microscope objective

Abstract

The present invention relates to a microscope objective lens, which comprises, from the object side, a first lens portion (D1) having positive focal power, a second lens portion (D2) having negative focal power, and a third lens portion (D3) having positive focal power. The first lens portion (D1) comprises a first lens (L1) adjacent to the object side, the surface of the first lens (L1) facing the object plane being convex. The second lens portion (D2) comprises a plurality of cemented lens groups. The third lens portion (D3) comprises a rearmost end lens (L2), the surface of the end lens (L2) facing away from the object plane being convex. The microscope objective lens of the present invention has a magnification of less than 2X and avoids generating large distortion, thereby avoiding image distortion under a large field of view.

Description

Technical Field

[0001] The present invention relates to the field of microscopes, and particularly to a microscope objective lens. Background Art

[0002] With the increasing requirements for observation resolution, imaging speed, and large-field observation in the fields of life science and industry, higher requirements are put forward for the chromatic aberration and observation field of view of microscope objective lenses. The magnification of common microscope objective lenses is generally between 4X and 100X, and there are few objective lenses below 2X. Moreover, low-magnification objective lenses are prone to cause large distortion, and image distortion is likely to occur in a large field of view. Summary of the Invention

[0003] The purpose of the present invention is to solve the above problems and provide a microscope objective lens.

[0004] To achieve the above purpose, the present invention provides a microscope objective lens, which sequentially includes from the object side: a first lens part with a positive optical power, a second lens part with a negative optical power, and a third lens part with a positive optical power;

[0005] The first lens part includes a first lens adjacent to the object side, and the surface of the first lens facing the object surface is a convex surface;

[0006] The second lens part is composed of multiple groups of cemented lens groups;

[0007] The third lens part includes an end lens located at the rearmost side, and the surface of the end lens away from the object surface is a convex surface.

[0008] According to one aspect of the present invention, the first lens part is composed of the first lens, and the first lens is a positive optical power lens;

[0009] The third lens part is composed of the end lens, and the end lens is a positive optical power lens.

[0010] According to one aspect of the present invention, the first lens part further includes a first cemented doublet lens group;

[0011] The third lens part further includes a second cemented doublet lens group.

[0012] According to one aspect of the present invention, 0.2 < M / fobj < 0.5, 135 < fobj, where M represents the distance from the object surface to the last surface of the microscope objective lens; fobj represents the focal length of the microscope objective lens.

[0013] According to one aspect of the present invention, 0.02 < NA < 0.06, where NA represents the numerical aperture of the object side of the microscope objective lens.

[0014] According to one aspect of the present invention, 0.01<|H2 / H1|<0.6, 0.1<|H2 / H3|<1.6, wherein H1 represents the highest projection height of the edge light of the central field of view on the lens surface; H2 represents the lowest projection height of the edge light of the central field of view on the lens surface; and H3 represents the projection height of the edge light of the central field of view on the surface of the last lens.

[0015] According to one aspect of the present invention, 0.07<|fD1 / fobj|, 0.01<|RD1 / fobj|<0.5, wherein fD1 represents the focal length of the first lens, with its convex surface facing the object plane; RD1 represents the radius value of the surface of the lens facing the object side; and fobj represents the focal length of the microscope objective lens.

[0016] According to one aspect of the present invention, |fD2 / fobj|<0.1, wherein fD2 is the combined focal length of the second lens portion, and fobj is the focal length of the microscope objective lens.

[0017] According to one aspect of the present invention, 0.01<|fD3 / fobj|<0.5, wherein fD3 is the combined focal length of the third lens portion, and fobj is the focal length of the microscope objective lens.

[0018] According to one aspect of the present invention, 0.01<|H2 / H1|<0.5, 0.1<|H2 / H3|<1.5, wherein H1 represents the highest projection height of the edge light of the central field of view on the lens surface; H2 represents the lowest projection height of the edge light of the central field of view on the lens surface; and H3 represents the projection height of the edge light of the central field of view on the surface of the last lens.

[0019] According to one aspect of the present invention, 0.1<|fD1 / fobj|, 0.01<|RD1 / fobj|<0.5, fD1 represents the focal length of the first lens, whose convex surface faces the object plane; RD1 represents the radius value of the surface of the lens facing the object side; fobj represents the focal length of the microscope objective lens.

[0020] According to one aspect of the present invention, -0.05<|fD2 / fobj|, wherein fD2 is the combined focal length of the second lens portion, and fobj is the focal length of the microscope objective lens.

[0021] According to one aspect of the present invention, 0.01<|fD3 / fobj|<0.5, wherein fD3 is the combined focal length of the third lens portion, and fobj is the focal length of the microscope objective lens.

[0022] According to one aspect of the present invention, the operating wavelength band of the microscope objective lens is 400-1000 nm.

[0023] According to one embodiment of the present invention, a microscope objective comprises, from the object side to the image side, a first lens section, a second lens section, and a third lens section. The first lens section may consist solely of the first lens or may also incorporate a first doublet lens group. The third lens section may consist solely of a terminal lens or may also incorporate a second doublet lens group. This section, along with the first lens section, contributes to the overall positive focal power of the system, increases the field of view, and corrects for field curvature.

[0024] According to one embodiment of the present invention, the second lens section is composed of cemented lens groups. These cemented lens groups contribute to the negative power of the entire system, correcting chromatic aberration, increasing aperture, and reducing light deflection angles, thereby reducing overall system sensitivity. By modifying the combination, thickness, curvature, and spacing of the cemented lens groups in the second lens section, it is possible to achieve reduced distortion or field curvature at a large field of view to suit different applications.

[0025] According to one embodiment of the present invention, the six lens groups, namely the first lens, the first doublet lens group, the third lens group, the fourth lens group, the second doublet lens group and the end lens, cleverly form a relatively symmetrical arrangement to correct the distortion and field curvature of the overall low-magnification objective lens.

[0026] According to one embodiment of the present invention, the microscope objective lens operates in the wavelength range of 436-1000 nm. This facilitates apochromatization, resulting in more accurate color reproduction of samples over a wide field of view. The overall working distance of the microscope objective lens can reach over 5 mm, but can also be between 0 mm and 5 mm.

[0027] According to one aspect of the present invention, the magnification of the microscope objective lens can be reduced to 1.25X, further increasing the area that can be observed at any one time. This nearly doubles the visible range of a 2X objective lens, making it easier to find the desired location within a large field of view. Furthermore, distortion is ≤0.2%, preventing image distortion in a wide field of view. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a structural diagram of a microscope objective lens according to a first embodiment of the present invention;

[0029] Figure 2 is a lateral aberration diagram of the zero field of view of the microscope objective lens according to the first embodiment of the present invention;

[0030] Figure 3 is a lateral aberration diagram of one field of view of the microscope objective lens according to the first embodiment of the present invention;

[0031] Figure 4 is an axial chromatic aberration diagram of the microscope objective lens according to the first embodiment of the present invention;

[0032] Figure 5 is a field curvature distortion diagram of a microscope objective lens according to a first embodiment of the present invention;

[0033] Figure 6 is a structural diagram of a microscope objective lens according to a second embodiment of the present invention;

[0034] Figure 7 is a lateral aberration diagram of the zero field of view of the microscope objective lens according to the second embodiment of the present invention;

[0035] Figure 8 is a lateral aberration diagram of one field of view of a microscope objective lens according to a second embodiment of the present invention;

[0036] Figure 9 is an axial chromatic aberration diagram of a microscope objective lens according to a second embodiment of the present invention;

[0037] Figure 10 is a field curvature distortion diagram of a microscope objective lens according to a second embodiment of the present invention;

[0038] Figure 11 is a structural diagram of a microscope objective lens according to a third embodiment of the present invention;

[0039] Figure 12 is a lateral aberration diagram of the zero field of view of the microscope objective lens according to the third embodiment of the present invention;

[0040] Figure 13 is a lateral aberration diagram of one field of view of a microscope objective lens according to a third embodiment of the present invention;

[0041] Figure 14 is an axial chromatic aberration diagram of a microscope objective lens according to a third embodiment of the present invention;

[0042] Figure 15 3 is a field curvature distortion diagram of a microscope objective lens according to a third embodiment of the present invention. DETAILED DESCRIPTION

[0043] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0044] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0045] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not limited to the following embodiments.

[0046] Figure 1 1 is a structural diagram of a microscope objective lens according to a first embodiment of the present invention. Figure 1 As shown, the microscope objective lens of the present invention includes, arranged in sequence from the object side, a first lens portion D1 with positive refractive power, a second lens portion D2 with negative refractive power, and a third lens portion D3 with positive refractive power.

[0047] In this invention, the three lens components are divided into two categories. The first category consists of the first lens component D1 consisting solely of the first lens L1, with its convex surface facing the object plane and the other surface being either flat or curved. The second lens component D2 is composed of multiple cemented lens groups, including but not limited to triplets or doublets. The third lens component D3 consists solely of the terminal lens L2, with its convex surface facing away from the object plane and the other surface being either flat or curved.

[0048] The microscope objective lens with this combination method satisfies the following conditions: 0.2 < M / fobj < 0.5, 135 < fobj; where M represents the distance from the object plane to the last surface of the microscope objective lens; fobj represents the focal length of the microscope objective lens. 0.02 < NA < 0.06; NA represents the numerical aperture of the object side of the microscope objective lens. 0.01 < |H2 / H1| < 0.6, 0.1 < |H2 / H3| < 1.6; where H1 represents the highest projection height of the marginal ray of the central field of view on the lens surface; H2 represents the lowest projection height of the marginal ray of the central field of view on the lens surface; H3 represents the projection height of the marginal ray of the central field of view on the surface of the last lens. 0.07 < |fD1 / fobj|, 0.01 < |RD1 / fobj| < 0.5; where fD1 represents the focal length of the first lens L1, with its convex surface facing the object plane; RD1 represents the radius value of the surface of the lens facing the object side; fobj represents the focal length of the microscope objective lens. |fD2 / fobj| < 0.1; where fD2 is the combined focal length of the second lens part D2, and fobj is the focal length of the microscope objective lens. 0.01 < |fD3 / fobj| < 0.5; where fD3 is the combined focal length of the third lens part D3, and fobj is the focal length of the microscope objective lens.

[0049] The second type is that the first lens part D1 includes the first lens L1 and the first doublet lens group G1, and the convex surface of the first lens L1 faces the object plane. The first doublet lens group G1 consists of a positive-power lens and a negative-power lens, with the convex surface (or plane) facing the object plane. The second lens part D2 includes the third lens group G3 and the fourth lens group G4. The third lens group G3 is a doublet lens group, consisting of a positive-power lens and a negative-power lens, with the concave surface facing the object plane. The fourth lens group G4 is a doublet lens group, consisting of a negative-power lens and a positive-power lens, with the concave surface facing the object plane. The material combination of the third lens group G3 and the fourth lens group G4 can be the same or different. The third lens part D3 includes the second doublet lens group G2 and the terminal lens L2, where the second doublet lens group G2 consists of a negative-power lens and a positive-power lens, with the concave surface facing the object plane. The terminal lens L2 is a positive-power lens.

[0050] The microscope objective lens with this combination method satisfies the following conditions. 0.2 < M / fobj < 0.5, 135 < fobj; where M represents the distance from the object plane to the last surface of the microscope objective lens; fobj represents the focal length of the microscope objective lens. 0.02 < NA < 0.06; NA represents the numerical aperture of the object side of the microscope objective lens. 0.01 < |H2 / H1| < 0.5, 0.1 < |H2 / H3| < 1.5; where H1 represents the highest projection height of the marginal ray of the central field of view on the lens surface; H2 represents the lowest projection height of the marginal ray of the central field of view on the lens surface; H3 represents the projection height of the marginal ray of the central field of view on the surface of the last lens. 0.1 < |fD1 / fobj|, 0.01 < |RD1 / fobj| < 0.5; fD1 represents the focal length of the first lens L1 with its convex surface facing the object plane; RD1 represents the radius value of the surface of this lens facing the object side; fobj represents the focal length of the microscope objective lens. -0.05 < |fD2 / fobj|; where fD2 is the combined focal length of the second lens part D2, and fobj is the focal length of the microscope objective lens. 0.01 < |fD3 / fobj| < 0.5; where fD3 is the combined focal length of the third lens part D3, and fobj is the focal length of the microscope objective lens.

[0051] The microscope objective lens of the present invention belongs to an infinity conjugate objective lens, and its working distance can reach 5 mm or more, and of course, it can also be between 0 mm and 5 mm. In some embodiments, the present invention can achieve an apochromatic effect in any interval of the 436 - 1000 nm band. By modifying the combination method, curvature, thickness, and interval of the doublet and triplet in D2, smaller distortion or smaller field curvature under a large field of view can be obtained to adapt to different uses.

[0052] The following gives three specific embodiments according to the above two types of microscope objective lens structures of the present invention to specifically illustrate the microscope objective lens according to the present invention. Among them, the first type of microscope objective lens structure corresponds to the first embodiment, and the second type corresponds to the second and third embodiments. In the following embodiments, the present invention numbers the surfaces of the lens from the object side to the image side in the structural order as S1, S2, S3..., and the cemented surface is denoted as the first surface.

[0053] The first embodiment:

[0054] Refer to Figure 1The microscope objective lens of this embodiment includes a first lens portion D1, a second lens portion D2, and a third lens portion D3, which are arranged in sequence from the object side to the image side. The first lens portion D1 has positive focal power and includes only the first lens L1, whose convex surface faces the object side. The second lens portion D2 has negative focal power and, from the object side to the image side, includes a first doublet lens group G1, a third lens group G3, a fourth lens group G4, and a second doublet lens group G2, wherein the fourth lens group G4 is a triplet lens group and the third lens group G3 is a doublet lens group, that is, the second lens portion D2 consists of three groups of doublet lenses and one group of triplet lenses. The third lens portion D3 has positive focal power and includes only one terminal lens L2, whose convex surface is farther away from the object side.

[0055] The overall structure includes 1 triplet lens group, 3 doublet lens groups and 2 lenses. The first lens L1 (i.e., the first lens part D1) with positive optical power has a convex surface facing the object plane, and can be a convex-concave, plano-convex or biconvex lens. The second lens part D2 has negative optical power, and the G1, G2, G3, and G4 lens groups therein share the optical power of D2. Among them, the first doublet lens group G1 is composed of a positive lens and a negative lens glued together, and the two non-glued surfaces are flat towards the object. The third lens group G3 is composed of a positive lens and a negative lens glued together, and the two non-glued convex surfaces are facing the object. The fourth lens group G4 is composed of two negative lenses and a positive lens glued together, and the two non-glued surfaces with large curvature face the object. In this embodiment, G1, G3, and G4 have convex and concave surfaces facing each other, respectively. The optical power of the two lenses of G1 is positive and negative from left to right, the optical power of the two lenses of G3 is positive and negative from left to right, and the optical power of the three lenses of G4 is negative and positive from left to right. This can better correct field curvature, chromatic aberration, and distortion, making the image plane flatter, the background color more perfect, and the image plane complete. The second double-cemented lens group G2 has negative optical power and is formed by cementing a negative lens and a positive lens, with the two non-cemented concave surfaces facing the object. The end lens L2 with positive optical power (i.e., the third lens part D1) is a double convex lens, and the surface with a larger curvature radius faces the object. The first lens part D1 and the third lens part D3 jointly bear the positive optical power of the entire system, and play a role in increasing the field of view and correcting field curvature. The second lens portion D2 (i.e., lens groups G1, G2, G3, and G4) jointly bears the negative optical power of the entire system, which is used to correct chromatic aberration, increase the aperture, and reduce the deflection angle of light, thereby reducing the sensitivity of the entire system.

[0056] Thus, the six lens groups (lenses) arranged sequentially from object to image—positive power first lens L1, positive power first doublet lens group G1, negative power third lens group G3, negative power fourth lens group G4, positive power second doublet lens group G2, and positive power terminal lens L2—ingeniously form a relatively symmetrical arrangement, which is used to correct the distortion and field curvature of the overall low-magnification objective lens. The microscope objective lens of this embodiment has a working distance of ≥5mm (the distance from the cover glass to the edge of the first lens L1), a focal length of 144mm, an adjustable cover glass thickness range of 0.17mm, and an acceptable tube lens focal length of 160-220mm.

[0057] In this embodiment, the axial difference between the best focusing point of the edge field of view of the objective lens and the best focusing point of the central field of view is less than λ / 2NA 2 , F light and C light are achromatic, and the axial chromatic aberration between d light and g light is less than λ / 2NA 2 Where λ is the center wavelength, NA is the numerical aperture of the objective lens, F' represents the wavelength of 0.479μm light, e represents the wavelength of 0.546μm light, C' represents the wavelength of 0.656μm light, and g represents the wavelength of 0.436μm light.

[0058] In this embodiment, the microscope objective lens satisfies the following conditions: Fobj = 143.96 mm; M = 49 mm; NA = 0.04; H1 = 5.76 mm; H2 = 0.3 mm; H3 = 0.2 mm; fD1 = 23.47 mm; fD2 = -1.86 mm; fD3 = 15.1 mm; RD1 = 12.95. M represents the distance from the object plane to the last surface of the microscope objective lens; fobj represents the focal length of the microscope objective lens; and NA represents the object-side numerical aperture of the microscope objective lens. H1 represents the highest projection height of the light at the edge of the central field of view on the lens surface; H2 represents the lowest projection height of the light at the edge of the central field of view on the lens surface; and H3 represents the projection height of the light at the edge of the central field of view on the surface of the last lens. fD1 represents the focal length of the first lens L1, with its convex surface facing the object plane; RD1 represents the radius of the lens surface facing the object; and fobj represents the focal length of the microscope objective lens. fD2 is the combined focal length of the second lens section D2, and fD3 is the combined focal length of the third lens section D3.

[0059] The thickness and radius of each lens of the microscope objective lens of this embodiment are shown in Table 1:

[0060] surface Radius (mm) Thickness (mm) Nd Vd S1 Inf 0.17 1.52 64.2 S2 12.95 5 S3 371.57 4.96 1.57 51.1 S4 Inf 3.98 S5 -22.73 1.65 1.46 90.3 S6 12.55 1 1.82 48.4 S7 23.32 4.51 S8 -9.33 1.98 1.60 37.4 S9 22.83 1 1.82 48.4 S10 Inf 7.12 S11 3.82 0.98 1.88 41.8 S12 -4.14 2.8 1.73 28.1 S13 -131.43 1.1 1.88 41.8 S14 -15.49 4.28 S15 11.33 1.3 1.95 32.2 S16 -9.7 2.61 1.43 96.9 S17 125.39 1.1 S18 -7.95 3.61 1.50 63

[0061] Table 1

[0062] In this embodiment, the first lens L1 is convex toward the object plane and is made of a material with a refractive index of n=1.57 and an Abbe number of v=51.1. The first doublet lens group G1, with its plane facing the object plane, comprises a positive lens with a refractive index of n=1.46 and an Abbe number of v=90.3, and a negative lens with a refractive index of n=1.82 and an Abbe number of v=48.4, respectively. The third lens group G3, with its surface with a larger radius of curvature facing the object plane, comprises a positive lens with a refractive index of n=1.60 and an Abbe number of v=37.4, and a negative lens with a refractive index of n=1.82 and an Abbe number of v=48.4, respectively. The fourth lens group G4, with its surface of greater curvature facing the object plane, consists of, in order, a negative power lens, a positive power lens, and a negative power lens. The materials used are refractive index n = 1.88, Abbe number v = 41.8, refractive index n = 1.73, Abbe number v = 28.1, refractive index n = 1.88, and Abbe number v = 41.8. The second doublet group G2, with its concave surface facing the object plane, consists of, in order, a negative power lens and a positive power lens. The materials used are refractive index n = 1.95, Abbe number v = 32.2, and refractive index n = 1.43, Abbe number v = 96.9. The final lens L2, with its greater radius of curvature facing the object plane, is made of a material with a refractive index n = 1.50 and an Abbe number v = 63.

[0063] The low-magnification, large-field-of-view apochromatic microscope objective lens of this embodiment has a spectral range of 436nm-1000nm, a field of view of ≥26.5mm, a numerical aperture of 0.04, and uses multiple fluorite materials to achieve apochromatism.

[0064] Figure 2 This is the lateral aberration diagram of the zero field of view of the microscope objective lens of the first embodiment, where the horizontal coordinates PY and PX represent the normalized entrance pupil size, the vertical coordinate represents the lateral aberration, the Y direction is the meridional direction, and the X direction is the sagittal direction. It can be seen from the figure that the aberration is well balanced and has good imaging performance.

[0065] Figure 3 This is a lateral aberration diagram of one field of view of the microscope objective lens of the first embodiment. It can be seen from the figure that the curve is close to the horizontal axis, which has good imaging performance.

[0066] Figure 4 This is the axial chromatic aberration curve of the microscope objective lens of the first embodiment. The full wavelength curve chromatic aberration correction is good, and the difference between any two curves in each field of view is less than λ / NA 2 .

[0067] Figure 5 This is the field curvature distortion diagram of the microscope objective lens of the first embodiment. The left figure is the field curvature diagram. The vertical axis represents the field of view and the horizontal axis represents the field curvature, and the unit is μm. The axial difference between the best focus point at the edge of the field of view and the best focus point at the center of the field of view is less than 2λ / NA 2The theoretical value satisfies the full field of view clarity and meets the requirements of a flat-field objective. The ordinate in the figure represents the normalized field of view; the abscissa represents the field curvature, with a maximum value of 0.05 and a minimum of -0.05. The figure on the right is a distortion diagram, with the ordinate representing the field of view and the abscissa representing 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 represents the normalized field of view, and the abscissa represents the distortion, with a maximum value of 0.5% and a minimum of -0.5%.

[0068] The second implementation method:

[0069] See also Figure 6 The microscope objective lens of this embodiment includes, from the object side, a first lens portion D1, a second lens portion D2, and a third lens portion D3. The first lens portion D1 has positive focal power and includes a first lens L1 (convex surface facing the object side) and a first doublet lens group G1. The second lens portion D2 has negative focal power and includes a third lens group G3 and a fourth lens group G4, both of which are doublet lens groups. The third lens portion D3 has positive focal power and includes a second doublet lens group G2 and an end lens L2 (whose convex surface is farther away from the object side). The overall structure includes 4 doublet lens groups and 2 lenses. Among them, the first lens L1 has positive focal power, with a convex surface facing the object plane, and can be a convex-concave, plano-convex, or biconvex lens. The first doublet lens group G1 has negative focal power and is composed of a positive lens and a negative lens glued together, with the two non-glued convex surfaces facing the object side. The third lens group G3 has negative focal power and is composed of a positive lens and a negative lens glued together. The fourth lens group G4 has positive focal power and is composed of a negative lens and a positive lens cemented together, with the two non-cemented surfaces concave facing the object. The second doublet lens group G2 has positive focal power and is composed of a negative lens and a positive lens cemented together, with the two non-cemented surfaces concave facing the object.

[0070] In this embodiment, the concave surfaces of the first doublet lens group G1 and the third lens group G3 are opposite each other, the concave surfaces of the third lens group G3 and the fourth lens group G4 are opposite each other, and the convex and concave surfaces of the fourth lens group G4 and the second doublet lens group G2 are opposite each other. The optical power of the two lenses of the first doublet lens group G1 is positive and negative from left to right, the optical power of the two lenses of the third lens group G3 is positive and negative from left to right, the optical power of the two lenses of the fourth lens group G4 is negative and positive from left to right, and the optical power of the two lenses of the second doublet lens group G2 is negative and positive from left to right. This can better correct field curvature, chromatic aberration and distortion, making the image plane flatter, the background color more perfect and the image plane complete. The terminal lens L2 has positive optical power and is a biconvex lens, with the surface with the larger radius of curvature facing the object.

[0071] Therefore, the six lens groups arranged in sequence from the object side to the image side, namely the positive optical power first lens L1, the negative optical power first doublet lens group G1, the negative optical power third lens group G3, the positive optical power fourth lens group G4, the positive optical power second doublet lens group G2 and the positive optical power terminal lens L2, cleverly form a relatively symmetrical arrangement, which is used to correct the distortion and field curvature of the overall low-power objective lens.

[0072] The working distance of the microscope objective lens of this embodiment is ≥5mm, the focal length of the objective lens is 144mm, the thickness of the cover glass can be adjusted in the range of 0.17mm, and the focal length of the tube lens that can be used by the objective lens is 160-220mm.

[0073] The axial difference between the best focusing point of the edge field of view of the objective lens and the best focusing point of the central field of view is less than λ / 2NA. 2 , F light and C light are achromatic, and the axial chromatic aberration between d light and g light is less than λ / 2NA 2 Where λ is the center wavelength, NA is the numerical aperture of the objective lens, F' represents the wavelength of 0.479μm light, e represents the wavelength of 0.546μm light, C' represents the wavelength of 0.656μm light, and g represents the wavelength of 0.436μm light.

[0074] In this embodiment, the microscope objective lens satisfies the following conditions: Fobj = 140.2 mm; M = 49.5 mm; NA = 0.04; H1 = 5.65 mm; H2 = 0.27 mm; H3 = 0.25 mm; fD1 = 19.68 mm; fD2 = -2.28 mm; fD3 = 16.02 mm; RD1 = 21.81 mm. M represents the distance from the object plane to the last surface of the microscope objective lens; fobj represents the focal length of the microscope objective lens; and NA represents the object-side numerical aperture of the microscope objective lens. H1 represents the highest projection height of the light at the edge of the central field of view on the lens surface; H2 represents the lowest projection height of the light at the edge of the central field of view on the lens surface; and H3 represents the projection height of the light at the edge of the central field of view on the surface of the last lens. fD1 represents the focal length of the first lens L1, with its convex surface facing the object plane; RD1 represents the radius of the lens surface facing the object; and fobj represents the focal length of the microscope objective lens. fD2 is the combined focal length of the second lens section D2, and fD3 is the combined focal length of the third lens section D3.

[0075] The thickness and radius of each lens in the microscope objective lens of this embodiment are shown in Table 2:

[0076] surface Radius (mm) Thickness (mm) Nd Vd S1 Inf 0.17 1.52 64.2 S2 21.81 5.23 S3 -32.95 3.93 1.85 23.8 S4 41.64 3.25 S5 -8.21 3.01 1.58 41.5 S6 22.52 1.03 1.83 42.7 S7 -32.32 8.77 S8 -3.85 1.85 1.67 48.3 S9 9.67 1 1.62 58.2 S10 -15.34 6.9 S11 -3.3 2.34 1.62 36.3 S12 -96.43 1 1.88 40.8 S13 -27.85 3.66 S14 25 1 1.83 37.2 S15 -10.34 3.57 1.49 70.2 S16 Inf 0.23 S17 -9.79 2.7 1.50 81.5

[0077] Table 2

[0078] In this embodiment, the first lens L1 is convex toward the object plane and is made of a material with a refractive index of n=1.85 and an Abbe number of v=23.8. The first doublet lens group G1 is convex toward the object plane and comprises, in order, a positive power lens and a negative power lens, respectively, using materials with a refractive index of n=1.58 and an Abbe number of v=41.5, and a refractive index of n=1.83 and an Abbe number of v=42.7. The third lens group G3 has its surface with a smaller radius of curvature facing the object plane and comprises, in order, a positive power lens and a negative power lens, respectively, using materials with a refractive index of n=1.67 and an Abbe number of v=48.3, and a refractive index of n=1.62 and an Abbe number of v=58.2. The fourth lens group G4 is concave toward the object plane and comprises, in order, a negative power lens and a positive power lens, respectively, using materials with a refractive index of n=1.62 and an Abbe number of v=36.3, and a refractive index of n=1.88 and an Abbe number of v=40.8. The second doublet lens group G2, concavely facing the object plane, consists of a negative power lens and a positive power lens, respectively, with a refractive index of n = 1.83 and an Abbe number of v = 37.2, and a refractive index of n = 1.49 and an Abbe number of v = 70.2. The final lens L2, with a larger radius of curvature facing the object plane, is made of a material with a refractive index of n = 1.50 and an Abbe number of v = 81.5.

[0079] The low-magnification, large-field-of-view apochromatic microscope objective lens of this embodiment has a spectral range of 436nm-1000nm, a field of view of ≥26.5mm, a numerical aperture of 0.04, and is made of fluorite material to achieve apochromatism.

[0080] Figure 7 This is the lateral aberration diagram of the zero field of view of the microscope objective lens of the second embodiment, wherein the horizontal coordinates PY and PX represent the normalized entrance pupil size, the vertical coordinate represents the lateral aberration, the Y direction is the meridional direction, and the X direction is the sagittal direction. It can be seen from the figure that the aberration is well balanced and has good imaging performance.

[0081] Figure 8 This is a lateral aberration diagram of one field of view of the microscope objective lens of the second embodiment. It can be seen from the figure that the curve is close to the horizontal axis, which has good imaging performance.

[0082] Figure 9 This is the axial chromatic aberration curve of the microscope objective lens of the second embodiment. The full wavelength curve chromatic aberration correction is good, and the difference between any two curves in each field of view is less than λ / NA 2 .

[0083] Figure 10 This is the field curvature distortion diagram of the microscope objective lens of the second embodiment. The left figure is the field curvature diagram. The vertical axis represents the field of view and the horizontal axis represents the field curvature, and the unit is μm. The axial difference between the best focus point at the edge of the field of view and the best focus point at the center of the field of view is less than 2λ / NA 2The theoretical value satisfies the requirement for full field of view clarity and meets the requirements of a flat-field objective. The ordinate in the figure represents the normalized field of view; the abscissa represents field curvature, with a maximum value of 0.05 and a minimum of -0.05. The figure on the right is a distortion diagram, with the ordinate representing the field of view and the abscissa representing the distortion (percentage). As can be seen from the figure, the distortion across the entire field of view is less than 0.2%. The ordinate in the figure represents the normalized field of view, and the abscissa represents the distortion, with a maximum value of 0.2% and a minimum of -0.2%.

[0084] The third implementation method:

[0085] See also Figure 11 The microscope objective lens of this embodiment includes a first lens section D1, a second lens section D2, and a third lens section D3, arranged in sequence from the object side to the image side. The first lens section D1 has positive focal power and includes a first lens L1 (convex surface facing the object side) and a first doublet lens group G1; the second lens section D2 has negative focal power and is composed of a third lens group G3 and a fourth lens group G4; the third lens section D3 has positive focal power and includes a second doublet lens group G2 and a terminal lens L2 (whose convex surface is farther from the object side than the convex surface). The overall structure includes four doublet lens groups and two lenses. The first lens L1 has positive focal power, with its convex surface facing the object plane, and can be a convex-concave, plano-convex, or biconvex lens. The first doublet lens group G1 has negative focal power and is composed of a positive lens and a negative lens cemented together, with the two non-cemented convex surfaces facing the object side. The third lens group G3 has negative focal power and is composed of a positive lens and a negative lens cemented together. The fourth lens group G4 has negative optical power and is composed of a negative lens and a positive lens cemented together, with the two non-cemented surfaces concave facing the object. The second doublet lens group G2 has positive optical power and is composed of a negative lens and a positive lens cemented together, with the two non-cemented surfaces concave facing the object.

[0086] In this embodiment, the concave surfaces of the first and third lens groups G1 and G3 face each other, the concave surfaces of the third and fourth lens groups G4 face each other, and the concave surfaces of the fourth and second lens groups G4 and G2 face each other. The focal powers of the two lenses of the first and third lens groups G1 are positive and negative from left to right, the focal powers of the two lenses of the third and fourth lens groups G3 are positive and negative from left to right, the focal powers of the two lenses of the fourth lens group G4 are positive and negative from left to right, and the focal powers of the two lenses of the second and third lens groups G2 are negative and positive from left to right. This can better correct field curvature, chromatic aberration, and distortion, making the image plane flatter, the background color more perfect, and the image plane complete. The terminal lens L2 has positive focal power and is a convex-concave lens with the concave surface facing the object plane.

[0087] Therefore, the six lens groups (lenses) arranged in sequence from the object side to the image side, namely the positive optical power first lens L1, the negative optical power first doublet lens group G1, the negative optical power third lens group G3, the negative optical power fourth lens group G4, the positive optical power second doublet lens group G2 and the terminal lens L2, cleverly form a relatively symmetrical arrangement, which is used to correct the distortion and field curvature of the overall low-power objective lens.

[0088] The working distance of the microscope objective lens of this embodiment is ≥5mm, the focal length of the objective lens is 144mm, the thickness of the objective lens cover glass can be adjusted in the range of 0.17mm, and the focal length of the tube lens that can be used for the objective lens is 160-220mm.

[0089] The axial difference between the best focusing point of the edge field of view of the objective lens and the best focusing point of the central field of view is less than λ / 2NA. 2 , F light and C light are achromatic, and the axial chromatic aberration between d light and g light is less than λ / 2NA 2 Where λ is the center wavelength, NA is the numerical aperture of the objective lens, F' represents the wavelength of 0.479μm light, e represents the wavelength of 0.546μm light, C' represents the wavelength of 0.656μm light, and g represents the wavelength of 0.436μm light.

[0090] In this embodiment, the microscope objective lens satisfies the following conditions: Fobj = 140 mm; M = 49.5 mm; NA = 0.04; H1 = 6.01 mm; H2 = 0.2 mm; H3 = 0.2 mm; fD1 = 29.6 mm; fD2 = -3.2 mm; fD3 = 114.9 mm; RD1 = 9.6. M represents the distance from the object plane to the last surface of the microscope objective lens; fobj represents the focal length of the microscope objective lens; and NA represents the object-side numerical aperture of the microscope objective lens. H1 represents the highest projection height of the light at the edge of the central field of view on the lens surface; H2 represents the lowest projection height of the light at the edge of the central field of view on the lens surface; and H3 represents the projection height of the light at the edge of the central field of view on the surface of the last lens. fD1 represents the focal length of the first lens L1, with its convex surface facing the object plane; RD1 represents the radius of the lens surface facing the object; and fobj represents the focal length of the microscope objective lens. fD2 is the combined focal length of the second lens section D2, and fD3 is the combined focal length of the third lens section D3.

[0091] The thickness and radius of the lens in the microscope objective lens of this embodiment are shown in Table 3:

[0092]

[0093]

[0094] Table 3

[0095] In this embodiment, the first lens L1 is convex toward the object plane and is made of a material with a refractive index of n=1.85 and an Abbe number of v=23.8. The first doublet lens group G1 is convex toward the object plane and comprises, in order, a positive power lens and a negative power lens, respectively, using materials with a refractive index of n=1.58 and an Abbe number of v=41.5, and a refractive index of n=1.83 and an Abbe number of v=42.7. The third lens group G3, with its larger radius of curvature facing the object plane, comprises, in order, a positive power lens and a negative power lens, respectively, using materials with a refractive index of n=1.67 and an Abbe number of v=48.3, and a refractive index of n=1.62 and an Abbe number of v=58.2. The fourth lens group G4, with its concave surface facing the object plane, comprises, in order, a positive power lens and a negative power lens, respectively, using materials with a refractive index of n=1.62 and an Abbe number of v=36.3, and a refractive index of n=1.88 and an Abbe number of v=40.8. The second doublet lens group G2, with its concave surface facing the object plane, consists of a negative power lens and a positive power lens, respectively, with a refractive index of n = 1.83 and an Abbe number of v = 37.2, and a refractive index of n = 1.49 and an Abbe number of v = 70.2. The final lens L2, with its concave surface facing the object plane, is made of a material with a refractive index of n = 1.50 and an Abbe number of v = 81.5.

[0096] The low-magnification, large-field-of-view apochromatic microscope objective lens of this embodiment has a spectral range of 436nm-1000nm, a field of view of ≥26.5mm, a numerical aperture of 0.04, and is made of fluorite material to achieve apochromatism.

[0097] Figure 12 This is the lateral aberration diagram of the zero field of view of the microscope objective lens of the third embodiment, where the horizontal coordinates PY and PX represent the normalized entrance pupil size, the vertical coordinate represents the lateral aberration, the Y direction is the meridional direction, and the X direction is the sagittal direction. It can be seen from the figure that the aberration is well balanced and has good imaging performance.

[0098] Figure 13 This is a lateral aberration diagram of one field of view of the microscope objective lens of the third embodiment. It can be seen from the figure that the curve is close to the horizontal axis, which has good imaging performance.

[0099] Figure 14 This is the axial chromatic aberration curve of the microscope objective lens of the third embodiment. The full wavelength curve chromatic aberration correction is good, and the difference between any two curves in each field of view is less than λ / NA 2 .

[0100] Figure 15 This is a field curvature distortion diagram of the microscope objective lens of the third embodiment. The left figure is the field curvature diagram. The vertical axis represents the field of view and the horizontal axis represents the field curvature, and the unit is μm. The axial difference between the best focus point at the edge of the field of view and the best focus point at the center of the field of view is less than 2λ / NA 2The theoretical value satisfies the full field of view clarity and meets the requirements of a flat-field objective. The ordinate in the figure represents the normalized field of view; the abscissa represents the field curvature, with a maximum value of 0.05 and a minimum of -0.05. The figure on the right is a distortion diagram, with the ordinate representing the field of view and the abscissa representing the distortion (percentage). As can be seen from the figure, the full field of view distortion is less than 0.2%. The ordinate in the figure represents the normalized field of view, and the abscissa represents the distortion, with a maximum of 0.5% and a minimum of -0.1%.

[0101] The 45mm parfocal, low-magnification, wide-field macroscopic observation microscope objective lens of the present invention has a relatively large numerical aperture of 0.04. Despite the low magnification, it has minimal distortion of ≤0.2% over a wide field of view, restoring the true-to-original appearance of the sample.

[0102] The above description is merely one embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A microscope objective lens, characterized in that: The lens comprises, in order from the object side, a first lens portion (D1) having positive refractive power, a second lens portion (D2) having negative refractive power, and a third lens portion (D3) having positive refractive power; The first lens portion (D1) comprises a first lens (L1) adjacent to the object side, wherein a surface of the first lens (L1) facing the object surface is a convex surface; The second lens portion (D2) is composed of multiple cemented lens groups; The third lens portion (D3) includes a rearmost end lens (L2), wherein a surface of the end lens (L2) away from the object plane is a convex surface; The microscope objective lens satisfies: |fD2 / fobj|=0.0229, wherein fD2 is the combined focal length of the second lens portion (D2), and fobj is the focal length of the microscope objective lens; The radius of curvature, thickness, refractive index Nd and Abbe number Vd of the lens in the microscope objective are as follows: 。 2. The microscope objective lens according to claim 1, characterized in that NA=0.04, where NA represents the object side numerical aperture of the microscope objective.

3. The microscope objective lens according to claim 1, characterized in that The working wavelength band of the microscope objective lens is 400-1000nm.

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