High-power digital microscope optical system capable of randomly enlarging depth of field through automatic focusing

Abstract

The utility model discloses a high-power digital microscope optical system capable of randomly enlarging depth of field through automatic focusing, which comprises a first objective lens group, a second objective lens group, a third objective lens group and an image sensor which are sequentially arranged between an object plane and an image plane at intervals, and the first objective lens group comprises a first lens, a second lens, a third lens and a fourth lens. The first objective lens group is fixed; the second objective lens group comprises a fifth lens and a sixth lens, the fifth lens and the sixth lens are glued together, and the second objective lens group is fixed; the third objective lens group is composed of a focusing lens, focusing is achieved by moving the focusing lens back and forth, the depth of field is enlarged, and an observed object is clearly imaged on the image sensor. The high-power digital microscope can neglect out-of-focus caused by height change due to the fact that a mechanical arm drives the high-power digital microscope to move horizontally, the depth of field is enlarged while automatic focusing is conducted, and therefore observation efficiency and observation accuracy are improved, and judgment on an observed object is more accurate.

Description

Technical Field

[0001] The utility model belongs to a high-power digital microscope optical system that randomly expands the depth of field through autofocusing. Background Art

[0002] Ordinary high-power microscopes have a very, very shallow depth of field, usually at the micron level. The depth of field of a high-power microscope is usually only a few microns. A micron-level movement in the optical axis direction will cause defocusing, making the image of the observed scene (or specimen) blurred. The usual method is to move the entire objective lens group of the microscope for focusing, as shown in Figure 1 shown. However, since the entire objective lens group of the microscope is heavy and large in volume, it is relatively slow to move, with a slow response speed and difficult to achieve autofocus quickly.

[0003] A high-power optical microscope generally consists of a stage, a condenser illumination system, an objective lens, an eyepiece, and a focusing mechanism. By using the focusing knob, the focusing mechanism can be driven to make the stage perform coarse and fine lifting movements, so that the observed object is focused clearly. The observed object is generally placed on a glass slide, and then the glass slide is placed on the stage for observation with a high-power optical microscope. The production of glass slides requires a preparation process. For specimen sections (sub-micron level), since an ordinary high-power microscope has a very, very shallow depth of field, and the production of glass slides is relatively flat, the impact on the depth of field is not too large because the change in the optical axis direction (i.e., the height direction) is relatively small.

[0004] A high-power microscope can only see 1 / 100 of the range of the specimen. Therefore, a manipulator needs to hold the high-power microscope and move it continuously on a plane to observe the entire range of the specimen. Due to the high-precision requirements of the high-power microscope, the range of the observed specimen (i.e., the observed object) is very large, while the range observed by the high-power microscope is very small. When using a manipulator to hold the high-power microscope and move it to observe the entire range of the observed object, the movement of the manipulator will cause a change in height, as shown in Figure 2 shown. Generally, the manufacturing accuracy of a robotic arm is at the 10μm level, while the depth of field of a high-power microscope is usually only a few microns. Therefore, the movement of the manipulator will cause defocusing of the high-power microscope, resulting in problems with observation efficiency and accuracy, and affecting the judgment of the observed object.

[0005] For example, the above problems will occur in some special occasions. Chips are crucial components in modern technology. It is a microelectronic component composed of hundreds of millions of tiny transistors and is used to process and store information. During the production of chips, microscopes play a crucial role. It allows us to see the tiny chip structure for inspection and optimization, as shown in Figure 3As shown. Through a microscope, we can also inspect the circuits in the chip. The chip has a complex circuit layout, where the wires and transistors are precisely connected together to achieve various functions. With the magnification function of the microscope, we can check whether each connection point is normal and whether there are any defects that may cause the circuit to malfunction. In this way, we can promptly detect problems and make repairs to ensure the quality and performance of the chip. In addition, the microscope can also help us observe the surface defects on the chip and the crystal structure of the chip. By observing the crystal structure, we can analyze and optimize the design and manufacturing process of the chip. In short, a high-power microscope plays a very important role in the chip manufacturing and inspection processes. It can help us observe the microstructures, circuit connections, and surface defects of the chip, as well as analyze and optimize the crystal structure of the chip. The high magnification function of the microscope enables us to see the details of the chip and promptly detect problems to ensure the quality and performance of the chip. In the ever-developing field of technology, the microscope remains an indispensable tool.

[0006] However, the current high-power microscopes still have the above two pain points: 1) Due to the precision requirements of high-power microscopes, the range of the specimen to be observed (i.e., the object to be observed) is very large, while the observation range of a high-power microscope is very small. When using a robotic arm to hold the high-power microscope and continue to move to observe the entire range of the object to be observed, the movement of the robotic arm will cause a change in height, resulting in defocusing of the high-power microscope, thus bringing problems with observation efficiency and observation accuracy and affecting the judgment of the object to be observed; 2) During the movement of the high-power microscope, it cannot automatically focus and randomly expand the depth of field to improve the observation efficiency and observation accuracy, which affects the judgment of the object to be observed. Summary of the Invention

[0007] The purpose of the present utility model is to provide a high-power digital microscope optical system that randomly expands the depth of field through automatic focusing, and solves the technical problem that when using a robotic arm to move a high-power microscope to observe the entire range of the object to be observed in the prior art, the movement of the robotic arm will cause a change in height, resulting in defocusing of the high-power microscope and inability to expand the depth of field, thus bringing problems with observation efficiency and observation accuracy and affecting the judgment of the object to be observed.

[0008] The technical solution of the present utility model is realized as follows:

[0009] A high-power digital microscope optical system that randomly expands the depth of field through automatic focusing, characterized in that: it includes a first objective lens group, a second objective lens group, a third objective lens group, and an image sensor that are sequentially arranged at intervals between the object plane and the image plane, where:

[0010] The first objective lens group includes lens one, lens two, lens three and lens four. The first objective lens group is fixed so that the working distance between the observed object and the microscope remains basically unchanged. Lens two and lens three are cemented together;

[0011] The second objective lens group includes lens five and lens six. Lens five and lens six are cemented together. The second objective lens group is fixed;

[0012] The third objective lens group consists of a focusing lens. By moving the focusing lens back and forth, focusing is achieved and the depth of field is expanded, so that the observed object is clearly imaged on the image sensor.

[0013] The above-mentioned first objective lens group has a positive focal power, the second objective lens group has a negative focal power, and the third objective lens group has a negative focal power. The distance between the first objective lens group and the object surface is greater than 10 mm. Among them, the focal length of lens one is f1, the focal length of lens two is f2, the focal length of lens three is f3, the focal length of lens four is f4, the focal length of lens five is f5, the focal length of lens six is f6, the focal length of the focusing lens is f7, and the focal length after lens two and lens three are cemented together is f 23 , and the focal length after lens five and lens six are cemented together is f 56 , and the focal lengths satisfy the following conditions:

[0014] -5 < f2 + f3 < -3, 1 < f5 + f6 < 4, 5 < f4 + f7 < 10, 1 < f1 + f4 < 3,

[0015] 50 < f 23 + f 56 < 60, -6 < (f 23 + f 56 ) / f7 < -5.

[0016] The refractive index of the material of the above-mentioned lens one is n1 and the Abbe number is v1; the refractive index of the material of lens two is n2 and the Abbe number is v2; the refractive index of the material of lens three is n3 and the Abbe number is v3; the refractive index of the material of lens four is n4 and the Abbe number is v4; the refractive index of the material of lens five is n5 and the Abbe number is v5; the refractive index of the material of lens six is n6 and the Abbe number is v6; the refractive index of the material of the focusing lens is n7 and the Abbe number is v7; among them:

[0017] The materials of lens two and lens three meet the following requirements:

[0018] 0.5 < n2 / n3 < 1.3, 0.15 < v2 / v3 < 4.6;

[0019] The materials of lens one and lens four meet the following requirements:

[0020] 0.6 < n1 / n4 < 1.43, 0.1 < v1 / v4 < 1.2;

[0021] The materials of the fifth lens, the sixth lens and the focusing lens meet the following requirements:

[0022] 1.4 < (n5 + n6) / n7 < 2.7, 1.1 < (v5 + v6) / v7 < 6.6.

[0023] The above-mentioned first lens has a positive optical power, and both surfaces are curved towards the object side; the second lens has a positive optical power, the third lens has a negative optical power, the cemented surface of the second lens and the third lens is curved towards the object side, the other surface of the third lens is also curved towards the object side, and the other surface of the second lens is curved towards the image side; the fourth lens has a positive optical power, one surface is curved towards the image side, and the other surface is a plane.

[0024] The above-mentioned aperture stop is located between the first objective lens group and the second objective lens group, and is closer to the first objective lens group.

[0025] The above-mentioned fifth lens is a biconcave lens with a negative optical power; the sixth lens is a biconvex lens with a positive optical power, and the curvature radii of the two convex surfaces of the sixth lens are equal.

[0026] The above-mentioned focusing lens is a lens with a negative optical power. The surface of the focusing lens close to the image sensor is a plane, and the other surface is a concave surface curved towards the object side.

[0027] Moving the above-mentioned focusing lens towards the image side expands the foreground depth of field; moving the focusing lens towards the object side expands the background depth of field.

[0028] The above-mentioned focusing lens is driven by a high-speed moving motor. The focusing lens in front of the image sensor moves driven by the high-speed moving motor to achieve fast autofocus.

[0029] Compared with the prior art, the present utility model has the following advantages:

[0030] Effect 1: The high-magnification digital microscope optical system of the present utility model adopts a first objective lens group, a second objective lens group, a third objective lens group and an image sensor that are sequentially arranged at intervals between the object side and the image side, wherein: the first objective lens group uses 4 lenses, and the second objective lens group uses 2 cemented lenses; the third objective lens group consists of a single focusing lens. Focusing is achieved and the depth of field is expanded by moving the focusing lens back and forth along the optical axis, so that the observed object is clearly imaged on the image sensor. After experimental testing, the depth of field can be expanded by using the autofocus of the moving focusing lens, and the depth of field can reach the level of 300 μm. The defocus of the high-magnification microscope caused by the height change due to the translation of the high-magnification digital microscope driven by the manipulator can be ignored, thereby improving the observation efficiency and observation accuracy, and making the judgment of the observed object more accurate.

[0031] Effect 2: During the process of the manipulator driving the high-power digital microscope to translate, one focusing lens in the objective lens group is driven by a high-speed moving motor to achieve rapid movement for automatic focusing. The reaction speed is fast, the depth of field is enlarged during the automatic focusing process, the working efficiency is high, and the object to be observed can be accurately judged.

[0032] Effect 3: When the high-power digital microscope optical system of the present invention focuses, instead of moving the entire objective lens group, only one focusing lens in the objective lens group is moved. The focusing lens is small in volume and light in weight, and is driven by a high-speed moving motor to achieve rapid movement for automatic focusing, forming a clear image on the image sensor. The working efficiency is high, and the object to be observed can be accurately judged. Brief Description of the Drawings

[0033] Figure 1 is the optical principle diagram of the existing high-power microscope optical system;

[0034] Figure 2 is the working schematic diagram of the existing high-power microscope;

[0035] Figure 3 is the structural schematic diagram of the existing chip;

[0036] Figure 4 is the optical path diagram of the high-power digital microscope optical system of the present invention;

[0037] Figure 5 is Figure 4 the partial schematic diagram of;

[0038] Figure 6 is Figure 4 the partial schematic diagram of;

[0039] Figure 7 is the change schematic diagram of the automatic focusing process of the high-power digital microscope optical system of the present invention;

[0040] Figure 8 is the three-dimensional view of one angle of the high-power digital microscope of the present invention;

[0041] Figure 9 is the three-dimensional view of another angle of the high-power digital microscope of the present invention;

[0042] Figure 10 is the structural cross-sectional view of the high-power digital microscope of the present invention;

[0043] Figure 11 is the spot diagram of the optical system of the present invention when the object distance is 10.4 mm;

[0044] Figure 12 is the transfer function diagram of the optical system of the present invention when the object distance is 10.4 mm;

[0045] Figure 13 It is the spot diagram of the optical system of the present utility model when the object distance is 10.25 mm;

[0046] Figure 14 It is the transfer function diagram of the optical system of the present utility model when the object distance is 10.25 mm;

[0047] Figure 15 It is the spot diagram of the optical system of the present utility model when the object distance is 10.55 mm;

[0048] Figure 16 It is the transfer function diagram of the optical system of the present utility model when the object distance is 10.55 mm. Detailed implementation manners

[0049] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0050] Embodiment 1:

[0051] As Figures 4 to 7 shown, this embodiment provides a high-power digital microscope optical system for automatically focusing and randomly expanding the depth of field, which is characterized in that: it includes a first objective lens group 2, a second objective lens group 3, a third objective lens group 4 and an image sensor 5 sequentially arranged at intervals between an object plane 1 and an image plane 6, wherein:

[0052] The first objective lens group 2 includes a lens one L1, a lens two L2, a lens three L3 and a lens four L4. The first objective lens group 2 is fixed and the lens two L2 and the lens three L3 are glued together;

[0053] The second objective lens group 3 includes a lens five L5 and a lens six L6. The lens five L5 and the lens six L6 are glued together and the second objective lens group 3 is fixed;

[0054] The third objective lens group 4 is composed of a focusing lens L7. By moving the focusing lens L7 back and forth, focusing is achieved and the depth of field is expanded, so that the observed object is clearly imaged on the image sensor 5.

[0055] The above-mentioned first objective lens group 2 has a positive optical power, the second objective lens group 3 has a negative optical power, the third objective lens group 4 has a negative optical power, and the distance between the first objective lens group 2 and the object plane 1 is greater than 10 mm. Among them, the focal length of lens one L1 is f1, the focal length of lens two L2 is f2, the focal length of lens three L3 is f3, the focal length of lens four L4 is f4, the focal length of lens five L5 is f5, the focal length of lens six L6 is f6, the focal length of the focusing lens L7 is f7, and the focal length after lens two L2 and lens three L3 are cemented is f 23 , and the focal length after lens five L5 and lens six L6 are cemented is f 56 , and the focal lengths satisfy the following conditions:

[0056] -5 < f2 + f3 < -3, 1 < f5 + f6 < 4, 5 < f4 + f7 < 10, 1 < f1 + f4 < 3,

[0057] 50 < f 23 + f 56 < 60, -6 < (f 23 + f 56 ) / f7 < -5.

[0058] The refractive index of the material of the above-mentioned lens one L1 is n1, and the Abbe number is v1; the refractive index of the material of lens two L2 is n2, and the Abbe number is v2; the refractive index of the material of lens three L3 is n3, and the Abbe number is v3; the refractive index of the material of lens four L4 is n4, and the Abbe number is v4; the refractive index of the material of lens five L5 is n5, and the Abbe number is v5; the refractive index of the material of lens six L6 is n6, and the Abbe number is v6; the refractive index of the material of the focusing lens L7 is n7, and the Abbe number is v7; among them:

[0059] The materials of lens two L2 and lens three L3 satisfy the following requirements:

[0060] 0.5 < n2 / n3 < 1.3, 0.15 < v2 / v3 < 4.6;

[0061] The materials of lens one L1 and lens four L4 satisfy the following requirements:

[0062] 0.6 < n1 / n4 < 1.43, 0.1 < v1 / v4 < 1.2;

[0063] The materials of lens five L5, lens six L6 and the focusing lens L7 satisfy the following requirements:

[0064] 1.4 < (n5 + n6) / n7 < 2.7, 1.1 < (v5 + v6) / v7 < 6.6.

[0065] The above-mentioned first lens L1 has a positive focal power, and both surfaces S1 and S2 of the first lens L1 are curved towards the object surface 1 side; the second lens L2 has a positive focal power, the third lens L3 has a negative focal power, the surfaces S4 of the second lens L2 and the surface S5 of the third lens L3 are cemented, and the cemented surface is curved towards the object surface 1 side, and the other surface S6 of the third lens L3 is also curved towards the object surface 1 side, and the other surface S3 of the second lens L2 is curved towards the image surface 6 side; the fourth lens L4 has a positive focal power, one surface S7 of the fourth lens L4 is curved towards the image surface 6 side, and the other surface S8 is a plane.

[0066] The above-mentioned aperture stop 7 is located between the first objective lens group 2 and the second objective lens group 3, and the aperture stop 7 is closer to the first objective lens group 2, and the structural configuration is more reasonable.

[0067] The above-mentioned fifth lens L5 is a biconcave lens with a negative focal power, having a concave surface S9 and a concave surface S10; the sixth lens L6 is a biconvex lens with a positive focal power, and the curvature radii of the convex surfaces S11 and S12 of the sixth lens L6 are equal, and the convex surface S11 of the sixth lens L6 is cemented to the concave surface S10 of the fifth lens L5.

[0068] The above-mentioned focusing lens L7 is a lens with a negative focal power, the surface S14 of the focusing lens L7 close to the image sensor 5 side is a plane, and the other surface S13 of the focusing lens L7 is a concave surface curved towards the object surface 1.

[0069] The above-mentioned focusing lens L7 moves along the optical axis towards the image surface 6 to expand the front depth of field; the focusing lens L7 moves along the optical axis towards the object surface 1 to expand the rear depth of field. Figure 7 When the focusing lens L7 moves towards the object surface 1 direction to the maximum range, while ensuring the image quality (see Figure 13 and Figure 14 ), a rear depth of field of 0.1500 mm is obtained. Figure 7 The units of the numbers marked in

[0070] are all mm (i.e., millimeters). Of course, the focusing lens L7 moves along the optical axis towards the image surface 6 to expand the front depth of field, which will not be described in detail here. Similarly, a front depth of field of 0.1500 mm can also be obtained, so that the overall depth of field is extended to the 300 μm level.

[0071] As Figure 8 、 Figure 9 and Figure 10 shown, the high-magnification digital microscope optical system for automatically focusing and randomly expanding the depth of field of the present invention is all installed inside the housing 100. The high-speed moving motor 8 is installed on the housing 100. The focusing lens L7 is driven by the high-speed moving motor 8, and the focusing lens L7 in front of the image sensor 5 moves under the drive of the high-speed moving motor to achieve fast automatic focusing.

[0072] The main advantages of the present utility model are as follows: 1. A first objective lens group, a second objective lens group, a third objective lens group, and an image sensor are sequentially arranged at intervals between the object surface and the image surface. Among them: the first objective lens group uses 4 lenses, and the second objective lens group uses 2 cemented lenses; the third objective lens group consists of a single focusing lens. By moving the focusing lens back and forth along the optical axis, focusing is achieved and the depth of field is enlarged, enabling the observed object to be clearly imaged on the image sensor. Through experimental tests, using the automatic focusing of the moving focusing lens to enlarge the depth of field can reach a depth of field at the 300-μm level, and the defocus of the high-power microscope caused by the height change due to the translation of the high-power digital microscope driven by the manipulator can be ignored, thereby improving the observation efficiency and observation accuracy, and making a more accurate judgment of the observed object. 2. During the translation of the high-power digital microscope driven by the manipulator in the present utility model, a focusing lens in the objective lens group is driven by a high-speed moving motor to achieve rapid movement and automatic focusing. The reaction speed is fast, the depth of field is enlarged during the automatic focusing process, the working efficiency is high, and the observed object can be accurately judged. 3. When the optical system of the high-power digital microscope of the present utility model focuses, instead of moving the entire objective lens group, only a focusing lens in the objective lens group is moved. The focusing lens is small in volume and light in weight, and is driven by a high-speed moving motor to achieve rapid movement and automatic focusing, forming a clear image on the image sensor. The working efficiency is high, and the observed object can be accurately judged.

[0073] As Figure 11 , Figure 12 , Figure 13 , Figure 14 , Figure 15 and Figure 16 shown, through theoretical calculation and actual tests, spot diagrams and transfer function diagrams at different object distances are obtained. An optical system of a high-power digital microscope with an automatically focused and randomly enlarged depth of field according to the present utility model fully meets the design requirements, that is, the focusing lens is driven by a high-speed moving motor to achieve rapid movement and automatic focusing, the reaction speed is fast, the depth of field is enlarged during the automatic focusing process, the working efficiency is high, and the observed object can be accurately judged.

[0074] The above embodiments are the preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited thereto. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present utility model are equivalent replacement methods and are all included in the protection scope of the present utility model.

Claims

1. A high-magnification digital microscope optical system that randomly expands the depth of field through autofocus, characterized in that: It includes a first objective lens group (2), a second objective lens group (3), a third objective lens group (4) and an image sensor (5) that are sequentially and spaced between an object surface (1) and an image surface (6), where: The first objective lens group (2) includes a first lens (L1), a second lens (L2), a third lens (L3) and a fourth lens (L4). The first objective lens group (2) is fixed, and the second lens (L2) and the third lens (L3) are cemented together; The second objective lens group (3) includes a fifth lens (L5) and a sixth lens (L6). The fifth lens (L5) and the sixth lens (L6) are cemented together, and the second objective lens group (3) is fixed; The third objective lens group (4) consists of a focusing lens (L7). Focusing is achieved by moving the focusing lens (L7) back and forth to expand the depth of field, so that the observed object is clearly imaged on the image sensor (5).

2. The high-magnification digital microscope optical system for randomly expanding the depth of field through autofocus according to claim 1, wherein: The first objective lens group (2) has a positive optical power, the second objective lens group (3) has a negative optical power, the third objective lens group (4) has a negative optical power, the distance between the first objective lens group (2) and the object plane (1) is greater than 10 mm. Among them, the focal length of lens one (L1) is f1, the focal length of lens two (L2) is f2, the focal length of lens three (L3) is f3, the focal length of lens four (L4) is f4, the focal length of lens five (L5) is f5, the focal length of lens six (L6) is f6, the focal length of the focusing lens (L7) is f7, and the focal length after lens two (L2) and lens three (L3) are cemented is f 23 , and the focal length after lens five (L5) and lens six (L6) are cemented is f 56 , and the following conditions are satisfied for each focal length: -5 < f2 + f3 < -3, 1 < f5 + f6 < 4, 5 < f4 + f7 < 10, 1 < f1 + f4 < 3, 50 < f 23 + f 56 < 60, -6 < (f 23 + f 56 ) / f7 < -5。 3. The high-magnification digital microscope optical system for randomly expanding the depth of field by autofocus according to claim 2, wherein: The material refractive index of the first lens (L1) is n1 and the Abbe number is v1; the material refractive index of the second lens (L2) is n2 and the Abbe number is v2; the material refractive index of the third lens (L3) is n3 and the Abbe number is v3; the material refractive index of the fourth lens (L4) is n4 and the Abbe number is v4; the material refractive index of the fifth lens (L5) is n5 and the Abbe number is v5; the material refractive index of the sixth lens (L6) is n6 and the Abbe number is v6; the material refractive index of the focusing lens (L7) is n7 and the Abbe number is v7; where: The materials of the second lens (L2) and the third lens (L3) meet the following requirements: 0.5 < n2 / n3 < 1.3, 0.15 < v2 / v3 < 4.6; The materials of the first lens (L1) and the fourth lens (L4) meet the following requirements: 0.6 < n1 / n4 < 1.43, 0.1 < v1 / v4 < 1.2; The materials of the fifth lens (L5), the sixth lens (L6) and the focusing lens (L7) meet the following requirements: 1.4 < (n5 + n6) / n7 < 2.7, 1.1 < (v5 + v6) / v7 < 6.

6.

4. The high-magnification digital microscope optical system for randomly expanding the depth of field by autofocus according to claim 1, characterized in that: The first lens (L1) has a positive optical power, and both surfaces are curved towards the object surface (1) side; the second lens (L2) has a positive optical power, the third lens (L3) has a negative optical power, the cemented surface of the second lens (L2) and the third lens (L3) is curved towards the object surface (1) side, the other surface of the third lens (L3) is also curved towards the object surface (1) side, and the other surface of the second lens (L2) is curved towards the image surface (6) side; the fourth lens (L4) has a positive optical power, one surface is curved towards the image surface (6) side, and the other surface is flat.

5. The high-magnification digital microscope optical system for randomly expanding the depth of field by autofocus according to claim 1 or 2 or 3 or 4, characterized in that: The aperture stop (7) is located between the first objective lens group (2) and the second objective lens group (3) and is closer to the first objective lens group (2).

6. The high-magnification digital microscope optical system for randomly expanding the depth of field by autofocus according to claim 5, wherein: The fifth lens (L5) is a biconcave lens with negative optical power; the sixth lens (L6) is a biconvex lens with positive optical power, and the curvature radii of the two convex surfaces of the sixth lens (L6) are equal.

7. The high-magnification digital microscope optical system for randomly expanding the depth of field through autofocus according to claim 5, characterized in that: The focusing lens (L7) is a lens with negative optical power. The surface of the focusing lens (L7) closer to the image sensor (5) is flat, and the other surface is a concave surface curved towards the object surface (1).

8. The high-power digital microscope optical system for randomly expanding the depth of field by autofocus according to claim 5, wherein: The focusing lens (L7) moves towards the image plane (6) to expand the foreground depth of field; the focusing lens (L7) moves towards the object plane (1) to expand the background depth of field.

9. The high magnification digital microscope optical system for randomly expanding the depth of field by autofocus according to claim 8, wherein: The focusing lens (L7) is driven by a high-speed moving motor. The focusing lens (L7) in front of the image sensor (5) moves driven by the high-speed moving motor to achieve fast autofocus.

Images