens groups of the third lens group are each a single lens and / or a cemented lens group;

[0014] According to an aspect of the present application, the distance D between the object plane and the last surface of the microscope objective along the optical axis from the object side to the image side and the focal length fobj of the microscope objective satisfy the relationship: 9 < D / fobj < 14;

[0015] According to an aspect of the present application, the object-side numerical aperture NA of the microscope objective satisfies the relationship: 0.8 < NA < 1.2;

[0016] According to an aspect of the present application, the relationship between the highest projection height H1 of the central field edge ray on the lens surface in all lens groups and the lowest projection height H2 of the central field edge ray on the lens surface in all lens groups satisfies the relationship: 0.1 < |H2 / H1| < 0.8;

[0017] The relationship between the lowest projection height H2 of the central field edge ray on the lens surface in all lens groups and the projection height H3 of the central field edge ray on the lens surface farthest from the object plane satisfies the relationship: 0.3 < |H2 / H3| < 1;

[0018] According to an aspect of the present application, the concave surface of the first lens of the first lens group faces the object plane along the optical axis from the object side to the image side, and the relationship between the focal length fL1 of the first lens and the focal length fobj of the microscope objective satisfies the relationship: 1 < |fL1 / fobj|;

[0019] The relationship between the radius value RL1 of the surface of the first lens facing the object side and the focal length fobj of the microscope objective satisfies the relationship: |RL1 / fobj| = ∞;

[0020] According to an aspect of the present application, the relationship between the combined focal length fT1 of the first lens group and the focal length fobj of the microscope objective satisfies the relationship: 1 < |fT1 / fobj|;

[0021] According to an aspect of the present application, the relationship between the combined focal length fT2 of the second lens group and the focal length fobj of the microscope objective satisfies the relationship: 1 < |fT2 / fobj| < 25;

[0022] According to an aspect of the present application, the following relation is satisfied between the combined focal length fT3 of the third lens group and the focal length fobj of the microscope objective: 1 < |fT3 / fobj|; and

[0023] According to an aspect of the present application, the working distance of the microscope objective is 2 mm or more, including a working distance of 0-2 mm.

[0024] According to the present application, the magnification of the microscope objective ranges from 20 to 30. From the object side, it includes three parts, the first lens group is composed of one doublet and one or two single lenses, which is used to improve the numerical aperture on the object side. The second lens group is composed of at least two cemented lens groups, which is used to eliminate chromatic aberration. The third lens group is composed of one positive lens group and one negative lens group, which is used to achieve the effect of flat field and increase the field of view. The maximum field number can reach 20, and the maximum numerical aperture can reach 1.1. The present objective can be used in biological sample scanning technology, and the lens groups in the second lens group can be translated in the vertical sample direction to achieve the purpose of clear imaging when observing thick samples. At the same time, it can be applied to multi-photon scanning technology, and has good imaging performance in the near-infrared band. Overall, the microscope objective has a long working distance, and uses the near-infrared band for imaging, which reduces the damage to the sample and the scattering of light by the sample. All lenses in the microscope objective are made of low autofluorescence material, which can improve the signal transmission rate and reduce noise. At the same time, the lens group can be adjusted to achieve thick sample observation.

[0025] According to one aspect of the present application, the working wavelength band of the microscope objective can be 486-656 nm, and the best complex chromatic aberration effect is in the 700-1400 nm band interval. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A schematic plan view of the microscope objective of embodiment 1 of the present application is shown;

[0027] Figure 2 A 0 field lateral aberration graph of the microscope objective of embodiment 1 of the present application is shown;

[0028] Figure 3 A 1 field lateral aberration graph of the microscope objective of embodiment 1 of the present application is shown;

[0029] Figure 4 A field curvature distortion graph of the microscope objective of embodiment 1 of the present application is shown;

[0030] Figure 5 A chromatic aberration graph of the microscope objective of embodiment 1 of the present application is shown;

[0031] Figure 6 A schematic plan view of the microscope objective of embodiment 2 of the present application is shown;

[0032] Figure 7 0 field lateral aberration map of the microscope objective of embodiment 2 of the present application;

[0033] Figure 8 1 field lateral aberration map of the microscope objective of embodiment 2 of the present application;

[0034] Figure 9 field curvature distortion map of the microscope objective of embodiment 2 of the present application;

[0035] Figure 10 chromatic aberration plot of the microscope objective of embodiment 2 of the present application;

[0036] Figure 11 plan view schematic of the microscope objective of embodiment 3 of the present application;

[0037] Figure 12 0 field lateral aberration map of the microscope objective of embodiment 3 of the present application;

[0038] Figure 13 1 field lateral aberration map of the microscope objective of embodiment 3 of the present application;

[0039] Figure 14 field curvature distortion map of the microscope objective of embodiment 3 of the present application;

[0040] Figure 15 chromatic aberration plot of the microscope objective of embodiment 3 of the present application;

[0041] Figure 16 plan view schematic of the microscope objective of embodiment 4 of the present application;

[0042] Figure 17 0 field lateral aberration map of the microscope objective of embodiment 4 of the present application;

[0043] Figure 18 1 field lateral aberration map of the microscope objective of embodiment 4 of the present application;

[0044] Figure 19 field curvature distortion map of the microscope objective of embodiment 4 of the present application;

[0045] Figure 20 chromatic aberration plot of the microscope objective of embodiment 4 of the present application;

[0046] Figure 21 plan view schematic of the microscope objective of embodiment 5 of the present application;

[0047] Figure 22 FIG. 5 is a lateral aberration map of the 0 field of a microscope objective according to an embodiment of the present application;

[0048] Figure 23 FIG. 6 is a lateral aberration map of the 1 field of a microscope objective according to an embodiment of the present application;

[0049] Figure 24 FIG. 7 is a field curvature distortion map of a microscope objective according to an embodiment of the present application;

[0050] Figure 25 FIG. 8 is a lateral aberration map of a microscope objective according to an embodiment of the present application. DETAILED DESCRIPTION

[0051] 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 also be obtained by those skilled in the art without any creative effort based on these drawings.

[0052] In the description of the embodiments of the present application, the terms "longitudinal", "lateral", "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.

[0053] 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.

[0054] In the present application, the medium between the observed object and the 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.

[0055] Due to changes in environmental temperature or sample thickness, or changes in the cover glass used by the user, a set of lens groups is needed to correct aberrations. In the present application, the lens group acting as a correction ring is the three-cemented lens group of the second lens group T2. In some embodiments, the working wavelength range of the microscope objective can be 486-656 nm, and the best effect of apochromatic correction is in the wavelength range of 700-1400 nm.

[0056] The microscope objective of the present application is an infinite conjugate objective. In the following various embodiments, the cemented surface of the cemented lens is denoted as a surface, for example, a double cemented lens group composed of two lenses has three surfaces, and a triple cemented lens group composed of three lenses has four surfaces.

[0057] Embodiment 1

[0058] Reference Figure 1 In the direction from the object side to the image side along the optical axis, the microscope objective of the present embodiment comprises a first lens group T1, a second lens group T2 and a third lens group T3 in sequence. It is mainly composed of seven lens groups and contains a total of 14 lenses. In the present embodiment, the first lens group T1 comprises a first lens group G1 and a second lens group in sequence. The first lens group G1 is a plano-convex lens with positive refractive power, which is a cemented lens group composed of a first lens L1 and a second lens L2. 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 thick meniscus lens. The second lens group is a third lens L3 of biconvex type. The first lens group T1 provides positive refractive power.

[0059] The second lens group T2 comprises a third lens group G2, a fourth lens group G3 and a fifth lens group G4 in sequence. The third lens group G2 is a triple cemented lens group composed of a fourth lens L4, a fifth lens L5 and a sixth lens L6. Two lenses have positive refractive power, and one lens has negative refractive power. The specific materials of the two lenses with positive refractive power can be the same or different, but they are all low dispersion materials. The fourth lens group G3 is composed of two lenses with negative refractive power and one lens with positive refractive power, which contains a double cemented lens group. The materials of the two lenses with negative refractive power can be the same or different; the material of the lens with positive refractive power is a low dispersion material. The fifth lens group G4 is a double cemented lens group composed of a tenth lens L10 and an eleventh lens L11, wherein the tenth lens L10 close to the object plane has positive refractive power, and the eleventh lens L11 has negative refractive power. The second lens group T2 is mainly used to correct chromatic aberration.

[0060] The third lens group T3 comprises a sixth lens group G5 and a seventh lens group in sequence. The sixth lens group G5 is a double cemented lens group composed of a twelfth lens L12 and a thirteenth lens L13, and forms a concave-convex structure with the fifth lens group G4. The seventh lens group is composed of a single lens, which is a fourteenth lens L14 with positive refractive power. The third lens group T3 is mainly used to correct field curvature and increase the field of view.

[0061] The microscope objective of the present embodiment comprises the following features:

[0062] D / fobj = 10.83; fobj = 7.2; NA = 1.03; wherein, D represents the distance from the object plane to the last surface of the microscope objective (i.e. the surface S22 of the fourteenth lens L14 away from the object plane), fobj represents the focal length of the microscope objective, and NA represents the object-side numerical aperture of the microscope objective.

[0063] |H2 / H3| = 0.58; |H2 / H1| = 0.55; wherein, H1 represents the highest projection height of the central field edge light ray on all lens surfaces, H2 represents the lowest projection height of the central field edge light ray on all lens surfaces, and H3 represents the projection height of the central field edge light ray on the lens surface farthest from the object plane.

[0064] |fL1 / fobj| = 2.416; |RL1 / fobj| = ∞; wherein, fL1 represents the focal length of the first lens L1 of the first lens group T1, which is concave toward the object plane, RL1 represents the radius value of the surface on the side toward the object, and fobj represents the focal length of the microscope objective.

[0065] |fT1 / fobj| = 1.632; |fT2 / fobj| = 4.218; |fT3 / fobj| = 15.75; wherein, fT1 represents the combined focal length of the first lens group T1, fT2 represents the combined focal length of the second lens group T2, fT3 represents the combined focal length of the third lens group T3, and fobj represents the focal length of the microscope objective.

[0066] The system focal length of the microscope objective of the embodiment is 7.2 mm, the working distance is 2.05 mm, and the numerical aperture is 1.03.

[0067] From the object side, the first surface of the first lens L1 is S1, and the surface of the last lens L14 away from the object plane is S22. The parameters of each lens of the microscope objective of the embodiment include: surface, radius, thickness, refractive index Nd, and Abbe number Vd, which satisfy the conditions shown in Table 1 as follows:

[0068] Surface Radius (mm) Thickness (mm) Refractive index Nd Abbe number Vd S22 557.239 3.00 1.56-1.77 31.5-52.1 S21 -33.517 0.44 S20 10.107 3.8 1.44-1.83 25.2-94.9 S19 14.652 3.00 1.44-1.83 25.2-94.9 S18 5.488 5.50 S17 -5.521 8.40 1.77-1.85 32.3-49.6 S16 -345.182 6.70 1.44-1.65 55.4-94.9 S15 -8.823 0.77 S14 98.811 1.50 1.59-1.68 32.2-49.6 S13 15.602 10.5 1.44 94.9 S12 -11.832 1.70 1.59-1.68 32.2-49.6 S11 -28.803 0.66 S10 28.803 3.80 1.44 94.9 S9 504.993 1.50 1.59-1.68 32.2-49.6 S8 19.392 9.50 1.44 94.9 S7 -19.392 0.13 S6 18.564 5.00 1.44-1.65 67.4-94.9 S5 -107.541 0.13 S4 8.942 8.50 1.71-1.92 30.1-51.2 S3 11.863 0.92 1.46 67.8 S2 Infinity 2.05 1.33 55.9 S1 Infinity 0.17 1.53 56.0

[0069] Table 1

[0070] Wherein, the radius refers to the radius of curvature of the lens 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.

[0071] Figure 2is the 0 field lateral aberration diagram of the microscope objective of Example 1, 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. As can be seen from the diagram, the aberration is well balanced, and the imaging performance is good.

[0072] Figure 3 is the 1 field lateral aberration diagram of the microscope objective of Example 1, and the scale is ±5 microns. As can be seen from the diagram, the curve is close to the abscissa, and the imaging performance is good.

[0073] Figure 4 is the field curvature distortion diagram of the microscope objective of Example 1. The left diagram is a field curvature diagram, wherein the ordinate represents the field of view, and the abscissa 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 , and the theoretical value meets the clear full field of view requirement, reaching the flat field objective requirement. The ordinate in the diagram is the normalized field of view; the abscissa represents the field curvature, with a maximum value of 10 μm and a minimum value of -10 μm. The right diagram is a distortion diagram, wherein the ordinate represents the field of view, and the abscissa represents the distortion (percentage). As can be seen from the diagram, the full field of view distortion is less than 0.1%. The ordinate in the diagram is the normalized field of view, and the abscissa represents the distortion, with a maximum value of 1% and a minimum value of -1%.

[0074] Figure 5 is the chromatic aberration curve diagram of the microscope objective of Example 1. The full wavelength curve chromatic aberration correction is good, and the difference is less than 2λ / NA 2 .

[0075] Example 2

[0076] With reference to Figure 6 , in the direction along the optical axis from the object side to the image side, the microscope objective of the present embodiment sequentially comprises a first lens group T1, a second lens group T2, and a third lens group T3. It is mainly composed of 8 mirror groups, and a total of 14 lenses are included. In the present embodiment, the first lens group T1 sequentially comprises a first mirror group G1, a second mirror group, and a third mirror group. Among them, the first mirror group G1 is a plano-convex lens with positive focal power, which is a cemented mirror group composed of a first lens L1 and a second lens L2. Among them, 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 thick meniscus shaped super-hemisphere lens. The second mirror group is a meniscus type third lens L3 with positive focal power, and its concave surface faces the object plane. The third mirror group is a meniscus type fourth lens L4 with positive focal power, which is a double-convex lens. The composition of each lens makes the first lens group T1 have positive focal power.

[0077] The second lens group T2 comprises a fourth lens group G2, a fifth lens group G3 and a sixth lens group G4 in sequence. The fourth lens group G2 is a three cemented lens group composed of a fifth lens L5, a sixth lens L6 and a seventh lens L7, wherein two lenses have positive refractive power and one lens has negative refractive power. The specific materials of the two lenses with positive refractive power can be the same or different, but are low dispersion materials. The fifth lens group G3 is a three cemented lens group composed of an eighth lens L8, a ninth lens L9 and a tenth lens L10, wherein two lenses have negative refractive power and one lens has positive refractive power. The materials of the two lenses with negative refractive power can be the same or different, and the lens with positive refractive power is a low dispersion material. The sixth lens group G4 is a double cemented lens group composed of an eleventh lens L11 and a twelfth lens L12, wherein the eleventh lens L11 close to the object plane has positive refractive power, and the twelfth lens L12 has negative refractive power. The second lens group T2 is mainly used for correcting chromatic aberration.

[0078] The third lens group T3 comprises a seventh lens group and an eighth lens group in sequence. The seventh lens group is a thirteenth lens L13 with thick meniscus, concave surface facing the object plane and negative refractive power, and the eighth lens group is a fourteenth lens L14 with meniscus, concave surface facing the object plane and positive refractive power, used for correcting field curvature and increasing the field of view.

[0079] The microscope objective of the embodiment comprises the following features:

[0080] D / fobj=10.83; fobj=7.2; NA=1.03; wherein D represents the distance from the object plane to the last surface of the microscope objective (i.e. the surface S23 of the fourteenth lens L14 away from the object plane), fobj represents the focal length of the microscope objective, and NA represents the object side numerical aperture of the microscope objective.

[0081] |H2 / H3|=0.351; |H2 / H1|=0.536; wherein H1 represents the highest projection height of the central field edge light on the lens surface in all lens groups, H2 represents the lowest projection height of the central field edge light on the lens surface in all lens groups, and H3 represents the projection height of the central field edge light on the lens surface farthest from the object plane.

[0082] |fL1 / fobj|=2.174; |RL1 / fobj|=∞; wherein fL1 represents the focal length of the first lens L1 of the first lens group T1, whose concave surface faces the object plane; RL1 represents the radius value of the surface of the first lens L1 towards the object side; and fobj represents the focal length of the microscope objective.

[0083] |fT1 / fobj| = 1.348; |fT2 / fobj| = 17.94; |fT3 / fobj| = 91.2; wherein fT1 represents the combined focal length of the first lens group T1, fT2 represents the combined focal length of the second lens group T2, fT3 represents the combined focal length of the third lens group T3, and fobj represents the focal length of the microscope objective.

[0084] The working distance of the microscope objective of the embodiment is 2.01 mm, and the working distance is the distance from the cover glass to the edge of the first lens group of the microscope objective. The large field of view, large numerical aperture apochromatic microscope objective of the embodiment has a spectral range of 700 nm-1400 nm, a field of view range of 18, and a numerical aperture of 1.03. Due to changes in ambient temperature or sample thickness, or the cover glass used by the user, a set of lens groups is needed to correct aberrations. In the embodiment, the moving lens group is the fifth lens group G3.

[0085] The system focal length of the microscope objective of the embodiment is 7.2 mm, the working distance is 2.05 mm, and the numerical aperture is 1.03.

[0086] From the object side, the first surface of the first lens L1 is S1, and the surface of the last lens L14 away from the object is S23. The parameters of each lens of the microscope objective of the embodiment include: surface, radius, thickness, refractive index Nd, and Abbe number Vd, which satisfy the conditions shown in Table 2 as follows:

[0087]

[0088]

[0089] Table 2

[0090] 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 the lens, or the axial air gap therebetween.

[0091] Figure 7 Figure 1 is the 0 field of view lateral aberration diagram of the microscope objective of the embodiment 2, 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. As can be seen from the figure, the aberration is well balanced, and has good imaging performance.

[0092] Figure 8 Figure 2 is the 1 field of view lateral aberration diagram of the microscope objective of the embodiment 2, and the scale is ±5 microns. As can be seen from the figure, the curve is close to the abscissa, and has good imaging performance.

[0093] Figure 9is the field curvature distortion graph of the microscope objective of Example 2, the left graph is the field curvature graph, the vertical coordinate represents the field of view, the horizontal coordinate represents the field curvature, and the unit is 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 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, the maximum value is 2 μm, and the minimum value is -2 μm. The right graph is a distortion graph, 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, the maximum is 1%, and the minimum is -1%.

[0094] Figure 10 is the chromatic aberration curve graph of the microscope objective of Example 1, the full-wavelength curve chromatic aberration correction is good, and the difference is less than λ / NA 2 .

[0095] Example 3

[0096] Reference Figure 11 , from the object side to the image side along the optical axis, the microscope objective of the present embodiment comprises a first lens group T1, a second lens group T2 and a third lens group T3 in sequence. It is mainly composed of 8 mirror groups, and a total of 14 lenses are included. In the present embodiment, the first lens group T1 comprises a first mirror group G1, a second mirror group and a third mirror group in sequence. Among them, the first mirror group G1 is a plano-convex lens with positive focal power, which is a cemented mirror group composed of a first lens L1 and a second lens L2. Among them, 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 thick meniscus lens. The second mirror group is a meniscus lens with positive focal power, and the concave surface faces the object plane. The third mirror group is a fourth lens L4 with positive focal power, which is a plano-convex lens. The first lens group T1 provides positive focal power.

[0097] The second lens group T2 comprises a fourth lens group G2, a fifth lens group G3 and a sixth lens group G4 in sequence. The fourth lens group G2 is a three cemented lens group composed of a fifth lens L5, a sixth lens L6 and a seventh lens L7. Two lenses have positive refractive power, and one lens has negative refractive power. The specific materials of the two lenses with positive refractive power can be the same or different, but are low dispersion materials. The fifth lens group G3 is a three cemented lens group composed of an eighth lens L8, a ninth lens L9 and a tenth lens L10. Two lenses have negative refractive power, and one lens has positive refractive power. The materials of the two lenses with negative refractive power can be the same or different; the material of the lens with positive refractive power is a low dispersion material. The sixth lens group G4 is a double cemented lens group composed of an eleventh lens L11 and a twelfth lens L12, wherein the eleventh lens L11 close to the object plane has positive refractive power, and the twelfth lens L12 has negative refractive power. The second lens group T2 is mainly used for correcting chromatic aberration.

[0098] The third lens group T3 comprises a seventh lens group and an eighth lens group in sequence. The seventh lens group is a thick meniscus type, with a concave surface facing the object plane, and the eighth lens group is a meniscus type, with a concave surface facing the image plane. The third lens group T3 is mainly used for correcting field curvature and increasing the field of view.

[0099] The microscope objective of the embodiment comprises the following features:

[0100] D / fobj=10.83; fobj=7.2; NA=1.08; wherein D represents the distance from the object plane to the last surface of the microscope objective (i.e. the surface S23 of the fourteenth lens L14 away from the object plane), fobj represents the focal length of the microscope objective, and NA represents the object side numerical aperture of the microscope objective.

[0101] |H2 / H3|=0.53; |H2 / H1|=0.33; wherein H1 represents the highest projection height of the central field edge light on the lens surface in all lens groups, H2 represents the lowest projection height of the central field edge light on the lens surface in all lens groups, and H3 represents the projection height of the central field edge light on the lens surface farthest from the object plane.

[0102] |fL1 / fobj|=2.174; |RL1 / fobj|=∞; wherein fL1 represents the focal length of the first lens L1 of the first lens group T1, whose concave surface faces the object plane; RL1 represents the radius value of the surface on the object side; and fobj represents the focal length of the microscope objective.

[0103] |fT1 / fobj|=1.416; |fT2 / fobj|=4.45; |fT3 / fobj|=14.83; wherein fT1 represents the combined focal length of the first lens group T1, fT2 represents the combined focal length of the second lens group T2, fT3 represents the combined focal length of the third lens group T3, and fobj represents the focal length of the microscope objective.

[0104] The system focal length of the microscope objective of the embodiment is 7.2 mm, the working distance is 2.05 mm, and the numerical aperture is 1.08.

[0105] From the object side, the first surface of the first lens L1 is S1, and the surface of the last lens L14 far from the object is S23. The parameters of each lens of the microscope objective of the embodiment include: surface, radius, thickness, refractive index Nd, and Abbe number Vd, which satisfy the conditions shown in Table 3 as follows:

[0106] Surface Radius (mm) Thickness (mm) Refractive index Nd Abbe number Vd S23 -107.241 2.9 1.63-1.92 31.5-52.1 S22 -31.165 0.15 S21 11.454 8.2 1.44-1.83 25.2-94.9 S20 5.727 6.4 S19 -5.168 3.7 1.63-1.92 31.5-52.1 S18 -42.825 6.7 1.44-1.65 55.4-94.9 S17 -8.438 1 S16 -77.964 1.5 1.59-1.68 32.2-49.6 S15 11.208 9.8 1.44 94.9 S14 -13.962 1.5 1.59-1.68 32.2-49.6 S13 -15.150 0.8 S12 19.907 5.8 1.44 94.9 S11 203.845 1.5 1.59-1.68 32.2-49.6 S10 15.198 9.2 1.44 94.9 S9 -25.361 0.15 S8 18.159 4.5 1.44-1.65 67.4-94.9 S7 125.463 0.15 S6 9.306 4.5 1.44-1.65 67.4-94.9 S5 18.125 0.15 S4 9.904 5.7 1.71-1.92 30.1-51.2 S3 7.683 0.92 1.46 67.8 S2 Infinity 2.05 1.33 55.9 S1 Infinity 0.17 1.53 56.0

[0107] Table 3

[0108] 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 the lens, or the axial air gap therebetween.

[0109] Figure 12 is the 0 field transverse aberration diagram of the microscope objective of Example 3, wherein the abscissa PY, PX represents 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 can be seen from the figure, the aberration is well balanced, and the imaging performance is good.

[0110] Figure 13 is the 1 field transverse aberration diagram of the microscope objective of Example 3, and the scale is ±5 microns. As can be seen from the figure, the curve is close to the abscissa, and the imaging performance is good.

[0111] Figure 14 is the field curvature distortion diagram of the microscope objective of Example 3. The left figure is a field curvature diagram, in which 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 , and the theoretical value satisfies the clear full field of view, meeting the requirements of a flat-field objective. The ordinate in the figure is the normalized field of view; the abscissa represents the field curvature, with a maximum value of 5 microns and a minimum value of -5 microns. The right figure is a distortion diagram, in which the ordinate represents the field of view, and the abscissa represents the distortion (percentage). As can be seen from the figure, the full field of view distortion is less than 0.5%. The ordinate in the figure is the normalized field of view, and the abscissa represents the distortion, with a maximum of 1% and a minimum of -1%.

[0112] Figure 15 is the chromatic aberration curve of the microscope objective of Example 3, the full- wavelength curve chromatic aberration correction is good, and the difference is less than λ / NA 2 .

[0113] Example 4

[0114] With reference to Figure 16 , from the object side to the image side along the optical axis, the microscope objective of the present embodiment comprises a first lens group T1, a second lens group T2 and a third lens group T3 in sequence. It is mainly composed of 8 mirror groups, and a total of 14 lenses are included. In the present embodiment, the first lens group T1 comprises a first mirror group G1, a second mirror group and a third mirror group in sequence. Among them, the first mirror group G1 is a plano-convex lens with positive focal power, which is a cemented mirror group composed of a first lens L1 and a second lens L2. Among them, 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 thick meniscus lens. The second mirror group is a meniscus lens with positive focal power, and the concave surface faces the object plane. The third mirror group is a meniscus lens with positive focal power, and the concave surface faces the object plane. The first lens group T1 provides positive focal power.

[0115] The second lens group T2 comprises a fourth mirror group G2, a fifth mirror group G3 and a sixth mirror group G4 in sequence. Among them, the fourth mirror group G2 is a three-cemented mirror group composed of a fifth lens L5, a sixth lens L6 and a seventh lens L7. Among them, two lenses have positive focal power, and one lens has negative focal power. The specific materials of the two lenses with positive focal power can be the same or different, but they are all low-dispersion materials. The fifth mirror group G3 is a three-cemented mirror group composed of an eighth lens L8, a ninth lens L9 and a tenth lens L10. Among them, two lenses have negative focal power, and one lens has positive focal power. The materials of the two lenses with negative focal power can be the same or different; the material of the lens with positive focal power is a low-dispersion material. The sixth mirror group G4 is a double-cemented mirror group composed of an eleventh lens L11 and a twelfth lens L12, wherein the eleventh lens L11 close to the object plane has positive focal power, and the twelfth lens L12 has negative focal power. The second lens group T2 is mainly used for correcting chromatic aberration.

[0116] The third lens group T3 comprises a seventh mirror group and an eighth mirror group in sequence. Among them, the seventh mirror group is a thick meniscus lens with the concave surface facing the object plane, and the eighth mirror group is a meniscus lens with the concave surface facing the image plane. The third lens group T3 is mainly used for correcting field curvature and increasing the field of view.

[0117] The microscope objective of the present embodiment comprises the following features:

[0118] D / fobj=13; fobj=6; NA=1.08; wherein, D represents the distance from the object plane to the last surface of the microscope objective (i.e. the surface S23 of the fourteenth lens L14 away from the object plane), fobj represents the focal length of the microscope objective, and NA represents the object-side numerical aperture of the microscope objective.

[0119] |H2 / H3|=0.5; |H2 / H1|=0.288; wherein, H1 represents the highest projection height of the central field edge ray on all lens surfaces, H2 represents the lowest projection height of the central field edge ray on all lens surfaces, and H3 represents the projection height of the central field edge ray on the lens surface farthest from the object plane.

[0120] |fL1 / fobj|=1.116; |RL1 / fobj|=∞; wherein, fL1 represents the focal length of the first lens L1 of the first lens group T1, which is concave toward the object plane, RL1 represents the radius value of the surface of the first lens L1 toward the object side, and fobj represents the focal length of the microscope objective.

[0121] |fT1 / fobj|=1.511; |fT2 / fobj|=3.896; |fT3 / fobj|=17.7; wherein, fT1 represents the combined focal length of the first lens group T1, fT2 represents the combined focal length of the second lens group T2, fT3 represents the combined focal length of the third lens group T3, and fobj represents the focal length of the microscope objective.

[0122] The system focal length f of the microscope objective of the embodiment is 6 mm, the working distance is 2 mm, and the numerical aperture is 1.08.

[0123] From the object side, the first surface of the first lens L1 is S1, and the surface of the last lens L14 away from the object plane is S23. The parameters of each lens of the microscope objective of the embodiment include: surface, radius, thickness, refractive index Nd, and Abbe number Vd, which satisfy the conditions shown in Table 4 as follows:

[0124]

[0125]

[0126] Table 4

[0127] 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.

[0128] Figure 17is the 0 field lateral aberration diagram of the microscope objective of Example 4, 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. As can be seen from the diagram, the aberration is well balanced, and the imaging performance is good.

[0129] Figure 18 is the 1 field lateral aberration diagram of the microscope objective of Example 4, and the scale is ±5 microns. As can be seen from the diagram, the curve is close to the abscissa, and the imaging performance is good.

[0130] Figure 19 is the field curvature distortion diagram of the microscope objective of Example 4. The left diagram is a field curvature diagram, in which the ordinate represents the field of view, and the abscissa 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 , and the theoretical value meets the requirement of clear full field of view, achieving the requirement of flat field objective. The ordinate in the diagram is the normalized field of view; the abscissa represents the field curvature, with a maximum value of 5 μm and a minimum value of -5 μm. The right diagram is a distortion diagram, in which the ordinate represents the field of view, and the abscissa represents the distortion (percentage). As can be seen from the diagram, the distortion of the full field of view is less than 0.5%. The ordinate in the diagram is the normalized field of view, and the abscissa represents the distortion, with a maximum value of 1% and a minimum value of -1%.

[0131] Figure 20 is the chromatic aberration curve diagram of the microscope objective of Example 4. The full wavelength curve chromatic aberration correction is good, and the difference is less than λ / NA 2 .

[0132] Due to changes in environmental temperature or sample thickness, or changes in the cover glass used by the user, a set of lens groups is needed to correct aberrations. In this embodiment, the movable lens group is the fifth lens group G3.

[0133] Example 5

[0134] With reference to Figure 21 , in the direction along the optical axis from the object side to the image side, the microscope objective of the present embodiment sequentially comprises a first lens group T1, a second lens group T2 and a third lens group T3. It mainly consists of 8 lens groups, and a total of 12 lenses are included. In the present embodiment, the first lens group T1 sequentially comprises a first lens group G1, a second lens group and a third lens group. Among them, the first lens group G1 is a first lens L1 with positive focal power, which is a plano-convex lens, and the surface close to the object side is a plane. The second lens group is a second lens L2 with positive focal power in a meniscus shape, with the concave surface facing the object plane. The third lens group is a third lens L3 with positive focal power, which is a double-convex lens. The first lens group T1 provides positive focal power.

[0135] The second lens group T2 comprises a fourth lens group G2, a fifth lens group G3 and a sixth lens group in sequence. The fourth lens group G2 is a three cemented lens group composed of a fourth lens L4, a fifth lens L5 and a sixth lens L6. Two lenses have positive refractive power, and one lens has negative refractive power. The specific materials of the two lenses with positive refractive power can be the same or different, but are low dispersion materials. The fifth lens group G3 is a three cemented lens group composed of a seventh lens L7, an eighth lens L8 and a ninth lens L9. Two lenses have negative refractive power, and one lens has positive refractive power. The materials of the two lenses with negative refractive power can be the same or different; the material of the lens with positive refractive power is a low dispersion material. The sixth lens group is a tenth lens L10 of thick meniscus type with a concave surface facing the image plane. The second lens group T2 is mainly used for correcting chromatic aberration.

[0136] The third lens group T3 comprises a seventh lens group and an eighth lens group in sequence. The seventh lens group is a eleventh lens L11 of thick meniscus type with a concave surface facing the object plane, and the eighth lens group is a twelfth lens L12 of meniscus type with a concave surface facing the image plane. The third lens group T3 is mainly used for correcting field curvature and increasing the field of view.

[0137] The microscope objective of the embodiment comprises the following features:

[0138] D / fobj = 8.667; fobj = 9; NA = 0.93; wherein D represents the distance from the object plane to the last surface of the microscope objective (i.e. the surface S21 of the twelfth lens L12 away from the object plane), fobj represents the focal length of the microscope objective, and NA represents the object-side numerical aperture of the microscope objective.

[0139] |H2 / H3| = 0.5; |H2 / H1| = 0.39; wherein H1 represents the highest projection height of the central field edge light on the lens surface in all lens groups, H2 represents the lowest projection height of the central field edge light on the lens surface in all lens groups, and H3 represents the projection height of the central field edge light on the lens surface farthest from the object plane.

[0140] |fL1 / fobj| = 1.68; |RL1 / fobj| = ∞; wherein fL1 represents the focal length of the first lens L1 of the first lens group T1, whose concave surface faces the object plane; RL1 represents the radius value of the surface of the first lens L1 towards the object side; and fobj represents the focal length of the microscope objective.

[0141] |fT1 / fobj| = 1.296; |fT2 / fobj| = 6.34; |fT3 / fobj| = 23.761; wherein fT1 represents the combined focal length of the first lens group T1, fT2 represents the combined focal length of the second lens group T2, fT3 represents the combined focal length of the third lens group T3, and fobj represents the focal length of the microscope objective.

[0142] The system focal length of the microscope objective of the embodiment is 9 mm, the working distance is 2 mm, and the numerical aperture is 0.93.

[0143] From the object side, the first surface of the first lens L1 is S1, and the surface of the last lens L12 far from the object is S21. The parameters of each lens of the microscope objective of the embodiment include: surface, radius, thickness, refractive index Nd, and Abbe number Vd, which satisfy the conditions shown in Table 5 as follows:

[0144]

[0145]

[0146] Table 5

[0147] 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 the lens, or the axial air gap therebetween.

[0148] Figure 22 is the 0 field transverse aberration diagram of the microscope objective of Example 5, wherein the abscissa PY, PX represents 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 can be seen from the figure, the aberration is well balanced, and the imaging performance is good.

[0149] Figure 23 is the 1 field transverse aberration diagram of the microscope objective of Example 5, and the scale is ± 5 microns. As can be seen from the figure, the curve is close to the abscissa, and the imaging performance is good.

[0150] Figure 24 is the field curvature distortion diagram of the microscope objective of Example 5. The left figure is a field curvature diagram, in which 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 , and the theoretical value satisfies the clear full field of view, meeting the requirements of a flat field objective. The ordinate in the figure is the normalized field of view, and the abscissa represents the field curvature, with a maximum value of 5 microns and a minimum value of -5 microns. The right figure is a distortion diagram, in which the ordinate represents the field of view, and the abscissa represents the distortion (percentage). As can be seen from the figure, the full field of view distortion is less than 0.1%. The ordinate in the figure is the normalized field of view, and the abscissa represents the distortion, with a maximum value of 1% and a minimum value of -1%.

[0151] Figure 25 is the chromatic aberration curve diagram of the microscope objective of Example 5. The full wavelength curve chromatic aberration correction is good, and the difference is less than λ / NA 2 .

[0152] Due to the change of ambient temperature or sample thickness, or the cover glass used by the user, a set of lens groups is needed to correct the aberration. In the embodiment, the moving lens group is the fourth lens group G2.

[0153] The above only describes one embodiment of the present application and is not intended 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, along the optical axis from the object side to the image side, the following components in sequence: The first lens group (T1) and the second lens group (T2) with positive optical power are characterized in that they further include a third lens group (T3) with negative or positive optical power. The first lens group (T1) includes at least one lens with positive optical power; The second lens group (T2) includes at least one cemented lens group; The third lens group (T3) comprises a lens group with positive optical power and a lens group with negative optical power; The first lens group (T1) includes a first lens group (G1) and a second lens group, wherein the second lens group includes one or two lenses with positive optical power. The third lens group (T3) has a negative optical power and is located close to the object surface; The highest projection height H1 of the central field of view edge rays on the lens surface among all lens groups and the lowest projection height H2 of the central field of view edge rays on the lens surface among all lens groups satisfy the following relationship: 0.1 < |H2 / H1| < 0.8; The lowest projection height H2 of the central field of view edge rays on the lens surface in all lens groups and the projection height H3 of the central field of view edge rays on the lens surface farthest from the object surface satisfy the following relationship: 0.3 < |H2 / H3| < 1.

2. The microscope objective according to claim 1, characterized in that, Along the optical axis from the object side to the image side, The first lens group (G1) is a cemented lens group or a plano-convex lens.

3. The microscope objective according to claim 2, characterized in that, Along the optical axis from the object side to the image side, The rear surface of the first mirror group (G1) is curved toward the object surface; The lens in the second lens group is a meniscus lens, a plano-convex lens, or a biconvex lens.

4. The microscope objective according to claim 1, characterized in that, The cemented lens group of the second lens group (T2) is either a cemented doublet consisting of two cemented lenses or a cemented triplet consisting of three cemented lenses.

5. The microscope objective according to claim 1, characterized in that, The two lens groups of the third lens group (T3) are both single lenses and / or cemented lens groups.

6. The microscope objective according to any one of claims 1-5, characterized in that, Along the optical axis from the object side to the image side, the distance D from the object surface to the last surface of the microscope objective and the focal length fobj of the microscope objective satisfy the following relationship: 9 <D / fobj<14。 7. The microscope objective according to any one of claims 1-5, characterized in that, The numerical aperture NA of the microscope objective lens satisfies the following relationship: 0.8 <NA<1.2。 8. The microscope objective according to any one of claims 1-5, characterized in that, Along the optical axis from the object side to the image side, the concave surface of the first lens (L1) of the first lens group (T1) faces the object surface, and the focal length fL1 of the first lens (L1) and the focal length fobj of the microscope objective satisfy the relationship: 1<|fL1 / fobj|. The radius value RL1 of the surface of the first lens (L1) facing the object satisfies the relationship between the focal length fobj of the microscope objective and the formula: |RL1 / fobj|=∞.

9. The microscope objective according to any one of claims 1-5, 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|.

10. The microscope objective according to any one of claims 1-5, characterized in that, 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.

11. The microscope objective according to any one of claims 1-5, 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 any one of claims 1-5, characterized in that, The working distance of the microscope objective lens is 2mm or more, including working distances of 0mm-2mm.

Images