Abstract:
A microchannel plate for detecting neutrons includes a hydrogen-rich polymer substrate that defines a plurality of channels extending from a top surface of the substrate to a bottom surface of the substrate, where neutrons interact with the plurality of channels to generate at least one secondary electron. A top electrode is positioned on the top surface of the substrate and a bottom electrode is positioned on the bottom surface of the substrate. A resistive layer is formed over an outer surface of the plurality of channels that provides ohmic conduction with a resistivity that is substantially constant. An emissive layer is formed over the resistive layer. Neutron interaction products interact with the plurality of channels defined by the substrate and the emissive films to generate secondary electrons that cascade within the plurality of channels to provide an amplified signal related to the detection of neutrons.
Abstract:
A system and method for identifying an optimal landing energy of a probe current in a scanning electron microscope system. A probe current having a known landing energy is directed at a sample for producing a signal electron beam. The current of the signal electron beam is measured by directing the beam to a current detector for calculating a current yield, which is the ratio of the signal current to the probe current. The landing energy can then be changed for subsequent measurements of the signal current to identify the landing energy which produces a desired current yield. Once identified, the landing energy value can be used to produce a signal electron beam directed towards an imaging detector to generate topographic images of samples.
Abstract:
A charged particle filter such as a Wien filter in which components used as the pole pieces and electrodes are precisely and reliably secured to a supporting structure through which they extend and to which they are brazed. Electrical insulating gaps in the magnetic circuit are located very remotely from the pole faces of the pole pieces so as to minimize any adverse effect of the gaps on the produced magnetic field.
Abstract:
A microchannel plate includes a substrate defining a plurality of channels extending from a top surface of the substrate to a bottom surface of the substrate. A resistive layer is formed over an outer surface of the plurality of channels that provides ohmic conduction with a predetermined resistivity that is substantially constant. An emissive layer is formed over the resistive layer. A top electrode is positioned on the top surface of the substrate. A bottom electrode positioned on the bottom surface of the substrate.
Abstract:
An image intensifying device includes a lens that is positioned at a light input that forms an image of a scene. The image intensifying device also includes an image intensifier tube that includes a photocathode that is positioned to receive the image formed by the lens. The photocathode generates photoelectrons in response to the light image of the scene. The image intensifier tube also includes a microchannel plate having an input surface comprising the photocathode. The microchannel plate receives the photoelectrons generated by the photocathode and generating secondary electrons. An electron detector receives the secondary electrons generated by the microchannel plate and generates an intensified image of the scene.
Abstract:
A method of fabricating a microchannel plate includes forming a plurality of pores in a silicon substrate. The plurality of pores is oxidized, thereby consuming silicon at surfaces of the plurality of pores and forming a silicon dioxide layer over the plurality of pores. At least a portion of the silicon dioxide layer is stripped, which reduces a surface roughness of the plurality of pores. A semiconducting layer can be deposited onto the surface of the silicon dioxide layer. The semiconducting layer is then oxidized, thereby consuming at least some of the polysilicon or amorphous silicon layer and forming an insulating layer. Resistive and secondary electron emissive layers are then deposited on the insulating layer by atomic layer deposition.
Abstract:
A microchannel plate for detecting neutrons includes a hydrogen-rich polymer substrate that defines a plurality of channels extending from a top surface of the substrate to a bottom surface of the substrate, where neutrons interact with the plurality of channels to generate at least one secondary electron. A top electrode is positioned on the top surface of the substrate and a bottom electrode is positioned on the bottom surface of the substrate. A resistive layer is formed over an outer surface of the plurality of channels that provides ohmic conduction with a resistivity that is substantially constant. An emissive layer is formed over the resistive layer. Neutron interaction products interact with the plurality of channels defined by the substrate and the emissive films to generate secondary electrons that cascade within the plurality of channels to provide an amplified signal related to the detection of neutrons.
Abstract:
An image intensifying device includes a lens that is positioned at a light input that forms an image of a scene. The image intensifying device also includes an image intensifier tube that includes a photocathode that is positioned to receive the image formed by the lens. The photocathode generates photoelectrons in response to the light image of the scene. The image intensifier tube also includes a microchannel plate having an input surface comprising the photocathode. The microchannel plate receives the photoelectrons generated by the photocathode and generating secondary electrons. An electron detector receives the secondary electrons generated by the microchannel plate and generates an intensified image of the scene.
Abstract:
A method of fabricating a microchannel plate includes defining a plurality of pores extending from a top surface of a substrate to a bottom surface of the substrate where the plurality of pores has a resistive material on an outer surface that forms a first emissive layer. A second emissive layer is formed over the first emissive layer. The second emissive layer is chosen to achieve at least one of an increase in secondary electron emission efficiency and a decrease in gain degradation as a function of time. A top electrode is formed on the top surface of the substrate and a bottom electrode is formed on the bottom surface of the substrate.
Abstract:
An apparatus for imaging the surface of a sample, such as a scanning electron microscope. The apparatus generates a beam of charged particles directed at the surface, and includes an objective lens and an electrostatic lens for controlling the particle beam. The objective lens and the electrostatic lens constitute a compound lens that has an axis. The beam is controlled so that it travels along the axis of the compound lens in order to avoid adverse consequences induced by, for example, mechanical misalignments and as manifested when the focus of one of the objective and electrostatic lenses is changed during operation of the apparatus.