CN117690770A - Centering method of lens system - Google Patents
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- CN117690770A CN117690770A CN202311426308.8A CN202311426308A CN117690770A CN 117690770 A CN117690770 A CN 117690770A CN 202311426308 A CN202311426308 A CN 202311426308A CN 117690770 A CN117690770 A CN 117690770A
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- 238000000034 method Methods 0.000 title claims abstract description 28
- 238000003384 imaging method Methods 0.000 claims abstract description 47
- 238000010894 electron beam technology Methods 0.000 claims abstract description 14
- 238000009826 distribution Methods 0.000 claims description 27
- 238000013016 damping Methods 0.000 claims 1
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- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
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- 238000007796 conventional method Methods 0.000 description 1
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Abstract
The application provides a centering method of a lens system. The centering method comprises the steps of sequentially arranging a light source assembly, at least one condensing lens and an imaging element; wherein, the center of the condensing lens is provided with a hole for the electron beam to pass through; applying a first centering operation to the light source assembly, passing light rays emitted from the light source assembly through the aperture of the at least one condenser lens, and forming a first desired image in the imaging element; an objective lens is arranged between the at least one condensing lens and the imaging element; wherein, the center of the objective lens is provided with a hole for the electron beam to pass through; a second centering operation is applied to the objective lens, so that light emitted from the light source assembly passes through the aperture of the at least one condenser lens and the aperture of the objective lens, and a second desired image is formed in the imaging element. The centering method is beneficial to ensuring the coaxiality of each lens element in the transmission electron microscope with high efficiency and low cost.
Description
Technical Field
The invention relates to the technical field of electron microscopy, in particular to a centering method of a lens system.
Background
Electron microscopes, such as transmission electron microscopes and scanning electron microscopes, are widely used as important tools for human exploration of the microscopic world in many fields such as material science, life science, semiconductor industry, geology, energy, medical treatment, and pharmaceutical industry, and play a great role in human scientific research and industrial production.
The condenser lens is a component for focusing the electron beam, and can maximize the brightness of the electron beam and change the size of the spot of the electron beam. The objective lens is used to magnify the electron image of the transmission electron microscope, and is also critical to determine the resolution and imaging quality of the transmission electron microscope, and the electron beam is required to pass through the aperture in the objective lens. In order to obtain better imaging quality, the aperture of the objective lens and the aperture of the condenser lens must have good coaxiality.
However, since the distance between the condenser lens and the objective lens is large, the distance from the objective lens to the observable port is also large, and the conventional method for measuring coaxiality by an optical microscope is not available. If a mechanical detection mode, such as a three-dimensional measuring instrument, is adopted to detect the coaxiality between the holes, the requirements on the precision of the probe, the precision of the mechanical arm and the control precision of equipment are very high, and the cost for researching or purchasing the equipment is also very high.
Disclosure of Invention
Based on this, the present invention aims to provide an improved centering method of a lens system to ensure the coaxiality of the lens elements in a transmission electron microscope with high efficiency and low cost.
In a first aspect, the present application provides a method of centering a lens system, comprising:
sequentially arranging a light source assembly, at least one condensing lens and an imaging element; wherein, the center of the condensing lens is provided with a hole for passing electron beams;
applying a first centering operation to the light source assembly, passing light rays emitted from the light source assembly through the aperture of the at least one condenser lens, and forming a first desired image in the imaging element;
providing an objective lens between the at least one condenser lens and the imaging element; wherein, the center of the objective lens is provided with a hole for passing the electron beam;
a second centering operation is applied to the objective lens, so that light rays emitted from the light source assembly pass through the aperture of the at least one condenser lens and the aperture of the objective lens, and a second desired image is formed in the imaging element.
The centering method of the lens system includes the steps of firstly applying a first centering operation to the light source assembly to enable a main axis of light rays emitted by the light source assembly to be centered with the hole of the at least one condensing lens when the light rays emitted by the light source assembly form a first expected image in the imaging element, and then applying a second centering operation to the objective lens to enable the hole of the objective lens to be centered with the main axis of the light rays emitted by the light source assembly when the light rays emitted by the light source assembly form a second expected image in the imaging element, so that the hole of the at least one condensing lens is effectively centered with the hole of the objective lens. The centering method can meet the coaxial requirement of the long-distance lens element in the lens system, can replace the traditional mechanical detection centering mode, is simple to operate, greatly improves centering efficiency, and reduces centering cost of the lens element in the transmission electron microscope; in addition, the device element adopting the method occupies smaller space compared with the traditional large-scale measuring equipment, and is convenient to move and reuse.
In one embodiment, the first desired image has a uniform pattern distribution in at least a first direction and a second direction perpendicular to the first direction; the second desired image has a uniform pattern distribution in at least the first direction and the second direction.
In one embodiment, the first centering operation includes: adjusting the position of at least one element in the light source assembly in the first direction until the image formed by the light rays emitted by the light source assembly in the imaging element has uniform pattern distribution in the first direction; and adjusting the position of at least one element in the light source assembly in the second direction until the image formed by the light rays emitted by the light source assembly in the imaging element has uniform pattern distribution in the second direction.
In one embodiment, the light source assembly includes a light source and a reflector configured to change a propagation direction of light rays emitted from the light source to project the light rays toward the lens system; wherein the first centering operation is applied to the mirror.
In one embodiment, after forming the first desired image, further comprising: applying a first perturbation operation to the light source assembly to cause a discernable minimum shift in the center of the first desired image; determining a first centering error of a principal axis of light rays emitted by the light source assembly relative to the aperture of the at least one condenser lens according to the minimum offset; if the first centering error meets a preset error requirement, arranging the objective lens between the at least one condensing lens and the imaging element; if the first centering error does not meet the preset error requirement, continuing to apply the first centering operation to the light source assembly until the first centering error meets the preset error requirement.
In one embodiment, the second centering operation includes: adjusting the position of the objective lens in the first direction until the image formed by the light rays emitted by the light source assembly in the imaging element has uniform pattern distribution in the first direction; and adjusting the position of the objective lens in the second direction until the image formed by the light rays emitted by the light source component in the imaging element has uniform pattern distribution in the second direction.
In one embodiment, after forming the second desired image, further comprising: applying a second perturbation operation to the objective lens to cause a minimum distinguishable shift in the center of the second desired image; determining a second centering error of the aperture of the objective lens with respect to a principal axis of the light emitted by the light source assembly according to the minimum offset; if the second centering error meets a preset error requirement, confirming that the lens system is centered; and if the second centering error does not meet the preset error requirement, continuing to apply the second centering operation to the objective lens until the second centering error meets the preset error requirement.
In one embodiment, the preset error requirement is that the centering error is less than or equal to 45um.
In one embodiment, at least the element of the light source assembly to which the first centering operation is applied, the at least one condenser lens, the objective lens, and the imaging element are disposed on a shock absorbing stage.
In one embodiment, if the aperture of the at least one condenser lens and the aperture of the objective lens are different, an adjustment element with an aperture is provided in the aperture of the at least one condenser lens and/or the aperture of the objective lens, wherein the aperture of the adjustment element is configured to compensate for the aperture difference of the aperture of the at least one condenser lens and the aperture of the objective lens.
Drawings
In order to more clearly illustrate the embodiments of the present description or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present description, and that other drawings may be obtained according to these drawings without inventive effort to a person skilled in the art.
FIG. 1 is a flow chart illustrating steps of a centering method according to an embodiment of the present application;
FIG. 2 is a schematic view of an optical path when a first centering operation is applied according to an embodiment of the present application;
FIG. 3 (a) illustrates a pattern distribution of a first desired image in a first direction according to an embodiment of the present application;
fig. 3 (b) and (c) illustrate pattern distributions in a first direction of an image formed in an imaging element when a first perturbation operation is applied in accordance with an embodiment of the present application;
fig. 4 (a) illustrates a pattern distribution of a first desired image in a second direction according to an embodiment of the present application;
fig. 4 (b) and (c) illustrate pattern distributions in the second direction of an image formed in the imaging element when the first perturbation operation is applied in accordance with an embodiment of the present application;
FIG. 5 is a schematic view of the optical path when a second centering operation is applied according to an embodiment of the present application;
FIG. 6 (a) illustrates a pattern distribution of a second desired image in a first direction according to an embodiment of the present application;
FIGS. 6 (b) and (c) illustrate pattern distributions in a first direction of images formed in an imaging element when a second perturbation operation is applied in accordance with an embodiment of the present application;
FIG. 7 (a) illustrates a pattern distribution of a second desired image in a second direction according to an embodiment of the present application;
fig. 7 (b) and (c) illustrate pattern distribution of an image formed in the imaging element in the second direction when the second perturbation operation is applied in accordance with an embodiment of the present application.
Detailed Description
In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the invention, whereby the invention is not limited to the specific embodiments disclosed below.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
It will be understood that when an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.
The embodiment of the application provides a centering method of a lens system, which can be used for centering all lens elements in a transmission electron microscope, and the coaxiality of all lens elements in the transmission electron microscope is ensured by observing images formed by light rays passing through holes of all lens elements in an imaging element and debugging the centering according to the change of the images.
As shown in fig. 1, an embodiment of the present application provides a method for centering a lens system, including the following steps:
s100, sequentially arranging a light source assembly, at least one condensing lens and an imaging element; wherein, the center of the condensing lens is provided with a hole for passing the electron beam.
As illustrated in fig. 2 and 5, the light source in the light source assembly may be a laser, and the condenser lens 1 and the condenser lens 2 are disposed between the light source assembly and an imaging element, wherein the imaging element may include a camera and a display, and the display may be used to display an image photographed by the camera for user's observation, alternatively, the camera may employ a complementary metal oxide semiconductor (CMOS, complementary Metal Oxide Semiconductor) image sensor or a Charge-coupled Device (CCD) image sensor. Illustratively, the distance between the condenser lens 1 and the condenser lens 2 is greater than or equal to 30mm, the centers of the condenser lens 1 and the condenser lens 2 are each provided with a hole through which the electron beam passes, and the sizes of the holes are all about 1 mm. It is understood that only one condensing lens or more condensing lenses may be provided, and the number of condensing lenses is not limited in this application.
And S200, applying a first centering operation to the light source assembly, enabling light rays emitted by the light source assembly to pass through the hole of the at least one condensing lens, and forming a first expected image in the imaging element.
Illustratively, the holes of the condensing lens 1 and the condensing lens 2 may be machined from the same workpiece at the same time, so that the holes of the condensing lens 1 and the condensing lens 2 may be already centered, and thus the centering method of the present application may be performed by operating the light source assembly to center the principal axis of the light emitted from the light source assembly with the holes of the condensing lens 1 and the condensing lens 2, and to center the principal axis of the light emitted from the light source assembly with the holes of the condensing lens 1 and the condensing lens 2 when the first desired image is formed in the imaging element.
By way of example, the first centering operation may be translating, rotating, bending, etc. at least one component of the light source assembly. For example, when the light source assembly includes only the light source, the first centering operation is applied to the light source; when the light source assembly includes not only a light source, the first centering operation may be applied to the light source and/or other components in the light source assembly. As shown in fig. 2 and 5, the light source assembly may include a reflecting mirror in addition to the light source (laser), and the reflecting mirror may more conveniently change the propagation direction of the light emitted from the light source to make the light be projected toward the lens system, so that the first centering operation may be applied to the reflecting mirror to facilitate implementation of the first centering operation. Illustratively, as shown in fig. 2, a fine tuning screw is provided on the mirror so that a user can perform operations such as translation, rotation, etc. on the mirror through the fine tuning screw.
S300, arranging an objective lens between at least one condensing lens and an imaging element; wherein the center of the objective lens is provided with a hole through which the electron beam passes.
Illustratively, the placement position of the objective lens is generally fixed, so that after the light emitted from the light source assembly is centered with the holes of the condenser lens 1 and the condenser lens 2, the objective lens can be disposed between the condenser lens 2 and the imaging element according to the placement position of the objective lens. Illustratively, the distance between the condenser lens 2 and the objective lens is greater than or equal to 30mm, and the center of the objective lens is also provided with a hole through which the electron beam passes, the size of the hole being about 1 mm.
And S400, applying a second centering operation to the objective lens, enabling light rays emitted by the light source assembly to pass through the hole of the at least one condensing lens and the hole of the objective lens, and forming a second expected image in the imaging element.
After the light emitted by the light source assembly is aligned with the holes of the condenser lens 1 and the condenser lens 2, the light source assembly, the condenser lens 1 and the condenser lens 2 can be kept motionless, the hole of the objective lens is aligned with the main axis of the light emitted by the light source assembly by operating the objective lens, and when a second desired image is formed in the imaging element, the hole of the objective lens is aligned with the main axis of the light emitted by the light source assembly. To this end, the aperture of the at least one condenser lens and the aperture of the objective lens are centered.
The second centering operation may be, for example, translating, rotating, bending, etc., the objective lens. Illustratively, as shown in fig. 5, a fine adjustment screw is provided on the objective lens, so that a user can perform operations such as translation, rotation, etc. on the objective lens through the fine adjustment screw.
The centering method of the lens system includes the steps of firstly applying a first centering operation to the light source assembly to enable a main axis of light rays emitted by the light source assembly to be centered with the hole of the at least one condensing lens when the light rays emitted by the light source assembly form a first expected image in the imaging element, and then applying a second centering operation to the objective lens to enable the hole of the objective lens to be centered with the main axis of the light rays emitted by the light source assembly when the light rays emitted by the light source assembly form a second expected image in the imaging element, so that the hole of the at least one condensing lens is effectively centered with the hole of the objective lens. The centering method can meet the coaxial requirement of the long-distance lens element in the lens system, can replace the traditional mechanical detection centering mode, is simple to operate, greatly improves centering efficiency, and reduces centering cost of the lens element in the transmission electron microscope; in addition, the device element adopting the method occupies smaller space compared with the traditional large-scale measuring equipment, and is convenient to move and reuse.
In some embodiments of the present application, the first desired image has a uniform pattern distribution in at least a first direction and a second direction perpendicular to the first direction. Taking the example shown in fig. 3 (a) and fig. 4 (a) as an example, the first expected image is a light spot pattern with alternate brightness, and the pattern distribution in the first direction and the second direction is uniform, so that the uniformity of the whole first expected image can be confirmed according to fewer resolution directions, and the centering efficiency is improved. Alternatively, as shown in fig. 2, the positions of the reflecting mirrors in the first direction and the second direction may be adjusted by fine adjustment screws, so that the first desired image may have a uniform pattern distribution in the first direction and the second direction, that is, no significant side-to-side size may occur. Optionally, the fine tuning screw of the mirror comprises a first adjusting screw for adjusting the position of the mirror in a first direction and a second adjusting screw for adjusting the position of the mirror in a second direction.
In some embodiments of the present application, the second desired image has a uniform pattern distribution in at least the first direction and the second direction. Taking the example shown in fig. 6 (a) and fig. 7 (a) as an example, the second desired image is also a light spot pattern with alternate brightness, but the pattern distribution is different from that of the first desired image, and the pattern distribution of the second desired image in the first direction and the second direction is also uniform, so that the uniformity of the whole second desired image can be confirmed according to fewer resolution directions, and the centering efficiency is improved. Alternatively, as shown in fig. 5, the positions of the objective lens in the first direction and the second direction may be adjusted by the trimming screw, so that the second desired image may have a uniform pattern distribution in the first direction and the second direction, that is, no significant side-to-side size may occur. Optionally, the fine tuning screw of the objective lens comprises a third adjusting screw for adjusting the position of the objective lens in the first direction and a fourth adjusting screw for adjusting the position of the objective lens in the second direction.
In some embodiments of the present application, after forming the first desired image, further comprising: applying a first perturbation operation to the light source assembly to cause a minimum distinguishable shift in the center of the first desired image; determining a first centering error of a principal axis of light rays emitted from the light source assembly with respect to a hole of at least one condenser lens according to the minimum offset; if the first centering error meets the preset error requirement, an objective lens is arranged between at least one condensing lens and the imaging element; if the first centering error does not meet the preset error requirement, continuing to apply the first centering operation to the light source assembly until the first centering error meets the preset error requirement. Therefore, the centering error of the first stage can be identified through the spot change corresponding to the disturbance of the light source assembly, and when the centering error does not meet the preset error requirement, the first centering operation is continuously applied to the light source assembly until the centering error meets the preset error requirement, so that the centering accuracy of the first stage is guaranteed.
Alternatively, when the first desired image is formed, the center of the first desired image at this time may be marked as the origin (i.e., 0 point), and the fine adjustment screw may be gently screwed to cause a minimum shift in the spot in the first direction. Alternatively, the minimum shift may be a shift when the minimum change of the spot pattern can be resolved on the CCD display screen during the first disturbance operation application, as shown in fig. 3 (b), in which the spot outermost ring is slightly shifted to the left, the center position of the spot pattern in the CCD is denoted as x1, as shown in fig. 3 (c), in which the spot outermost ring is slightly shifted to the right, and the center position of the spot pattern in the CCD is denoted as x2. Then, the screw is screwed to return the center of the spot pattern to the origin position. Next, the fine adjustment screw may be gently screwed to cause the spot to have a minimum shift in the second direction, as shown in fig. 4 (b), in which the spot outermost ring has a minimum shift toward the upper side, and the spot pattern in the CCD has a center position of y1, as shown in fig. 4 (c), in which the spot outermost ring has a minimum shift toward the lower side, and in which the spot outermost ring has a maximum shift toward the lower side, and the spot pattern in the CCD has a center position of y2. And finally, screwing the screw to enable the center of the light spot pattern to return to the original point position.
Wherein x1, x2, y1, y2 are first centering errors of the principal axis of the light emitted by the light source assembly relative to the hole of the at least one condensing lens, and if x1, x2, y1, y2 all meet preset error requirements, the objective lens can be continuously arranged; if one of x1, x2, y1, y2 does not meet the preset error requirement, continuing to apply the first centering operation to the mirror until all of x1, x2, y1, y2 meet the preset error requirement.
Alternatively, since the purpose of the present application is to ensure coaxiality of the condenser lens 1, the condenser lens 2, and the objective lens (placement position is fixed in advance), the centering error of the aperture of the condenser lens at this time with respect to the placement position of the objective lens can be calculated based on x1, x2, y1, y2. As shown in fig. 2 and 5, x1, x2, y1, y2 may be multiplied by an adjustment factor to represent the centering error at the placement position with respect to the objective lens, respectively, alternatively, by a similar triangle principle, it is known that the adjustment factor may be expressed as (l1+l2)/(l1+l1'). For example, if L1 is 50mm, L2 is 300mm, and L1' is 480mm, the adjustment coefficient is 35/53. x1 is-40.3 um, x2 is +22um, y1 is-40.6 um, y2 is +36.7um, then the error of the hole of the condensing lens 1 relative to the position where the objective lens is placed in the first direction is-26.6 um-14.5 um, and the error of the hole in the second direction is-26.8 um-24.2 um.
In some embodiments of the present application, after forming the second desired image, further comprising: applying a second perturbation operation to the objective lens to cause a minimum distinguishable shift in the center of the second desired image; determining a second centering error of the aperture of the objective lens with respect to the principal axis of the light rays emitted by the light source assembly according to the minimum offset; if the second centering error meets the preset error requirement, confirming that the lens system finishes centering; if the second centering error does not meet the preset error requirement, continuing to apply the second centering operation to the objective lens until the second centering error meets the preset error requirement. Therefore, the centering error of the second stage can be identified through the spot change corresponding to the disturbance of the objective lens, and when the centering error does not meet the preset error requirement, the second centering operation is continuously applied to the objective lens until the centering error meets the preset error requirement, so that the centering accuracy of the second stage is guaranteed.
Alternatively, when forming the second desired image, the center of the second desired image may be marked as the origin (i.e., 0 point) at this time, and the fine adjustment screw may be gently screwed to cause a minimum shift in the spot in the first direction. Alternatively, the minimum shift may be a shift at which a minimum change in the spot pattern can be recognized on the CCD display screen during the second disturbance operation application, where the center position of the spot pattern in the CCD is denoted as x3 when the minimum shift occurs to the left in the outermost circle of the spot as illustrated in fig. 6 (b), and where the center position of the spot pattern in the CCD is denoted as x4 when the minimum shift occurs to the right in the outermost circle of the spot as illustrated in fig. 6 (c). Then, the screw is screwed to return the center of the spot pattern to the origin position. Next, the fine adjustment screw may be gently screwed to cause the spot to have a minimum shift in the second direction, as shown in fig. 7 (b), in which the spot outermost ring has a minimum shift toward the upper side, and the spot pattern in the CCD has a center position of y3, as shown in fig. 7 (c), in which the spot outermost ring has a minimum shift toward the lower side, and in which the spot outermost ring has a large upper side and a small lower side, and the spot pattern in the CCD has a center position of y4. And finally, screwing the screw to enable the center of the light spot pattern to return to the original point position.
Wherein x3, x4, y3, y4 are the second centering errors of the aperture of the objective lens relative to the main axis of the light emitted by the light source assembly, and if x3, x4, y3, y4 all meet the preset error requirement, the axis combination of the aperture of the condensing lens and the aperture of the objective lens can be confirmed; if one of x3, x4, y3, y4 does not meet the preset error requirement, continuing to apply the second centering operation to the objective lens until all of x3, x4, y3, y4 meet the preset error requirement. As shown in fig. 6 and 7, x3 may be-5 um, x4 may be +5um, y3 may be-5 um, and y4 may be +5um.
In some embodiments of the present application, the predetermined error requirement is that the centering error is less than or equal to 45um. Since the resultant axis error of the transmission electron microscope is generally required to be not more than 30um, the minimum offset distance of the corresponding spot pattern in the imaging element is in the range of 45um or less when a disturbance operation is applied. Therefore, when the centering accuracy is evaluated according to the calculated centering error, the centering error at the objective lens can be saved, and the centering efficiency is improved.
In some embodiments of the present application, at least the element of the light source assembly to which the first centering operation is applied, at least one condenser lens, an objective lens, and an imaging element are disposed on a shock absorbing platform to avoid vibrations during operation or other external vibrations affecting centering accuracy.
In some embodiments of the present application, if the aperture of the at least one condenser lens and the aperture of the objective lens are different, an adjustment element with an aperture is provided in the aperture of the at least one condenser lens and/or the aperture of the objective lens, wherein the aperture of the adjustment element is configured to compensate for the aperture difference of the aperture of the at least one condenser lens and the aperture of the objective lens. Taking the example shown in fig. 2 as an example, when the aperture of the condensing lens 1 is greater than 1mm, and the apertures of the condensing lens 2 and the objective lens are 1mm, the adjusting element with the aperture of 1mm may be installed into the aperture of the condensing lens 1, so that the apertures of the condensing lens 1, the condensing lens 2 and the objective lens are identical (all are 1 mm), which is beneficial to better ensuring the accuracy of coaxial alignment of the three.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (10)
1. A method of centering a lens system, comprising:
sequentially arranging a light source assembly, at least one condensing lens and an imaging element; wherein, the center of the condensing lens is provided with a hole for passing electron beams;
applying a first centering operation to the light source assembly, passing light rays emitted from the light source assembly through the aperture of the at least one condenser lens, and forming a first desired image in the imaging element;
providing an objective lens between the at least one condenser lens and the imaging element; wherein, the center of the objective lens is provided with a hole for passing the electron beam;
a second centering operation is applied to the objective lens, so that light rays emitted from the light source assembly pass through the aperture of the at least one condenser lens and the aperture of the objective lens, and a second desired image is formed in the imaging element.
2. The centering method as claimed in claim 1, wherein,
the first desired image has a uniform pattern distribution in at least a first direction and a second direction perpendicular to the first direction;
the second desired image has a uniform pattern distribution in at least the first direction and the second direction.
3. The centering method of claim 2, wherein the first centering operation comprises:
adjusting the position of at least one element in the light source assembly in the first direction until the image formed by the light rays emitted by the light source assembly in the imaging element has uniform pattern distribution in the first direction;
and adjusting the position of at least one element in the light source assembly in the second direction until the image formed by the light rays emitted by the light source assembly in the imaging element has uniform pattern distribution in the second direction.
4. A centering method as claimed in claim 3, wherein,
the light source assembly includes a light source and a reflector configured to change a propagation direction of light rays emitted from the light source to project the light rays toward the lens system;
wherein the first centering operation is applied to the mirror.
5. The centering method of claim 1, further comprising, after forming the first desired image:
applying a first perturbation operation to the light source assembly to cause a discernable minimum shift in the center of the first desired image;
determining a first centering error of a principal axis of light rays emitted by the light source assembly relative to the aperture of the at least one condenser lens according to the minimum offset;
if the first centering error meets a preset error requirement, arranging the objective lens between the at least one condensing lens and the imaging element;
if the first centering error does not meet the preset error requirement, continuing to apply the first centering operation to the light source assembly until the first centering error meets the preset error requirement.
6. The centering method of claim 2, wherein the second centering operation comprises:
adjusting the position of the objective lens in the first direction until the image formed by the light rays emitted by the light source assembly in the imaging element has uniform pattern distribution in the first direction;
and adjusting the position of the objective lens in the second direction until the image formed by the light rays emitted by the light source component in the imaging element has uniform pattern distribution in the second direction.
7. The centering method of claim 1, further comprising, after forming the second desired image:
applying a second perturbation operation to the objective lens to cause a minimum distinguishable shift in the center of the second desired image;
determining a second centering error of the aperture of the objective lens with respect to a principal axis of the light emitted by the light source assembly according to the minimum offset;
if the second centering error meets a preset error requirement, confirming that the lens system is centered;
and if the second centering error does not meet the preset error requirement, continuing to apply the second centering operation to the objective lens until the second centering error meets the preset error requirement.
8. The centering method as claimed in claim 5 or 7, wherein the predetermined error requirement is that the centering error is less than or equal to 45um.
9. The centering method as claimed in any one of claims 1 to 7, characterized in that at least the element of the light source assembly to which the first centering operation is applied, the at least one condenser lens, the objective lens and the imaging element are arranged on a damping platform.
10. Centring method according to any of claims 1 to 7, wherein an adjustment element with a hole is provided in the hole of the at least one condenser lens and/or in the hole of the objective lens if the hole diameter of the hole of the at least one condenser lens and the hole diameter of the hole of the objective lens are different, wherein the hole diameter of the hole of the adjustment element is configured to compensate for the difference in the hole diameters of the hole of the at least one condenser lens and the hole diameter of the hole of the objective lens.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311426308.8A CN117690770A (en) | 2023-10-31 | 2023-10-31 | Centering method of lens system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311426308.8A CN117690770A (en) | 2023-10-31 | 2023-10-31 | Centering method of lens system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117690770A true CN117690770A (en) | 2024-03-12 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311426308.8A Pending CN117690770A (en) | 2023-10-31 | 2023-10-31 | Centering method of lens system |
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| Country | Link |
|---|---|
| CN (1) | CN117690770A (en) |
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2023
- 2023-10-31 CN CN202311426308.8A patent/CN117690770A/en active Pending
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