50 has a predetermined spectral response (e.g., optimized to the emission spectrum of the at least one scintillator 20).

In certain implementations, the apparatus 10 further comprises an x-ray detector system 60 (e.g., one or more type-I x-ray imaging detectors) configured to receive and use (e.g., for imaging) at least some of the x-rays of the second portion 12b that propagate through the at least one mirror 40. For example, as shown in FIG. 1, the x-ray detector system 60 can be positioned sequentially along the x-ray propagation direction 13 (e.g., downstream from the at least one mirror 40). Examples of the x-ray detector system 60 can include, but are not limited to: a scintillator and an optical lens that does not have a hole or aperture (e.g., the x-ray detector system 60 is not configured to transmit x-rays); an x-ray camera; a flat panel detector; a pixel array photon counting detector; an amorphous Se pixel array detector. For example, a flat panel detector of the x-ray detector system 60 can comprise single-crystal, high efficiency scintillator microstructures having a thickness (e.g., greater than or equal to 150 microns; in a range of 150 microns to 500 microns; greater than or equal to 500 microns), configured to reduce (e.g., minimize) scattering or other factors that can otherwise degrade spatial resolution.

Example Implementations

FIGS. 2A-2F schematically illustrate various example apparatus 100 in accordance with certain implementations described herein. Each of the example apparatus 100 of FIGS. 2A-2F comprises a plurality of x-ray imaging detectors 110 sequentially arranged along an x-ray propagation direction 13. For example, the plurality (e.g., array) of x-ray imaging detectors 110 can comprise at least a first x-ray imaging detector 110a and a second x-ray imaging detector 110b, the first and second x-ray imaging detectors 110a,b configured sequentially along the x-ray beam propagation direction 13 (e.g., the second x-ray imaging detector 110b downstream from the first x-ray imaging detector 110a).

In certain implementations, each x-ray imaging detector 110 of the plurality of x-ray imaging detectors 110 is configured to provide a spatial resolution finer than 25 microns (e.g., less than 10 microns; less than 2 microns; less than 1 micron). In certain implementations, the plurality of x-ray imaging detectors 110 comprises at least two (e.g., more than 2; more than 5, more than 10) x-ray imaging detectors 110 configured to achieve sufficiently high x-ray detection efficiency to facilitate x-ray imaging applications with x-rays having energies greater than 15 keV (e.g., greater than 30 keV; greater than 60 keV). Certain such implementations can facilitate optimizing resolution and detector efficiency and/or x-ray spectral response by selecting appropriate scintillator materials. In certain implementations, the first x-ray imaging detector 110a has a first field-of-view and the second x-ray imaging detector 110b has a second field-of-view, and a ratio of the first field-of-view to the second field-of-view is in a range of 1 to 50 and/or a ratio of the second field-of-view to the first field-of-view is in a range of 1 to 50.

FIG. 2A schematically illustrates an example apparatus 100 configured to receive an x-ray beam 2 propagating along the x-ray propagation direction 13 and comprising at least two type-I x-ray imaging detectors configured sequentially along the x-ray propagation direction 13 in accordance with certain implementations described herein. As shown in FIG. 2A, the first x-ray imaging detector 110a (e.g., a type-I x-ray imaging detector) comprises a first scintillator 20a, a first optical lens system 30a (e.g., downstream from the first scintillator 20a), a first mirror 40a (e.g., downstream from the first optical lens system 30a), and a first optical detector system 50a. The first scintillator 20a is configured to be irradiated by an x-ray beam 2 propagating along an x-ray propagation direction 13, to generate first visible light 22a in response to at least some of the x-rays of the x-ray beam 2 (e.g., a first fraction of the x-rays incident on the first scintillator 20a), and to allow at least some x-rays of the x-ray beam 2 to propagate through the first scintillator 20a. The first optical lens system 30a is configured to receive at least some of the first visible light 22a from the first scintillator 20a and to allow at least some x-rays of the x-ray beam 2 that propagate through the first scintillator 20a to propagate through the first optical lens system 30a. For example, the first optical lens system 30a can comprise a first x-ray transmissive region 32a (e.g., a first aperture, hole, or pupil) having a width substantially perpendicular to the x-ray propagation direction 13 and in the range of 0.3 millimeter to 40 millimeters (e.g., in a range of 0.5 millimeter to 6 millimeters; in a range of 5 millimeters to 20 millimeters). The first mirror 40a is configured to reflect at least some of the first visible light 22a from the first optical lens system 30a in a first direction non-parallel relative to the x-ray propagation direction 13 and to allow at least some x-rays of the x-ray beam 2 that propagate through the first optical lens system 30a to propagate through the first mirror 40a. For example, the first mirror 40a can comprise a second x-ray transmissive region 42a (e.g., a second aperture, hole, or pupil; a solid portion sufficiently thin to allow at least 20% of the incident x-rays within a predetermined spectral region of the x-ray beam 2 to propagate therethrough) having a width substantially perpendicular to the x-ray propagation direction 13 and in the range of 0.3 millimeter to 40 millimeters (e.g., in a range of 0.5 millimeter to 6 millimeters; in a range of 5 millimeters to 20 millimeters). The first optical detector system 50a (e.g., comprising a first camera 52a and a first lens 54a configured to receive and focus the first visible light 22a from the first mirror 40a onto the first camera 52a) is configured to receive the first visible light 22a reflected by the first mirror 40a and to generate a first image in response to the received first visible light 22a.

As shown in FIG. 2A, the second x-ray imaging detector 110b (e.g., a type-I x-ray imaging detector) comprises a second scintillator 20b, a second optical lens system 30b (e.g., downstream from the second scintillator 20b), a second mirror 40b (e.g., downstream from the second optical lens system 30b), and a second optical detector system 50b. The second scintillator 20b is configured to be irradiated by the x-rays of the x-ray beam 2 that propagate through the first mirror 40a, to generate second visible light 22b in response to at least some of the x-rays of the x-ray beam 2 (e.g., a second fraction of the x-rays incident on the second scintillator 20b), and to allow at least some x-rays of the x-ray beam 2 to propagate through the second scintillator 20b. The second optical lens system 30b is configured to receive at least some of the second visible light 22b from the second scintillator 20b and to allow at least some x-rays of the x-ray beam 2 that propagate through the second scintillator 20b to propagate through the second optical lens system 30b. For example, the second optical lens system 30b can comprise a third x-ray transmissive region 32b (e.g., a third aperture, hole, or pupil) having a width substantially perpendicular to the x-ray propagation direction 13 and in the range of 0.3 millimeter to 40 millimeters (e.g., in a range of 0.5 millimeter to 6 millimeters; in a range of 5 millimeters to 20 millimeters). The second mirror 40b is configured to reflect at least some of the second visible light 22b from the second optical lens system 30b in a second direction non-parallel relative to the x-ray propagation direction 13 and to allow at least some x-rays of the x-ray beam 2 that propagate through the second optical lens system 30b to propagate through the second mirror 40b. For example, the second mirror 40b can comprise a fourth x-ray transmissive region 42b (e.g., a fourth aperture, hole, or pupil; a solid portion sufficiently thin to allow at least 20% of the incident x-rays within a predetermined spectral region of the x-ray beam 2 to propagate through) having a width substantially perpendicular to the x-ray propagation direction 13 and in the range of 0.3 millimeter to 40 millimeters (e.g., in a range of 0.5 millimeter to 6 millimeters; in a range of 5 millimeters to 20 millimeters). The second optical detector system 50b (e.g., comprising a second camera 52b and a second lens 54b configured to receive and focus the second visible light 22b from the second mirror 40b onto the second camera 52b) is configured to receive the second visible light 22b reflected by the second mirror 40b and to generate a second image in response to the received second visible light 22b.

While FIG. 2A shows that each of the first scintillator 20a and the second scintillator 20b is substantially perpendicular to the x-ray propagation direction 13, in certain other implementations, at least one of the first and second scintillators 20a,b is configured to be tilted to be non-normal to the x-ray propagation direction 13 (e.g., with the respective first and/or second optical lens system 30a,b also tilted correspondingly relative to the x-ray propagation direction 13). In certain implementations, the first scintillator 20a and the second scintillator 20b comprise different scintillating materials from one another (e.g., visible light 22a,6 emitted from the first and second scintillators 20a,b, respectively, have different spectral ranges from one another). In certain implementations, as shown in FIG. 2A, the first mirror 40a and the second mirror 40b reflect the first visible light 22a and the second visible light 22b, respectively, in first and second directions, respectively, that are substantially parallel to one another (e.g., the reflected first visible light 22a and the reflected second visible light 22b are at substantially equal non-zero angles relative to the x-ray propagation direction 13) and the first optical detector system 50a and the second optical detector system 50b are positioned at the same side of the x-ray propagation direction 13 (e.g., at substantially the same azimuthal angle about the x-ray propagation direction 13). In certain other implementations, the first mirror 40a and the second mirror 40b reflect the first visible light 22a and the second visible light 22b, respectively, in first and second directions, respectively, that are different from one another (e.g., that are not substantially parallel to one another; the reflected first visible light 22a and the reflected second visible light 22b are at substantially different non-zero angles relative to the x-ray propagation direction 13) and/or the first optical detector system 50a and the second optical detector system 50b are positioned at different azimuthal angles about (e.g., different sides of) the x-ray propagation direction 13.

Each of FIGS. 2B-2D schematically illustrates an example apparatus 100 configured to receive an x-ray beam 2 propagating along the x-ray propagation direction 13 and comprising at least one type-I x-ray imaging detector and at least one type-II x-ray imaging detector configured sequentially along the x-ray propagation direction 13 in accordance with certain implementations described herein. As shown in FIGS. 2B-2D, in certain implementations, the at least one type-II x-ray imaging detector is downstream from the at least one type-I x-ray imaging detector, while in certain other implementations, the at least one type-I x-ray imaging detector is downstream from the at least one type-II x-ray imaging detector. Although each of the example apparatus 100 shown in FIGS. 2A-2D comprises only two x-ray imaging detectors 100a,b, other implementations can comprise more than two x-ray imaging detectors (e.g., comprising at least two type-I x-ray imaging detectors and at least one type-II x-ray imaging detector or comprising at least one type-I x-ray imaging detector and at least two type-II x-ray imaging detectors) configured sequentially along the x-ray beam propagation direction 13.

As shown in FIG. 2B, the first x-ray imaging detector 110a (e.g., a type-I x-ray imaging detector) can comprise a first scintillator 20a, a first optical lens system 30a (e.g., downstream from the first scintillator 20a), a first mirror 40a (e.g., downstream from the first optical lens system 30a), and a first optical detector system 50a. The first scintillator 20a can be configured to be irradiated by an x-ray beam 2 propagating along an x-ray propagation direction 13, to generate first visible light 22a in response to at least some of the x-rays of the x-ray beam 2 (e.g., a first fraction of the x-rays incident on the first scintillator 20a), and to allow at least some x-rays of the x-ray beam 2 to propagate through the first scintillator 20a. The first optical lens system 30a can be configured to receive at least some of the first visible light 22a from the first scintillator 20a and to allow at least some x-rays of the x-ray beam 2 that propagate through the first scintillator 20a to propagate through the first optical lens system 30a. For example, the first optical lens system 30a can comprise a first x-ray transmissive region 32a (e.g., a first aperture, hole, or pupil) having a width substantially perpendicular to the x-ray propagation direction 13 and in the range of 0.3 millimeter to 40 millimeters (e.g., in a range of 0.5 millimeter to 6 millimeters; in a range of 5 millimeters to 20 millimeters). The first mirror 40a can be configured to reflect at least some of the first visible light 22a from the first optical lens system 30a in a first direction non-parallel relative to the x-ray propagation direction 13 and to allow at least some x-rays of the x-ray beam 2 that propagate through the first optical lens system 30a to propagate through the first mirror 40a. For example, the first mirror 40a can comprise a second x-ray transmissive region 42a (e.g., a second aperture, hole, or pupil; a solid portion sufficiently thin to allow at least 20% of the incident x-rays within for a predetermined spectral region of the x-ray beam 2 to propagate therethrough) having a width substantially perpendicular to the x-ray propagation direction 13 and in the range of 0.3 millimeter to 40 millimeters (e.g., in a range of 0.5 millimeter to 6 millimeters; in a range of 5 millimeters to 20 millimeters). The first optical detector system 50a (e.g., comprising a first camera 52a and a first lens 54a configured to receive and focus the first visible light 22a from the first mirror 40a onto the first camera 52a) can be configured to receive the first visible light 22a reflected by the first mirror 40a and to generate a first image in response to the received first visible light 22a.

As shown in FIG. 2B, the second x-ray imaging detector 110b (e.g., a type-II x-ray imaging detector) can comprise a second scintillator 20b, a second mirror 40b (e.g., downstream from the second scintillator 20b), and a second optical detector system 50b. The second scintillator 20b can be configured to be irradiated by the x-rays of the x-ray beam 2 that propagate through the first mirror 40a, to generate second visible light 22b in response to at least some of the x-rays of the x-ray beam 2 (e.g., a second fraction of the x-rays incident on the second scintillator 20b), and to allow at least some x-rays of the x-ray beam 2 to propagate through the second scintillator 20b. The second mirror 40b can be configured to reflect at least some of the second visible light 22b from the second scintillator 20b in a second direction non-parallel relative to the x-ray propagation direction 13 and to allow at least some x-rays of the x-ray beam 2 that propagate through the second scintillator 20b to propagate through the second mirror 40b. For example, the second mirror 40b can comprise a third x-ray transmissive region 42b (e.g., a third aperture, hole, or pupil; a solid portion sufficiently thin to allow at least 20% of the incident x-rays within a predetermined spectral region of the x-ray beam 2 to propagate therethrough) having a width substantially perpendicular to the x-ray propagation direction 13 and in the range of 0.3 millimeter to 40 millimeters (e.g., in a range of 0.5 millimeter to 6 millimeters; in a range of 5 millimeters to 20 millimeters). The second optical detector system 50b (e.g., comprising a second camera 52b and a second lens 54b configured to receive and focus the second visible light 22b from the second mirror 40b onto the second camera 52b) can be configured to receive the second visible light 22b reflected by the second mirror 40b and to generate a second image in response to the received second visible light 22b. While FIG. 2A shows that each of the first scintillator 20a and the second scintillator 20b is substantially perpendicular to the x-ray propagation direction 13, in certain other implementations, at least one of the first and second scintillators 20a,b is configured to be tilted to be non-normal to the x-ray propagation direction 13.

As shown in FIGS. 2C and 2D, the first x-ray imaging detector 110a (e.g., a type-II x-ray imaging detector) can comprise a first scintillator 20a, a first mirror 40a, and a first optical detector system 50a. The first scintillator 20a can be configured to be irradiated by the x-rays of the x-ray beam 2, to generate first visible light 22a in response to at least some of the x-rays of the x-ray beam 2 (e.g., a first fraction of the x-rays incident on the first scintillator 20a), and to allow at least some x-rays of the x-ray beam 2 to propagate through the first scintillator 20a. The first mirror 40a can be configured to reflect at least some of the first visible light 22a from the first scintillator 20a in a first direction non-parallel relative to the x-ray propagation direction 13 and to allow at least some x-rays of the x-ray beam 2 that propagate through the first scintillator 20a to propagate through the first mirror 40a. For example, the first mirror 40a can comprise a first x-ray transmissive region 42a (e.g., an aperture, hole, or pupil; a solid portion sufficiently thin to allow at least 20% of the incident x-rays within a predetermined spectral region of the x-ray beam 2 to propagate therethrough) having a width substantially perpendicular to the x-ray propagation direction 13 and in the range of 0.3 millimeter to 40 millimeters (e.g., in a range of 0.5 millimeter to 6 millimeters; in a range of 5 millimeters to 20 millimeters). The first optical detector system 50a (e.g., comprising a first camera 52a and a first lens 54a configured to receive and focus the first visible light 22a from the first mirror 40a onto the first camera 52a) can be configured to receive the first visible light 22a reflected by the first mirror 40a and to generate a first image in response to the received first visible light 22a.

As shown in FIGS. 2C and 2D, the second x-ray imaging detector 110b (e.g., a type-I x-ray imaging detector) can comprise a second scintillator 20b, an optical lens system 30b (e.g., downstream from the first scintillator 20b), a second mirror 40b (e.g., downstream from the optical lens system 30b), and a second optical detector system 50b. The second scintillator 20b can be configured to be irradiated by the portion of the x-ray beam 2 propagating along the x-ray propagation direction 13 through the first x-ray transmissive region 42a, to generate second visible light 22b in response to at least some of the x-rays of the x-ray beam 2 (e.g., a second fraction of the x-rays incident on the second scintillator 20b), and to allow at least some x-rays of the x-ray beam 2 to propagate through the second scintillator 20b. The optical lens system 30b can be configured to receive at least some of the second visible light 22b from the second scintillator 20b and to allow at least some x-rays of the x-ray beam 2 that propagate through the second scintillator 20b to propagate through the optical lens system 30b. For example, the optical lens system 30b can comprise a second x-ray transmissive region 32b (e.g., a second aperture, hole, or pupil) having a width substantially perpendicular to the x-ray propagation direction 13 and in the range of 0.3 millimeter to 40 millimeters (e.g., in a range of 0.5 millimeter to 6 millimeters; in a range of 5 millimeters to 20 millimeters). The second mirror 40b can be configured to reflect at least some of the second visible light 22b from the optical lens system 30b in a second direction non-parallel relative to the x-ray propagation direction 13 and to allow at least some x-rays of the x-ray beam 2 that propagate through the optical lens system 30b to propagate through the second mirror 40b. For example, the second mirror 40b can comprise a third x-ray transmissive region 42b (e.g., a third aperture, hole, or pupil; a solid portion sufficiently thin to allow at least 20% of the incident x-rays within a predetermined spectral region of the x-ray beam 2 to propagate therethrough) having a width substantially perpendicular to the x-ray propagation direction 13 and in the range of 0.3 millimeter to 40 millimeters (e.g., in a range of 0.5 millimeter to 6 millimeters; in a range of 5 millimeters to 20 millimeters). The second optical detector system 50b (e.g., comprising a second camera 52b and a second lens 54b configured to receive and focus the second visible light 22b from the second mirror 40b onto the second camera 52b) can be configured to receive the second visible light 22b reflected by the second mirror 40b and to generate a second image in response to the received second visible light 22b. While FIG. 2A shows that each of the first scintillator 20a and the second scintillator 20b is substantially perpendicular to the x-ray propagation direction 13, in certain other implementations, at least one of the first and second scintillators 20a,b is configured to be tilted to be non-normal to the x-ray propagation direction 13.

As shown in FIG. 2C, the first mirror 40a is downstream from the first scintillator 20a, while in certain other implementations, as shown in FIG. 2D, the first mirror 40a is upstream from the first scintillator 20a and the first scintillator 20a is irradiated by at least some of the x-rays of the x-ray beam 2 that propagate through the first x-ray transmissive region 42a of the first mirror 40a. In certain implementations, as shown in FIG. 2D, the first scintillator 20a and the second scintillator 20b can be adjacent to one another. The apparatus 100 can comprise a light blocker (not shown) between the first and second scintillators 20a,b that is optically opaque but is transmissive to the x-rays of the x-ray beam 2 (e.g., x-ray transmission greater than 20% for x-rays having energies greater than 5 keV). For example, the light blocker can comprise a thin graphite plate or a plastic film coated with a carbon layer or a thin Al layer.

FIG. 2E schematically illustrates an example apparatus 100 configured to receive an x-ray beam 2 propagating along the x-ray propagation direction 13 and comprising at least two type-II x-ray imaging detectors configured sequentially along the x-ray propagation direction 13 in accordance with certain implementations described herein. As shown in FIG. 2E, the first x-ray imaging detector 110a (e.g., a type-II x-ray imaging detector) can comprise a first scintillator 20a, a first mirror 40a, and a first optical detector system 50a, as described herein with regard to FIGS. 2C and 2D, and the second x-ray imaging detector 110b (e.g., a type-II x-ray imaging detector) can comprise a second scintillator 20b, a second mirror 40b (e.g., downstream from the second scintillator 20b), and a second optical detector system 50b, as described herein with regard to FIG. 2B. While FIG. 2E shows the first mirror 40a is downstream from the first scintillator 20a and the second mirror 40b is downstream from the second scintillator 20b, in certain other implementations, the first mirror 40a is upstream from the first scintillator 20a (see, e.g., FIG. 2D) and/or the second mirror 40b is upstream from the second scintillator 20b.

As shown in FIGS. 2B-2E, in certain implementations, the apparatus 100 further comprises an x-ray detector system 60 (e.g., one or more type-I x-ray imaging detectors; one or more type-II x-ray imaging detectors) configured to receive and use (e.g., for imaging) at least some of the x-rays of the x-ray beam 2 that propagate through both the first x-ray imaging detector 110a and the second x-ray imaging detector 110b. For example, as shown in FIGS. 2B-2E, the x-ray detector system 60 can be positioned sequentially along the x-ray propagation direction 13 (e.g., downstream from the first and second x-ray imaging detectors 110a,b). Examples of the x-ray detector system 60 can include, but are not limited to: a scintillator and an optical lens that does not have a hole or aperture (e.g., the x-ray detector system 60 is not configured to transmit x-rays); an x-ray camera; a flat panel detector; a pixel array photon counting detector; an amorphous Se pixel array detector. For example, a flat panel detector of the x-ray detector system 60 can comprise single-crystal, high efficiency scintillator microstructures having a thickness (e.g., greater than or equal to 250 microns; in a range of 150 microns to 250 microns; greater than or equal to 500 microns), configured to reduce (e.g., minimize) scattering or other factors that can otherwise degrade spatial resolution. While FIG. 2E shows that each of the first scintillator 20a and the second scintillator 20b is substantially perpendicular to the x-ray propagation direction 13, in certain other implementations, at least one of the first and second scintillators 20a,b is configured to be tilted to be non-normal to the x-ray propagation direction.

FIG. 2F schematically illustrates an example apparatus 100 comprising a plurality of x-ray imaging detectors 110a,b, . . . , n configured sequentially along an x-ray beam propagation direction 13 in accordance with certain implementations described herein. As shown in FIG. 2F, each x-ray imaging detector 110a,b, . . . , n comprises at least one scintillator 20a,b, . . . , n configured to allow a portion of the x-ray beam 2 incident on the at least one scintillator 20a,b, . . . , n to propagate through the at least one scintillator 20a,b, . . . , n and to generate visible light 22a,b, . . . , n in response to at least some of the x-rays of the x-ray beam 2. Each x-ray imaging detector 110a,b, . . . , n further comprises an objective 140a,b, . . . , n comprising at least one mirror 40a,b, . . . , n configured to allow propagation of at least a portion of the x-ray beam 2 through the objective 140a,b, . . . n and to reflect at least some of the visible light 22a,b, . . . , n from the at least one scintillator 20a,b, . . . , n in a direction non-parallel (e.g., substantially perpendicular) relative to the x-ray propagation direction 13 of the x-ray beam 2. Each x-ray imaging detector 110a,b, . . . , n further comprises at least one optical detector system 50a,b, . . . , n (e.g., each comprising a camera 52a,b, . . . , n and a lens 54a,b, . . . , n) configured to receive the visible light 22a,b, . . . , n reflected by the objective 140a,b, . . . , n and to generate an image in response to the received visible light 22a,b, . . . , n. While FIG. 2F shows that each of the at least one scintillator 20a,b, . . . , n is substantially perpendicular to the x-ray propagation direction 13, in certain other implementations, at least one of scintillators 20a,b, . . . , n is configured to be tilted to be non-normal to the x-ray propagation direction 13 (e.g., with the respective optical detector system 50a,b, . . . , n also tilted correspondingly relative to the x-ray propagation direction 13).

In certain implementations, as shown in FIG. 2F, each x-ray imaging detector 110a,b, . . . , n can comprise an objective enclosure 141a,b, . . . , n containing at least a portion of the at least one mirror 40a,b, . . . , n. The at least one mirror 40a,b, . . . , n can comprise a first mirror 142a,b, . . . , n (e.g., convex mirror), a second mirror 144a,b, . . . , n (e.g., concave mirror), and a third mirror 146a,b, . . . , n (e.g., substantially flat mirror). For example, both the first mirror 142a,b, . . . n and the second mirror 144a,b, . . . , n can be within the objective enclosure 140a,b, . . . , n (e.g., with the first mirror 142a,b, . . . , n downstream from the second mirror 144a,b, . . . , n) and the third mirror 146a,b, . . . , n can be outside the objective enclosure 140a,b, . . . , n (e.g., downstream from the first mirror 142a,b, . . . , n). Each of the first mirror 142a,b, . . . , n, the second mirror 144a,b, . . . , n, and the third mirror 146a,b, . . . , n can comprise an x-ray transmissive region 42a,b, . . . , n configured to allow at least a portion of the x-ray beam 2 to propagate therethrough.

The first mirror 142a,b, . . . , n can be configured to receive and reflect the visible light 22a,b, . . . , n from the at least one scintillator 20a,b, . . . , n to the second mirror 144a,b, . . . , n. The second mirror 144a,b, . . . , n can be configured to receive and reflect the visible light 22a,b, . . . , n from the first mirror 142a,b, . . . , n to the third mirror 146a,b, . . . , n. For example, the first mirror 142a,b, . . . , n can comprise an aperture configured to allow the visible light 22a,b, . . . , n to propagate through the first mirror 142a,b, . . . , n from the second mirror 144a,b, . . . , n to the third mirror 146a,b, . . . , n. The third mirror 146a,b, . . . , n can be configured to receive and reflect the visible light 22a,b, . . . , n (e.g., by an angle substantially equal to 45 degrees) to the optical detector system 50a,b, . . . , n.

While FIG. 2F shows each of the x-ray imaging detectors 110a,b, . . . n as having substantially identical structures to one another (e.g., each comprises a type-II x-ray imaging detector), in certain other implementations, two or more of the x-ray imaging detectors 110a,b, . . . n have different structures from one another (e.g., at least one type-I x-ray imaging detector and at least one type-II x-ray imaging detector).

In certain implementations, the scintillator materials of the at least one scintillator 20a,b, . . . , n are configured to have sufficiently high x-ray absorption of the x-rays of the x-ray beam 2 in a predetermined energy band, based on the absorption edges of a high atomic number (Z) elements of the scintillator materials. For example, ten x-ray imaging detectors 110, each with a 5-micron LSO scintillator 20 and a reflective microscope objective 140 with 0.5 NA, can be used for sub-micron resolution imaging with an effective total 50-micron LSO scintillator thickness with ten type-I and/or type-II x-ray imaging detectors. In certain implementations, the sequentially arranged plurality of x-ray imaging detectors 110 can offer up to 10× imaging speed/throughput as compared to a single x-ray imaging detector with the same scintillator 20 and the same optical lens system 30. In certain implementations, the LSO scintillator can be replaced by other scintillator materials or other thickness, or a different optical lens system can be used. For example, five x-ray imaging detectors 110 each with a 150-micron LSO scintillator and a 0.14 NA objective can be used for 6-micron resolution imaging with an effective 750-micron LSO scintillator thickness, which can offer up to 5× imaging speed/throughput compared to a single x-ray imaging detector with the same scintillator 20 and the optical lens system 30.

In certain implementations, the sequentially arranged plurality of x-ray imaging detectors 110 are configured to obtain a spatial resolution less than 10 microns (e.g., less than 3 microns; less than 1 micron) by utilizing scintillator materials emitting short wavelength light (e.g., less than 400 nm wavelength) and/or utilizing high NA lens systems (e.g., NA greater than 0.1, greater than 0.5, or greater than 0.7), and/or utilizing thin scintillators (e.g., thicknesses along the x-ray propagation direction 13 that are less than 5 microns). In certain implementations, the sequentially arranged plurality of x-ray imaging detectors 110 are configured to obtain a spatial resolution less than 10 microns (e.g., less than 3 microns; less than 1 micron) and another x-ray detector system 60 (e.g., a flat panel detector; pixel array photon counting detector; a pixel array amorphous Se detector) is positioned sequentially along the x-ray propagation direction 13 (e.g., downstream from the plurality of x-ray imaging detectors 110) and is configured for high x-ray detection efficiency with coarser spatial resolution (e.g., greater than 10 microns; greater than 25 microns; greater than 50 microns).

In certain implementations, the sequentially arranged plurality of x-ray imaging detectors 110 comprise different scintillation materials and thicknesses to obtain predetermined detection efficiency for x-rays within predetermined energy bandwidths. For example, LSO scintillators absorb more strongly for x-rays of energies greater than 63.3 keV (which corresponds to the K absorption edge of lutetium) than do CsI scintillators of the same thickness. In certain implementations, the LSO scintillator can be replaced by other scintillator materials or other thickness to obtain high x-ray detection efficiency for x-rays of another predetermined energy range (e.g., GaGG for x-rays of energies in a range of 50.3 keV to 63 keV; YAG for x-rays of energies in a range of 17 keV to 35 keV; GLO for x-rays of energies in a range of 50.3 keV to 100 keV). In certain implementations, at least two scintillators 20 of different materials (e.g., YAG; CsI; GaGG; LSO; GLO) are used for their different spectral absorption efficiency responses as the x-ray absorption efficiency of a scintillator depends on the scintillator material (e.g., x-rays of energies higher than an absorption edge of a key atomic element in the scintillator are more strongly absorbed than x-rays of energies below the absorption edge). For example, three x-ray imaging detectors 110, each having a scintillator 20 with a scintillator material of CsI, GaGG, and LSO, respectively, can provide improved x-ray absorption for x-rays of energies across the range of 10 keV to 160 keV, as compared to all three x-ray imaging detectors 110 using the same scintillator material. In certain implementations, a plurality of x-ray imaging detectors 110 with two or more different scintillator materials are used with another x-ray detector system 60 (e.g., a flat panel detector; pixel array photon counting detector; a pixel array amorphous Se detector) and the recorded images can be processed to obtain spatially resolved spectral absorption information of an object being imaged. In certain implementations, at least one spectral filter comprising a high atomic number element and a predetermined thickness is positioned upstream of an x-ray imaging detector 110 to change the spectral response of the x-ray imaging detector 110. In certain implementations, another x-ray detector system 60 (e.g., a flat panel detector; pixel array photon counting detector; a pixel array amorphous Se detector) is used together with the plurality of x-ray imaging detectors 110 to obtain additional detection efficiency over a predetermined energy bandwidths (e.g., use of energy thresholds in a pixel array photon counting detector).

In certain implementations, the plurality of x-ray imaging detectors 110, with or without another x-ray detector system 60 (e.g., a flat panel detector; pixel array photon counting detector; a pixel array amorphous Se detector) is configured with predetermined separation distances between adjacent x-ray imaging detectors 110 along the x-ray beam propagation direction 13 to obtain angular divergence information of the x-ray beam 2, effectively acting as a 3D x-ray detector that records both positional information as well as angular information.

Various applications are compatible with certain such implementations. For example, such arrangement can be used for x-ray imaging of an object with absorption, and/or scattering (e.g., darkfield), and/or refraction contrast. For another example, certain implementations can be used to record the origin of x-rays diffracted by crystallites in an object illuminated by a focused x-ray beam 2, either a point focus x-ray beam 2 or a sheet focus x-ray beam 2. Using a 3D x-ray detector, a diffracted x-ray beam (e.g., having a narrow energy band) can be triangulated together with the focused x-ray beam 2 to localize the origin of a diffracted x-ray beam. Multiple diffracted beams can be recorded. For example, the scintillator material and the thickness of the scintillator 20 of the upstream x-ray imaging detector 110 can be configured such that the scintillator 20 has an x-ray transmission greater than 5% for the diffracted x-rays so that the transmitted diffracted x-rays can be recorded by a downstream detector. In certain implementations, the separation distance and the spatial resolution of the x-ray imaging detectors 110 can determine the precision for localizing the origin of a diffracted x-ray beam. In certain implementations in which the energies of the diffracted x-ray beams are less than 15 keV, scintillators of low atomic number (Z) materials (e.g., CaF₂) or scintillators based on high Z materials (e.g., Lu, Gd, Y, CsI, and Cd) with thicknesses less than 50 microns can be used. In certain implementations, a plurality of different scintillator materials with predetermined thicknesses can be used to obtain energy information of the diffracted x-ray beam.

In certain implementations, the scintillator 20 of the x-ray imaging detector 110 closest to an object (e.g., sample being analyzed) is placed as close to the object as possible (e.g., less than 1 mm, less than 5 mm, less than 20 mm, less than 100 mm). In certain implementations, the scintillators 20 of at least two x-ray imaging detectors 110, for example, with another x-ray detector system 60 (e.g., a flat panel detector; pixel array photon counting detector; a pixel array amorphous Se detector) are configured with a separation distance between the scintillator 20 of one x-ray imaging detector 110 and the scintillator 20 of another adjacent x-ray imaging detector 110 along the x-ray propagation direction 13 greater than 10 mm (e.g., greater than 100 mm; greater than 1000 mm).

In certain implementations, at least two x-ray imaging detectors 110 or at least one x-ray imaging detector 110 and another x-ray detector system 60 (e.g., a flat panel detector; pixel array photon counting detector; a pixel array amorphous Se detector) are configured with predetermined separation distances between adjacent x-ray detectors so that the pixel size projected on an object in a projection x-ray microscope geometry is substantially equal. As scattering and/or refraction of incident x-rays by an object leads to angular change, an x-ray imaging detector 110 placed close to the object will not be sensitive to the angular change while an x-ray imaging detector 110 placed farther away from the object will be more sensitive to the angular change. By recording and processing x-ray images taken by two or more x-ray imaging detectors 110 and/or a flat panel, a pixel array photon counting detector, a pixel array amorphous Se detector, images with absorption, phase, and scattering contrast can be obtained.

In certain implementations, at least two x-ray imaging detectors, or at least one x-ray imaging detector and another x-ray detector system 60 (e.g., a flat panel detector; pixel array photon counting detector; a pixel array amorphous Se detector) are configured with field-of-view differences greater than 1.5×, greater than 3×, or greater than 10×. In certain implementations, the different fields-of-view are centered to each other. In certain implementations, the centers of the different fields-of-view have an offset relative to one another. In certain implementations, a field-of-view image with a smaller area has a higher spatial resolution than a field-of-view image with a larger area. In certain implementations, the smaller field-of-view image with higher resolution is used to improve the spatial resolution of the larger field-of-view image with coarser resolution.

In certain implementations, at least two x-ray imaging detectors 110 are configured to have the same pixel resolution as one another on a plane substantially perpendicular to the x-ray beam propagation direction 13 and are shifted by an integer fraction of the pixel resolution in a direction substantially perpendicular to the x-ray beam propagation direction 13 (e.g., the integer equal to the number of x-ray imaging detectors 110). In certain implementation, the x-ray imaging detectors 110 are configured to have the same pixel resolution as one another on a plane substantially perpendicular to the x-ray beam propagation direction 13 in the sample and are shifted by an integer fraction of the pixel resolution in two substantially orthogonal directions substantially perpendicular to the x-ray beam propagation direction 13 (e.g., with the integer equaling the number of x-ray imaging detectors 110 in the respective direction). In certain implementations, at least two x-ray imaging detectors 110 can be displaced (e.g., shifted) relative to each other in a direction substantially perpendicular to the x-ray beam propagation direction 13. Certain such implementations can concurrently record x-ray transmission images and can use resolution image processing algorithms to obtain better spatial resolution than a single x-ray imaging detector (e.g., by a factor up to the number of x-ray imaging detectors 110 in the respective direction).

In certain implementations, higher resolution in a predetermined direction is used (e.g., direction along a surface normal of an electronic package). To minimize pixel resolution change along the x-ray beam propagation direction 13 within a sample, small separations between the scintillators 20 of the x-ray imaging detectors 110 can be used. Images recorded by these x-ray imaging detectors 110 can be processed using algorithms developed for super resolution by collecting and processing x-ray images before and after shifting (e.g., dithering) a detector 50.

Certain implementations described herein provide one or more features, examples of which include but are not limited to:

- Increasing imaging throughput by allowing x-rays transmitted through a thin scintillator 20 to be used for imaging with at least one of: a substantially similar x-ray camera with an aperture, a substantially similar x-ray camera without an aperture, a flat panel detector, a pixel array photon counting detector, an amorphous Se pixel array detector. Certain implementations can use a plurality of similar x-ray cameras configured along the x-ray beam 2 to facilitate high resolution x-ray imaging: high NA for high spatial resolution with short depth-of-focus and a thin scintillator 20 with low x-ray absorption and low detector efficiency.
- Concurrent imaging of small field-of-view with high resolution and large field-of-view with coarser resolution. For example, by using high resolution images that overlap with large field-of-view images with coarser resolution, the resolution of the large field-of-view images can be improved.
- Obtaining material composition information by utilizing different scintillator properties (e.g., materials and thickness) of x-ray cameras and flat panels or photoconductor materials of photon counting detectors. In certain implementations, the scintillator properties can be used in conjunction with the energy windows of a photon counting detector.
- Concurrently imaging with absorption contrast, refraction, and darkfield imaging based on the distance of a camera from the sample as angular change due to scattering and refraction by a feature can be measured by the shift of the image position on a camera/detector, with plural cameras and/or detectors configured with predetermined distances from the sample. For example, a camera placed close to the sample can record mostly the absorption contrast image, a camera/detector position away from the sample can contain a superposition of images from scattering, refraction and darkfield images. By using predetermined distances, the recorded images can be processed according to predetermined algorithms to obtain darkfield, absorption, and phase contrast images.
- 3D camera to track origins of diffracted x-ray beams, which are generally monochromatic, for performing 3D x-ray diffraction tomography or microscopy by selecting appropriate distances between at least two x-ray imaging detectors to be in a range of 2 mm to 300 mm (e.g., in a range of 5 mm to 100 mm; in a range of 10 mm to 50 mm).
- Improving signal-to-noise ratio (S/N) in some images with optimal energy bandwidth and lower radiation dose as compared to a single integrated detector.
- Switching scintillator materials and thicknesses in response to sample composition and size.
- Smaller scintillators in at least one direction.
- Smaller aperture s (e.g., slits or 2D aperture) for high resolution.
  
  Applications in x-Ray Imaging Systems

In certain implementations, a projection x-ray imaging system or a laminography system (e.g., microscope) comprises an apparatus 10,100 in accordance with certain implementations described herein. The system can further comprise an x-ray source for generating x-rays for illuminating an object and can use the apparatus 10,100 as disclosed herein for recording x-rays transmitted through the object. In certain implementations, the upstream-most x-ray imaging detector 110 (e.g., closest to the object) comprises a scintillator 20 and a scintillator holder having one dimension that is comparable or slightly larger than the field-of-view of the x-ray imaging detector 110 in one direction (e.g., to allow an extended flat sample to rotate). In certain implementations, the x-ray source comprises multiple operator-selectable target materials to select x-rays with certain spectral characteristics. In certain implementations, the apparatus 10,100 is configured to obtain an x-ray absorption contrast image and x-ray scattering (e.g., darkfield) image and/or x-ray phase contrast image concurrently.

Certain implementations are configured for imaging and inspection of hybrid bonding of semiconductor packaging. A first x-ray imaging detector 110a configured with high spatial resolution (e.g., less than 1 micron; less than 3 microns) can be placed close to a test sample and a second x-ray detector 60 (e.g., a flat panel detector, pixel array photon counting detector, or a pixel array amorphous Se detector) can be placed at a distance such that the projected pixel size of the second detector 60 at the sample is comparable to that of the first x-ray imaging detector 110 placed close to the sample. In another implementation, at least one x-ray imaging detector 110 with a spatial resolution better than 10 microns (e.g., better than 5 microns) is configured between the high resolution first x-ray imaging detector 110 and the second detector 60 and the second detector 60 is configured with a resolution comparable with a resolution of the first x-ray imaging detector 110 placed close to the sample. For imaging hybrid bonding integrated circuit (IC) packages, parameters of an x-ray laminography imaging system can be: an x-ray source with a target material producing characteristic line around 20 keV (e.g., Mo, Rh, Pd, and Ag), an x-ray imaging detector 110 with a thin scintillator 20 (e.g., thickness less than 50 microns; less than 20 microns; less than 10 microns) comprising a scintillator material with high x-ray absorption efficiency for x-rays of energies in a range of 15 keV to 30 keV, and a pixel array amorphous Se detector 60 with Se thickness in a range of 100 microns to 400 microns (e.g., approximately equal to 200 microns) placed at a distance such that a projected pixel size of the pixel array amorphous Se detector 60 at the sample position is small (e.g., less than or equal to 3 microns; less than or equal to 1 micron) and a laminography slant angle (e.g., the angle between the x-ray imaging beam axis and a plane perpendicular to the sample rotation axis) in a range of 5 degrees to 45 degrees (e.g., in a range of 10 degrees to 30 degrees). Additional x-ray imaging detectors 110 between the first x-ray imaging detector 110 and the pixel array amorphous Se detector 60 can be added to improve imaging speed and/or additional materials information.