Sample holder, detector mask, and scope system
Inventors
Holm, Jason D. • Keller, Robert R. • RICE, KATHERINE P.
Assignees
United States Department of Commerce
Publication Number
US-9970859-B2
Publication Date
2018-05-15
Expiration Date
2037-01-11
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Abstract
A detector mask transmits selectively a plurality of probe particles to a particle detector, the detector mask includes: a plate including a plate wall disposed in the plate and enclosing a transmission orifice arranged in a transmission profile to: transmit probe particles having a trajectory coincident with the transmission orifice, block probe particles having a trajectory external to the transmission orifice, and form a probe particle beam comprising the probe particles transmitted by the transmission orifice to the particle detector, wherein the transmission profile includes a sector, a semi-circle, an annular sector, or a combination including at least one of the foregoing first transmission profiles.
Core Innovation
The invention provides a detector mask that selectively transmits a plurality of probe particles to a particle detector. The detector mask includes one or more plates comprising plate walls enclosing transmission orifices arranged in specific transmission profiles such as sectors, semi-circles, annular sectors, or combinations thereof. These transmission profiles allow the detector mask to transmit probe particles with trajectories coincident with the transmission orifices while blocking those with trajectories external to them, thereby forming a probe particle beam for improved imaging.
A complementary sample holder is disclosed that holds a sample for microscopy or spectroscopy using opposing flexible cantilever arms. The sample holder includes a basal member with an inferior cantilever arm to receive the sample and a superior cantilever arm opposing it, where the superior arm has a depressible crook allowing the arms to flex and clamp or release the sample. This design enables arbitrary positioning and orientation of the sample relative to a particle source and detector while providing protection against damage due to accidental contact with other scope components.
Moreover, a scope system incorporating the sample holder and detector mask is described. In this system, the sample holder positions the sample exposed to a plurality of source particles, which in turn emit probe particles. The detector mask then selectively transmits the probe particles based on the transmission profiles to the particle detector, facilitating imaging modes such as bright field or dark field microscopy and providing angular acceptances for improved imaging contrast and resolution.
Claims Coverage
The patent defines one independent claim focusing on a multi-plate detector mask and its transmission control features.
Multi-plate detector mask with stacked plates
A detector mask comprising at least a first plate and a second plate arranged in a stack, each plate having a plate wall enclosing a transmission orifice arranged in a transmission profile, wherein the first plate selectively transmits probe particles forming a first probe particle beam, and the second plate receives this beam and selectively transmits probe particles coincident with its transmission orifice to form a second probe particle beam. The combination of the first and second transmission profiles provides a mask transmission profile through which probe particles are transmitted to the particle detector.
Additional plates for enhanced transmission control
The detector mask can further include a third and fourth plate stacked similarly, each with plate walls enclosing transmission orifices arranged in corresponding transmission profiles. Each successive plate receives the probe particle beam from the preceding plate and further selectively transmits particles within its transmission orifice to form subsequent probe particle beams. The combined transmission profiles across all plates define the overall mask transmission profile for transmitting particles to the detector.
Transmission profiles for imaging modes
The transmission profiles of the plates independently comprise various imaging mode-defining shapes and types, including bright field, dark field, annular dark field, low-angle annular dark field, medium angle annular dark field, high angle annular dark field, annular bright field, or combinations thereof.
Mask mounting and detector compatibility
The detector mask includes a support on which the plates are disposed, and this support mounts on the particle detector. Probe particles processed through the mask can include photons, electrons, ions, or combinations thereof, and the particle detector can be an electron detector, photon detector, ion detector, or a combination thereof.
Plate segmentation and rotation for dynamic transmission profiles
The plates can be segmented into multiple quadrants or sectors having independent transmission orifices with various transmission profiles such as circles, sectors, semi-circles, annular sectors, rectangles, or combinations thereof. Plates are configured to rotate independently relative to each other, allowing selection of mask transmission profiles dynamically by alignment of the transmission orifices over the detector's active regions.
The claims collectively cover a detector mask composed of multiple stacked plates with independently selectable transmission orifices and profiles that can be combined and dynamically adjusted to define complex mask transmission profiles. This allows precise control over probe particle acceptance angles and imaging modes compatible with various particle types and detector configurations.
Stated Advantages
The sample holder provides tool-free clamping and arbitrary positioning of samples with flexible cantilever arms to avoid damage to microscope components.
The detector mask enables fine or coarse control over particle acceptance angles, facilitating multiple imaging modes such as bright field and dark field in microscopy and spectroscopy.
The combination of sample holder and detector mask in a scope system improves transmission imaging and contrast control over a large camera length range without the need for post-sample lenses.
The sample holder design is cost-effective, easy to use and fabricate, robust against accidental collisions, and supports edge or full clamping of self-supporting samples.
Documented Applications
The scope system is used in microscopy and spectroscopy, including scanning transmission electron microscopy (STEM), to position samples for exposure to probe particles and selective detection via detector masks.
The detector mask and sample holder combination is applied in electron microscopes to achieve various imaging modalities such as bright field, dark field, annular dark field, and annular bright field imaging modes.
Use cases include imaging of multi-wall carbon nanotubes, single-wall carbon nanotubes, Au and TiO2 nanoparticles, and exfoliated two-dimensional zeolites with improved contrast and angular selectivity.
The detector mask and sample holder facilitate modulation of acceptance angles and camera length ranges in electron microscopy to enhance image contrast, resolution, and material discrimination.
The system is compatible with various particle types including photons, electrons, ions, and can be used with detectors such as electron detectors, photon detectors, and ion detectors for microscopy or spectroscopy.
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