Towards Realization of an Atomic de Broglie Microscope: Helium Atom Focusing Using Fresnel Zone Plates

A neutral, ground-state, ${}^4\mathrm{He}$ atom beam has been focused using Fresnel zone plates. At only moderate demagnification $(0.40\times )$, a focused spot diameter of $\le 2.0\mu \mathrm{m}$ is achieved at a signal intensity of 500 counts/s. This is an improvement over previous work by a factor of 10 in resolution, ${10}^3$ in signal intensity, and ${10}^8$ in focused beam density, and allows the full intrinsic intensity profile of a focused atomic Fresnel spot to be measured for the first time. Raster scans of 15 and $25\mu \mathrm{m}$ wide slits across the focused spot demonstrate transmission scanning helium de Broglie microscopy of micron resolution.