Abstract: An x-ray source for use in Phase Contrast Imaging is disclosed. In particular, the x-ray source includes a cathode array of individually controlled field-emission electron guns. The field emission guns include very small diameter tips capable of producing a narrow beam of electrons. Beams emitted from the cathode array are accelerated through an acceleration cavity and are directed to a transmission type anode, impinging on the anode to create a small spot size, typically less than five micrometers. The individually controllable electron guns can be selectively activated in patterns, which can be advantageously used in Phase Contrast Imaging.

Abstract: Described here is a method for performing phase contrast imaging using an array of independently controllable x-ray sources. The array of x-ray sources can be controlled to produce a distinct spatial pattern of x-ray radiation and thus can be used to encode phase contrast signals without the need for a coded aperture. The lack of coded aperture increases the flexibility of the imaging method. For instance, because a fixed, coded aperture is not required, the angular resolution of the imaging technique can be increased as compared to coded-aperture imaging. Moreover, the lack of a radioopaque coded aperture increases the photon flux that reaches the subject, thereby increasing the attainable signal-to-noise ratio.

Abstract: Methods for fabrication of self-aligned gated tip arrays are described. The methods are performed on a multilayer structure that includes a substrate, an intermediate layer that includes a dielectric material disposed over at least a portion of the substrate, and at least one gate electrode layer disposed over at least a portion of the intermediate layer. The method includes forming a via through at least a portion of the at least one gate electrode layer. The via through the at least one gate electrode layer defines a gate aperture. The method also includes etching at least a portion of the intermediate layer proximate to the gate aperture such that an emitter structure at least partially surrounded by a trench is formed in the multilayer structure.

Abstract: Methods for pumping a chamber to generate substantially adsorbate-free surfaces are described. Pumping systems for achieving a vacuum based on surface adsorption are also described.

Abstract: Methods for pumping a chamber to generate substantially adsorbate-free surfaces are described. Pumping systems for achieving a vacuum based on surface adsorption are also described.

Abstract: Methods for fabrication of self-aligned gated tip arrays are described. The methods are performed on a multilayer structure that includes a substrate, an intermediate layer that includes a dielectric material disposed over at least a portion of the substrate, and at least one gate electrode layer disposed over at least a portion of the intermediate layer. The method includes forming a via through at least a portion of the at least one gate electrode layer. The via through the at least one gate electrode layer defines a gate aperture. The method also includes etching at least a portion of the intermediate layer proximate to the gate aperture such that an emitter structure at least partially surrounded by a trench is formed in the multilayer structure.

Abstract: A hand assembled MEMS apparatus includes meso-scale microfabricated components adapted for being moved by hand relative to one another from a loose-fit preliminary alignment orientation to a relatively tight-fit assembled orientation. A microfabricated spring member is integrally disposed on one of the components to bias the other component towards the assembled orientation. A cam surface disposed on the other component is configured to slidably engage and move the spring member against its bias upon continued hand movement in the assembly direction. A microfabricated abutment is disposed to limit relative movement of the components in at least one direction other than the assembly direction. A microfabricated tactile feedback member is configured to disrupt the hand movement in the assembly direction once the components have substantially reached the assembled orientation.

Abstract: A hand assembled MEMS apparatus includes meso-scale microfabricated components adapted for being moved by hand relative to one another from a loose-fit preliminary alignment orientation to a relatively tight-fit assembled orientation. A microfabricated spring member is integrally disposed on one of the components to bias the other component towards the assembled orientation. A cam surface disposed on the other component is configured to slidably engage and move the spring member against its bias upon continued hand movement in the assembly direction. A microfabricated abutment is disposed to limit relative movement of the components in at least one direction other than the assembly direction. A microfabricated tactile feedback member is configured to disrupt the hand movement in the assembly direction once the components have substantially reached the assembled orientation.

Abstract: A patterned field emission device fabricated using conducting or semiconducting organic materials is described.

Abstract: A patterned field emission device fabricated using conducting or semiconducting organic materials is described.