Flat-field apochromatic objective lens and optical microscope

Abstract

The invention provides a flat-field apochromatic objective lens and an optical microscope, and relates to the technical field of optical imaging. The flat-field apochromatic objective lens comprises a first lens group, a second lens group and a third lens group which are sequentially arranged from an object plane to an image plane, both the first lens group and the second lens group have positive refractive power, the third lens group has positive refractive power or negative refractive power, the first lens group comprises at least two sub-lens groups with positive refractive power, and the second lens group comprises at least two sub-lens groups with negative refractive power. The sub-lens group is a single lens or a balsaming lens formed by gluing at least two single lenses, and the second lens group comprises at least one balsaming lens with positive refractive power and at least one balsaming lens with positive refractive power or negative refractive power. The third lens group includes at least one cemented lens having a positive refractive power and at least one cemented lens having a positive refractive power or a negative refractive power. On the basis, the flat-field apochromatic objective lens has a large field of view, a large numerical aperture and a long working distance.

Description

Technical Field

[0001] The present application relates to the field of optical imaging technology, and in particular to a plan apochromatic objective lens and an optical microscope. Background Art

[0002] A microscope is an optical instrument that magnifies tiny objects and enables them to be observed by the human eye. It is mainly divided into optical microscopes and electron microscopes. For optical microscopes, the key component that determines its resolution and magnification is the objective lens. A single optical microscope usually has multiple objective lenses with different magnifications (such as 4×, 10×, 40×, 100×, etc.) so that objective lenses of different magnifications can be switched according to different observation needs. In the related art, the objective lens of an optical microscope can adopt a plan-field apochromatic objective lens, which can not only accurately correct the chromatic aberration of red, green, and blue light, but also correct the field curvature, so that the image within the entire field of view can be clearly presented, but the field of view of this objective lens is not large enough, the working distance is not long enough, and the numerical aperture is not large enough. Summary of the invention

[0003] The present application provides a plan apochromatic objective lens and an optical microscope, aiming to solve the problems of small field of view, short working distance and small numerical aperture of the plan apochromatic objective lens in the related art.

[0004] In order to solve the above-mentioned drawbacks existing in the related art, the first aspect of the present application provides a plan-apochromatic objective lens, comprising a first lens group, a second lens group and a third lens group arranged in sequence from the object plane to the image plane, the first lens group and the second lens group both have positive refractive power, and the third lens group has positive refractive power or negative refractive power. Specifically, the first lens group includes at least two sub-lens groups, the sub-lens groups are single lenses or cemented lenses formed by cementing at least two single lenses, and the sub-lens groups have positive refractive power; the second lens group includes at least one cemented lens with positive refractive power, and at least one cemented lens with positive refractive power or negative refractive power; the third lens group includes at least one cemented lens with positive refractive power, and at least one cemented lens with positive refractive power or negative refractive power.

[0005] In some implementations, the first lens group includes at least one single lens having positive refractive power and an Abbe number greater than 60; the second lens group includes at least two single lenses having positive refractive power and an Abbe number greater than 60; and the third lens group includes at least one single lens having positive refractive power and a refractive index greater than 1.75.

[0006] In some implementations, a plan apochromatic objective satisfies the relationship 1.1 <f G1 / f<1.8、3.2 <f G2 / f<12.3, -4 <f G3 / f < 18 and 6 < L / f < 7.5; where f represents the focal length of the plan apochromat objective lens, f G1 represents the focal length of the first lens group, f G2 represents the focal length of the second lens group, f G3 represents the focal length of the third lens group, and L represents the overall length of the plan apochromat objective lens.

[0007] In some implementation solutions, the first lens group includes a first singlet lens, a second singlet lens, a third singlet lens, and a fourth singlet lens sequentially arranged from the object plane to the image plane, and the first singlet lens and the second singlet lens are cemented to form a first cemented lens; the second lens group includes a fifth singlet lens, a sixth singlet lens, a seventh singlet lens, an eighth singlet lens, and a ninth singlet lens sequentially arranged from the object plane to the image plane, and the fifth singlet lens, the sixth singlet lens, and the seventh singlet lens are cemented to form a second cemented lens, and the eighth singlet lens and the ninth singlet lens are cemented to form a third cemented lens; the third lens group includes a tenth singlet lens, an eleventh singlet lens, a twelfth singlet lens, and a thirteenth singlet lens sequentially arranged from the object plane to the image plane, and the tenth singlet lens and the eleventh singlet lens are cemented to form a fourth cemented lens, and the twelfth singlet lens and the thirteenth singlet lens are cemented to form a fifth cemented lens.

[0008] In some implementation solutions, the first singlet lens satisfies the relational expressions 0.4 < f L1 / f < 0.8 and 0.6 < R L1 / f < 1.1; where f L1 represents the focal length of the first singlet lens, and R L1 represents the radius of curvature of the surface of the first singlet lens close to the object plane, and f represents the focal length of the plan apochromat objective lens.

[0009] In some implementation solutions, among the first singlet lens and the second singlet lens, one has positive refractive power and the other has negative refractive power; the fifth singlet lens has positive refractive power, the sixth singlet lens has negative refractive power, and the seventh singlet lens has positive refractive power; the tenth singlet lens has positive refractive power, the eleventh singlet lens has negative refractive power, the twelfth singlet lens has negative refractive power, and the thirteenth singlet lens has positive refractive power. In one of the implementation solutions, the first singlet lens has positive refractive power, the second singlet lens has negative refractive power, the third singlet lens has positive refractive power, the fourth singlet lens has positive refractive power, the eighth singlet lens has positive refractive power, and the ninth singlet lens has negative refractive power. In one of the implementation solutions, the first singlet lens has positive refractive power, the second singlet lens has negative refractive power, both the third singlet lens and the fourth singlet lens have positive refractive power, the eighth singlet lens has negative refractive power, and the ninth singlet lens has positive refractive power.

[0010] In some implementation solutions, the spherical aberration amount of the plan apochromat objective lens is within ±0.5 mm, the object plane offset amount is within ±0.3 mm, and the distortion amount is within ±2%.

[0011] A second aspect of the present application provides an optical microscope, which includes at least one plan apochromatic objective lens mentioned in the first aspect of the present application.

[0012] The plan apochromatic objective lens provided in the first aspect of the present application is composed of a first lens group, a second lens group and a third lens group arranged in sequence from the object plane to the image plane, the first lens group and the second lens group both have positive refractive power, the third lens group has positive refractive power or negative refractive power, the first lens group includes at least two sub-lens groups with positive refractive power, the sub-lens groups are single lenses or cemented lenses formed by cementing at least two single lenses, the second lens group includes at least one cemented lens with positive refractive power, and at least one cemented lens with positive refractive power or negative refractive power, and the third lens group includes at least one cemented lens with positive refractive power, and at least one cemented lens with positive refractive power or negative refractive power. It can be understood that the present application arranges the first lens group, the second lens group and the third lens group so that the first lens group and the second lens group both have positive refractive power, and the third lens group has positive refractive power or negative refractive power, which ensures a large numerical aperture under a large field of view; at the same time, the present application arranges the single lens / cemented lens and its refractive power in the first lens group, the second lens group and the third lens group so that the plan-apochromatic objective has a longer working distance, and is beneficial to the improvement of resolution, the correction of chromatic aberration and the imaging performance under a wide band.

[0013] For the optical microscope provided in the second aspect of the present application, since the optical microscope includes the plan apochromatic objective lens provided in the first aspect of the present application, the optical microscope has all the advantages of the plan apochromatic objective lens provided in the first aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the related technologies or the embodiments of the present application, the drawings required for use in the description of the related technologies or the embodiments of the present application will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, not all embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 A schematic structural diagram of a first plan apochromatic objective lens provided in an embodiment of the present application;

[0016] Figure 2 A spherical aberration diagram of the first plan apochromatic objective lens provided in an embodiment of the present application;

[0017] Figure 3A field curvature diagram of the first plan apochromatic objective lens provided in an embodiment of the present application;

[0018] Figure 4 A distortion diagram of the first plan apochromatic objective lens provided in an embodiment of the present application;

[0019] Figure 5 A schematic structural diagram of a second plan apochromatic objective lens provided in an embodiment of the present application;

[0020] Figure 6 A spherical aberration diagram of the second plan apochromatic objective lens provided in an embodiment of the present application;

[0021] Figure 7 A field curvature diagram of the second plan apochromatic objective lens provided in an embodiment of the present application;

[0022] Figure 8 A distortion diagram of the second plan apochromatic objective lens provided in an embodiment of the present application;

[0023] Fig. 9 A schematic structural diagram of a third plan apochromatic objective lens provided in an embodiment of the present application;

[0024] Fig.10 A spherical aberration diagram of the third plan apochromatic objective lens provided in an embodiment of the present application;

[0025] Fig.11 A field curvature diagram of the third plan apochromatic objective lens provided in an embodiment of the present application;

[0026] Fig.12 This is a distortion diagram of the third plan apochromatic objective lens provided in an embodiment of the present application.

[0027] The marks in the above drawings respectively represent: 1-first lens group, 2-second lens group, 3-third lens group, 11-first cemented lens, 21-second cemented lens, 22-third cemented lens, 31-fourth cemented lens, 32-fifth cemented lens, 111-first single lens, 112-second single lens, 12-third single lens, 13-fourth single lens, 211-fifth single lens, 212-sixth single lens, 213-seventh single lens, 221-eighth single lens, 222-ninth single lens, 311-tenth single lens, 312-eleventh single lens, 321-twelfth single lens, 322-thirteenth single lens. DETAILED DESCRIPTION

[0028] In the related art, the objective lens of an optical microscope can adopt a plan-apochromatic objective lens, which can not only perform relatively accurate chromatic aberration correction on the three colors of red, green and blue light, but also correct the image field curvature, so that the image in the entire field of view can be presented clearly. However, the existing plan-apochromatic objective lens still has many shortcomings, such as poor chromatic aberration correction capability in the full band of visible light, small field of view, short working distance, small numerical aperture, large field curvature, large spherical aberration, large distortion, low resolution, etc. In view of this, the present application proposes a plan-apochromatic objective lens and an optical microscope in the embodiments below to solve the above-mentioned drawbacks existing in the related art.

[0029] In order to make the purpose, technical solutions and advantages of the present application more obvious and easy to understand, the present application will be clearly and completely described below in conjunction with the embodiments of the present application and the corresponding drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. It should be understood that the embodiments of the present application described below are only used to explain the present application and are not used to limit the present application, that is, based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0030] See also Figure 1 , Figure 1 It is a schematic diagram of the structure of the first plan apochromatic objective lens. This embodiment provides a plan apochromatic objective lens, which includes a first lens group 1, a second lens group 2 and a third lens group 3 arranged in sequence from the object plane to the image plane (i.e., along the direction from the object plane to the image plane), the first lens group 1 and the second lens group 2 both have positive refractive power, and the third lens group 3 has positive refractive power or negative refractive power. In this embodiment, the first lens group 1 includes at least two sub-lens groups (not shown in the figure), the sub-lens groups can be either single lenses or cemented lenses (formed by cementing at least two single lenses), and each sub-lens group has positive refractive power; for the second lens group 2 and the third lens group 3, they both include at least one cemented lens with positive refractive power, and at least one cemented lens with positive refractive power or negative refractive power.

[0031] Specifically, the first lens group 1 includes a first single lens 111, a second single lens 112, a third single lens 12 and a fourth single lens 13 which are sequentially arranged from the object plane to the image plane, and the first single lens 111 and the second single lens 112 are glued together to form a first glued lens 11; the second lens group 2 includes a fifth single lens 211, a sixth single lens 212, a seventh single lens 213, an eighth single lens 221 and a ninth single lens 222 which are sequentially arranged from the object plane to the image plane, and the fifth single lens 211, the sixth single lens 212 and The seventh single lens 213 is glued to form the second glued lens 21, the eighth single lens 221 and the ninth single lens 222 are glued to form the third glued lens 22; the third lens group 3 includes a tenth single lens 311, an eleventh single lens 312, a twelfth single lens 321 and a thirteenth single lens 322 arranged in sequence from the object plane to the image plane, the tenth single lens 311 and the eleventh single lens 312 are glued to form the fourth glued lens 31, and the twelfth single lens 321 and the thirteenth single lens 322 are glued to form the fifth glued lens 32.

[0032] As can be seen from the above, in this embodiment, the first lens group 1, the second lens group 2 and the third lens group 3 are arranged so that the first lens group 1 has positive refractive power, the second lens group 2 has positive refractive power and the third lens group 3 has positive refractive power or negative refractive power, which ensures a large numerical aperture under a large field of view; at the same time, in this embodiment, through the arrangement of the first single lens 111 to the thirteenth single lens 322, the plan apochromatic objective lens has a long working distance, which is beneficial to the improvement of resolution, the correction of chromatic aberration and the imaging performance under a wide band. In addition, it should be noted that the plan apochromatic objective lens of the present embodiment can be used in an optical microscope, and the optical microscope can include one or more plan apochromatic objective lenses, which can be installed on an electric objective lens converter, and the switching of the plan apochromatic objective lenses can be achieved through the electric objective lens converter; of course, in addition to the electric objective lens converter and one or more plan apochromatic objective lenses, the optical microscope should also include other structures that constitute the optical microscope in the field, such as eyepieces, lens barrels, lens arms, lens mounts, stages, reflectors, coarse focusing screws, fine focusing screws and condensers, etc., which will not be described in detail in this application.

[0033] In some embodiments, in order to make the plan apochromatic objective have high resolution and maintain the characteristics of small spherical aberration, small field curvature and small distortion while achieving chromatic aberration correction, it is necessary to design the optical parameters of the first lens group 1, the second lens group 2, the third lens group 3 and the first single lens 111 to the thirteenth single lens 322; specifically, one of the first single lens 111 and the second single lens 112 has positive refractive power and the other has negative refractive power; the fifth single lens 211 has positive refractive power, the sixth single lens 212 has negative refractive power, and the seventh single lens 213 has positive refractive power; the tenth single lens 311 has positive refractive power, the eleventh single lens 312 has negative refractive power, the twelfth single lens 321 has negative refractive power, and the thirteenth single lens 322 has positive refractive power. In one embodiment, the first single lens 111 has positive refractive power, the second single lens 112 has negative refractive power, the third single lens 12 and the fourth single lens 13 both have positive refractive power, the eighth single lens 221 has positive refractive power, and the ninth single lens 222 has negative refractive power. In another embodiment, the first single lens 111 has positive refractive power, the second single lens 112 has negative refractive power, the third single lens 12 and the fourth single lens 13 both have positive refractive power, the eighth single lens 221 has negative refractive power, and the ninth single lens 222 has positive refractive power.

[0034] Furthermore, the plan apochromatic objective lens satisfies the following relationship:

[0035] 1.1 <f G1 / f<1.8、3.2 <f G2 / f<12.3, -4 <f G3 / f<18 and 6 <L / f<7.5;

[0036] Where f represents the focal length (i.e. focal length) of the plan apochromatic objective lens, f G1 represents the focal length of the first lens group 1, f G2 represents the focal length of the second lens group 2, f G3 represents the focal length of the third lens group 3, and L represents the total length of the plan apochromat objective lens (i.e., the distance between the vertex of the surface of the thirteenth single lens 322 close to the image plane and the object plane).

[0037] Furthermore, the first single lens 111 satisfies the following relationship:

[0038] 0.4 <f L1 / f<0.8 and 0.6 <R L1 / f<1.1;

[0039] Among them, f L1 represents the focal length of the first single lens 111, R L1represents the radius of curvature of the surface of the first single lens 111 close to the object plane.

[0040] It can be understood that by limiting the focal distances of the first lens group 1, the second lens group 2, and the third lens group 3, not only can the plan apochromatic objective lens achieve a longer working distance and a larger numerical aperture under the condition of a large field of view, but also the spherical aberration, field curvature, and distortion of the plan apochromatic objective lens can be preliminarily corrected (the spherical aberration is within ±0.5 mm, the object plane offset is within ±0.3 mm, and the distortion is within ±2%), and the size of the plan apochromatic objective lens is minimized. In addition, by limiting the refractive power of the first single lens 111 to the thirteenth single lens 322, especially limiting the focal distance and curvature radius of the first single lens 111, the aberration can be further corrected.

[0041] In some embodiments, in order to enable the plan-apochromatic objective lens to have the ability to correct chromatic aberration in the entire visible light band, it is necessary to design the Abbe number, refractive index, etc. of each single lens material in the first lens group 1, the second lens group 2, and the third lens group 3. Specifically, the first lens group 1 includes at least one single lens with positive refractive power and an Abbe number greater than 60; the second lens group 2 includes at least two single lenses with positive refractive power and an Abbe number greater than 60; the third lens group 3 includes at least one single lens with positive refractive power and a refractive index greater than 1.75. In other words, by limiting the refractive index and Abbe number of the first single lens 111 to the thirteenth single lens 322, the chromatic aberration of the plan-apochromatic objective lens in the entire visible light band can be corrected, so that the plan-apochromatic objective lens has the ability to correct chromatic aberration in the entire visible light band.

[0042] In order to enable those skilled in the art to more clearly understand the advantages of the plan apochromatic objective lens provided by the present application, three specific examples and related experimental data are given below.

[0043] Before describing each example, the various surfaces involved in the plan apochromatic objective are defined. The plan apochromatic objective has a first surface (represented by S1), a second surface (represented by S2), a third surface (represented by S3), a fourth surface (represented by S4), a fifth surface (represented by S5), a sixth surface (represented by S6), a seventh surface (represented by S7), an eighth surface (represented by S8), a ninth surface (represented by S9), a tenth surface (represented by S10), an eleventh surface (represented by S11), a twelfth surface (represented by S12), a thirteenth surface (represented by S13), a fourteenth surface (represented by S14), a fifteenth surface (represented by S15), a sixteenth surface (represented by S16), a seventeenth surface (represented by S17), an eighteenth surface (represented by S18), a nineteenth surface (represented by S19), and a twentieth surface (represented by S20) formed in sequence from the object plane to the image plane.

[0044] Wherein, S1 indicates the surface of the first single lens 111 close to the object plane, S2 indicates the bonding surface between the first single lens 111 and the second single lens 112, S3 indicates the surface of the second single lens 112 close to the image plane, S4 and S5 respectively indicate two opposite surfaces of the third single lens 12, S6 and S7 respectively indicate two opposite surfaces of the fourth single lens 13, S8 indicates the surface of the fifth single lens 211 close to the object plane, S9 indicates the bonding surface between the fifth single lens 211 and the sixth single lens 212, S10 indicates the bonding surface between the sixth single lens 212 and the seventh single lens 213, S11 indicates the surface of the seventh single lens 213 close to the image plane, and S12 indicates the surface of the seventh single lens 213 close to the image plane. 2 indicates the surface of the eighth single lens 221 close to the object plane, S13 indicates the cemented surface between the eighth single lens 221 and the ninth single lens 222, S14 indicates the surface of the ninth single lens 222 close to the image plane, S15 indicates the surface of the tenth single lens 311 close to the object plane, S16 indicates the cemented surface between the tenth single lens 311 and the eleventh single lens 312, S17 indicates the surface of the eleventh single lens 312 close to the image plane, S18 indicates the surface of the twelfth single lens 321 close to the object plane, S19 indicates the cemented surface between the twelfth single lens 321 and the thirteenth single lens 322, and S20 indicates the surface of the thirteenth single lens 322 close to the image plane.

[0045] For the first example, see Figure 1The plan apochromatic objective lens includes a first single lens 111 with positive refractive power, a second single lens 112 with negative refractive power, a third single lens 12 with positive refractive power, a fourth single lens 13 with positive refractive power, a fifth single lens 211 with positive refractive power, a sixth single lens 212 with negative refractive power, a seventh single lens 213 with positive refractive power, an eighth single lens 221 with positive refractive power, a ninth single lens 222 with negative refractive power, a tenth single lens 311 with positive refractive power, an eleventh single lens 312 with negative refractive power, a twelfth single lens 321 with negative refractive power, and a thirteenth single lens 322 with positive refractive power, which are arranged in sequence from the object plane to the image plane.

[0046] Among them, the first single lens 111 and the second single lens 112 are glued to form a first glued lens 11 with a focal length of -234.3 mm; the fifth single lens 211, the sixth single lens 212 and the seventh single lens 213 are glued to form a second glued lens 21 with a focal length of 47.5 mm; the eighth single lens 221 and the ninth single lens 222 are glued to form a third glued lens 22 with a focal length of -105.3 mm; the tenth single lens 311 and the eleventh single lens 312 are glued to form a fourth glued lens 31 with a focal length of 511.1 mm; the twelfth single lens 321 and the thirteenth single lens 322 are glued to form a fifth glued lens 32 with a focal length of 158.9 mm.

[0047] In the first example, the numerical aperture NA of the plan apochromat objective is 0.8, the field of view is 1.6 mm, the focal distance f is 9 mm, the working distance is 0.87 mm, and the magnification is 20×. The focal length of the first lens group 1 is 14.9 mm, the focal length of the second lens group 2 is 59.1 mm, and the focal length of the third lens group 3 is 151.7 mm. The plan apochromat objective satisfies the following relationship:

[0048] f G1 / f=1.7,f G2 / f=6.6,f G3 / f=16.9, L / f=6.4, f L1 / f=0.6, R L1 / f=0.8, V13=70.4, f13=45.4mm, V14=70.4, f14=52.0mm, V21=70.4, f21=29.8mm, V23=70.4, f23=17.5mm, N31=1.76, f31=15.0mm, N34=1.75, f34=19.5mm;

[0049] Among them, V13 is the Abbe number of the third single lens 12 in the first lens group 1, f13 is the focal length of the third single lens 12 in the first lens group 1, V14 is the Abbe number of the fourth single lens 13 in the first lens group 1, f14 is the focal length of the fourth single lens 13 in the first lens group 1, V21 is the Abbe number of the fifth single lens 211 in the second lens group 2, f21 is the focal length of the fifth single lens 211 in the second lens group 2, V23 is the Abbe number of the seventh single lens 213 in the second lens group 2, f23 is the focal length of the seventh single lens 213 in the second lens group 2, N31 is the refractive index of the tenth single lens 311 in the third lens group 3, f31 is the focal length of the tenth single lens 311 in the third lens group 3, N34 is the refractive index of the thirteenth single lens 322 in the third lens group 3, and f34 is the focal length of the thirteenth single lens 322 in the third lens group 3.

[0050] In the first example, the first surface to the twentieth surface satisfy the following Table 1.

[0051]

[0052] Figure 2 This is the spherical aberration diagram of the first plan apochromatic objective. The horizontal axis is the spherical aberration amount (in mm), and the vertical axis is the normalized field of view (image height), with a maximum of 1. Figure 2 In the figure, the solid line represents 644nm, the dotted line represents 546nm, the dashed line represents 480nm, and the dash-dotted line represents 436nm. From the distribution of spherical aberration, it can be seen that the spherical aberration of the first plan-apochromat objective is controlled within ±0.5mm, indicating that the plan-apochromat objective has good axial chromatic aberration and a higher resolution at the center of the picture.

[0053] Figure 3 This is the field curvature diagram of the first plan apochromatic objective, with the horizontal axis being the object plane offset (in mm) and the vertical axis being the normalized field of view (image height), with a maximum of 1. Figure 3 In the figure, the solid line represents the meridian plane of the light, and the dotted line represents the sagittal plane of the light. From the distribution of field curvature, it can be seen that the field curvature of the first plan apochromat objective is controlled within ±0.3mm, indicating that the plan apochromat objective with large numerical aperture and large field of view has a good degree of flatness.

[0054] Figure 4 This is the distortion diagram of the first plan apochromat objective. The horizontal axis is the distortion amount (in %), and the vertical axis is the normalized field of view (image height), with a maximum of 1. From the distribution of distortion, it can be seen that the distortion of the first plan apochromat objective is controlled within ±2%, indicating that it has smaller distortion.

[0055] For the second example, see Figure 5 , Figure 5The schematic diagram of the structure of the second plan apochromatic objective lens is shown. The plan apochromatic objective lens includes a first single lens 111 with positive refractive power, a second single lens 112 with negative refractive power, a third single lens 12 with positive refractive power, a fourth single lens 13 with positive refractive power, a fifth single lens 211 with positive refractive power, a sixth single lens 212 with negative refractive power, a seventh single lens 213 with positive refractive power, an eighth single lens 221 with negative refractive power, a ninth single lens 222 with positive refractive power, a tenth single lens 311 with positive refractive power, an eleventh single lens 312 with negative refractive power, a twelfth single lens 321 with negative refractive power, and a thirteenth single lens 322 with positive refractive power, which are sequentially arranged from the object plane to the image plane.

[0056] Among them, the first single lens 111 and the second single lens 112 are glued to form a first glued lens 11 with a focal length of -1342mm, the fifth single lens 211, the sixth single lens 212 and the seventh single lens 213 are glued to form a second glued lens 21 with a focal length of 47.3mm, the eighth single lens 221 and the ninth single lens 222 are glued to form a third glued lens 22 with a focal length of 147.2mm, the tenth single lens 311 and the eleventh single lens 312 are glued to form a fourth glued lens 31 with a focal length of -32.3mm, and the twelfth single lens 321 and the thirteenth single lens 322 are glued to form a fifth glued lens 32 with a focal length of 317.9mm.

[0057] In the second example, the numerical aperture NA of the plan apochromat objective is 0.8, the field of view is 1.6 mm, the focal distance f is 9 mm, the working distance is 0.83 mm, and the magnification is 20×. The focal length of the first lens group 1 is 12.0 mm, the focal length of the second lens group 2 is 36.6 mm, and the focal length of the third lens group 3 is -45.9 mm. The plan apochromat objective satisfies the following relationship:

[0058] f G1 / f=1.3,f G2 / f=4.1,f G3 / f=-5.1, L / f=6.7, f L1 / f=0.6, R L1 / f=0.7, V13=70.4, f13=48.9mm, V14=70.4, f14=36.2mm, V21=70.4, f21=22.7mm, V23=70.4, f23=19.7mm, N34=1.83, f34=16.1mm.

[0059] In the second example, the first surface to the twentieth surface satisfy the following Table 2.

[0060]

[0061] Figure 6 This is the spherical aberration diagram of the second type of plan apochromatic objective. The horizontal axis is the spherical aberration amount (in mm), and the vertical axis is the normalized field of view (image height), with a maximum of 1. Figure 6 In the figure, the solid line represents 644nm, the dotted line represents 546nm, the dashed line represents 480nm, and the dash-dotted line represents 436nm. From the distribution of spherical aberration, it can be seen that the spherical aberration of the second plan-apochromat objective is controlled within ±0.3mm, indicating that the plan-apochromat objective has good axial chromatic aberration and a higher resolution in the center of the picture.

[0062] Figure 7 This is the field curvature diagram of the second type of plan apochromatic objective. Its horizontal axis is the object plane offset (unit is mm), and the vertical axis is the normalized field of view (image height), with a maximum of 1. Figure 7 In the figure, the solid line represents the meridian plane of the light, and the dotted line represents the sagittal plane of the light. From the distribution of field curvature, it can be seen that the field curvature of the second plan apochromat objective is controlled within ±0.3mm, indicating that the plan apochromat objective with large numerical aperture and large field of view has a good degree of flatness.

[0063] Figure 8 This is the distortion diagram of the second type of plan apochromat objective. The horizontal axis is the distortion amount (in %), and the vertical axis is the normalized field of view (image height), with a maximum of 1. From the distribution of distortion, it can be seen that the distortion of the second type of plan apochromat objective is controlled within ±1%, indicating that it has smaller distortion.

[0064] For the third example, see Fig. 9 , Fig. 9 1 is a schematic diagram of the structure of the third plan apochromatic objective lens. The plan apochromatic objective lens comprises a first single lens 111 with positive refractive power, a second single lens 112 with negative refractive power, a third single lens 12 with positive refractive power, a fourth single lens 13 with positive refractive power, a fifth single lens 211 with positive refractive power, a sixth single lens 212 with negative refractive power, a seventh single lens 213 with positive refractive power, an eighth single lens 221 with negative refractive power, a ninth single lens 222 with positive refractive power, a tenth single lens 311 with positive refractive power, an eleventh single lens 312 with negative refractive power, a twelfth single lens 321 with negative refractive power, and a thirteenth single lens 322 with positive refractive power, which are sequentially arranged from the object plane to the image plane.

[0065] Among them, the first single lens 111 and the second single lens 112 are glued to form a first glued lens 11 with a focal length of 65.0 mm, the fifth single lens 211, the sixth single lens 212 and the seventh single lens 213 are glued to form a second glued lens 21 with a focal length of 46.4 mm, the eighth single lens 221 and the ninth single lens 222 are glued to form a third glued lens 22 with a focal length of -66.6 mm, the tenth single lens 311 and the eleventh single lens 312 are glued to form a fourth glued lens 31 with a focal length of 40.3 mm, and the twelfth single lens 321 and the thirteenth single lens 322 are glued to form a fifth glued lens 32 with a focal length of 850 mm.

[0066] In the third example, the numerical aperture NA of the plan apochromat objective is 0.8, the field of view is 1.6 mm, the focal distance f is 9 mm, the working distance is 0.85 mm, and the magnification is 20×. The focal length of the first lens group 1 is 12.5 mm, the focal length of the second lens group 2 is 102.5 mm, and the focal length of the third lens group 3 is 49.2 mm. The plan apochromat objective satisfies the following relationship:

[0067] f G1 / f=1.4,f G2 / f=11.4,f G3 / f=5.5, L / f=6.2, f L1 / f=0.7, R L1 / f=1.0, V13=70.4, f13=35.6mm, V14=70.4, f14=45.8mm, V21=70.4, f21=35.3mm, V23=70.4, f23=18.7mm, N34=1.83, f34=24.3mm.

[0068] In the third example, the first surface to the twentieth surface satisfy the following Table 3.

[0069]

[0070] Fig.10 This is the spherical aberration diagram of the third type of plan apochromatic objective. The horizontal axis is the spherical aberration amount (in mm), and the vertical axis is the normalized field of view (image height), with a maximum of 1. Fig.10 In the figure, the solid line represents 644nm, the dotted line represents 546nm, the dashed line represents 480nm, and the dash-dotted line represents 436nm. From the distribution of spherical aberration, it can be seen that the spherical aberration of the third plan-apochromat objective is controlled within ±0.25mm, indicating that the plan-apochromat objective has good axial chromatic aberration and a higher resolution in the center of the picture.

[0071] Fig.11This is the field curvature diagram of the third type of plan apochromatic objective. The horizontal axis is the object plane offset (in mm), and the vertical axis is the normalized field of view (image height), with a maximum of 1. Fig.11 In the figure, the solid line represents the meridian plane of the light, and the dotted line represents the sagittal plane of the light. From the distribution of field curvature, it can be seen that the field curvature of the third plan apochromat objective is controlled within ±0.25mm, indicating that the plan apochromat objective with large numerical aperture and large field of view has a good degree of flatness.

[0072] Fig.12 This is the distortion diagram of the third type of plan apochromat objective. The horizontal axis is the distortion amount (in %), and the vertical axis is the normalized field of view (image height), with a maximum of 1. From the distribution of distortion, it can be seen that the distortion of the third type of plan apochromat objective is controlled within ±1%, indicating that it has smaller distortion.

[0073] The above embodiments are only preferred implementations of the present application, and are not the only limitations on the plan apochromatic objective lens and the optical microscope related contents; in this regard, those skilled in the art can flexibly set them according to the actual application scenarios based on the above embodiments. It can be understood that, through the implementation of the above embodiments of the present application, the first lens group 1, the second lens group 2 and the third lens group 3, which are arranged in sequence from the object plane to the image plane, together constitute a plan apochromatic objective lens, and the first lens group 1 includes a first single lens 111, a second single lens 112, a third single lens 12 and a fourth single lens 13, which are arranged in sequence from the object plane to the image plane, and the first single lens 111 and the second single lens 112 are glued to form a glued lens; the second lens group 2 includes a fifth single lens 211, a sixth single lens 212, a seventh single lens 213, The eighth single lens 221 and the ninth single lens 222, the fifth single lens 211, the sixth single lens 212 and the seventh single lens 213 are cemented to form a cemented lens, and the eighth single lens 221 and the ninth single lens 222 are cemented to form a cemented lens; the third lens group 3 includes a tenth single lens 311, an eleventh single lens 312, a twelfth single lens 321 and a thirteenth single lens 322 arranged in sequence from the object plane to the image plane, the tenth single lens 311 and the eleventh single lens 312 are cemented to form a cemented lens, and the twelfth single lens 321 and the thirteenth single lens 322 are cemented to form a cemented lens. On this basis, the present application arranges the first lens group 1, the second lens group 2 and the third lens group 3 so that the first lens group 1 and the second lens group 2 both have positive refractive power, and the third lens group 3 has positive refractive power or negative refractive power, which ensures a large numerical aperture under a large field of view; the present application arranges the first single lens 111 to the thirteenth single lens 322 so that the plan apochromatic objective lens has a long working distance, which is beneficial to the improvement of resolution, the correction of chromatic aberration and the imaging under a wide band; the present application limits the focal lengths of the first lens group 1, the second lens group 2 and the third lens group 3, which not only makes the plan The apochromatic objective lens achieves a longer working distance and a larger numerical aperture under the condition of a large field of view, and also enables the spherical aberration, field curvature and distortion of the plan apochromatic objective lens to be initially corrected, and ensures that the size of the plan apochromatic objective lens is minimized; the present application can further correct aberrations by limiting the refractive power of the first single lens 111 to the thirteenth single lens 322, especially limiting the focal length and the curvature radius of the first single lens 111; the present application can correct the chromatic aberration of the plan apochromatic objective lens in the full band of visible light by limiting the refractive index and Abbe number of the first single lens 111 to the thirteenth single lens 322.

[0074] It should be noted that the several embodiments shown in the present application are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can refer to each other. It should also be noted that in the text description of the present application, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is such an actual relationship or order between these entities or operations. Further, the terms "include", "comprise" or any other corresponding variants are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only these elements, but also other elements that are not explicitly listed, or may also include elements inherent to such process, method, article or equipment; and, in the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements.

[0075] In addition, by implementing the several embodiments shown above in the present application, professionals and technicians in this field can implement or use the present application. For the several embodiments shown above in the present application, various modifications will be obvious to professionals and technicians in this field, and the general principles defined in the present application can be implemented in other embodiments not shown without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the several embodiments shown above, but will comply with the widest range consistent with the principles and novel features disclosed in the present application.

Claims

1. A plan apochromatic objective lens, characterized in that: The lens comprises a first lens group, a second lens group and a third lens group which are arranged in sequence from the object plane to the image plane, wherein the first lens group and the second lens group both have positive refractive power, and the third lens group has positive refractive power or negative refractive power; The first lens group includes at least two sub-lens groups, each of which is a single lens or a cemented lens formed by cementing at least two single lenses, and each of which has positive refractive power; the second lens group includes at least one cemented lens with positive refractive power, and at least one cemented lens with positive refractive power or negative refractive power; the third lens group includes at least one cemented lens with positive refractive power, and at least one cemented lens with positive refractive power or negative refractive power.

2. The plan apochromatic objective lens according to claim 1, characterized in that: The first lens group includes at least one single lens with positive refractive power and an Abbe number greater than 60; the second lens group includes at least two single lenses with positive refractive power and an Abbe number greater than 60; and the third lens group includes at least one single lens with positive refractive power and a refractive index greater than 1.

75.

3. The plan apochromatic objective lens according to claim 1, characterized in that: Satisfy the relational expression 1.1 < f G1 / f < 1.8, 3.2 < f G2 / f < 12.3, -4 < f G3 / f < 18 and 6 < L / f < 7.5; where f represents the focal length of the apochromatic field flattener objective lens, f G1 represents the focal length of the first lens group, f G2 represents the focal length of the second lens group, f G3 represents the focal length of the third lens group, and L represents the overall length of the apochromatic field flattener objective lens.

4. The plan apochromatic objective lens according to claim 1, characterized in that: The first lens group includes a first single lens, a second single lens, a third single lens and a fourth single lens which are sequentially arranged from the object plane to the image plane, and the first single lens and the second single lens are glued to form a first glued lens; the second lens group includes a fifth single lens, a sixth single lens, a seventh single lens, an eighth single lens and a ninth single lens which are sequentially arranged from the object plane to the image plane, the fifth single lens, the sixth single lens and the seventh single lens are glued to form a second glued lens, and the eighth single lens and the ninth single lens are glued to form a third glued lens; the third lens group includes a tenth single lens, an eleventh single lens, a twelfth single lens and a thirteenth single lens which are sequentially arranged from the object plane to the image plane, the tenth single lens and the eleventh single lens are glued to form a fourth glued lens, and the twelfth single lens and the thirteenth single lens are glued to form a fifth glued lens.

5. The plan apochromatic objective lens according to claim 4, characterized in that: The first single lens satisfies the relationship 0.4 <f L1 / f<0.8 and 0.6 <R L1 / f<1.1; where f L1 represents the focal length of the first single lens, R L1 represents the radius of curvature of the surface of the first single lens close to the object plane, and f represents the focal length of the plan apochromatic objective lens.

6. The plan apochromatic objective lens according to claim 4, characterized in that: One of the first single lens and the second single lens has positive refractive power and the other has negative refractive power; the fifth single lens has positive refractive power, the sixth single lens has negative refractive power, and the seventh single lens has positive refractive power; the tenth single lens has positive refractive power, the eleventh single lens has negative refractive power, the twelfth single lens has negative refractive power, and the thirteenth single lens has positive refractive power.

7. The plan apochromatic objective lens according to claim 6, characterized in that: The first single lens has positive refractive power, the second single lens has negative refractive power, the third single lens and the fourth single lens both have positive refractive power, the eighth single lens has positive refractive power, and the ninth single lens has negative refractive power.

8. The plan apochromatic objective lens according to claim 6, characterized in that: The first single lens has positive refractive power, the second single lens has negative refractive power, the third single lens and the fourth single lens both have positive refractive power, the eighth single lens has negative refractive power, and the ninth single lens has positive refractive power.

9. The plan apochromatic objective lens according to claim 1, characterized in that: The spherical aberration is within ±0.5mm, the object plane offset is within ±0.3mm, and the distortion is within ±2%.

10. An optical microscope, characterized in that: Comprising at least one plan apochromatic objective lens as claimed in any one of claims 1 to 9.

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