Free-standing silicon-nitride zoneplates for neutral-helium microscopy
| Autor: | Martin M. Greve, Thomas Reisinger, Sabrina Eder, Henry I. Smith, Bodil Holst |
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| Rok vydání: | 2010 |
| Předmět: |
Diffraction
Fabrication business.industry Chemistry Condensed Matter Physics Diffraction efficiency Atomic and Molecular Physics and Optics Surfaces Coatings and Films Electronic Optical and Magnetic Materials chemistry.chemical_compound Optics Silicon nitride Microscopy Scanning transmission electron microscopy Atom optics Electrical and Electronic Engineering business Beam (structure) |
| Zdroj: | Microelectronic Engineering. 87:1011-1014 |
| ISSN: | 0167-9317 |
| DOI: | 10.1016/j.mee.2009.11.107 |
| Popis: | The ground-state helium-4 beam employed by the microscopy technique discussed in this article interacts exclusively with the atoms in the topmost sample-monolayer. Its low-energy (tens of meV) and chemical inertness make the beam an almost 'ideal' imaging probe in the sense that a sample surface can be imaged without alteration by the probe. The microscopy technique therefore has promising applications in the imaging of fragile samples and metrology. In this article we present a fabrication process for the diffraction-based focusing element (Fresnel Zoneplate) in such a setup. Zoneplates made previously for this purpose have suffered from low transmission, a problem we have solved with our new process. In addition, we have measured the first-order diffraction efficiency of three zoneplates fabricated with this process. The efficiency of a zoneplate with 388@mm diameter was close to 70% of the theoretically predicted value. We believe the reduction stems mainly from misalignment between the writefields used to pattern the zoneplate. The fabricated zoneplates of 190@mm diameter, which we patterned using a single writefield, have close to the theoretically predicted transmission characteristics; a result that has not been achieved before for neutral atom Fresnel lenses. |
| Databáze: | OpenAIRE |
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