Patent Number: 
Section: claims

1. An apparatus for providing a variable X-ray aperture, the apparatus comprising:a first substrate;a second substrate located opposite the first substrate and spaced apart from the first substrate to form a gap between the first substrate and the second substrate;an X-ray attenuation fluid located in the gap between the first substrate and the second substrate;at least one charging electrode in electrical contact with the X-ray attenuation fluid; andat least one displacing electrode located on a surface of the first substrate facing the gap or on a surface of the second substrate facing the gap, wherein the displacing electrode is configured to displace the X-ray attenuation fluid to provide an aperture within the X-ray attenuation fluid. 2. The apparatus of claim 1, further comprising a controller operably coupled to the at least one displacing electrode. 3. The apparatus of claim 1, wherein the X-ray attenuation fluid forms a fluid layer in contact with the surface of the first substrate facing the gap and the surface of the second substrate facing the gap. 4. The apparatus of claim 1, further comprising a fluid reservoir in fluid communication with the X-ray attenuation fluid located in the gap between the first substrate and the second substrate. 5. The apparatus of claim 1, wherein the at least one displacing electrode comprises a thin-film electrode deposited on the surface of the first substrate facing the gap or on the surface of the second substrate facing the gap. 6. The apparatus of claim 1, wherein the at least one displacing electrode comprises at least two displacing electrodes, a first displacing electrode located on the surface of the first substrate facing the gap, and a second displacing electrode located on the surface of the second substrate facing the gap. 7. The apparatus of claim 1, wherein the at least one displacing electrode comprises a plurality of displacing electrodes comprising an annular shape and arranged concentrically on the surface of the first substrate facing the gap and/or on the surface of the second substrate facing the gap. 8. The apparatus of claim 1, wherein the at least one displacing electrode comprises a plurality of displacing electrodes arranged in an array on the surface of the first substrate facing the gap and/or on the surface of the second substrate facing the gap. 9. The apparatus of claim 1, wherein the X-ray attenuation fluid comprises a fluid metal or fluid alloy. 10. The apparatus of claim 1, wherein the first substrate and the second substrate independently comprise aluminum, glass, or silicon, or combinations of any thereof. 11. The apparatus of claim 2, wherein the controller is configured to provide an electrical charge to the displacing electrode to displace the X-ray attenuation fluid from at least a portion of the gap by electrostatic force between the displacing electrode and the X-ray attenuation fluid. 12. The apparatus of claim 4, wherein the fluid reservoir is configured to releasably hold X-ray attenuation fluid displaced from at least a portion of the gap by electrostatic force between the at least one displacing electrode and the X-ray attenuation fluid. 13. The apparatus of claim 4, wherein the fluid reservoir is located at a perimeter of the gap between the first substrate and the second substrate. 14. The apparatus of claim 9, wherein the X-ray attenuation fluid comprises mercury. 15. An apparatus for providing a variable X-ray aperture, the apparatus comprising:a first substrate;a second substrate located opposite the first substrate, and spaced apart from the first substrate to form a gap between the first substrate and the second substrate;a mercury layer located in the gap between the first substrate and the second substrate, the mercury layer in contact with a surface of the first substrate facing the gap and a surface of the second substrate facing the gap;at least one charging electrode in electrical contact with the mercury layer;at least one displacing electrode located on the surface of the first substrate facing the gap or on the surface of the second substrate facing the gap; anda controller operably coupled to the at least one displacing electrode;wherein the controller is configured to provide the displacing electrode with an electrical charge that displaces the mercury layer from at least a portion of the gap by electrostatic force between the displacing electrode and the mercury layer to provide an aperture within the attenuation fluid. 16. The apparatus of claim 15, further comprising a fluid reservoir in fluid communication with the mercury layer located in the gap between the first substrate and the second substrate, wherein the fluid reservoir is configured to releasably hold mercury displaced from at least a portion of the gap by electrostatic force between the at least one displacing electrode and the mercury. 17. The apparatus of claim 15, wherein the at least one displacing electrode comprises a plurality of thin-film electrodes deposited on the surface of the first substrate facing the gap and on the surface of the second substrate facing the gap, wherein the plurality of displacing electrodes comprise an annular shape and are arranged concentrically, or wherein the plurality of displacing electrodes are arranged in an array, on the surface of the first substrate facing the gap and/or on the surface of the second substrate facing the gap. 18. The apparatus of claim 15, wherein the first substrate and the second substrate independently comprise a material selected from the group consisting of aluminum, glass, silicon, and combinations of any thereof. 19. An apparatus for providing a variable aperture to control electromagnetic radiation, the apparatus comprising:a first substrate;a second substrate located opposite the first substrate and spaced apart from the first substrate to form a gap between the first substrate and the second substrate;an attenuation fluid located in the gap between the first substrate and the second substrate, the attenuation fluid configured to absorb electromagnetic radiation of a predetermined wavelength;at least one charging electrode in electrical contact with the attenuation fluid; andat least one displacing electrode located on a surface of the first substrate facing the gap or on a surface of the second substrate facing the gap, wherein the displacing electrode is configured to displace the attenuation fluid to provide an aperture within the attenuation fluid. 20. The apparatus of claim 19, wherein the attenuation fluid is configured to absorb electromagnetic radiation having a wavelength in the range of 0.01 to 10 nanometers.