Micro-optical imaging objective

Abstract

The present application relates to the field of optical imaging technology, and more particularly to a microscopic optical imaging objective, which is composed of a first lens group with negative focal length, a second lens group with negative focal length, a third lens group with positive focal length and a fourth lens group with positive focal length arranged in sequence from the image side to the object side, and specifically composed of a first lens with positive focal length, a second lens with negative focal length, a third lens with positive focal length, a fourth lens with negative focal length, a fifth lens with positive focal length, a sixth lens with positive focal length, a seventh lens with negative focal length, an eighth lens with positive focal length, a ninth lens with negative focal length, a tenth lens with negative focal length, an eleventh lens with positive focal length and a twelfth lens, and the advantage is that the exit pupil aberration of the lens is improved, and the back focal aberration correction of the diaphragm surface of the microscopic optical imaging objective is realized through the layout of the lens, the selection of the focal length and the shape structure and the selection of the material of the specific lens.

Description

Technical Field

[0001] This invention relates to an optical imaging objective, and more particularly to a microscopic optical imaging objective. Background Technology

[0002] In optical system design, the correction of exit pupil aberration and the correction of field aberration are two independent yet mutually constraining objectives. Optical design requires different lens components to undertake different aberration correction tasks, thereby achieving an overall balance of system aberrations. Because traditional optical design involves numerous and interrelated aberrations, the wavefront quality of the exit pupil exists as a result of the overall system aberration balance, making it difficult to optimize the exit pupil separately. This means that even if the objective lens performs well under conventional aberration evaluation metrics (such as modulation transfer function, field curvature, and chromatic aberration), significant residual aberrations may still exist at the exit pupil.

[0003] Chinese invention patent application CN120928553A discloses a differential interferometry optical system for detecting conductive particles in semiconductors. This DIC optical system, specifically designed for semiconductor conductive particle detection, features a finely grouped objective lens assembly: the front assembly ensures a large aperture angle and minimizes the introduction of spherical and chromatic aberrations; the middle assembly compensates for various aberrations introduced by the front assembly; and the rear assembly corrects field curvature. However, this design primarily focuses on the overall correction of object-side aberrations and does not specifically optimize for exit pupil aberration. Summary of the Invention

[0004] This invention provides a microscopic optical imaging objective lens for improving imaging performance. While maintaining good resolution and field of view, it can correct the exit pupil aberration of the microscopic optical imaging objective lens and increase the field of view range of the microscopic optical imaging objective lens.

[0005] This invention provides a microscopic optical imaging objective, comprising a first lens group with negative optical power, a second lens group with negative optical power, a third lens group with positive optical power, and a fourth lens group with positive optical power, arranged sequentially from the image side to the object side. From the image side to the object side, the first lens group consists of a first lens with positive optical power and a second lens with negative optical power; the second lens group consists of a third lens with positive optical power and a fourth lens with negative optical power; the third lens group consists of a fifth lens with positive optical power; and the fourth lens group consists of a sixth lens with positive optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, and a ninth lens with negative optical power. The microscope consists of a ninth lens, a tenth lens with negative optical power, an eleventh lens with positive optical power, and a twelfth lens with either positive or negative optical power. The first lens has a convex image-side surface and a concave or flat object-side surface. The second lens has a concave or flat object-side surface. The third lens has a concave image-side surface and a convex or flat object-side surface. The fourth lens has a concave image-side surface and a convex object-side surface. The fifth lens is a biconvex lens with an Abbe number greater than 70. The numerical aperture of the microscope optical imaging objective satisfies the condition: 0.2 ≤ NA ≤ 0.3. The object-side field of view of the microscope optical imaging objective is 3 mm to 4 mm.

[0006] Compared with existing technologies, the advantages of this invention lie in the fact that, through the selection of lens layout, optical power, and shape, combined with the selection of specific lens materials, it corrects the exit pupil aberration of the microscope optical imaging objective without sacrificing resolution or field of view, thereby improving the stereoscopic effect in imaging. The first lens group is used to adjust the position of the objective's exit pupil plane, and the fourth lens group can correct chromatic aberration and spherical aberration of the microscope optical imaging objective. Furthermore, the shape and layout of the optical lenses in the first and second lens groups enhance the field of view.

[0007] In one feasible implementation, the seventh lens can be a meniscus lens, the ninth lens can be a biconcave lens, and the tenth lens can be a meniscus lens.

[0008] In one feasible implementation, the sixth lens can be cemented with the seventh lens to form a cemented doublet, the eighth lens can be cemented with the ninth lens to form a cemented doublet, and the tenth lens can be cemented with the eleventh lens to form a cemented doublet. Thus, the fourth lens group consists of three cemented doublet lenses and one single lens.

[0009] In another alternative embodiment, the sixth lens can be cemented with the seventh lens to form a doublet cemented lens, the eighth lens can be cemented with the ninth lens to form a doublet cemented lens, and the tenth lens, the eleventh lens and the twelfth lens can be cemented together to form a triplet cemented lens. In this case, the fourth lens group consists of two doublet cemented lenses and one triplet cemented lens.

[0010] In an alternative embodiment, the focal length f of the micro optical imaging objective satisfies: 20.2mm<f<28mm, and the focal length f1 of the first lens group, the focal length f2 of the second lens group, the focal length f3 of the third lens group and the focal length f4 of the fourth lens group satisfy: -5.9<f1 / f<-4.2, -1.5<f2 / f<-0.9, 1.5<f3 / f<2.0, 1.3<f4 / f<2.0. The four lens groups of the micro optical imaging objective of the present invention adopt a power arrangement of negative, negative, positive and positive. By controlling the ratio of each lens group's focal length relative to the entire micro optical imaging objective, the aberrations of the imaging surface and the differential interference surface can be optimized simultaneously, so as to achieve the purpose of improving optical performance.

[0011] In an alternative embodiment, the curvature radius R of the image-side surface of the fourth lens 像 and the curvature radius R of the object-side surface 物 satisfies: |R 物 |<|R 像 |.

[0012] In an alternative embodiment, the second lens consists of a first sub-lens and a second sub-lens that are cemented to each other.

[0013] In an alternative embodiment, the distance from the object-side surface of the twelfth lens to the object plane is less than 100mm, and the exit pupil position of the micro optical imaging objective coincides with the back focal plane. Description of Drawings

[0014] Figure 1 is a schematic structural diagram of the first example of a micro optical imaging objective provided by an embodiment of the present invention;

[0015] Figure 2 is a schematic diagram of exit pupil aberration of the first example according to an embodiment of the present invention;

[0016] Figure 3 is a schematic diagram of axial chromatic aberration at the object plane of the objective lens of the first example according to an embodiment of the present invention;

[0017] Figure 4 is a schematic diagram of axial chromatic aberration at the exit pupil plane of the objective lens of the first example according to an embodiment of the present invention;

[0018] Figure 5 This is a schematic diagram of the structure of a second example of a microscopic optical imaging objective provided in an embodiment of the present invention;

[0019] Figure 6 This is a schematic diagram of the exit pupil aberration in Example 2 of Embodiment 2 of the present invention;

[0020] Figure 7 This is a schematic diagram of the axial chromatic aberration of the objective lens surface in Example 2 of this embodiment of the invention;

[0021] Figure 8 This is a schematic diagram of the axial chromatic aberration at the exit pupil plane of the objective lens in Example 2 of this embodiment of the invention;

[0022] Figure 9 This is a schematic diagram of the structure of Example 3 of a microscopic optical imaging objective provided in an embodiment of the present invention;

[0023] Figure 10 This is a schematic diagram of the exit pupil aberration in Example 3 of Embodiment 3 of the present invention;

[0024] Figure 11 This is a schematic diagram of the axial chromatic aberration of the objective lens surface in Example 3 of this embodiment of the invention;

[0025] Figure 12 This is a schematic diagram of the axial chromatic aberration of the objective lens exit pupil plane in Example 3 of this embodiment of the invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] G01, First lens group; G02, Second lens group; G03, Third lens group; G04, Fourth lens group; L1, First lens; L2, Second lens; L21, First sub-lens; L22, Second sub-lens; L3, Third lens; L4, Fourth lens; L5, Fifth lens; L6, Sixth lens; L7, Seventh lens; L8, Eighth lens; L9, Ninth lens; L10, Tenth lens; L11, Eleventh lens; L12, Twelfth lens. Detailed Implementation

[0028] The following description, in conjunction with the accompanying drawings, illustrates specific examples of the present invention. The drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention.

[0029] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. The drawings are for illustrative purposes only and are not drawn to scale.

[0030] Figure 1A micro-optical imaging objective according to an embodiment of the present invention is shown, the numerical aperture satisfies: 0.2 ≤ NA ≤ 0.3, the object-side field of view of the micro-optical imaging objective is 3 mm to 4 mm, the distance from the object-side surface of the twelfth lens L12 to the object plane is less than 100 mm, and the exit pupil position coincides with the back focal plane. The micro-optical imaging objective consists of a first lens group G01 with negative power, a second lens group G02 with negative power, a third lens group G03 with positive power and a fourth lens group G04 with positive power, which are arranged sequentially from the image side to the object side. In order to adjust the exit pupil position of the objective, the first lens group G01 consists of a first lens L1 with positive power and a second lens L2 with negative power from the image side to the object side, the second lens group G02 consists of a third lens L3 with positive power and a fourth lens L4 with negative power from the image side to the object side. In order to increase the field of view of the micro-optical imaging objective, it can be selected that the image-side surface of the first lens L1 is a convex surface, the object-side surface is a concave surface or a plane, the object-side surface of the second lens L2 is a concave surface or a plane, the image-side surface of the third lens L3 is a concave surface, the object-side surface is a convex surface or a plane, the image-side surface of the fourth lens is a concave surface, the object-side surface is a convex surface, and the radius of curvature of the image-side surface of the fourth lens L4 R 像 and the radius of curvature of the object-side surface R 物 satisfies: |R 物 |<|R 像 |. The third lens group G03 consists of a fifth lens L5 with positive power, the fifth lens L5 is a biconvex lens, and a specific material is selected, that is, the Abbe number is greater than 70. In order to correct chromatic aberration and spherical aberration of the micro-optical imaging objective, the fourth lens group G04 may consist of a sixth lens L6 with positive power, a seventh lens L7 with negative power, an eighth lens L8 with positive power, a ninth lens L9 with negative power, a tenth lens L10 with negative power, an eleventh lens L11 with positive power, and a twelfth lens L12 with positive or negative power, which are arranged sequentially from the image side to the object side. The seventh lens L7 may be a meniscus lens, the ninth lens L9 may be a biconcave lens, and the tenth lens L10 may be a meniscus lens. In order to simultaneously optimize the aberrations of the imaging surface and the differential interference surface, so as to achieve the purpose of improving optical performance, the four lens groups of the micro-optical imaging objective of the present invention adopt a negative-negative-positive-positive power arrangement, and control the ratio of each focal length group relative to the entire micro-optical imaging objective. The focal length f of the micro-optical imaging objective satisfies: 20.2 mm < f < 28 mm. The focal length f1 of the first lens group G01, the focal length f2 of the second lens group G02, the focal length f3 of the third lens group G03 and the focal length f4 of the fourth lens group G04 are strictly controlled to satisfy the conditions: -5.9 < f1 / f < -4.2, -1.5 < f2 / f < -0.9, 1.5 < f3 / f < 2.0, 1.3 < f4 / f < 2.0.

[0031] in Figure 1 and Figure 9In the illustrated embodiment, the sixth lens L6 and the seventh lens L7 are cemented together to form a cemented doublet lens, the eighth lens L8 and the ninth lens L9 are cemented together to form a cemented doublet lens, the tenth lens L10 and the eleventh lens L11 are cemented together to form a cemented doublet lens, and the twelfth lens L12 is a single lens.

[0032] And in Figure 5 In one embodiment shown, the second lens L2 is composed of a first sub-lens L21 and a second sub-lens L22 cemented together; the sixth lens L6 and the seventh lens L7 are cemented together to form a cemented doublet; the eighth lens L8 and the ninth lens L9 are cemented together to form a cemented doublet; and the tenth lens L10, the eleventh lens L11 and the twelfth lens L12 are cemented together to form a cemented triplet.

[0033] To help better understand the technical solutions of the embodiments of the present invention, three specific examples are provided below.

[0034] Example 1: Its structure is as follows Figure 1 As shown, the microscopic optical imaging objective lens, from the image side to the object side, consists of a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, and a twelfth lens L12. The first lens L1 and the second lens L2 form the first lens group G01, the third lens L3 and the fourth lens L4 form the second lens group G02, the fifth lens L5 forms the third lens group G03, and the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the eleventh lens L11, and the twelfth lens L12 form the fourth lens group G04. Among them, the sixth lens L6 and the seventh lens L7 are cemented together to form a cemented doublet, the eighth lens L8 and the ninth lens L9 are cemented together to form a cemented doublet, the tenth lens L10 and the eleventh lens L11 are cemented together to form a cemented doublet, and the twelfth lens L12 is a single lens. The relevant parameters of each lens are shown in Table 1.

[0035] Table 1

[0036] In this example, the focal length f of the microscopic optical imaging objective is 26.69mm, f1 / f=-4.60, f2 / f=-1.27, f3 / f=1.89, and f4 / f=1.68. When used with a 200mm focal length tube lens, it can achieve 7.5x magnification. The NA of this objective is 0.3, the working distance is 31mm, and the object-side field of view is not less than 4mm. Figure 2In the image, the side length of the square cell corresponding to each marker is 2 micrometers. The image corresponding to marker (a) is a dot plot at a wavelength of 546 nm at a pupil radius of 0 mm; the image corresponding to marker (b) is a dot plot at a wavelength of 546 nm at a pupil radius of 4 mm; the image corresponding to marker (c) is a dot plot at a wavelength of 546 nm at a pupil radius of 5.656 mm; and the image corresponding to marker (d) is a dot plot at a wavelength of 546 nm at a pupil radius of 8 mm. Figure 2 It can be seen that the aberrations of the dot pattern on the objective lens exit pupil plane are well corrected, and the blur spots in each field of view are concentrated and the energy distribution is uniform, indicating that the exit pupil imaging quality is excellent. Figure 3 In the diagram, the curve marked 436nm represents the axial chromatic aberration shift curve of the objective lens surface corresponding to light with a center wavelength of 436nm within the pupil range; the curve marked 480nm represents the axial chromatic aberration shift curve of the objective lens surface corresponding to light with a center wavelength of 480nm within the pupil range; the curve marked 546nm represents the axial chromatic aberration shift curve of the objective lens surface corresponding to light with a center wavelength of 546nm within the pupil range; and the curve marked 644nm represents the axial chromatic aberration shift curve of the objective lens surface corresponding to light with a center wavelength of 644nm within the pupil range. Figure 3 It can be seen that the axial chromatic aberration of the objective lens surface is effectively corrected across the entire wavelength range, and the axial chromatic aberration shift is significantly reduced. Figure 4 In the diagram, the curve marked 436nm represents the axial chromatic aberration shift curve of the objective lens exit pupil surface corresponding to light with a center wavelength of 436nm within the pupil range; the curve marked 480nm represents the axial chromatic aberration shift curve of the objective lens exit pupil surface corresponding to light with a center wavelength of 480nm within the pupil range; the curve marked 546nm represents the axial chromatic aberration shift curve of the objective lens exit pupil surface corresponding to light with a center wavelength of 546nm within the pupil range; and the curve marked 644nm represents the axial chromatic aberration shift curve of the objective lens exit pupil surface corresponding to light with a center wavelength of 644nm within the pupil range. Figure 4 It can be seen that the axial chromatic aberration at the objective lens exit pupil is also well balanced and controlled.

[0037] The working distance mentioned in Example 1 refers to the distance from the object to the vertex of the object-side lens of the twelfth lens L12. The objective lens described in Example 1 is an infinity-correcting objective lens.

[0038] Example 2: The structure of the microscope optical imaging objective in Example 2 is as follows: Figure 5As shown, the structures of the other lenses are the same as in Example 1, except that the second lens L2 is composed of a first sub-lens L21 and a second sub-lens L22 cemented together, and the tenth lens L10, the eleventh lens L11, and the twelfth lens L12 are cemented together to form a cemented triplet lens. Furthermore, the relevant parameters of each lens are different. The relevant parameters of each lens in the microscopic optical imaging objective of Example 2 are shown in Table 2.

[0039] Table 2

[0040] In this example two, the focal length f of the microscopic optical imaging objective is 26.71mm, f1 / f=-5.23, f2 / f=-1.25, f3 / f=1.69, and f4 / f=1.74. When used with a 200mm focal length tube lens, it can achieve 7.5x magnification. The NA of this objective is 0.3, the working distance is 31mm, and the object-side field of view is not less than 4mm. Figure 6 In the image, the side length of the square cell corresponding to each marker is 1 micrometer. The image corresponding to marker (a) is a dot plot at a wavelength of 546 nm at a pupil radius of 0 mm; the image corresponding to marker (b) is a dot plot at a wavelength of 546 nm at a pupil radius of 4 mm; the image corresponding to marker (c) is a dot plot at a wavelength of 546 nm at a pupil radius of 5.656 mm; and the image corresponding to marker (d) is a dot plot at a wavelength of 546 nm at a pupil radius of 8 mm. Figure 6 It can be seen that the aberrations of the dot pattern on the objective lens exit pupil plane are well corrected, and the blur spots in each field of view are concentrated and the energy distribution is uniform, indicating that the exit pupil imaging quality is excellent. Figure 7 In the diagram, the curve marked 436nm represents the axial chromatic aberration shift curve of the objective lens surface corresponding to light with a center wavelength of 436nm within the pupil range; the curve marked 470nm represents the axial chromatic aberration shift curve of the objective lens surface corresponding to light with a center wavelength of 470nm within the pupil range; the curve marked 546nm represents the axial chromatic aberration shift curve of the objective lens surface corresponding to light with a center wavelength of 546nm within the pupil range; and the curve marked 644nm represents the axial chromatic aberration shift curve of the objective lens surface corresponding to light with a center wavelength of 644nm within the pupil range. Figure 7 It can be seen that the axial chromatic aberration of the objective lens surface is effectively corrected across the entire wavelength range, and the axial chromatic aberration shift is significantly reduced. Figure 8In the diagram, the curve marked 436nm represents the axial chromatic aberration shift curve of the objective lens exit pupil surface corresponding to light with a center wavelength of 436nm within the pupil range; the curve marked 470nm represents the axial chromatic aberration shift curve of the objective lens exit pupil surface corresponding to light with a center wavelength of 470nm within the pupil range; the curve marked 546nm represents the axial chromatic aberration shift curve of the objective lens exit pupil surface corresponding to light with a center wavelength of 546nm within the pupil range; and the curve marked 644nm represents the axial chromatic aberration shift curve of the objective lens exit pupil surface corresponding to light with a center wavelength of 644nm within the pupil range. Figure 8 It can be seen that the axial chromatic aberration at the objective lens exit pupil is also well balanced and controlled.

[0041] The working distance mentioned in Example 2 also refers to the distance from the object to the vertex of the object-side lens of the twelfth lens L12. The objective lens described in Example 2 is also an infinity-corrected objective lens.

[0042] Example 3: The structure of the microscope optical imaging objective in Example 3 is as follows: Figure 9 As shown, the lens structure is the same as in Example 1, but the relevant parameters of each lens are different. The relevant parameters of each lens in the microscopic optical imaging objective of Example 3 are shown in Table 3.

[0043] Table 3

[0044] In this example three, the focal length f of the microscopic optical imaging objective is 26.68mm, f1 / f=-5.48, f2 / f=-1.1, f3 / f=1.68, and f4 / f=1.54. When used with a 200mm focal length tube lens, it can achieve 7.5x magnification. The NA of this objective is 0.3, the working distance is 25.97mm, and the object-side field of view is 4mm. Figure 10 In the image, the side length of the square cell corresponding to each marker is 4 micrometers. The image corresponding to marker (a) is a dot plot at a wavelength of 546 nm at a pupil radius of 0 mm; the image corresponding to marker (b) is a dot plot at a wavelength of 546 nm at a pupil radius of -2.5 mm; the image corresponding to marker (c) is a dot plot at a wavelength of 546 nm at a pupil radius of -4.3 mm; and the image corresponding to marker (d) is a dot plot at a wavelength of 546 nm at a pupil radius of -5.4 mm. Figure 10 It can be seen that the aberrations of the dot pattern on the objective lens exit pupil plane are well corrected, and the blur spots in each field of view are concentrated and the energy distribution is uniform, indicating that the exit pupil imaging quality is excellent. Figure 11In the diagram, the curve marked 436nm represents the axial chromatic aberration shift curve of the objective lens surface corresponding to light with a center wavelength of 436nm within the pupil range; the curve marked 470nm represents the axial chromatic aberration shift curve of the objective lens surface corresponding to light with a center wavelength of 470nm within the pupil range; the curve marked 546nm represents the axial chromatic aberration shift curve of the objective lens surface corresponding to light with a center wavelength of 546nm within the pupil range; and the curve marked 644nm represents the axial chromatic aberration shift curve of the objective lens surface corresponding to light with a center wavelength of 644nm within the pupil range. Figure 11 It can be seen that the axial chromatic aberration of the objective lens surface is effectively corrected across the entire wavelength range, and the axial chromatic aberration shift is significantly reduced. Figure 12 In the diagram, the curve marked 436nm represents the axial chromatic aberration shift curve of the objective lens exit pupil surface corresponding to light with a center wavelength of 436nm within the pupil range; the curve marked 470nm represents the axial chromatic aberration shift curve of the objective lens exit pupil surface corresponding to light with a center wavelength of 470nm within the pupil range; the curve marked 546nm represents the axial chromatic aberration shift curve of the objective lens exit pupil surface corresponding to light with a center wavelength of 546nm within the pupil range; and the curve marked 644nm represents the axial chromatic aberration shift curve of the objective lens exit pupil surface corresponding to light with a center wavelength of 644nm within the pupil range. Figure 12 It can be seen that the axial chromatic aberration at the objective lens exit pupil is also well balanced and controlled.

[0045] The working distance mentioned in Example 3 also refers to the distance from the object to the vertex of the object-side lens of the twelfth lens L12. The objective lens described in Example 3 is also an infinity-corrected objective lens.

[0046] Some structural and performance parameters of the three examples above are shown in Table 4.

[0047] Table 4

[0048] The embodiments provided in this application can achieve 7.5x magnification when used with an F200mm focal length tube lens. The magnification can be proportionally increased through the optical system and adjusted to be compatible with F180mm and F160mm focal length tube lenses, including but not limited to the optical systems of these two different tube lenses.

[0049] The examples shown above are merely individual examples of the present invention and do not limit the scope of protection of the present invention. Therefore, equivalent changes made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A microscopic optical imaging objective, characterized in that, The micro optical imaging objective as described is composed of a first lens group with negative power, a second lens group with negative power, a third lens group with positive power and a fourth lens group with positive power, which are sequentially arranged from an image side to an object side. From the image side to the object side, the first lens group consists of a first lens with positive power and a second lens with negative power; the second lens group consists of a third lens with positive power and a fourth lens with negative power; the third lens group consists of a fifth lens with positive power; the fourth lens group consists of a sixth lens with positive power, a seventh lens with negative power, an eighth lens with positive power, a ninth lens with negative power, a tenth lens with negative power, an eleventh lens with positive power, and a twelfth lens with positive or negative power. The image side surface of the first lens is a convex surface, and the object side surface thereof is a concave surface or a plane; the object side surface of the second lens is a concave surface or a plane; the image side surface of the third lens is a concave surface, and the object side surface thereof is a convex surface or a plane; the image side surface of the fourth lens is a concave surface, and the object side surface thereof is a convex surface; the fifth lens is a biconvex lens, and the Abbe number of the fifth lens is greater than 70. The numerical aperture of the micro optical imaging objective satisfies: 0.2≤NA≤0.3, and the object-side field of view of the micro optical imaging objective ranges from 3mm to 4mm.

2. A microscopic optical imaging objective as described in claim 1, characterized in that, The seventh lens is a meniscus lens, the ninth lens is a biconcave lens, and the tenth lens is a meniscus lens.

3. A microscopic optical imaging objective as described in claim 2, characterized in that, The sixth lens and the seventh lens are cemented to form a doublet lens, the eighth lens and the ninth lens are cemented to form a doublet lens, and the tenth lens and the eleventh lens are cemented to form a doublet lens.

4. A microscopic optical imaging objective as described in claim 2, characterized in that, The sixth lens and the seventh lens are cemented to form a doublet lens, the eighth lens and the ninth lens are cemented to form a doublet lens, and the tenth lens, the eleventh lens and the twelfth lens are cemented to form a triplet lens.

5. A microscopic optical imaging objective as described in claim 3 or 4, characterized in that, The focal length f of the micro optical imaging objective satisfies: 20.2mm<f<28mm, and the focal length f1 of the first lens group, the focal length f2 of the second lens group, the focal length f3 of the third lens group and the focal length f4 of the fourth lens group satisfy: -5.9<f1 / f<-4.2, -1.5<f2 / f<-0.9, 1.5<f3 / f<2.0, 1.3<f4 / f<2.

0.

6. A microscopic optical imaging objective as described in claim 1, characterized in that, The radius of curvature R of the image side surface of the fourth lens 像 Radius of curvature R of the object's side surface 物 Satisfy: |R 物 |<|R 像 | 7. A microscopic optical imaging objective as described in claim 1, characterized in that, The second lens is composed of a first sub-lens and a second sub-lens that are cemented to each other.

8. A microscopic optical imaging objective as described in claim 1, characterized in that, The distance from the object side surface of the twelfth lens to the object plane is less than 100mm, and the exit pupil position of the micro optical imaging objective coincides with the back focal plane.

Images