FI129478B - A method and a system for radiation-based imaging - Google Patents

A method and a system for radiation-based imaging Download PDF

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Publication number
FI129478B
FI129478B FI20196001A FI20196001A FI129478B FI 129478 B FI129478 B FI 129478B FI 20196001 A FI20196001 A FI 20196001A FI 20196001 A FI20196001 A FI 20196001A FI 129478 B FI129478 B FI 129478B
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radiation
artifact
steps
based imaging
imaging
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FI20196001A
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Finnish (fi)
Swedish (sv)
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FI20196001A1 (en
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Edward Haeggström
Ivan Kassamakov
Anton Nolvi
Niklas Sandler
Alejandro Perez
Tapani Viitala
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Nanojet Oy
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G01B11/25—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures by projecting a pattern, e.g. one or more lines, moiré fringes on the object
    • G01B11/2504—Calibration devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
    • G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
    • G01B21/04—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness by measuring coordinates of points
    • G01B21/042—Calibration or calibration artifacts
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02055—Reduction or prevention of errors; Testing; Calibration
    • G01B9/0207—Error reduction by correction of the measurement signal based on independently determined error sources, e.g. using a reference interferometer
    • G01B9/02072—Error reduction by correction of the measurement signal based on independently determined error sources, e.g. using a reference interferometer by calibration or testing of interferometer
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B21/00—Microscopes

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Optics & Photonics (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)

Abstract

A system for radiation-based imaging of a sample (724) comprises an imaging device (720) and an artifact (700) so that the sample and the artifact are concurrently in a field-of-view of the imaging device. The artifact has a stepped thickness profile where adjacent steps interact differently with radiation used in the radiation-based imaging. Thus, it is possible to identify which step, in each imaging situation, is vertically closest to an imaging plane related to the radiationbased imaging. Thus, a pre-determined vertical position-value related to the closest one of the steps can be used as a vertical position-value related to a radiation-based imaging result obtained in the imaging situation.

Description

A method and a system for radiation-based imaging This is a divisional of FI20166039. Technical field The disclosure relates to a method for improving vertical resolution of radiation- based imaging such as for example microscopy. Furthermore, the disclosure relates to a system for radiation-based imaging. Background In microscopy and in other corresponding radiation-based imaging, important metrics include magnification, field-of-view “FOV”, lateral resolution, vertical resolution, sensitivity, and depth of field “DOF” in the vertical direction. The vertical direction is substantially parallel with the main propagation direction of radiation used in the radiation-based imaging, whereas lateral directions are perpendicular to the vertical direction. The lateral resolution depends on the numerical aperture “NA” related to the radiation based imaging so that the size of the finest detail that can be resolved in a lateral direction is proportional to A/2NA, where A is the center wavelength of the radiation. NA is n x sind, where n is the index of refraction of the medium in which the objective lens is working and 6 is the maximal half-angle of the cone of light that can enter or exit the objective lens. The vertical resolution depends on the above-mentioned NA so that the size of the finest detail that can be resolved " 20 in the vertical direction is proportional to A/NA2.
O N In microscopy and in other corresponding radiation based imaging, beams are not 2 directed via a single ideal focus point but a beam distribution becomes hourglass AN shaped, having a finite waist in a focal plane. The lateral width of the beam E: distribution as a function of position in the vertical direction is usually called a waist S 25 function. The non-ideality of the waist function limits the resolution that is achievable 3 with microscopy and/or other corresponding radiation based imaging. Especially the > resolution in the vertical direction is limited due to the non-ideality of the waist function.
Publication CN1920476 describes a nanometer multi-step height sample template.
The production of the sample template comprises transforming thickness of a film into a step height of the sample template and controlling the thickness of the film to control the step height by etching the step shape via dry and/or wet etching techniques.
Publication JP2008170279 describes a three-dimensional shape measuring device that comprises an image capture unit having a line sensor for capturing an optical pattern as an image, a movement unit for moving an object to be measured, and an image processing unit for controlling the movement unit and for measuring a three- dimensional shape of the object by analyzing the image captured by the line sensor.
Correction of height is carried out by using a correction target having a plurality of flat surfaces in a stepwise manner.
The image processing unit projects the optical pattern to one of the flat surfaces of the correction target and reads the projected optical pattern as an image by using the line sensor, and then repeats this processing with respect to the other faces of the correction target.
Publication WO2016083661 describes a method for calibrating electromagnetic radiation-based three-dimensional imaging.
The method comprises: obtaining a calibration imaging result at least partly based on electromagnetic waves received from a calibration artifact, forming calibration data based on the calibration imaging result and a known thickness profile of the calibration artifact, and correcting, with the aid of the calibration data, an imaging result obtained at least partly based on electromagnetic waves received from a sample to be imaged.
The calibration artifact 3 comprises layers, for example Langmuir-Blodgett films, having pre-determined < thicknesses and stacked on each other to achieve a pre-determined thickness 2 25 profile of the calibration artifact.
A three-dimensional imaging system configured to 2 carry out the method is presented too. a 3 Summary 2 The following presents a simplified summary to provide a basic understanding of N some aspects of different invention embodiments.
The summary is not an extensive overview of the invention.
It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention.
The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying and non-limiting embodiments of the invention. In accordance with the invention, there is provided a new method for improving vertical resolution of radiation-based imaging of a sample. The radiation-based imaging can be microscopy or other corresponding radiation-based imaging. In this document, the term "vertical resolution” is to be understood in a broad sense so that, depending on a case under consideration, the vertical resolution determines the precision with which one can determine the vertical location of a single feature and/or the ability to distinguish two or more vertically nearby features and/or the accuracy of vertical profiling. A method according to the invention comprises: - placing the sample and an artifact to be concurrently in the field-of-view “FOV” during the radiation-based imaging, the artifact having a stepped thickness profile with steps, and adjacent ones of the steps being arranged to interact differently with radiation used in the radiation-based imaging so that each step is arranged to interact differently with the radiation than any step adjacent to the first-mentioned step, - producing a radiation-based imaging result when one of the steps of the artifact is, in the vertical direction, closer to the imaging plane related to the radiation- N based imaging than any other step of the artifact, and
O N - associating, with the radiation-based imaging result, a pre-determined vertical ? position-value related to the one of the steps.
N z As each step of the above-mentioned artifact is arranged to interact differently with = 25 the radiation than any step adjacent to the first-mentioned step, it is possible to S identify which step is, in each imaging situation, vertically closest to the imaging = plane related to the radiation-based imaging. Thus, a pre-determined vertical N position-value related to the closest one of the steps can be used as a vertical position-value related to a radiation-based imaging result that is obtained in the imaging situation under consideration. In accordance with the invention, there is provided also a new system for radiation- based imaging of a sample. A system according to the invention comprises: - an artifact having a stepped thickness profile with steps, adjacent ones of the steps being arranged to interact differently with radiation used in the radiation- based imaging so that each step is arranged to interact differently with the radiation than any step adjacent to the first-mentioned step, and - animaging device for producing an imaging result based on first waves arriving from the sample and second waves arriving from the artifact when the sample and the artifact are concurrently in the field-of-view of the imaging device. The imaging device comprises a translation mechanism for vertically translating the imaging plane related to the radiation-based imaging.
As it is possible to associate appropriate vertical position-values with radiation- based imaging results obtained with different vertical positions of the imaging plane, it is possible to use for example an ordinary microscope, which is designed for two- dimensional “2D” imaging, for three-dimensional “3D” imaging so that 2D-images are associated with appropriate vertical position-values based on the artifact. The above-mentioned artifact may comprise, for example but not necessarily, layers N 20 — with pre-determined thicknesses so that the layers are stacked on top of each other O in a partially overlapping way to form the above-mentioned stepped thickness 5 profile. One or more of the above-mentioned layers can be, for example but not © necessarily, Langmuir-Blodgett films “LBF”. The LBFs can be manufactured in a = known way to have a constant thickness of e.g. 2.5 nm. Consequently, the thickness = 25 — profile of the artifact can be controlled with about 2.5 nm steps by controlling the S number of LBFs stacked on each other. The stepped thickness profile can be = achieved by arranging different numbers of stacked LBFs on different portions of N the artifact. The artifact may further comprise steps created by one or more layers each being made of highly ordered pyrolytic graphite “HOPG” and having the thickness greater than that of a LBF. The thickness of each HOPG layer can be e.g. about 2 um. The thickness of each HOPG layer can be controlled with steps of about
0.3 nm. With the aid of the one or more HOPG layers, a sufficient thickness of the artifact can be achieved with a smaller number of LBFs. There can be different 5 numbers of HOPG layers in different portions of the artifact so as to achieve the stepped thickness profile. In many cases it is advantageous that each layer that constitutes at least part of an outer surface of the artifact where the radiation depart from the artifact is a LBF because, compared to e.g. HOPG, the optical properties of a LBF are closer to the optical properties of many biological samples. — An artifact of the kind described above can be manufactured e.g. in the following way. First, one takes a substrate of HOPG and peels off, in a known manner, a sufficient number of HOPG layers in order to have a desired thickness. A more controlled thickness can be achieved by using electron-beam lithography to cut away HOPG material. Next, LBF of a lipid film, e.g. stearic acid or —phopshatidylcholine, is deposited on top of the HOPG substrate by immersing the HOPG substrate, in a known manner, through a monolayer residing on a sub-phase containing monolayer stabilizing counter ions e.g. Uranyl acetate or CdCl, The stepped thickness profile can be achieved by immersing the calibration artifact being manufactured less deep into the sub-phase for the subsequently made LBF layers. Adjacent steps of the artifact can be arranged to interact differently with imaging radiation for example by using different and/or differently doped LBF film materials for the adjacent steps, by using e.g. electron-beam lithography to create different N patterns and/or textures on surfaces of the adjacent steps, and/or in other suitable
O N ways. 5 © 25 Possible materials for preparing the artifact by the Langmuir Blodgett “LB” 2 deposition are fatty acids, fatty alcohols, fatty amines, phospholipids, sterols, and * any amphiphilic derivatives of these because these can be used to form even single 3 layers of precise thicknesses between 2-4 nm. The preferential step heights can be 2 produced by repetitive multiple deposition of these flat single layers by the Langmuir N 30 Blodgett technique.
The above-mentioned layers do not necessarily comprise LBFs but films constituting the layers can be produced as well by moulding, spinning, punching, or casting.
The films could be produced on glass slides or on any other substrate.
In some cases, it is advantageous that the substrate is transparent to the radiation.
A base layer can be produced first on the substrate and then the layers constituting the stepped thickness profile can be produced on top the base layer.
For another example, the artifact can be manufactured so that a sufficiently thick layer is first produced on a substrate and then a form made of e.g. metal and having a stepped shape profile is pressed against the layer in order to shape the layer to have the stepped thickness profile.
It is worth noting that the above-mentioned materials and methods for manufacturing the artifact are non-limiting examples only, and artifacts for methods and systems according to different embodiments of the invention can be manufactured in different ways and of different materials which have suitable interacting properties with the radiation used in the imaging and which are suitable for manufacturing an appropriate stepped thickness profile.
Exemplifying and non-limiting embodiments of the invention are described in accompanied dependent claims.
Various exemplifying and non-limiting embodiments of the invention both as to constructions and to methods of operation, together with additional objects and N advantages thereof, are best understood from the following description of specific O exemplifying embodiments when read in connection with the accompanying 5 drawings.
N The verbs “to comprise” and “to include” are used in this document as open E 25 limitations that neither exclude nor require the existence of un-recited features.
The S features recited in dependent claims are mutually freely combinable unless > otherwise explicitly stated.
Furthermore, it is to be understood that the use of “a” or S “an”, i.e. a singular form, throughout this document does not exclude a plurality.
Brief description of figures
Exemplifying and non-limiting embodiments of the invention and their advantages are explained in greater detail below with reference to the accompanying drawings, in which: figures 1a and 1b illustrate an artifact for methods and systems according to exemplifying and non-limiting embodiments of the invention, figure 2 illustrates an artifact for methods and systems according to exemplifying and non-limiting embodiments of the invention, figure 3 illustrates an artifact for methods and systems according to exemplifying and non-limiting embodiments of the invention, figures 4a and 4b illustrate an artifact for methods and systems according to exemplifying and non-limiting embodiments of the invention, figures 5a and 5b illustrate an artifact for methods and systems according to exemplifying and non-limiting embodiments of the invention, figure 6 shows a flowchart of a method according to an exemplifying and non-limiting embodiment of the invention for improving the vertical resolution of radiation-based imaging, figure 7 illustrates a system according to an exemplifying and non-limiting embodiment of the invention for radiation-based imaging, N figure 8 illustrates a part of a system according to an exemplifying and non-limiting N 20 embodiment of the invention for radiation-based imaging, and
S © figure 9 illustrates a part of a system according to an exemplifying and non-limiting I embodiment of the invention for radiation-based imaging. Ao a
O
O > S Description of exemplifying and non-limiting embodiments The specific examples provided in the description given below should not be construed as limiting the scope and/or the applicability of the appended claims. Lists and groups of examples provided in the description given below are not exhaustive unless otherwise explicitly stated.
Figures 1a and 1b illustrate an artifact 100 for improving vertical resolution of radiation-based imaging.
The vertical direction of the radiation-based imaging is assumed to be parallel with the z-axis of a coordinate system 199. Figure 1a shows a view of a section taken along a line A-A shown in figure 1b, whereas figure 1b shows a schematic top view of the artifact 100. In figure 1a, the section plane is parallel with the xz-plane of the coordinate system 199. In this exemplifying case, the artifact 100 comprises a substrate 116 and layers 101, 102, 103, 104, and 105 on top of the substrate.
The layers 101-105 are stacked on top of each other in a partially overlapping way so as to form a stepped thickness profile having steps 106, 107, 108, 109, and 110. The stepped thickness profile is shown in figure 1a.
The layers 101-105 may comprise organic material in order to achieve a situation in which appropriate material properties of the artifact 100 are sufficiently close to appropriate material properties of biological or synthetic organic samples to be examined.
Organic materials are defined in modern chemistry as carbon-based compounds, originally derived from living organisms but now including lab- synthesized versions as well.
The layers 101-105 can be, for example but not necessarily, Langmuir-Blodgett films “LBF” or suitable polymer films.
The substrate 102 can be made of e.g. highly ordered pyrolytic graphite “HOPG”, SiOz, metal, metal oxide, or silicon.
Adjacent steps of the stepped thickness profile of the artifact 100 are arranged to N interact differently with the radiation used in the radiation-based imaging.
Thus, it is = possible to identify which one of the steps 106-110 is, in each imaging situation, c 25 vertically closest to the imaging plane related to the radiation-based imaging.
Thus, I a pre-determined vertical position-value related to the closest one of the steps 106- E 110 can be used as a vertical position-value related to an imaging result that is 3 obtained in the imaging situation under consideration. > S In the exemplifying artifact 100 illustrated in figures 1a and 1b, the substantially horizontal surfaces 111, 112, 113, 114, and 115 of the steps 106-110 are arranged to have different reflective and/or scattering properties concerning the radiation used in the radiation-based imaging. In this document, the “reflective properties” are properties which describe how a surface reflects arriving radiation so that the reflection angle with respect to a vector, normal to the surface, is substantially the same as the incident angle with respect to the above-mentioned vector normal to the surface. In this document, the “scattering properties” are properties which describe how a surface scatters arriving radiation into many directions. The layers 101-105 may comprise for example substances having wavelength-dependent interacting properties with the radiation used in the radiation-based imaging so that the interacting properties of adjacent steps have different wavelength dependencies. In a case where the radiation is polychromatic visible light, the above-mentioned substances can be color pigments so that adjacent ones of the steps 106-110 have different colors. The color pigments can be mixed into the base materials of the layers 101-105, or the color pigments may constitute the topmost surfaces of the layers 101-105. In figure 1b, horizontal hatchings with different spacing depict different wavelength-dependent interacting properties with the radiation, e.g. different colors and/or different interference patterns. In some cases, the wavelength-dependent interacting properties can be dependent also on a viewing angle. In an exemplifying case, the layers 101-105 comprise particles interacting with the radiation used in the radiation-based imaging so that adjacent steps have different interacting properties with the radiation. Adjacent steps of the artifact can be made different from each other by using different particles in different ones of the layers N 101-105. It is also possible that the amount of the particles per a unit volume is S different in different ones of the layers 101-105. Furthermore, it is also possible that 5 25 the particles are non-evenly distributed in the layers 101-105 so that the particles & are arranged to constitute different geometric patterns in different ones of the layers E 101-105.
S Figure 2 shows a side view of an artifact 200 for improving vertical resolution of O radiation-based imaging. The vertical direction of the radiation-based imaging is N 30 assumed to be parallel with the z-axis of a coordinate system 299. The artifact 200 comprises a substrate 216 and layers 201, 202, 203, 204, and 205 on top of the substrate. The layers 201-205 are stacked on top of each other in a partially overlapping way so as to form a stepped thickness profile having steps 206, 207, 208, 209, and 210. Adjacent ones of the steps 206-210 of the artifact 200 are arranged to interact differently with the radiation used in the radiation-based imaging. In this exemplifying case, the adjacent ones of the steps 206-210 have different radiation-transmission properties for radiation that passes through the artifact 200 along the positive z-direction of the coordinate system 299. In figure 2, the radiation that penetrates the artifact 200 in the positive z-direction is depicted with dashed line arrows. The different radiation-transmission properties of the steps 206-210 can be implemented for example by providing the substantially horizontal — surfaces 211, 212, 213, 214, and 215 with suitable coatings and/or by arranging roughness and/or other properties of the surfaces 211-215 to differ from each other. It is also possible that the different radiation-transmission properties are implemented by using different materials on different layers of the artifact and/or by using different blend components in the base materials of the different layers and/or by blending different particles into the base materials of the different layers and/or by blending particles in different ways into the base materials of the different layers, e.g. so that the amount of blended particles per a unit volume is different for different layers. Thus, there are many ways to implement the different radiation-transmission properties of the steps 206-210.
Figure 3 shows a side view of an artifact 300 for improving vertical resolution of radiation-based imaging. The vertical direction of the radiation-based imaging is assumed to be parallel with the z-axis of a coordinate system 399. The artifact 300 N comprises a substrate 316 and layers 301, 302, 303, 304, and 305 on top of the S substrate. The layers 301-305 are stacked on top of each other in a partially 5 25 overlapping way so as to form a stepped thickness profile having steps 306, 307, & 308, 309, and 310. Adjacent steps of the artifact 300 are arranged to interact E differently with the radiation used in the radiation-based imaging. In this exemplifying S case, surfaces 311, 312, 313, 314, and 315 of the steps 306-310 have textures so 3 that the surfaces of adjacent steps have different textures which have different > 30 scattering properties for the radiation used in the radiation-based imaging. The different textures of the surfaces 313 and 314 are illustrated with partial magnifications 340 and 341 shown in figure 3.
Figures 4a and 4b illustrate an artifact 400 for improving vertical resolution of radiation-based imaging.
The vertical direction of the radiation-based imaging is assumed to be parallel with the z-axis of a coordinate system 499. Figure 4a shows a schematic top view of the artifact 400, whereas figure 4b shows a view of a section taken along a line A-A shown in figure 4a.
In figure 4b, the section plane is parallel with the xz-plane of the coordinate system 499. The artifact 400 comprises layers 401, 402, 403, 404, and 405 that are stacked on top of each other in a partially overlapping way so as to form a stepped thickness profile having steps 406, 407, 408, 409, and 410. Adjacent steps of the artifact 400 are arranged to interact differently with the radiation used in the radiation-based imaging.
In this exemplifying case, surfaces 411, 412, 413, 414, and 415 of the steps 406-410 have geometric patterns of areas having different interacting properties with the radiation used in the radiation-based imaging so that adjacent steps have different geometric patterns.
Areas depicted in figure 4a with cross-hatching have first interacting properties with the radiation, and areas depicted in figure 4a without cross-hatching have second interacting properties with the radiation, where the second interacting properties differ from the first interacting properties.
In a case where the radiation is polychromatic visible light, the areas depicted with the cross-hatching may have a first color and the areas depicted without cross-hatching may have a second color different from the first color.
It is also possible that the areas depicted with the cross- hatching may produce a first interference pattern and the areas depicted without cross-hatching may produce a second interference pattern different from the first interference pattern.
In some cases, the interacting properties can depend also on
3 viewing angle. 5 25 Figures 5a and 5b illustrate an artifact 500 for improving vertical resolution of & radiation-based imaging.
The vertical direction of the radiation-based imaging is E assumed to be parallel with the z-axis of a coordinate system 599. Figure 5a shows S a schematic top view of the artifact 500, and figure 5b shows a view of a section 3 taken along a line A-A shown in figure 5a.
In figure 5b, the section plane is parallel > 30 with the xz-plane of the coordinate system 599. The artifact 500 comprises a layer 501 that has been shaped to form a stepped thickness profile having steps 506, 507, 508, 509, and 510. Adjacent steps of the artifact 500 are arranged to interact differently with the radiation used in the radiation-based imaging. In this exemplifying case, surfaces 511, 512, 513, 514, and 515 of the steps 506-510 have geometric patterns of areas having different interacting properties with the radiation used in the radiation-based imaging so that the steps have similar geometric patterns. In the exemplifying case illustrated in figure 5a, each of the surfaces 511-515 has a diagonal geometric pattern constituted by first areas depicted in figure 5a with vertical hatching and by second areas depicted in figure 5a with horizontal hatching. The surfaces 511-515 are differentiated from each other so that the second areas of different ones of the surfaces 511-515 have different interacting properties with the radiation used in the radiation-based imaging. In figure 5a, the differences in the interacting properties are depicted with the spacing of the horizontal hatching. Figure 6 shows a flowchart of a method according to an exemplifying and non- limiting embodiment of the invention for improving vertical resolution of radiation- based imaging of a sample. The method comprises the following actions: - action 601: placing the sample and an artifact to be concurrently in the field- of-view “FOV” during the radiation-based imaging, adjacent steps of a stepped thickness profile of the artifact interacting differently with the radiation used in the radiation-based imaging, - action 602: producing a radiation-based imaging result when one of the steps of the artifact is, in the vertical direction, closer to the imaging plane related to the radiation-based imaging than any other step of the artifact, and 3 - action 603: associating, with the radiation-based imaging result, a pre- = determined vertical position-value related to the one of the steps of the artifact. N The above-mentioned artifact can be, for example but not necessarily, similar to the E 25 artifact 100 illustrated in figures 1a and 1b, or to the artifact 200 illustrated in figure S 2, orto the artifact 300 illustrated in figure 3, or to the artifact 400 illustrated in figures 3 4a and 4b, or to the artifact 500 illustrated in figures 5a and 5b.
N A method according to an exemplifying and non-limiting embodiment of the invention comprises, prior to the producing the imaging result, adjusting a vertical position of the imaging plane so that the one of the steps of the artifact is closer to the imaging plane in the vertical direction than any other step of the artifact.
In a method according to an exemplifying and non-limiting embodiment of the invention, the radiation-based imaging is microscopy and the imaging plane is a focal plane of a microscope used for the radiation-based imaging.
Figure 7 shows a schematic illustration of a system according to an exemplifying and non-limiting embodiment of the invention for radiation-based imaging of a sample 724. The system comprises an artifact 700 that can be, for example but not necessarily, similar to the artifact 100 illustrated in figures 1a and 1b, or to the artifact 300 illustrated in figure 3, or to the artifact 400 illustrated in figures 4a and 4b, or to the artifact 500 illustrated in figures 5a and 5b.
The artifact 700 has a stepped thickness profile where adjacent steps are arranged to interact differently with the electromagnetic radiation used in the radiation-based imaging.
In the exemplifying case shown in figure 7, the artifact 700 has six steps at vertical positions indicated — by vertical position-values z1, z2, z3, z4, z5, and z6. The vertical positions can be defined as vertical distances from a suitable reference level.
In the exemplifying case shown in figure 7, the vertical distances are measured along the z-direction of a coordinate system 799. The system comprises an imaging device 720 for producing an imaging result based — on first waves arriving from the sample 724 and second waves arriving from the artifact 700 when the sample and the artifact are concurrently in the field-of-view N “FOV” 722 of the imaging device 720. In the exemplifying system illustrated in figure N 7, the imaging device 720 comprises a radiation source 733 and a dichroic mirror O 732 for directing the radiation to the sample 724 and to the artifact 700. The imaging N 25 device 720 comprises an imaging sensor 727 that can be e.g. a charge-coupled E device “CCD” sensor.
Furthermore, the imaging device 720 comprises lenses for 5 focusing and collimating the radiation in desired ways.
The imaging device 720 3 comprises a translation mechanism 721 for vertically translating the imaging plane S 723 related to the radiation-based imaging.
In the exemplifying situation shown in figure 7, the vertical position of the imaging plane 723 is such that the imaging plane 723 substantially coincides with the step 709 of the artifact 700. Therefore, an imaging result obtained in the exemplifying situation shown in figure 7 can be associated with the vertical position-value z5.
Figure 8 illustrates a part of a system according to an exemplifying and non-limiting embodiment of the invention for radiation-based imaging of a sample 824. The system comprises an artifact 800 that is located together with the sample 824 in the field-of-view “FOV” 822 related to the radiation-based imaging. In this exemplifying case, the radiation penetrates the sample 824 and the artifact 800 in the positive z- direction of a coordinate system 899. The artifact 800 can be, for example but not necessarily, similar to the artifact 200 illustrated in figure 2.
Figure 9 illustrates a part of a system according to an exemplifying and non-limiting embodiment of the invention for radiation-based imaging of a sample 924. The system comprises an artifact 900 that is located together with the sample 924 in the field-of-view “FOV” 922 related to the radiation-based imaging. In this exemplifying case, the radiation arrives obliquely from above and the radiation is scattered and reflected from the sample 924 and from the artifact 900. The artifact 900 can be, for example but not necessarily, similar to the artifact 100 illustrated in figures 1a and 1b, or to the artifact 300 illustrated in figure 3, or to the artifact 400 illustrated in figures 4a and 4b, or to the artifact 500 illustrated in figures 5a and 5b.
The non-limiting, specific examples provided in the description given above should not be construed as limiting the scope and/or the applicability of the appended claims. Furthermore, any list or group of examples presented in this document is not N exhaustive unless otherwise explicitly stated. &
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Claims (15)

What is claimed is:
1. A method for improving vertical resolution of radiation-based imaging of a sample, the method comprising: - placing (601) the sample and an artifact to be concurrently in a field-of-view during the radiation-based imaging, the artifact having a stepped thickness profile with steps (106-110, 206-210, 306-310, 406-410, 506-510), and adjacent ones of the steps being arranged to interact differently with radiation used in the radiation-based imaging so that each step is arranged to interact differently with the radiation than any step adjacent to the first-mentioned step, - producing (602) a radiation-based imaging result, and - associating (603), with the radiation-based imaging result, a pre-determined vertical position-value related to one of the steps of the artifact, characterized in that the radiation-based imaging result is produced (602) when the one of the steps of the stepped thickness profile of the artifact is, in a vertical direction, closer to an imaging plane related to the radiation-based imaging than any other one of the steps.
2. A method according to claim 1, wherein the radiation-based imaging is microscopy and the imaging plane is a focal plane of a microscope used for the N 20 — radiation-based imaging. & At
3. A system for radiation-based imaging of a sample, the system comprising:
O N - an artifact (100, 200, 300, 400, 500, 700) having a stepped thickness profile E with steps (106-110, 206-210, 306-310, 406-410, 506-510), adjacent ones of S the steps being arranged to interact differently with radiation used in the 3 25 radiation-based imaging so that each step is arranged to interact differently > with the radiation than any step adjacent to the first-mentioned step, and - animaging device (720) for producing an imaging result based on first waves arriving from the sample and second waves arriving from the artifact when the sample and the artifact are concurrently in a field-of-view of the imaging device, characterized in that the imaging device comprises a translation mechanism (721) for vertically translating an imaging plane related to the radiation-based imaging.
4 A system according to claim 3, wherein surfaces (111-115) of the adjacent ones of the steps (106-110) of the artifact have different reflective properties.
5. A system according to claim 3 or 4, wherein the adjacent ones of the steps (206-210) of the artifact have different radiation-transmission properties.
6. A system according to any one of claims 3-5, wherein surfaces (311-315) of the adjacent ones of the steps (306-310) of the artifact have different scattering properties.
7. A system according to any one of claims 3-6, wherein the artifact comprises substances having wavelength-dependent interacting properties with radiation used in the radiation-based imaging so that the interacting properties of the adjacent ones of the steps have different wavelength dependencies.
8. A system according to any one of claims 3-7, wherein surfaces (411-415) of the steps of the artifact have geometric patterns of areas having different interacting properties with radiation used in the radiation-based imaging so that the adjacent ones of the steps have different geometric patterns. N 20 9 A system according to any one of claims 3-8, wherein surfaces (511-515) of = the steps of the artifact have geometric patterns of areas having different interacting 2 properties with radiation used in the radiation-based imaging so that the adjacent - ones of the steps have similar geometric patterns so that the interacting properties E of at least one of the areas of a first one of the similar geometric patterns differs S 25 from the interacting properties of a corresponding one of the areas of a second one 3 of the similar geometric patterns.
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10. A system according to any of claims 3-9, wherein surfaces (311-315) of the steps of the artifact have textures having different interacting properties with radiation used in the radiation-based imaging so that adjacent ones of the steps have different textures.
11. A system according to any of claims 3-10, wherein the artifact comprises particles interacting with radiation used in the radiation-based imaging so that the adjacent ones of the steps have different interacting properties with the radiation used in the radiation-based imaging.
12. A system according to any one of claims 3-11, wherein the artifact comprises a substrate (116) and material constituting the stepped thickness profile is on top of the substrate.
13. Asystem according to any of claims 3-12, wherein the artifact comprises layers (101-105, 201-205, 301-305, 401-405) having pre-determined thicknesses and being stacked on top of each other in a vertical direction and in a partially overlapping way so as to form the stepped thickness profile.
14. A system according to claim 13, wherein at least one of the layers comprises a polymer film.
15. A system according to claim 13, wherein at least one of the layers comprises a Langmuir-Blodgett film.
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FI20196001A 2016-12-28 2016-12-28 A method and a system for radiation-based imaging FI129478B (en)

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