WO2023039774A1

WO2023039774A1 - Imaging methods using multiple radiation beams

Info

Publication number: WO2023039774A1
Application number: PCT/CN2021/118628
Authority: WO
Inventors: Peiyan CAO
Original assignee: Shenzhen Xpectvision Technology Co., Ltd.
Priority date: 2021-09-16
Filing date: 2021-09-16
Publication date: 2023-03-23
Also published as: TW202314291A; CN117940808A

Abstract

An imaging method,comprising :sending M bombardment beams (bombardment beams (i), i=1, …, M) (712a) respectively toward target spots (720a,72b,720c) (i), i=1, …, M on a target (725) resulting in radiation beams (722a)(i), i=1, …, M emitting respectively from the target spots (i), i=1, …, M and propagating toward an object (730), wherein M is an integer greater than 1; and for each value of i, obtaining a 2D (two-dimensional) image (i) of the object (730) using radiation of the radiation beam (i) that has passed through the object (730), wherein the target (725) is stationary with respect to the object (730).

Description

IMAGING METHODS USING MULTIPLE RADIATION BEAMS

Background

A radiation detector is a device that measures a property of a radiation. Examples of the property may include a spatial distribution of the intensity, phase, and polarization of the radiation. The radiation may be one that has interacted with an object. For example, the radiation measured by the radiation detector may be a radiation that has penetrated the object. The radiation may be an electromagnetic radiation such as infrared light, visible light, ultraviolet light, X-ray, or γ-ray. The radiation may be of other types such as α-rays and β-rays. An imaging system may include one or more image sensors each of which may have multiple radiation detectors.

Summary

Disclosed herein is a method comprising: sending M bombardment beams (bombardment beams (i) , i=1, …, M) respectively toward target spots (i) , i=1, …, M on a target resulting in radiation beams (i) , i=1, …, M emitting respectively from the target spots (i) , i=1, …, M and propagating toward an object, wherein M is an integer greater than 1; and for each value of i, obtaining a 2D (two-dimensional) image (i) of the object using radiation of the radiation beam (i) that has passed through the object, wherein the target is stationary with respect to the object.

In an aspect, the method further comprises reconstructing a 3D (three-dimensional) image of the object from the 2D images (i) , i=1, …, M.

In an aspect, said obtaining the 2D image (i) of the object comprises: capturing Ni partial images of the object one by one using the radiation of the radiation beam (i) that has passed through the object, wherein Ni is an integer greater than 1; and stitching the Ni partial images of the object resulting in the 2D image (i) of the object.

In an aspect, all Ni, i=1, …, M are the same.

In an aspect, each of the M bombardment beams comprises an electron beam.

In an aspect, the target comprises copper or tungsten.

In an aspect, the bombardment beams (i) , i=1, …, M are sent one by one.

In an aspect, an image sensor obtains all the 2D images (i) , i=1, …, M.

In an aspect, said sending the M bombardment beams is performed using a bombardment beam generator which comprises multiple electron guns each of which sends at least one of the M bombardment beams.

In an aspect, the bombardment beam generator is physically fixed to the target.

Disclosed herein is an imaging system, comprising: a bombardment beam generator; a target; and an image sensor system comprising at least an image sensor, wherein the bombardment beam generator is configured to send M bombardment beams (bombardment beams (i) , i=1, …, M) respectively toward target spots (i) , i=1, …, M on the target resulting in radiation beams (i) , i=1, …, M emitting respectively from the target spots (i) , i=1, …, M and propagating toward an object, wherein M is an integer greater than 1, wherein the image sensor system is configured to, for each value of i, obtain a 2D (two-dimensional) image (i) of the object using radiation of the radiation beam (i) that has passed through the object, and wherein the target is stationary with respect to the object.

In an aspect, the image sensor system is further configured to reconstruct a 3D (three-dimensional) image of the object from the 2D images (i) , i=1, …, M.

In an aspect, the image sensor system is further configured to obtain the 2D image (i) of the object by: capturing Ni partial images of the object one by one using the radiation of the radiation beam (i) that has passed through the object, wherein Ni is an integer greater than 1; and stitching the Ni partial images of the object resulting in the 2D image (i) of the object.

In an aspect, all Ni, i=1, …, M are the same.

In an aspect, each of the M bombardment beams comprises an electron beam.

In an aspect, the target comprises copper or tungsten.

In an aspect, the bombardment beams (i) , i=1, …, M are sent one by one.

In an aspect, an image sensor of the image sensor system obtains all the 2D images (i) , i=1, …, M.

In an aspect, the bombardment beam generator comprises multiple electron guns each of which sends at least one of the M bombardment beams.

In an aspect, the bombardment beam generator is physically fixed to the target.

Brief Description of Figures

Fig. 1 schematically shows a radiation detector, according to an embodiment.

Fig. 2 schematically shows a simplified cross-sectional view of the radiation detector, according to an embodiment.

Fig. 3 schematically shows a detailed cross-sectional view of the radiation detector, according to an embodiment.

Fig. 4 schematically shows a detailed cross-sectional view of the radiation detector, according to an alternative embodiment.

Fig. 5 schematically shows a top view of a package including the radiation detector and a printed circuit board (PCB) , according to an embodiment.

Fig. 6 schematically shows a cross-sectional view of an image sensor including the packages of Fig. 5 mounted to a system PCB (printed circuit board) , according to an embodiment.

Fig. 7A-Fig. 7C schematically show perspective views of an imaging system in operation, according to an embodiment.

Fig. 8 shows a flowchart generalizing the operation of the imaging system.

Detailed Description

RADIATION DETECTOR

Fig. 1 schematically shows a radiation detector 100, as an example. The radiation detector 100 may include an array of pixels 150 (also referred to as sensing elements 150) . The array may be a rectangular array (as shown in Fig. 1) , a honeycomb array, a hexagonal array, or any other suitable array. The array of pixels 150 in the example of Fig. 1 has 4 rows and 7 columns; however, in general, the array of pixels 150 may have any number of rows and any number of columns.

Each pixel 150 may be configured to detect radiation from a radiation source (not shown) incident thereon and may be configured to measure a characteristic (e.g., the energy of the particles, the wavelength, and the frequency) of the radiation. A radiation may include particles such as photons and subatomic particles. Each pixel 150 may be configured to count numbers of particles of radiation incident thereon whose energy falls in a plurality of bins of energy, within a period of time. All the pixels 150 may be configured to count the numbers of particles of radiation incident thereon within a plurality of bins of energy within the same period of time. When the incident particles of radiation have similar energy, the pixels 150 may be simply configured to count numbers of particles of radiation incident thereon within a period of time, without measuring the energy of the individual particles of radiation.

Each pixel 150 may have its own analog-to-digital converter (ADC) configured to digitize an analog signal representing the energy of an incident particle of radiation into a digital signal, or to digitize an analog signal representing the total energy of a plurality of incident particles of radiation into a digital signal. The pixels 150 may be configured to operate in parallel. For example, when one pixel 150 measures an incident particle of radiation, another pixel 150 may be waiting for a particle of radiation to arrive. The pixels 150 may not have to be individually addressable.

The radiation detector 100 described here may have applications such as in an X-ray telescope, X-ray mammography, industrial X-ray defect detection, X-ray microscopy or microradiography, X-ray casting inspection, X-ray non-destructive testing, X-ray weld inspection, X-ray digital subtraction angiography, etc. It may be suitable to use this radiation detector 100 in place of a photographic plate, a photographic film, a PSP plate, an X-ray image intensifier, a scintillator, or another semiconductor X-ray detector.

Fig. 2 schematically shows a simplified cross-sectional view of the radiation detector 100 of Fig. 1 along a line 2-2, according to an embodiment. Specifically, the radiation detector 100 may include a radiation absorption layer 110 and an electronics layer 120 (which may include one or more ASICs or application-specific integrated circuits) for processing or analyzing electrical signals which incident radiation generates in the radiation absorption layer 110. The radiation detector 100 may or may not include a scintillator (not shown) . The radiation absorption layer 110 may include a semiconductor material such as silicon, germanium, GaAs, CdTe, CdZnTe, or a combination thereof. The semiconductor material may have a high mass attenuation coefficient for the radiation of interest.

Fig. 3 schematically shows a detailed cross-sectional view of the radiation detector 100 of Fig. 1 along the line 2-2, as an example. Specifically, the radiation absorption layer 110 may include one or more diodes (e.g., p-i-n or p-n) formed by a first doped region 111, one or more discrete regions 114 of a second doped region 113. The second doped region 113 may be separated from the first doped region 111 by an optional intrinsic region 112. The discrete regions 114 may be separated from one another by the first doped region 111 or the intrinsic region 112. The first doped region 111 and the second doped region 113 may have opposite types of doping (e.g., region 111 is p-type and region 113 is n-type, or region 111 is n-type and region 113 is p-type) . In the example of Fig. 3, each of the discrete regions 114 of the second doped region 113 forms a diode with the first doped region 111 and the optional intrinsic region 112. Namely, in the example in Fig. 3, the radiation absorption layer 110 has a plurality of diodes (more specifically, 7 diodes corresponding to 7 pixels 150 of one row in the array of Fig. 1, of which only 2 pixels 150 are labeled in Fig. 3 for simplicity) . The plurality of diodes may have an electrical contact 119A as a shared (common) electrode. The first doped region 111 may also have discrete portions.

The electronics layer 120 may include an electronic system 121 suitable for processing or interpreting signals generated by the radiation incident on the radiation absorption layer 110. The electronic system 121 may include an analog circuitry such as a filter network, amplifiers, integrators, and comparators, or a digital circuitry such as a microprocessor, and memory. The electronic system 121 may include one or more ADCs (analog to digital converters) . The electronic system 121 may include components shared by the pixels 150 or components dedicated to a single pixel 150. For example, the electronic system 121 may include an amplifier dedicated to each pixel 150 and a microprocessor shared among all the pixels 150. The electronic system 121 may be electrically connected to the pixels 150 by vias 131. Space among the vias may be filled with a filler material 130, which may increase the mechanical stability of the connection of the electronics layer 120 to the radiation absorption layer 110. Other bonding techniques are possible to connect the electronic system 121 to the pixels 150 without using the vias 131.

When radiation from the radiation source (not shown) hits the radiation absorption layer 110 including diodes, particles of the radiation may be absorbed and generate one or more charge carriers (e.g., electrons, holes) by a number of mechanisms. The charge carriers may drift to the electrodes of one of the diodes under an electric field. The electric field may be an external electric field. The electrical contact 119B may include discrete portions each of which is in electrical contact with the discrete regions 114. The term “electrical contact” may be used interchangeably with the word “electrode. ” In an embodiment, the charge carriers may drift in directions such that the charge carriers generated by a single particle of the radiation are not substantially shared by two different discrete regions 114 ( “not substantially shared” here means less than 2%, less than 0.5%, less than 0.1%, or less than 0.01%of these charge carriers flow to a different one of the discrete regions 114 than the rest of the charge carriers) . Charge carriers generated by a particle of the radiation incident around the footprint of one of these discrete regions 114 are not substantially shared with another of these discrete regions 114. A pixel 150 associated with a discrete region 114 may be an area around the discrete region 114 in which substantially all (more than 98%, more than 99.5%, more than 99.9%, or more than 99.99%of) charge carriers generated by a particle of the radiation incident therein flow to the discrete region 114. Namely, less than 2%, less than 1%, less than 0.1%, or less than 0.01%of these charge carriers flow beyond the pixel 150.

Fig. 4 schematically shows a detailed cross-sectional view of the radiation detector 100 of Fig. 1 along the line 2-2, according to an alternative embodiment. More specifically, the radiation absorption layer 110 may include a resistor of a semiconductor material such as silicon, germanium, GaAs, CdTe, CdZnTe, or a combination thereof, but does not include a diode. The semiconductor material may have a high mass attenuation coefficient for the radiation of interest. In an embodiment, the electronics layer 120 of Fig. 4 is similar to the electronics layer 120 of Fig. 3 in terms of structure and function.

When the radiation hits the radiation absorption layer 110 including the resistor but not diodes, it may be absorbed and generate one or more charge carriers by a number of mechanisms. A particle of the radiation may generate 10 to 100,000 charge carriers. The charge carriers may drift to the

electrical contacts

119A and 119B under an electric field. The electric field may be an external electric field. The electrical contact 119B may include discrete portions. In an embodiment, the charge carriers may drift in directions such that the charge carriers generated by a single particle of the radiation are not substantially shared by two different discrete portions of the electrical contact 119B ( “not substantially shared” here means less than 2%, less than 0.5%, less than 0.1%, or less than 0.01%of these charge carriers flow to a different one of the discrete portions than the rest of the charge carriers) . Charge carriers generated by a particle of the radiation incident around the footprint of one of these discrete portions of the electrical contact 119B are not substantially shared with another of these discrete portions of the electrical contact 119B. A pixel 150 associated with a discrete portion of the electrical contact 119B may be an area around the discrete portion in which substantially all (more than 98%, more than 99.5%, more than 99.9%or more than 99.99%of) charge carriers generated by a particle of the radiation incident therein flow to the discrete portion of the electrical contact 119B. Namely, less than 2%, less than 0.5%, less than 0.1%, or less than 0.01%of these charge carriers flow beyond the pixel associated with the one discrete portion of the electrical contact 119B.

RADIATION DETECTOR PACKAGE

Fig. 5 schematically shows a top view of a package 500 including the radiation detector 100 and a printed circuit board (PCB) 510. The term “PCB” as used herein is not limited to a particular material. For example, a PCB may include a semiconductor. The radiation detector 100 may be mounted to the PCB 510. The wiring between the radiation detector 100 and the PCB 510 is not shown for the sake of clarity. The PCB 510 may have one or more radiation detectors 100. The PCB 510 may have an area 512 not covered by the radiation detector 100 (e.g., for accommodating bonding wires 514) . The radiation detector 100 may have an active area 190 which is where the pixels 150 (Fig. 1) are located. The radiation detector 100 may have a perimeter zone 195 near the edges of the radiation detector 100. The perimeter zone 195 has no pixels 150, and the radiation detector 100 does not detect particles of radiation incident on the perimeter zone 195.

IMAGE SENSOR

Fig. 6 schematically shows a cross-sectional view of an image sensor 600, according to an embodiment. The image sensor 600 may include one or more packages 500 of Fig. 5 mounted to a system PCB 650. Fig. 6 shows 2 packages 500 as an example. The electrical connection between the PCBs 510 and the system PCB 650 may be made by bonding wires 514. In order to accommodate the bonding wires 514 on the PCB 510, the PCB 510 may have the area 512 not covered by the radiation detector 100. In order to accommodate the bonding wires 514 on the system PCB 650, the packages 500 may have gaps in between. The gaps may be approximately 1 mm or more. Particles of radiation incident on the perimeter zones 195, on the area 512, or on the gaps cannot be detected by the packages 500 on the system PCB 650. A dead zone of a radiation detector (e.g., the radiation detector 100) is the area of the radiation-receiving surface of the radiation detector, on which incident particles of radiation cannot be detected by the radiation detector. A dead zone of a package (e.g., package 500) is the area of the radiation-receiving surface of the package, on which incident particles of radiation cannot be detected by the radiation detector or detectors in the package. In this example shown in Fig. 5 and Fig. 6, the dead zone of the package 500 includes the perimeter zones 195 and the area 512. A dead zone (e.g., 688) of an image sensor (e.g., image sensor 600) with a group of packages (e.g., packages 500 mounted on the same PCB and arranged in the same layer or in different layers) includes the combination of the dead zones of the packages in the group and the gaps between the packages.

In an embodiment, the radiation detector 100 (Fig. 1) operating by itself may be considered an image sensor. In an embodiment, the package 500 (Fig. 5) operating by itself may be considered an image sensor.

The image sensor 600 including the radiation detectors 100 may have the dead zone 688 incapable of detecting incident radiation. However, the image sensor 600 may capture multiple partial images of an object or scene (not shown) , and then these captured partial images may be stitched to form an image of the entire object or scene.

IMAGING SYSTEM

Fig. 7A –Fig. 7C schematically show perspective views of an imaging system 700 in operation, according to an embodiment. In an embodiment, the imaging system 700 may include a bombardment beam generator 710, a target 725, and an image sensor system 100a+100b+100c. In an embodiment, the bombardment beam generator 710 may be configured to generate bombardment beams (e.g., electron beams) toward the target 725.

In an embodiment, the target 725 may have the shape of a ring as shown. In an embodiment, there may be 3

target spots

720a, 720b, and 720c on the surface of the target 725. Each of the

target spots

720a, 720b, and 720c may be an area or region on the surface of the target 725 that is to receive bombardment particles (e.g., electrons) from the bombardment beam generator 710. The 3 dark circles representing the 3

target spots

720a, 720b, and 720c indicate just roughly the locations of the

target spots

720a, 720b, and 720c on the target 725 and do not necessarily indicate the sizes, shapes, or orientations of the

target spots

720a, 720b, and 720c.

In an embodiment, the target 725 may be made of copper or tungsten. The target 725 may be one-piece as shown. Alternatively, the target 725 may include multiple separate pieces (not shown) .

In an embodiment, the image sensor system 100a+100b+100c may include 3

radiation detectors

100a, 100b, and 100c which may be similar to the radiation detector 100 of Fig. 1. The 3 parallelograms representing the 3

radiation detectors

100a, 100b, and 100c indicate just roughly the locations and orientations of the

radiation detectors

100a, 100b, and 100c and do not necessarily indicate the sizes and shapes of the

radiation detectors

100a, 100b, and 100c. In an embodiment, the

radiation detectors

100a, 100b, and 100c may be physically fixed to a circular rail 105 as shown.

In an embodiment, an object 730 may be positioned between the

target spots

720a, 720b, and 720c and the image sensor system 100a+100b+100c as shown so as to be imaged by the imaging system 700. The object 730 may be a patient whose body parts need to be imaged for medical diagnostic purposes. In an embodiment, the

target spots

720a, 720b, and 720c may be such that when bombardment beams (e.g., electron beams) from the bombardment beam generator 710 bombard the target 725 at the

target spots

720a, 720b, and 720c, radiation beams (e.g., X-rays) would emit from the

target spots

720a, 720b, and 720c and propagate toward the object 730.

In an embodiment, the target 725 may be stationary with respect to object 730 during the operation of the imaging system 700 in imaging the object 730. In an embodiment, the rail 105 may be stationary with respect to the object 730 during the operation of the imaging system 700 in imaging the object 730.

FIRST 2D IMAGE CAPTURE

In an embodiment, with reference to Fig. 7A, a first 2D (two-dimensional) image capture may be performed as follows. The bombardment beam generator 710 may generate a bombardment beam 712a toward the target spot 720a on the target 725 thereby causing the emission of a radiation beam 722a from the target spot 720a toward the object 730. Using the radiation of the radiation beam 722a that has passed through the object 730, the radiation detector 100a may capture a first 2D image of the object 730.

SECOND 2D IMAGE CAPTURE

In an embodiment, with reference to Fig. 7B, a second 2D image capture may be performed as follows. The bombardment beam generator 710 may generate a bombardment beam 712b toward the target spot 720b on the target 725 thereby causing the emission of a radiation beam 722b from the target spot 720b toward the object 730. Using the radiation of the radiation beam 722b that has passed through the object 730, the radiation detector 100b may capture a second 2D image of the object 730.

THIRD 2D IMAGE CAPTURE

In an embodiment, with reference to Fig. 7C, a third 2D image capture may be performed as follows. The bombardment beam generator 710 may generate a bombardment beam 712c toward the target spot 720c on the target 725 thereby causing the emission of a radiation beam 722c from the target spot 720c toward the object 730. Using the radiation of the radiation beam 722c that has passed through the object 730, the radiation detector 100c may capture a third 2D image of the object 730.

FLOWCHART FOR GENERALIZATION

Fig. 8 shows a flowchart 800 generalizing the operation of the imaging system 700 described above. Specifically, in step 810, M bombardment beams (bombardment beams (i) , i=1, …, M) are sent respectively toward target spots (i) , i=1, …, M on a target resulting in radiation beams (i) , i=1, …, M emitting respectively from the target spots (i) , i=1, …, M and propagating toward an object, wherein M is an integer greater than 1. For example, with reference to Fig. 7A -Fig. 8, three

bombardment beams

712a, 712b, and 712c (here M=3) are sent respectively toward the

target spots

720a, 720b, and 720c on the target 725 resulting in the

radiation beams

722a, 722b, and 722c emitting respectively from the

target spots

720a, 720b, and 720c and propagating toward the object 730.

In step 820, for each value of i, a 2D image (i) of the object is obtained using radiation of the radiation beam (i) that has passed through the object. For example, for i=1, the first 2D image of the object 730 is obtained using the radiation of the radiation beam 722a (Fig. 7A) that has passed through the object 730. For i=2, the second 2D image of the object 730 is obtained using the radiation of the radiation beam 722b (Fig. 7B) that has passed through the object 730. For i=3, the third 2D image of the object 730 is obtained using the radiation of the radiation beam 722c (Fig. 7C) that has passed through the object 730.

Also in step 820, the target is stationary with respect to the object. For example, the target 725 is stationary with respect to the object 730.

3D IMAGE RECONSTRUCTION

In an embodiment, with reference to step 820 in the flowchart 800 of Fig. 8, a 3D (three-dimensional) image of the object may be reconstructed from the 2D images (i) , i=1, …, M. For example, with reference to Fig. 7A –Fig. 7C, a 3D image of the object 730 may be reconstructed from the first 2D image, the second 2D image, and the third 2D image (described above) of the object 730. In an embodiment, the

radiation detectors

100a, 100b, and 100c may be configured to communicate with each other so that at least one of them can have access to all the first, second, and third 2D images and can perform the reconstruction of the 3D image from the first, second, and third 2D images.

SINGLE RADIATION DETECTOR OBTAINS ALL 2D IMAGES

In an embodiment, with reference to step 820 in the flowchart 800 of Fig. 8, all the 2D images (i) , i=1, …, M may be obtained using a single image sensor. For example, with reference to Fig. 7A –Fig. 7C, instead of 3

radiation detectors

100a, 100b, and 100c being used to obtain the first, second, and third 2D images respectively as described above, the radiation detector 100a (which by itself may be considered an image sensor) may move along the rail 105 and obtain all the first, second, and third 2D images. This may be made possible if the first 2D image capture, the second 2D image capture, and the third 2D image capture are performed one by one. This means that the bombardment beam generator 710 sends the

bombardment beams

712a, 712b, and 712c one by one.

Specifically, when the bombardment beam generator 710 sends the bombardment beam 712a (Fig. 7A) , the radiation detector 100a may be at its location as shown in Fig. 7A and may capture the first 2D image. Later, in an embodiment, when the bombardment beam generator 710 sends the bombardment beam 712b (Fig. 7B) , the radiation detector 100a may be at the location of the radiation detector 100b as shown in Fig. 7B and may capture the second 2D image. Later, in an embodiment, when the bombardment beam generator 710 sends the bombardment beam 712c (Fig. 7C) , the radiation detector 100a may be at the location of the radiation detector 100c as shown in Fig. 7C and may capture the third 2D image. As a result, the radiation detector 100a obtains all the first, second, and third 2D images.

MULTIPLE PARTIAL IMAGES FOR EACH 2D IMAGE

In an embodiment, with reference to step 820 in the flowchart 800 of Fig. 8, said obtaining the 2D image (i) of the object may include (A) capturing Ni partial images of the object one by one using the radiation of the radiation beam (i) that has passed through the object, wherein Ni is an integer greater than 1; and (B) stitching the Ni partial images of the object resulting in the 2D image (i) of the object. For example, with reference to Fig. 7A, for the first 2D image capture (i.e., for i=1) , instead of capturing the first 2D image in one shot as described above, the radiation detector 100a may capture N1 partial images of the object 730 using the radiation of the radiation beam 722a that has passed through the object 730.

Specifically, assuming N1=3, while the radiation beam 722a is on, the radiation detector 100a may capture a first partial image of the object 730 while the radiation detector 100a is at a first location as shown in Fig. 7A. Next, in an embodiment, while the radiation beam 722a is still on, the radiation detector 100a may move along the rail 105 to a second location (not shown) and then capture a second partial image of the object 730 while the radiation detector 100a is at the second location. Next, in an embodiment, while the radiation beam 722a is still on, the radiation detector 100a may move further along the rail 105 to a third location (not shown) and then capture a third partial image of the object 730 while the radiation detector 100a is at the third location. Next, in an embodiment, the first, second, and third partial images may be stitched by the radiation detector 100a resulting in the first 2D image of the object 730.

In an embodiment, the second 2D image and the third 2D image may be obtained in a similar manner by the

radiation detectors

100b and 100c, respectively. Alternatively, the radiation detector 100a alone may move along the rail 105 and capture all the 9 partial images of the object 730 (assuming N1=N2=N3=3) and thereby obtain all the first, second, and third 2D images of the object 730.

In an embodiment, all Ni, i=1, …, M may be the same. For example, in the embodiments described above, N1=N2=N3=3. In other words, to obtain each 2D image of the first, second, and third 2D images, 3 partial images of the object 730 may be captured one by one and then stitched so as to obtain that 2D image as described above. In general, Ni, i=1, …, M are not necessarily the same. For example, it may be possible that N1=3, N2=4, and N3=2.

MORE ABOUT BOMBARDMENT BEAM GENERATOR

In an embodiment, with reference to Fig. 7A –Fig. 7C, the bombardment beam generator 710 may be stationary with respect to the object 730. In an embodiment, the bombardment beam generator 710 may be physically fixed to the target 725.

In an embodiment, the bombardment beam generator 710 may include multiple electron guns (not shown) each of which may send at least one of the

bombardment beams

712a, 712b, and 712c. For example, the bombardment beam generator 710 may include a first electron gun and a second electron gun (not shown) wherein the first electron gun sends the bombardment beam 712a, whereas the second electron gun sends the bombardment beams 712b and 712c. In an embodiment, the second electron gun may send the bombardment beams 712b and 712c one by one.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

A method, comprising:

sending M bombardment beams (bombardment beams (i) , i=1, …, M) respectively toward target spots (i) , i=1, …, M on a target resulting in radiation beams (i) , i=1, …, M emitting respectively from the target spots (i) , i=1, …, M and propagating toward an object, wherein M is an integer greater than 1; and

for each value of i, obtaining a 2D (two-dimensional) image (i) of the object using radiation of the radiation beam (i) that has passed through the object,

wherein the target is stationary with respect to the object.
The method of claim 1, further comprising reconstructing a 3D (three-dimensional) image of the object from the 2D images (i) , i=1, …, M.
The method of claim 1, wherein said obtaining the 2D image (i) of the object comprises:

capturing Ni partial images of the object one by one using the radiation of the radiation beam (i) that has passed through the object, wherein Ni is an integer greater than 1; and

stitching the Ni partial images of the object resulting in the 2D image (i) of the object.
The method of claim 3, wherein all Ni, i=1, …, M are the same.
The method of claim 1, wherein each of the M bombardment beams comprises an electron beam.
The method of claim 1, wherein the target comprises copper or tungsten.
The method of claim 1, wherein the bombardment beams (i) , i=1, …, M are sent one by one.
The method of claim 1, wherein an image sensor obtains all the 2D images (i) , i=1, …, M.
The method of claim 1, wherein said sending the M bombardment beams is performed using a bombardment beam generator which comprises multiple electron guns each of which sends at least one of the M bombardment beams.
The method of claim 9, wherein the bombardment beam generator is physically fixed to the target.
An imaging system, comprising:

a bombardment beam generator;

a target; and

an image sensor system comprising at least an image sensor,

wherein the bombardment beam generator is configured to send M bombardment beams (bombardment beams (i) , i=1, …, M) respectively toward target spots (i) , i=1, …, M on the target resulting in radiation beams (i) , i=1, …, M emitting respectively from the target spots (i) , i=1, …, M and propagating toward an object, wherein M is an integer greater than 1,

wherein the image sensor system is configured to, for each value of i, obtain a 2D (two-dimensional) image (i) of the object using radiation of the radiation beam (i) that has passed through the object, and

wherein the target is stationary with respect to the object.
The imaging system of claim 11, wherein the image sensor system is further configured to reconstruct a 3D (three-dimensional) image of the object from the 2D images (i) , i=1, …, M.
The imaging system of claim 11, wherein the image sensor system is further configured to obtain the 2D image (i) of the object by:

capturing Ni partial images of the object one by one using the radiation of the radiation beam (i) that has passed through the object, wherein Ni is an integer greater than 1; and

stitching the Ni partial images of the object resulting in the 2D image (i) of the object.
The imaging system of claim 13, wherein all Ni, i=1, …, M are the same.
The imaging system of claim 11, wherein each of the M bombardment beams comprises an electron beam.
The imaging system of claim 11, wherein the target comprises copper or tungsten.
The imaging system of claim 11, wherein the bombardment beams (i) , i=1, …, M are sent one by one.
The imaging system of claim 11, wherein an image sensor of the image sensor system obtains all the 2D images (i) , i=1, …, M.
The imaging system of claim 11, wherein the bombardment beam generator comprises multiple electron guns each of which sends at least one of the M bombardment beams.
The imaging system of claim 19, wherein the bombardment beam generator is physically fixed to the target.