CN114415325B - Focusing optical imaging system - Google Patents
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- CN114415325B CN114415325B CN202210161373.1A CN202210161373A CN114415325B CN 114415325 B CN114415325 B CN 114415325B CN 202210161373 A CN202210161373 A CN 202210161373A CN 114415325 B CN114415325 B CN 114415325B
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- 238000012634 optical imaging Methods 0.000 title claims abstract description 43
- 230000003287 optical effect Effects 0.000 claims abstract description 73
- 230000008859 change Effects 0.000 claims abstract description 7
- 238000005259 measurement Methods 0.000 claims description 62
- 238000003384 imaging method Methods 0.000 claims description 44
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 7
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 239000010703 silicon Substances 0.000 claims description 7
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
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- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
- G02B7/04—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification
- G02B7/09—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification adapted for automatic focusing or varying magnification
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/28—Systems for automatic generation of focusing signals
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Abstract
A focusing optical imaging system relates to the technical field of optics, and comprises a marking plate, a first focusing lens group, a second focusing lens group, a barrel lens, an objective lens and an object plane plate for placing an object to be measured, wherein the marking plate, the first focusing lens group, the second focusing lens group, the barrel lens and the object plane plate are sequentially arranged at intervals along the direction of a first optical axis; the object plane plate is configured to be movable in a first optical axis direction to change an optical axis distance between the object plane plate and the objective lens; the focusing optical imaging system further comprises a third focusing lens group and an image acquisition device which are sequentially arranged along the second optical axis direction; the first optical axis direction is perpendicular to the second optical axis direction; a turning reflector is arranged between the first focusing lens group and the second focusing lens group; the turning mirror is configured to reflect light transmitted in the first optical axis direction to transmit in the second optical axis direction; the marking plate is provided with a measuring marking hole. The application aims to provide a focusing optical imaging system so as to solve the technical problems of longer focusing time and poorer focusing precision in the prior art to a certain extent.
Description
Technical Field
The application relates to the technical field of optics, in particular to a focusing optical imaging system.
Background
With the rise of semiconductor manufacturing nodes, the requirements on a silicon wafer alignment imaging optical system are higher and higher, and especially for the silicon wafer alignment imaging optical system based on an image recognition technology, the accuracy of automatic focusing is a key for determining the alignment imaging optical system. Most of the existing common automatic focusing technologies adopt a technical route of a software algorithm, and the main principle is that images aligned to an imaging optical system are collected, the contrast of the images is extracted, the images are collected again after the distance is adjusted to calculate the contrast, the optimal contrast position is determined after multiple iterations, and at the moment, the automatic focusing work is completed. But this scheme needs to adjust axial distance many times, gradually converges and step by step just can accomplish whole autofocus process, has the defect such as governing time is long, regulation precision is not enough, and has autofocus work inefficacy's risk under comparatively serious defocusing condition.
Disclosure of Invention
The application aims to provide a focusing optical imaging system so as to solve the technical problems of longer focusing time and poorer focusing precision in the prior art to a certain extent.
In order to achieve the above object, the present application provides the following technical solutions:
a focusing optical imaging system comprises a marking plate, a first focusing lens group, a second focusing lens group, a barrel lens, an objective lens and an object plane plate for placing an object to be measured, wherein the marking plate, the first focusing lens group, the second focusing lens group, the barrel lens and the object plane plate are sequentially arranged at intervals along the direction of a first optical axis; the object plane plate is configured to be movable in a first optical axis direction to change an optical axis distance between the object plane plate and the objective lens;
the focusing optical imaging system further comprises a third focusing lens group and an image acquisition device which are sequentially arranged along the second optical axis direction; the first optical axis direction is perpendicular to the second optical axis direction;
a turning reflector is arranged between the first focusing lens group and the second focusing lens group; the turning mirror is configured to reflect light rays transmitted in the first optical axis direction to transmit in the second optical axis direction;
the marking plate is provided with a measuring marking hole; the light passes through the measurement marking hole and forms measurement incident light, and the measurement incident light sequentially passes through the first focusing lens group, the second focusing lens group, the cylindrical lens and the objective lens and is incident to the object to be measured on the object plane plate at a certain incident angle; the measuring incident light is reflected by an object to be measured on the object plane plate to form measuring reflected light, the measuring reflected light sequentially penetrates through the objective lens, the barrel lens and the second focusing lens group and is reflected to the third focusing lens group through the turning mirror, and after the measuring reflected light penetrates through the third focusing lens group, measuring mark imaging is formed on the image acquisition device.
In any of the foregoing solutions, optionally, the focusing optical imaging system further includes a hollow mirror disposed between the second focusing lens group and the barrel mirror;
the center of the hollow reflecting mirror is provided with a through hole, and the edge of the hollow reflecting mirror is a reflecting mirror;
the marking plate is provided with a reference marking hole; the light passes through the reference mark hole and forms reference incident light, the reference incident light sequentially passes through the first focusing lens group and the second focusing lens group, is reflected by the edge of the hollow reflecting mirror and passes through the second focusing lens group, and is reflected by the turning reflecting mirror to the third focusing lens group, and the reference incident light forms reference mark imaging on the image acquisition device after passing through the third focusing lens group;
after the measuring incident light passes through the second focusing lens group, the measuring incident light passes through the through hole of the hollow reflector and is incident to the cylindrical lens; after the measuring reflected light passes through the cylindrical mirror, the measuring reflected light passes through the through hole of the hollow reflecting mirror and enters the second focusing lens group.
In any of the above solutions, optionally, the measurement mark hole includes a plurality of measurement mark small holes, the reference mark hole includes a plurality of reference mark small holes, and a pattern formed by the plurality of measurement mark small holes is disposed inside a pattern formed by the plurality of reference mark small holes;
the plurality of reference mark small holes are distributed in a square shape or a round shape.
In any of the above technical solutions, optionally, an incident angle of the incident light beam to the object to be measured on the object plane plate is 4 ° -10 °;
and/or the measurement mark imaging on the image acquisition device is 2-10 times of the measurement mark hole on the mark plate.
In any of the above technical solutions, optionally, an incident angle of the incident light beam to the object to be measured on the object plane plate is 4 ° -6 °;
and the measurement mark imaging on the image acquisition device is 3-5 times of the measurement mark hole on the mark plate.
In any of the above technical solutions, optionally, the image capturing device employs a linear array CCD.
In any of the above solutions, optionally, the marking plate is a chromed marking plate;
in any of the foregoing solutions, optionally, the focusing optical imaging system further includes a driving device;
the driving device is connected with the object plane plate so as to drive the object plane plate to be close to or far away from the objective lens along the first optical axis direction.
In any of the above solutions, optionally, the focusing optical imaging system further includes a light source; the light source is arranged on one side of the marking plate far away from the first focusing lens group;
optionally, the light source is a laser light source or an LED light source.
In any of the above technical solutions, optionally, the object side plane plate is placed with a silicon wafer.
The beneficial effects of the application are mainly as follows:
the marking plate, the first focusing lens group, the second focusing lens group, the barrel lens, the objective lens, the turning mirror, the third focusing lens group and the image acquisition device form an automatic focusing system, wherein the barrel lens and the objective lens belong to a part of an alignment imaging optical system, namely the automatic focusing system shares a barrel lens and an objective lens light path with the alignment imaging optical system, so that focusing time can be reduced to a certain extent, and focusing precision can be improved. Specifically, the focusing optical imaging system converts first optical axis direction measurement mark information of a measurement mark hole on a mark plate into second optical axis direction measurement mark information of an image acquisition device through a folding reflector; the first focusing lens group, the second focusing lens group, the barrel lens, the objective lens and the third focusing lens group can amplify measurement mark information, the distance between the objective lens and an object plane plate for placing an object to be measured can be accurately positioned by combining image recognition of the image acquisition device, the object to be measured is always positioned at the optimal focal plane position in the alignment imaging optical system, the focusing time is shortened to a certain extent, the focusing precision is improved, and the influence of defocusing on the alignment precision of the object to be measured on the alignment imaging optical system can be reduced to the minimum.
In order to make the above objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a focusing optical imaging system according to an embodiment of the present application;
fig. 2 is another schematic structural diagram of a focusing optical imaging system according to an embodiment of the present application.
Icon: 1-a marking plate; 2-a first focusing lens group; 3-a second focusing lens group; 4-a hollow mirror; 5-a barrel lens; 6-an objective lens; 7-an object plane plate; 8-turning mirrors; 9-a third focusing lens group; 10-an image acquisition device.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. The components of the embodiments of the present application generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the application, as presented in the figures, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the present application, it should be noted that, directions or positional relationships indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., are directions or positional relationships based on those shown in the drawings, or are directions or positional relationships conventionally put in use of the inventive product, are merely for convenience of describing the present application and simplifying the description, and are not indicative or implying that the apparatus or element to be referred to must have a specific direction, be constructed and operated in a specific direction, and thus should not be construed as limiting the present application. Furthermore, the terms "first," "second," "third," and the like are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.
Furthermore, the terms "horizontal," "vertical," "overhang," and the like do not denote a requirement that the component be absolutely horizontal or overhang, but rather may be slightly inclined. As "horizontal" merely means that its direction is more horizontal than "vertical", and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the present application, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present application will be understood in specific cases by those of ordinary skill in the art.
Some embodiments of the present application are described in detail below with reference to the accompanying drawings. The following embodiments and features of the embodiments may be combined with each other without conflict.
Examples
The present embodiment provides a focusing optical imaging system; referring to fig. 1 and 2, fig. 1 and 2 are schematic diagrams of two structures of a focusing optical imaging system according to the present embodiment, wherein a hollow mirror is added in fig. 2 compared with the focusing optical imaging system shown in fig. 1. In fig. 1 and 2, the measured incident light is shown by a solid line, the measured reflected light is shown by a broken line, the reference incident light is shown by a dash-dot line, and the arrow direction in the figure is the direction of light transmission.
The focusing optical imaging system provided by the embodiment is used for aligning an imaging optical system, in particular to a silicon wafer aligning imaging optical system based on an image recognition technology.
Referring to fig. 1 and 2, the focusing optical imaging system according to the present embodiment includes a marking plate 1, a first focusing lens group 2, a second focusing lens group 3, a barrel lens 5, an objective lens 6, and an object plane plate 7 for placing an object to be measured, which are sequentially arranged at intervals along a first optical axis direction; alternatively, the object to be measured is, for example, a silicon wafer, i.e., the object side surface plate 7 is placed with the silicon wafer. The object to be measured can also be other materials, for example other semiconductor materials. Alternatively, the object plane plate 7 is configured to be movable in the first optical axis direction to change the optical axis distance between the object plane plate 7 and the objective lens 6; for example, the focusing optical imaging system further comprises a driving means; the driving device is connected to the object plane plate 7 to drive the object plane plate 7 to approach or separate from the objective lens 6 along the first optical axis direction, so as to change the optical axis distance between the object plane plate 7 and the objective lens 6, so that the object to be measured on the object plane plate 7 is in an optimal focal plane position in the alignment imaging optical system.
The focusing optical imaging system further comprises a third focusing lens group 9 and an image acquisition device 10 which are sequentially arranged along the second optical axis direction; the first optical axis direction is perpendicular or approximately perpendicular to the second optical axis direction.
A turning mirror 8 is arranged between the first focusing lens group 2 and the second focusing lens group 3; the turning mirror 8 is configured to reflect light transmitted in the first optical axis direction to transmit in the second optical axis direction; that is, by turning the reflecting mirror 8, the direction of optical path transmission is changed, and the first optical axis direction measurement mark information of the measurement mark hole on the mark plate 1 is converted into the second optical axis direction measurement mark information where the image pickup device 10 is located, for example, the flat axis measurement mark information is converted into the vertical axis measurement mark information.
The marking plate 1 is provided with a measuring marking hole; the light passes through the measuring marking hole of the marking plate 1 and forms measuring incident light (the measuring incident light is shown by a solid line in fig. 1 and 2), and the measuring incident light sequentially passes through the first focusing lens group 2, the second focusing lens group 3, the barrel lens 5 and the objective lens 6 and is incident to an object to be measured on the object plane plate 7 at a certain incident angle; the measurement incident light is reflected by the object to be measured on the object plane plate 7 to form measurement reflected light (the measurement reflected light is shown by a dotted line in fig. 1 and 2), the measurement reflected light sequentially passes through the objective lens 6, the barrel lens 5 and the second focusing lens group 3, and is reflected to the third focusing lens group 9 by the turning mirror 8, and after the measurement reflected light passes through the third focusing lens group 9, measurement mark imaging is formed on the image acquisition device 10.
Alternatively, light passing through the measurement marking hole of the marking plate 1 forms an enlarged measurement marking image on the image pickup device 10. For example, the measurement indicia on the image acquisition device 10 are imaged 2-10 times the measurement indicia aperture on the indicia plate 1, or other magnification. Alternatively, the measurement indicia on the image acquisition device 10 are imaged 3-5 times the measurement indicia aperture on the indicia plate 1. In this embodiment, the first focusing lens group 2, the second focusing lens group 3, the upper barrel lens 5, the objective lens 6, and the third focusing lens group 9 can magnify the optical axis measurement mark information, for example, by 3 times, 4 times, 8 times, or other times.
In the focusing optical imaging system described in this embodiment, the marking plate 1, the first focusing lens group 2, the second focusing lens group 3, the barrel lens 5, the objective lens 6, the turning mirror 8, the third focusing lens group 9 and the image acquisition device 10 form an automatic focusing system, wherein the barrel lens 5 and the objective lens 6 are part of an alignment imaging optical system, that is, the automatic focusing system shares the optical paths of the barrel lens 5 and the objective lens 6 with the alignment imaging optical system, so that focusing time can be reduced to a certain extent and focusing accuracy can be improved. Specifically, the focusing optical imaging system converts first optical axis direction measurement mark information of a measurement mark hole on the mark plate 1 into second optical axis direction measurement mark information where the image pickup device 10 is located by the folding mirror 8; the first focusing lens group 2, the second focusing lens group 3, the barrel lens 5, the objective lens 6 and the third focusing lens group 9 can amplify measurement mark information, the distance between the objective lens 6 and the object plane plate 7 for placing an object to be measured can be accurately positioned by combining image recognition of the image acquisition device 10, the object to be measured is always positioned at the optimal focal plane position in the alignment imaging optical system, the focusing time is shortened to a certain extent, the focusing precision is improved, and the influence of defocus on the alignment precision of the object to be measured on the alignment imaging optical system can be minimized.
Referring to fig. 2, in an alternative of the present embodiment, the focusing optical imaging system further includes a hollow mirror 4 disposed between the second focusing lens group 3 and the barrel mirror 5.
The center of the hollow reflector 4 is provided with a through hole, and the edge of the hollow reflector 4 is a reflector; i.e. the through-hole of the hollow mirror 4 is for passing light, and the edge of the hollow mirror 4 is for reflecting light. It will be appreciated that the through hole of the hollow mirror 4 is used to pass through and transmit the measurement mark light, the edge of the hollow mirror 4 is used to reflect the reference mark light, and the reference mark and the measurement mark can be combined to quickly and accurately determine the defocus amount.
Specifically, the marking plate 1 is provided with a reference mark hole; the light passes through the reference mark hole of the mark plate 1 and forms a reference incident light (the reference incident light is shown by a dot-dash line in fig. 2), the reference incident light sequentially passes through the first focusing lens group 2 and the second focusing lens group 3, is reflected by the edge of the hollow reflector 4 and passes through the second focusing lens group 3, and is reflected by the turning reflector 8 to the third focusing lens group 9, and the reference incident light forms a reference mark image on the image acquisition device 10 after passing through the third focusing lens group 9.
After the incident light is measured to pass through the second focusing lens group 3, the incident light passes through the through hole of the hollow reflector 4 and is incident to the cylindrical lens 5; after the reflected light passes through the cylindrical mirror 5, the reflected light passes through the through hole of the hollow reflecting mirror 4 and is incident to the second focusing lens group 3. That is, the light passes through the measurement marking hole of the marking plate 1 and forms measurement incident light (the measurement incident light is shown by a solid line in fig. 2), the measurement incident light sequentially passes through the first focusing lens group 2 and the second focusing lens group 3, passes through the through hole of the hollow reflecting mirror 4 and is incident to the barrel mirror 5, and is incident to the object to be measured on the object plane plate 7 at a certain incident angle through the objective lens 6; the measurement incident light is reflected by the object to be measured on the object plane plate 7 to form measurement reflected light (the measurement reflected light is shown by a dotted line in fig. 2), the measurement reflected light sequentially passes through the objective lens 6 and the barrel lens 5, passes through the through hole of the hollow reflector 4 and is incident to the second focusing lens group 3, is reflected to the third focusing lens group 9 by the turning reflector 8, and forms measurement mark imaging on the image acquisition device 10 after passing through the third focusing lens group 9.
Alternatively, light passing through the reference mark apertures of the marking plate 1 forms enlarged reference mark images on the image pickup device 10. For example, the reference mark imaging on the image acquisition device 10 is 2-10 times the reference mark aperture on the marking plate 1, or other magnification.
In this embodiment, the first focusing lens group 2 is used to make the parallel light beam parallel to the first optical axis direction converge at the focus; the second focusing lens group 3 is used for readjusting the off-axis light rays converged by the focus into parallel light beams with a certain angle, so that the parallel light beams are beneficial to being reflected back to the image acquisition device 10 through the edge of the hollow reflecting mirror 4; the cylindrical lens 5 and the objective lens 6 function to provide a sufficient angle of view to ensure that a symmetrical light beam can pass through after being specularly reflected by the object plane plate 7; the third focusing lens group 9 is used for changing the light from the turning mirror 8 into parallel light to be incident on the image acquisition device 10 so as to facilitate mark imaging.
In the focusing optical imaging system of the embodiment, the reference mark imaging can be formed on the image acquisition device 10 through the hollow reflecting mirror 4 and the reference mark hole on the marking plate 1; that is, the imaging on the image acquisition device 10 is divided into two parts, one part is reference mark imaging and the other part is measurement mark imaging, and the defocusing condition of the object to be measured is determined by measuring the relative position change of the reference mark imaging and the measurement mark imaging when the object to be measured is defocused, so as to drive the object plane plate 7 to move to complete the automatic focusing work.
According to the focusing optical imaging system, the first focusing lens group 2, the second focusing lens group 3, the barrel lens 5 and the objective lens 6 are original imaging light path parts, the hollow reflecting mirror 4 and the turning reflecting mirror 8 are added on the basis of not changing original light paths, the first optical axis direction information of the system to be detected is converted into the second optical axis direction information on the image acquisition device 10, meanwhile, a certain magnification is provided, the optical axis direction distance between the objective lens 6 and the object plane plate 7 for placing the object to be detected can be accurately positioned by combining with the image identification of the image acquisition device 10, the object to be detected is always in the optimal focal plane position of the alignment imaging optical system, focusing time is reduced to a certain extent, focusing precision is improved, and the influence of the defocus on the alignment precision of the object to be detected on the imaging optical system can be reduced to the minimum.
Compared with the prior art, the focusing optical imaging system of the embodiment has the following advantages:
1. a larger focus range can be obtained independent of the relatively sensitive contrast difference at shorter distance defocus.
2. The focusing system has better linearity, and can keep better linearity in a longer focusing range.
3. Only one hollow reflecting mirror 4 and a folding reflecting mirror 8 are added, and the rest lens parts are all on the same optical axis with the imaging optical system which is actually aligned, so that compared with an independent optical automatic focusing system, the focusing optical imaging system has simpler structure.
4. The automatic focusing system and the alignment imaging optical system adopt the same optical axis design, are not limited by factors such as distance between the objective lens 6 and the object plane plate 7 for placing the object to be measured, space size and the like, and have wider space applicability.
In the present embodiment, the focusing optical imaging system shown in fig. 1 adopts the same optical axis design for the auto-focusing system and the alignment imaging optical system, and the in-focus position can be determined by calculating the relationship between the measurement mark imaging and the reference origin of the image pickup device 10. But the alignment accuracy is slightly worse than the technical proposal with reference marks. The focusing optical imaging system shown in fig. 2 determines the defocusing condition of the object to be measured by adopting the hollow reflecting mirror 4 and the reference mark hole on the marking plate 1 and measuring the relative position change of the reference mark imaging and the measuring mark imaging when the object to be measured is defocused, and further drives the object plane plate 7 to move to complete the automatic focusing operation, so that the focusing precision can be further improved.
In an alternative to this embodiment, the measurement indicia bores comprise a plurality of measurement indicia bores.
In an alternative to this embodiment, the reference mark apertures comprise a plurality of reference mark apertures.
Optionally, the pattern formed by the plurality of measurement mark apertures is disposed inside the pattern formed by the plurality of reference mark apertures; to facilitate contrast between reference mark imaging and measurement mark imaging.
Alternatively, the plurality of reference mark apertures may be distributed in a square or circular shape, or may be distributed in other shapes.
Referring to fig. 1 and 2, in the alternative of the present embodiment, the incident angle of the incident light beam to the object to be measured on the object plane plate 7 is measured to be 4 ° -10 °; for example, the incident angle of the measurement-target object, at which the incident light is incident on the object plane plate 7, is 4 °, 5 °, 7 °, 8 °, or the like. For example, an object to be measured, which is incident on the object plane plate 7 at positive 5 °, is measured, and the object to be measured is reflected at negative 5 °.
Alternatively, the angle of incidence of the measuring incident light ray on the object plane plate 7 is 4 ° -6 °.
In an alternative to this embodiment, the image capture device 10 employs a linear array CCD. Wherein CCD is the abbreviation of Charge Coupled Device, and Chinese name is charge coupled device. The linear array CCD has the advantages of simple structure and lower cost, and the measuring range can be larger on the premise of equal measuring precision.
In an alternative to this embodiment, the marking plate 1 is a chrome-plated marking plate, or other marking plate.
In an alternative of this embodiment, the focusing optical imaging system further includes a light source. The light source is arranged on the side of the marking plate 1 remote from the first focusing lens group 2.
Alternatively, the light source is a laser light source or an LED light source, or other light source.
The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (10)
1. The focusing optical imaging system is characterized by comprising a marking plate (1), a first focusing lens group (2), a second focusing lens group (3), a barrel lens (5), an objective lens (6) and an object plane plate (7) for placing an object to be measured, wherein the marking plate, the first focusing lens group (2), the second focusing lens group (3), the barrel lens (5) and the object plane plate (7) are sequentially arranged at intervals along the first optical axis direction; -the object plane plate (7) is configured to be movable in a first optical axis direction to change an optical axis distance between the object plane plate (7) and the objective lens (6);
the focusing optical imaging system further comprises a third focusing lens group (9) and an image acquisition device (10) which are sequentially arranged along the second optical axis direction; the first optical axis direction is perpendicular to the second optical axis direction;
a turning reflector (8) is arranged between the first focusing lens group (2) and the second focusing lens group (3); the turning mirror (8) is configured to reflect light rays transmitted in the first optical axis direction to be transmitted in the second optical axis direction;
the marking plate (1) is provided with a measuring marking hole; the light passes through the measurement marking hole and forms measurement incident light, and the measurement incident light sequentially passes through the first focusing lens group (2), the second focusing lens group (3), the cylindrical lens (5) and the objective lens (6) and is incident to an object to be measured on the object plane plate (7) at a certain incident angle; the measuring incident light is reflected by an object to be measured on the object plane plate (7) to form measuring reflected light, the measuring reflected light sequentially penetrates through the objective lens (6), the barrel lens (5) and the second focusing lens group (3), and is reflected to the third focusing lens group (9) through the turning mirror (8), and after the measuring reflected light penetrates through the third focusing lens group (9), measuring mark imaging is formed on the image acquisition device (10).
2. Focusing optical imaging system according to claim 1, further comprising a hollow mirror (4) arranged between the second focusing lens group (3) and the barrel mirror (5);
the center of the hollow reflecting mirror (4) is provided with a through hole, and the edge of the hollow reflecting mirror (4) is a reflecting mirror;
the marking plate (1) is provided with a reference marking hole; the light passes through the reference mark hole and forms reference incident light, the reference incident light sequentially passes through the first focusing lens group (2) and the second focusing lens group (3), is reflected by the edge of the hollow reflecting mirror (4) and passes through the second focusing lens group (3), and is reflected to the third focusing lens group (9) by the turning reflecting mirror (8), and the reference incident light forms reference mark imaging on the image acquisition device (10) after passing through the third focusing lens group (9);
after the measuring incident light rays penetrate through the second focusing lens group (3), the measuring incident light rays penetrate through the through hole of the hollow reflecting mirror (4) and are incident to the cylindrical lens (5); after the measuring reflected light passes through the cylindrical mirror (5), the measuring reflected light passes through the through hole of the hollow reflecting mirror (4) and enters the second focusing lens group (3).
3. The focusing optical imaging system of claim 2, wherein the measurement mark aperture comprises a plurality of measurement mark apertures, the reference mark aperture comprises a plurality of reference mark apertures, and a pattern formed by a plurality of the measurement mark apertures is disposed inside a pattern formed by a plurality of the reference mark apertures;
the plurality of reference mark small holes are distributed in a square shape or a round shape.
4. A focusing optical imaging system according to any one of claims 1-3, characterized in that the angle of incidence of the measuring incident light rays on the object plane plate (7) to be measured is 4 ° -10 °;
and/or the measurement mark imaging on the image acquisition device (10) is 2-10 times of the diameter of the measurement mark hole on the marking plate (1).
5. Focusing optical imaging system according to claim 4, characterized in that the angle of incidence of the measuring incident light rays on the object plane plate (7) to be measured is 4 ° -6 °;
the measuring mark imaging on the image acquisition device (10) is 3-5 times of the diameter of the measuring mark hole on the marking plate (1).
6. A focusing optical imaging system according to any one of claims 1-3, characterized in that the image acquisition device (10) employs a linear array CCD.
7. A focusing optical imaging system according to any of claims 1-3, characterized in that the marking plate (1) is a chrome-plated marking plate.
8. A focusing optical imaging system according to any one of claims 1-3, further comprising driving means;
the driving device is connected with the object plane plate (7) so as to drive the object plane plate (7) to be close to or far away from the objective lens (6) along the first optical axis direction.
9. The focused optical imaging system of any of claims 1-3, further comprising a light source; the light source is arranged on one side of the marking plate (1) far away from the first focusing lens group (2);
the light source is a laser light source or an LED light source.
10. A focusing optical imaging system according to any of claims 1-3, characterized in that the object plane plate (7) is placed with a silicon wafer.
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