Tabletop nanometer extreme ultraviolet imaging in an extended reflection mode using coherent Fresnel ptychography

We demonstrate the first (to our knowledge) general purpose full-field reflection-mode extreme ultraviolet (EUV) microscope based on coherent diffractive imaging. This microscope is capable of nanoscale amplitude and phase imaging of extended surfaces at an arbitrary angle of incidence in a noncontact, nondestructive manner. We use coherent light at 29.5 nm from high-harmonic upconversion to illuminate a surface, directly recording the scatter as the surface is scanned. Ptychographic reconstruction is then combined with tilted plane correction to obtain an image with amplitude and phase information. The image quality and detail from this diffraction-limited tabletop EUV microscope compares favorably with both scanning electron microscope and atomic force microscope images. The result is a general and completely extensible imaging technique that can provide a comprehensive and definitive characterization of how light at any wavelength scatters from a surface, with imminent feasibility of elemental imaging with few-nanometer resolution. © 2014 Optical Society of America