Ridged mirror

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In atomic physics, ridged mirror (or ridged atomic mirror) is 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. [1].

The ridges enhance the quantum reflection from the surface, reducing the effective constant $~C~$ of the van der Waals attraction of atoms to the surface. Such interpretation leads to the estimate of the reflectivity

where $~\ell~$ is width of the ridges, $~L~$ is distance between ridges, $\displaystyle ~\theta~$ is grazing angle, and $~K=mV/\hbar~$ is wavenumber and $~R_0(C,k)~$ is coefficient of reflection of atoms with wavenumber $~k~$ from a flat surface at the normal incidence. Such estimate predicts the enhancement of the reflectivity at the increase of period $~L~$ .

For narrow ridges with large period $L$ , the ridges just blocks the part of the wavefront. Then, it can be interpreted in terms of the Fresnel diffraction [2]. or the the Zeno effect [3]; such interpretation leads to the estimate the reflectivity

where grazing ange $\displaystyle ~\theta~$ is supposed to be small. This estimate predicts enhancement of the reflectivity at the reduction of period $~L~$ . This estimate requires that $~\ell/L \ll 1~$ . The width of the ridges cannot be smaller than the size of atom; this sets the fundamental limit of performance of the ridged mirrors.

The reflectivity of a ridged atomic mirror can be orders of magnitude better than that of a flat surface. The ridged mirror can reflect also the visible light [4]; however, for the light waves, the performance is not better than that of a flat surface. Ellipsoidal ridged mirror is proposed as focusing element for the atom optical system with submicron resolution (atomic nanoscope).

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[1] F. Shimizu and J. Fujita. Giant Quantum Reflection of Neon Atoms from a Ridged Silicon Surface. Journal of the Physical Society of Japan, Vol. 71 No. 1, January, 2002 pp. 5-8 URL : http://jpsj.ipap.jp/link?JPSJ/71/5/

[2] H.Oberst, D.Kouznetsov, K.Shimizu, J.Fujita, F.Shimizu. Fresnel diffraction mirror for an atomic wave. PRL 94, 013203 (2005). URL: http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000094000001013203000001&idtype=cvips&gifs=yes

[3] D.Kouznetsov, H.Oberst. Reflection of Waves from a Ridged Surface and the Zeno Effect. Optical Review, Vol. 12, No. 5 (2005) p. 363-366 URL: http://annex.jsap.or.jp/OSJ/opticalreview/TOC-Lists/vol12/12e0363tx.htm

[4] D. Kouznetsov, H. Oberst, K. Shimizu, A. Neumann, Y. Kuznetsova, J.-F. Bisson, K. Ueda, S. R. J. Brueck. Ridged atomic mirrors and atomic nanoscope. J. Phys. B, v. 39 (2006) p. 1605-1623 URL :http://stacks.iop.org/0953-4075/39/1605

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Category: Atomic, molecular, and optical physics

Ridged mirror

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