In atomic physics, a ridged mirror (or ridged atomic mirror, or Fresnel diffraction mirror) is a kind of atomic mirror, designed for the specular reflection of neutral particles (atoms) coming at the grazing incidence angle, characterised in the following: in order to reduce the mean attraction of particles to the surface and increase the reflectivity, this surface has narrow ridges.
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Reflectivity of ridged atomic mirrors
Various estimates for the efficiency of quantum reflection of waves from ridged mirror were discussed in the literature. All the estimates explicitly use the de Broglie theory about wave properties of reflected atoms.
Scaling of the van der Waals force
The ridges enhance the quantum reflection from the surface, reducing the effective constant
where
Interpretation as Zeno effect
For narrow ridges with large period
where the grazing angle
Fundamental limit
For efficient ridged mirrors, both estimates above should predict high reflectivity. This implies reduction of both, width,
Applications of ridged mirrors
Ridged mirrors are not yet commercialized, although certain achievements can be mentioned. The reflectivity of a ridged atomic mirror can be orders of magnitude better than that of a flat surface. The use of a ridged mirror as an atomic hologram has been demonstrated. In Shimizu's and Fujita's work, atom holography is achieved via electrodes implanted into SiN4 film over an atomic mirror, or maybe as the atomic mirror itself.
Ridged mirrors can also reflect visible light; however, for light waves, the performance is not better than that of a flat surface. An ellipsoidal ridged mirror is proposed as the focusing element for an atomic optical system with submicrometre resolution (atomic nanoscope).