Microscopic imaging system with relay zooming

Abstract

The embodiment of the invention provides a microscopic imaging system with relay zoom, which comprises a microscope objective, a relay system, a diaphragm and a zoom system which are coaxially arranged from an object side to an image side, and is characterized in that the focal length range of the microscope objective is [3.5 mm, 10mm], and the microscope objective is used for collimating and emitting reflected light and / or scattered light of an object to be measured; the relay system comprises a first positive focal power lens group, a field lens and a second positive focal power lens group, and is used for adjusting an exit pupil of the microscope objective to a diaphragm so as to amplify or reduce the size of a light beam collimated and emitted by the microscope objective; the diaphragm is used for modulating the size of an exit pupil of the microscope objective; the zoom system comprises a fixed lens group, a zoom lens group and a compensation lens group.

Description

Technical Field

[0001] The present invention relates to the field of optical detection technology, and in particular to a microscopic imaging system with relay magnification. Background Art

[0002] Semiconductor defect inspection optical systems are microscopic imaging systems used to detect defects in semiconductor wafers. The core optical components typically include an objective lens and a tube lens. Tube lenses typically have a fixed focal length, but in some specialized applications, variable magnification imaging systems replace fixed-focal-length tube lenses when it's desirable to view object details at varying magnifications.

[0003] However, the zoom imaging systems in the prior art generally include a two-component zoom structure, which is large in size and size. The reason is that the objective lens uses a special long-focal-length objective lens to increase the field of view. However, in some scenarios, a large field of view is not required, so a short-focal-length objective lens has also become an option. However, there is no zoom system in the prior art microscopic imaging system that is suitable for short-focal-length objective lenses. Summary of the Invention

[0004] An embodiment of the present invention provides a microscopic imaging system with relay zoom, which is used to provide a microscope objective lens suitable for a focal length range of 3.5 mm to 10 mm, so as to reduce the volume of the microscopic imaging system.

[0005] The present invention provides a microscopic imaging system, comprising:

[0006] The microscope objective lens, relay system, diaphragm and zoom system are coaxially arranged from the object space to the image space, wherein:

[0007] The focal length range of the microscope objective lens includes [3.5mm, 10mm], and is used to collimate the reflected light and / or scattered light of the object to be measured;

[0008] The relay system comprises a first positive power lens group, a field lens and a second positive power lens group, and is used to adjust the exit pupil of the microscope objective lens to the aperture, so as to amplify or reduce the size of the collimated light beam emitted by the microscope objective lens;

[0009] The aperture is used to modulate the size of the exit pupil of the microscope objective lens;

[0010] The zoom system includes a fixed lens group, a zoom lens group and a compensation lens group, wherein the fixed lens group is used to image the parallel light beam emitted by the second positive focal length lens group to a preset fixed position, the zoom lens group is used to secondary image the image formed by the fixed lens group, and the compensation lens group is used to image the image formed by the zoom lens group to a preset image plane, which is located at a fixed position.

[0011] Preferably, the magnification range of the relay system includes 0.75 times to 1.5 times.

[0012] Preferably, the zoom ratio of the zoom system is less than or equal to 3.

[0013] Preferably, the focal length range of the zoom system includes 100mm-300mm, and 300mm to 900mm.

[0014] Preferably, the front working distance of the relay system ranges from 100 mm to 300 mm, and the rear working distance of the relay system ranges from 100 mm to 300 mm.

[0015] Preferably, the ratio of the total length L1 of the optical elements of the relay system to the total working length L2 of the relay system is less than or equal to 0.6, wherein L1 is the distance between the aperture and the last lens in the relay system along the optical axis, and L2 is the distance from the aperture to the image plane of the relay system.

[0016] Preferably, the distance from the aperture to the first lens in the zoom system along the optical axis is greater than 40 mm.

[0017] Preferably, the zoom system is configured as a PNP structure or an NPP structure, and the rear working distance when the zoom system is configured as the PNP structure is smaller than the rear working distance when the zoom system is configured as the NPP structure, wherein N represents negative optical power and P represents positive optical power.

[0018] Preferably, if the magnification system is configured as the PNP structure, the sum of the optical focal lengths of the fixed lens group and the magnification lens group is less than 0, the sum of the optical focal lengths of the magnification lens group and the compensation lens group is also less than 0, and the distance between the magnification lens group and the compensation lens group decreases as the focal length of the relay magnification system increases.

[0019] Preferably, the ratio of the optical element length L3 of the zoom system to the total length L4 of the zoom system satisfies the following relationship:

[0020] 0.5≤L3 / L4≤0.8,

[0021] The L3 is the distance between the aperture and the last lens of the zoom system along the optical axis, and the L4 is the distance between the aperture and the image plane of the zoom system.

[0022] Preferably, if the focal length of the fixed lens group is f1, the focal length of the variable magnification lens group is f2, the focal length of the supplementary lens group is f3, and the focal length range of the variable magnification system includes [F1, F2], then the following relationship is satisfied:

[0023] 0.2≤f1 / F2≤1; 0.4≤-f2 / F1≤1; 0.5≤f3 / F1≤1.2.

[0024] Preferably, if the magnification system is configured as the NPP structure, the sum of the optical focal lengths of the fixed lens group and the magnification lens group is less than 0, the sum of the optical focal lengths of the magnification lens group and the compensation lens group is greater than 0, and the distance between the magnification lens group and the compensation lens group increases with the increase of the focal length of the relay magnification system.

[0025] Preferably, the ratio of the optical element length L5 of the zoom system to the total length L6 of the zoom system satisfies the following relationship:

[0026] 0.6≤L5 / L6≤0.8,

[0027] The L5 is the distance between the aperture and the last lens of the zoom system along the optical axis, and the L6 is the distance between the aperture and the image plane of the zoom system.

[0028] Preferably, if the focal length of the fixed lens group is f1, the focal length of the variable magnification lens group is f2, the focal length of the supplementary lens group is f3, and the focal length range of the variable magnification system includes [F1, F2], then the following relationship is satisfied:

[0029] 0.5≤-f1 / F2≤1; 1≤f2 / F1≤2; 0.8≤f3 / F1≤1.2.

[0030] Preferably, the optical coupling length of the zoom system is a fixed value.

[0031] It can be seen from the above technical solutions that the embodiments of the present invention have the following advantages:

[0032] Because the zoom system in the embodiment of the present application is composed of three lens groups, and the image formed by the relay system is finally imaged at a fixed image plane position after passing through the zoom system, that is, the optical coupling length of the zoom system in the embodiment of the present application is a fixed value, thereby ensuring the stability of the microscopic imaging system structure. Furthermore, the zoom system in the embodiment of the present application can be adapted to microscope objectives with a focal length range of 3.5mm-10mm, thereby realizing the zoom function while ensuring the field of view requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of an embodiment of a microscopic imaging system with relay zoom in an embodiment of the present application;

[0034] Figure 2 This is a schematic diagram of an embodiment of a relay system in an embodiment of the present application;

[0035] Figure 3 This is a schematic diagram of an embodiment of a zoom system in an embodiment of the present application;

[0036] Figure 4 This is a schematic diagram of another embodiment of the zoom system in the embodiment of the present application;

[0037] Figure 5 This is a schematic diagram of an embodiment of a relay system in an embodiment of the present application;

[0038] Figure 6 This is a schematic diagram of another embodiment of the zoom system in the embodiment of the present application;

[0039] Figure 7 This is a schematic diagram of another embodiment of the zoom system in the embodiment of the present application;

[0040] Figure 8 This is a schematic diagram of another embodiment of the zoom system in the embodiment of the present application;

[0041] Figure 9 This is a schematic diagram of another embodiment of the zoom system in the embodiment of the present application. DETAILED DESCRIPTION

[0042] An embodiment of the present invention provides a microscopic imaging system with relay zoom, which is used to provide a microscope objective lens suitable for a focal length range of 3.5 mm to 10 mm, so as to reduce the volume of the microscopic imaging system.

[0043] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0044] The terms "first," "second," "third," "fourth," and the like in the specification and claims of the present invention and in the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0045] For ease of understanding, the microscopic imaging system in the embodiments of the present application is described below. Figure 1 , an embodiment of the microscopic imaging system in the embodiment of the present application includes:

[0046] The microscope objective lens 10, the relay system 20, the aperture 30 and the zoom system 40 are coaxially arranged from the object side to the image side, wherein:

[0047] The operating wavelength range of the microscope objective lens 10 includes [260nm, 450nm], and the focal length range of the microscope objective lens 10 includes [3.5mm, 10mm], and is used to collimate the reflected light and / or scattered light of the object to be measured;

[0048] The relay system 20 includes a first positive power lens group 201, a field lens 202 (wherein the field lens is used to match the size of the output light beam of the first positive power lens group 201 to the size of the second positive power lens group 203), and a second positive power lens group 203, which is used to adjust the exit pupil of the microscope objective 10 to the aperture to magnify or reduce the size of the collimated light beam emitted by the microscope objective.

[0049] Specifically, as an optional embodiment, the first positive focal power lens group 201 and the second positive focal power lens group 203 can respectively include multiple positive lenses, or can include multiple positive lenses and negative lenses that cooperate with each other, as long as the focal power of the combination of the positive lens and the negative lens is positive focal power.

[0050] The aperture 30 is used to modulate the size of the exit pupil of the microscope objective lens 10 .

[0051] The zoom system 40 includes a fixed lens group 401, a zoom lens group 402 and a compensation lens group 403, wherein the fixed lens group 401 is used to image the parallel light beam emitted by the second positive focal length lens group to a preset fixed position, the zoom lens group 402 is used to secondary image the image formed by the fixed lens group, and the compensation lens group 403 is used to image the image formed by the zoom lens group 402 to a preset image plane, which is located at a fixed position.

[0052] Specifically, when the fixed lens group 401, the zoom lens group 402 and the compensation lens group 403 in the zoom system 40 cooperate with each other, as long as they can magnify the image formed by the relay system, there is no specific restriction on the lens composition structure of the fixed lens group 401, the zoom lens group 402 and the compensation lens group 403.

[0053] Furthermore, after the fixed lens group 401 images the parallel light beam emitted by the second positive focal length lens group to a preset fixed position, the zoom lens group 402 is used to secondary image the image formed by the fixed lens group. Because the position of the secondary image will change when the zoom lens group 402 changes at different magnifications, in order to image the final image to a fixed image plane position, a compensation lens group 403 is provided, wherein the compensation lens group 403 compensates for the changed position when the position of the secondary image changes, so that the image formed by the zoom system 40 is finally located at a fixed image plane position.

[0054] Because the zoom system in the embodiment of the present application is composed of three lens groups, and the image formed by the relay system is finally imaged at a fixed image plane position after passing through the zoom system, that is, the optical coupling length of the zoom system in the embodiment of the present application is a fixed value, thereby ensuring the stability of the microscopic imaging system structure. Furthermore, the zoom system in the embodiment of the present application can be adapted to microscope objectives with a focal length range of 3.5mm-10mm, thereby realizing the zoom function while ensuring the field of view requirements.

[0055] based on Figure 1 The following describes the relay system 20 in the microscopic imaging system. Figure 2 :

[0056] Specifically, the relay system 20 includes a first positive power lens group 201, a field lens 202 (wherein the field lens is used to make the size of the output light beam of the first positive power lens group 201 match the size of the second positive power lens group 203) and a second positive power lens group 203, so as to adjust the exit pupil of the microscope objective 10 to the aperture 30, so as to enlarge or reduce the size of the collimated light beam emitted by the microscope objective 10.

[0057] As an optional embodiment, the magnification range of the relay system 20 in the embodiment of the present application includes 0.75 times to 1.5 times, the front working distance of the relay system 20 includes 100mm to 300mm, and the rear working distance range of the relay system 20 includes 100mm to 300mm.

[0058] Because when the front working distance of the relay system 20 is less than 100mm, the distance between the microscope objective lens 10 and the relay system 20 is too small to provide enough space to insert the intervention mechanism, such as insufficient space to insert the reflector to connect with other systems (such as autofocus system, reflector, etc.). When the front working distance of the relay system 20 is greater than 300mm, the workbench cannot provide sufficient space for layout. Figure 1 Microscopic imaging system.

[0059] When the back working distance of the relay system 20 is less than 100 mm, there is not enough space to place other lens groups (such as filter groups) at the exit pupil position of the microscope objective lens 10. When the back working distance of the relay system 20 is greater than 300 mm, the workbench cannot provide enough space for arrangement. Figure 1 Microscopic imaging system.

[0060] As another optional embodiment, in the embodiment of the present application, the ratio of the total length L1 of the optical elements of the relay system to the total working length L2 of the relay system is less than or equal to 0.6, wherein L1 is the distance between the aperture 30 and the last lens in the relay system 20 along the optical axis, and L2 is the distance from the aperture 30 to the image plane of the relay system.

[0061] Because the larger the ratio of the total length L1 of the optical elements of the relay system to the total working length L2 of the relay system, the smaller the front working distance of the first positive focal power lens group 201 and the rear working distance of the second positive focal power lens group 203, which results in the smaller focal length of the first positive focal power lens group 201 and the second positive focal power lens group 203. The smaller the focal length, while the size of the aperture 30 remains unchanged, the smaller the F number (where F = focal length / aperture) of the first positive focal power lens group 201 and the second positive focal power lens group 203, so the more difficult it is to control aberrations such as spherical aberration and chromatic aberration, and more lenses are needed to balance the aberrations, which will also lead to a decrease in the system transmittance.

[0062] based on Figure 1 The following describes the zoom system 40 in the microscopic imaging system.

[0063] Specifically, the magnification system 40 includes a fixed lens group 401, a magnification lens group 402 and a compensation lens group 403, wherein the fixed lens group 401 is used to image the parallel light beam emitted by the second positive focal length lens group to a preset fixed position, the magnification lens group 402 is used to secondary image the image formed by the fixed lens group 401, and the compensation lens group 403 is used to image the image formed by the magnification lens group 402 to a preset image plane, which is located at a fixed position.

[0064] As an optional embodiment, the zoom ratio of the zoom system 40 in the embodiment of the present application is less than or equal to 3, that is, when the minimum focal length of the zoom system 40 is 100mm, the corresponding maximum focal length of the zoom system 40 is 300mm, and when the minimum focal length 40 of the zoom system is 300mm, the corresponding maximum focal length of the zoom system 40 is 900mm.

[0065] Because when the magnification ratio of the magnification system 40 is greater than 3, the number of lenses of the magnification system will increase, and too many lenses will result in a lower light transmittance of the magnification system. Furthermore, in order to achieve continuous zooming of the magnification system 40, the embodiment of the present application can also set the focal length of the magnification system 40 in segments, that is, when the minimum focal length of the magnification system 40 is 100mm, the corresponding maximum focal length of the magnification system 40 is 300mm, and when the minimum focal length of the magnification system 40 is 300mm, the corresponding maximum focal length of the magnification system 40 is 900mm, thereby achieving continuous zooming of the focal length of the magnification system 40 from 100mm to 900mm.

[0066] Furthermore, in order to install the aperture 30, the embodiment of the present application also sets the distance between the aperture 30 and the first lens along the optical axis in the magnification system 40 to be greater than 40 mm, so that there is sufficient space structure to accommodate the aperture 30 and the mechanical structure supporting the aperture 30.

[0067] In the embodiment of the present application, the zoom ratio of the zoom system 40 and the focal length variation range of the zoom system 40 are described in detail, thereby realizing continuous zooming of the zoom system while saving the number of lenses.

[0068] Furthermore, the focal length range of the zoom system 40 can be set in segments, so that the focal length of the zoom system can be freely adjusted between 100mm and 300mm, and between 300mm and 900mm, thereby achieving free adjustment between the focal length of 100mm and 900mm while saving the number of lenses.

[0069] based on Figure 1 The following describes the zoom system 40 in the microscopic imaging system.

[0070] As an optional embodiment, the zoom system 40 in the embodiment of the present application can be configured as a PNP structure or an NPP structure, where N represents negative optical power and P represents positive optical power. When the zoom system 40 is configured as a PNP structure, the back working distance of the zoom system 40 is smaller than the back working distance of the zoom system 40 with an NPP structure. The PNP and NPP mentioned here both refer to the distribution order of lens groups of different focal length types.

[0071] As an alternative embodiment, see Figure 3When the zoom system 40 is configured as a PNP structure, the sum of the optical focal lengths of the fixed lens group 401 and the zoom lens group 402 is less than 0, and the sum of the optical focal lengths of the zoom lens group 402 and the compensation lens group 403 is also less than 0, and the distance between the zoom lens group 402 and the compensation lens group 403 decreases as the focal length of the relay zoom system increases, that is, when the focal length of the relay zoom system 40 increases, the zoom lens group 402 and the compensation lens group 403 move toward each other.

[0072] In order to achieve the zoom ratio of the zoom system 40 (the zoom ratio of the zoom system is less than or equal to 3), when the zoom system 40 is configured as a PNP structure, the parameters of each lens group in the zoom system 40 need to be designed to satisfy the following formulas:

[0073] The ratio of the optical element length L3 of the zoom system to the total length L4 of the zoom system satisfies the following relationship: 0.5≤L3 / L4≤0.8.

[0074] L3 is the distance between the aperture 30 and the last lens of the zoom system 40 along the optical axis, and L4 is the distance between the aperture 30 and the image plane of the zoom system 40.

[0075] If the focal length of the fixed lens group is f1, the focal length of the zoom lens group is f2, the focal length of the supplementary lens group is f3, and the focal length range of the zoom system includes [F1, F2], then the following relationships are satisfied: 0.2≤f1 / F2≤1; 0.4≤-f2 / F1≤1; 0.5≤f3 / F1≤1.2.

[0076] As another alternative embodiment, see Figure 4 When the zoom system 40 is configured as an NPP structure, the sum of the optical focal lengths of the fixed lens group 401 and the zoom lens group 402 is less than 0, the sum of the optical focal lengths of the zoom lens group 402 and the compensation lens group 403 is greater than 0, and the distance between the zoom lens group 402 and the compensation lens group 403 increases with the increase of the focal length of the relay zoom system, that is, when the focal length of the relay zoom system increases, the zoom lens group 402 and the compensation lens group 403 move away from each other.

[0077] In order to achieve the zoom ratio of the zoom system 40 (the zoom ratio of the zoom system is less than or equal to 3), when the zoom system 40 is configured as an NPP structure, the parameters of each lens group in the zoom system 40 need to be designed to satisfy the following formulas:

[0078] The ratio of the optical element length L5 of the zoom system to the total length L6 of the zoom system satisfies the following relationship: 0.6≤L5 / L6≤0.8.

[0079] L5 is the distance between the aperture 30 and the last lens of the zoom system 40 along the optical axis, and L6 is the distance between the aperture 30 and the image plane of the zoom system 40.

[0080] If the focal length of the fixed lens group is f1, the focal length of the zoom lens group is f2, the focal length of the supplementary lens group is f3, and the focal length range of the zoom system includes [F1, F2], then the following relationships are satisfied: 0.5≤-f1 / F2≤1; 1≤f2 / F1≤2; 0.8≤f3 / F1≤1.2.

[0081] For ease of understanding, the microscopic imaging system in the embodiment of the present application is described below through different embodiments. Figure 5 , Figure 5 This is a schematic diagram of an embodiment of the relay system 20 in the microscopic imaging system of the present application:

[0082] Specifically, the magnification ratio of the relay system 20 in the embodiment of the present application is 1.2, the front working distance of the relay system 20 is 100 mm, the rear working distance is also 100 mm, the focal length of the first positive focal power lens group 201 in the relay system 20 is 117 mm, and the focal length of the second positive focal power lens group 203 is 140.4 mm, that is, the ratio of the focal length of the second positive focal power lens group to the focal length of the first positive focal power lens group is equal to 1.2.

[0083] The relay system 20 in the embodiment of the present application has a total of 11 lenses, among which the first positive power lens group 201 includes 5 lenses, and the second positive power lens group 203 includes 5 lenses. The distribution of the first positive power lens group 201 and the second positive power lens group 203 is basically symmetrical, that is, the first positive power lens group 201 includes 3 positive lenses and 2 negative lenses, and the second positive power lens group 203 also includes 3 positive lenses and 2 negative lenses. Because the combination of positive and negative lenses can correct spherical aberration and chromatic aberration, and the spacing between the first positive power lens group 201 and the second positive power lens group 203 is basically symmetrical, the phase difference can be effectively corrected.

[0084] In the embodiment of the present application, the length of the optical element of the relay system is 300 mm, and the total length of the relay system is 500 mm.

[0085] Next, the zoom system in the microscopic imaging system of the present application is described. Figure 6 and Figure 7 :

[0086] Figure 6The zoom system 40 in the embodiment is a PNP zoom system with a focal range of 300mm-900mm. When the focal length of the zoom system is 300mm, the rear working distance is 295mm; when the focal length of the zoom system is 900mm, the rear working distance is 490mm. The optical length of the zoom system 40 is 300-500mm, and the total length (aperture to image plane) is 800mm.

[0087] The zoom system 40 uses a total of 15 lenses: four in the fixed lens group 401, four in the zoom lens group 402, and nine in the compensating lens group 403. The focal length of the fixed lens group 401 is 250mm, the focal length of the zoom lens group 402 is -133mm, and the focal length of the compensating lens group 403 is 275mm. All lenses are single lenses, with no cemented lens groups. They are made of fused quartz and calcium fluoride. The compensating lens group 403 has a larger number because the movement of the compensating lens group 403 increases the light's height, increasing spherical and chromatic aberrations and requiring more lenses for correction.

[0088] Figure 7 The zoom system 40 in the embodiment is also a PNP zoom system with a focal range of 100mm-300mm. When the focal length of the zoom system is 100mm, the rear working distance is 138mm; when the focal length of the zoom system is 300mm, the rear working distance is 191mm. The optical length of the zoom system 40 is 300-500mm, and the total length (aperture to image plane) is 429mm.

[0089] The zoom system 40 uses a total of 16 lenses: two in the fixed lens group 401, four in the zoom lens group 402, and ten in the compensating lens group 403. The focal length of the fixed lens group 401 is 223mm, the focal length of the zoom lens group 402 is -82mm, and the focal length of the compensating lens group 403 is 119mm. All lenses are single lenses, with no cemented lens groups. They are made of fused quartz and calcium fluoride. The compensating lens group 403 has a larger number because the movement of the compensating lens group increases the light's height, increasing spherical and chromatic aberrations, necessitating more lenses for correction.

[0090] Next, the zoom system in the microscopic imaging system of the present application is described. Figure 8 and Figure 9 :

[0091] Figure 8The zoom system 40 in this embodiment is an NPP zoom system with a focal range of 300-900 mm. When the zoom system's focal length is 300 mm, the back working distance is 443 mm; when the zoom system's focal length is 900 mm, the back working distance is 250 mm. The optical length of the zoom system 40 is 450-650 mm, and the total length (from the aperture to the image plane) is 900 mm.

[0092] The zoom system 40 utilizes a total of 16 lenses: three in the fixed lens group 401, three in the zoom lens group 402, and ten in the compensating lens group 403. The focal length of the fixed lens group 401 is -223mm, the focal length of the zoom lens group 402 is 82mm, and the focal length of the compensating lens group 403 is 119mm. All lenses are single elements, with no cemented lens groups. They are made of fused quartz and calcium fluoride. The larger number of lenses in the compensating lens group 403 is due to the increased height of the light beam during movement, which increases spherical and chromatic aberrations and requires more lenses to correct.

[0093] Figure 9 The zoom system 40 in the embodiment is an NPP zoom system with a focal range of 100-300 mm. When the focal length of the zoom system is 100 mm, the rear working distance is 175 mm; when the focal length of the zoom system is 300 mm, the rear working distance is 100 mm. The optical length of the zoom system 40 is 424-500 mm, and the total length (aperture to image plane) is 600 mm.

[0094] The zoom system 40 utilizes a total of 16 lenses: three in the fixed lens group 401, five in the zoom lens group 402, and eight in the compensating lens group 403. The focal length of the fixed lens group 401 is -150mm, the focal length of the zoom lens group 402 is 116mm, and the focal length of the compensating lens group 403 is 154mm. All lenses are single lenses, with no cemented lens groups. They are made of fused quartz and calcium fluoride. The large number of lenses in the compensating lens group 403 is due to the increased light height during the movement of the compensating lens group, which increases spherical and chromatic aberrations and requires more lenses for correction. The NPP structure differs from the PNP structure in that the zoom and compensating groups move in opposite directions from short to long focus during zooming.

[0095] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A microscopic imaging system with relay zoom, characterized in that: include: The microscope objective lens, relay system, diaphragm and zoom system are coaxially arranged from the object space to the image space, wherein: The focal length range of the microscope objective lens includes [3.5mm, 10mm], and is used to collimate the reflected light and / or scattered light of the object to be measured; The relay system comprises a first positive power lens group, a field lens and a second positive power lens group, and is used to adjust the exit pupil of the microscope objective lens to the aperture, so as to amplify or reduce the size of the collimated light beam emitted by the microscope objective lens; The aperture is used to modulate the size of the exit pupil of the microscope objective lens; The zoom system includes a fixed lens group, a zoom lens group and a compensation lens group, wherein the fixed lens group is used to image the parallel light beam emitted by the second positive focal length lens group to a preset fixed position, the zoom lens group is used to secondary image the image formed by the fixed lens group, and the compensation lens group is used to image the image formed by the zoom lens group to a preset image plane, which is located at a fixed position.

2. The microscopic imaging system according to claim 1, wherein: The magnification range of the relay system includes 0.75 times to 1.5 times.

3. The microscopic imaging system according to claim 1, characterized in that The zoom ratio of the zoom system is less than or equal to 3.

4. The microscopic imaging system according to claim 3, characterized in that: The focal length range of the zoom system includes 100mm-300mm, and 300mm to 900mm.

5. The microscopic imaging system according to claim 1, wherein: The front working distance of the relay system ranges from 100 mm to 300 mm, and the rear working distance of the relay system ranges from 100 mm to 300 mm.

6. The microscopic imaging system according to claim 1, wherein: The ratio of the total length L1 of the optical elements of the relay system to the total working length L2 of the relay system is less than or equal to 0.6, wherein L1 is the distance between the aperture and the last lens in the relay system along the optical axis, and L2 is the distance from the aperture to the image plane of the relay system.

7. The microscopic imaging system according to claim 1, characterized in that: The distance from the aperture to the first lens in the zoom system along the optical axis is greater than 40 mm.

8. The microscopic imaging system according to claim 1, wherein: The zoom system is configured as a PNP structure or an NPP structure. The rear working distance of the zoom system when configured as the PNP structure is smaller than the rear working distance when configured as the NPP structure, wherein N represents negative optical power and P represents positive optical power.

9. The microscopic imaging system according to claim 8, characterized in that: If the magnification system is configured as a PNP structure, the sum of the optical focal lengths of the fixed lens group and the magnification lens group is less than 0, the sum of the optical focal lengths of the magnification lens group and the compensation lens group is also less than 0, and the distance between the magnification lens group and the compensation lens group decreases as the focal length of the relay magnification system increases.

10. The microscopic imaging system according to claim 9, characterized in that: The ratio between the optical element length L3 of the zoom system and the total length L4 of the zoom system satisfies the following relationship: 0.5≤L3 / L4≤0.8, The L3 is the distance between the aperture and the last lens of the zoom system along the optical axis, and the L4 is the distance between the aperture and the image plane of the zoom system.

11. The microscopic imaging system according to claim 9, wherein: If the focal length of the fixed lens group is f1, the focal length of the zoom lens group is f2, the focal length of the supplementary lens group is f3, and the focal length range of the zoom system includes [F1, F2], then the following relationship is satisfied: 0.2≤f1 / F2≤1; 0.4≤-f2 / F1≤1; 0.5≤f3 / F1≤1.

2.

12. The microscopic imaging system according to claim 8, characterized in that If the magnification system is configured as an NPP structure, the sum of the optical focal lengths of the fixed lens group and the magnification lens group is less than 0, the sum of the optical focal lengths of the magnification lens group and the compensation lens group is greater than 0, and the distance between the magnification lens group and the compensation lens group increases with the increase of the focal length of the relay magnification system.

13. The microscopic imaging system according to claim 12, wherein: The ratio between the optical element length L5 of the zoom system and the total length L6 of the zoom system satisfies the following relationship: 0.6≤L5 / L6≤0.8, The L5 is the distance between the aperture and the last lens of the zoom system along the optical axis, and the L6 is the distance between the aperture and the image plane of the zoom system.

14. The microscopic imaging system according to claim 12, wherein: If the focal length of the fixed lens group is f1, the focal length of the zoom lens group is f2, the focal length of the supplementary lens group is f3, and the focal length range of the zoom system includes [F1, F2], then the following relationship is satisfied: 0.5≤-f1 / F2≤1; 1≤f2 / F1≤2; 0.8≤f3 / F1≤1.

2.

15. The microscopic imaging system according to any one of claims 1 to 14, characterized in that: The optical coupling length of the zoom system is a fixed value.

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