text: Interference of atom matter waves was first observed by Esterman and Stern in 1930, when a Na beam was diffracted off a surface of NaCl. The short de Broglie wavelength of atoms prevented progress for many years until two technological breakthroughs revived interest: microlithography allowing precise small devices and laser cooling allowing atoms to be slowed, increasing their de Broglie wavelength. 
  Until 2006, the resolution of imaging systems based on atomic beams was not better than that of an optical microscope, mainly due to the poor performance of the focusing elements. Such elements use small numerical aperture; usually, atomic mirrors use grazing incidence, and the reflectivity drops drastically with increase of the grazing angle; for efficient normal reflection, atoms should be ultracold, and dealing with such atoms usually involves magnetic, magneto-optical or optical traps.
  At the beginning of the 21st century scientific publications about "atom nano-optics", evanescent field lenses and ridged mirrors
  showed significant improvement.
   In particular, an atomic hologram can be realized.