Development of a supersonic beam allowed us to overcome the aforementioned problems. By producing an atomic beam through a supersonic expansion, atomic wave sources with well-defined kinetic energy are available [ref]. A combination of the supersonic nozzle with advanced technological developments in laser and nanotechnology accelerated the progress of atom optics. Ability to tune the laser frequency enabled us to observe Bragg scattering and the Kapitza-Dirac effect of atomic waves by adjusting the detuning frequency with respect to the transition frequency of atoms [11-14]. It motivated the first approach to the practical atomic mirror known as the evanescent wave mirror [15-17]. In addition, the establishment of nano-fabricated devices has served as atomic optical elements such as transmission grating[18-20] and Fresnel zone plate [21]. Until now, those instruments have been the basis of matter-wave interferometry [22-26] as well as atomic de Broglie microscopy [21]. 
  Nonetheless, previous studies of atomic reflection by surface carried out with thermal beams have shown the efficiency limit due to its high sensitivity to the surface quality. Since atomic de Broglie wavelengths of such beams (around sub-angstroms) are much smaller than the characteristic surface roughness (usually 100 angstroms), this reflection occurs at the repulsive potential. Such a mechanism is called classical reflection. When atoms are classically reflected from the surface, they are close to the surface atoms, feeling the local variation over the surface. In order to avoid an incoherent reflection which may be caused by adsorbates on the surface, complicated surface-preparation processes like annealing and sputtering are crucial to render surfaces smooth at the atomic-level [8-10]. However, it is difficult to maintain its surface cleanliness during the whole scattering experiment in practice. Besides, even if the perfect clean surfaces are available, unexpected surface defects will cause decreased reflectivity. Thus, for a long time, atom-surface interaction had been considered as an obstacle to deteriorate coherent reflection from the surface, being a sticking point for solid surfaces to be a decent atomic mirror. Because of that reasons, electromagnetic of magnetic field has been applied along the surface so that additional potential is generated over the surface to prevent atoms from colliding with the surface at the initial stage of atomic mirrors surface such as evanescent wave mirror and magnetic mirror. 
 Attempts to utilize advanced laser technology to explore the atomic motion has led to the advent of atomic-cooling and -trapping techniques in the late 20th century. It gives rise to creation of laser-cooled and trapped atoms whose much larger de Broglie wavelength emphasize the wave nature of atoms and it made a significant advance in atomic mirrors. Magneto-optically trapped(MOT) metastable neon atoms, for instance, has led to the first observation of a quantum reflection of the atomic wave from the solid surface in 2001 [27]. Here, quantum reflection is a quantum mechanical phenomenon in which a particle is reflected at the attractive part of the van der Waals potential. Since it occurs away from the surface, local variation on the surface harldy affect the reflectivity. Which means, surface-preparation is not required. It is noteworthy that bare solid surface without any applied fields can be atomic mirror under quantum refleciton. In order to investigate quantum reflection experimentally, the particle’s kinetic energy perpendicular to the surface must be sufficiently small. One way to achieve this prerequisite is employing a grazing incidence condition. In typical experimental conditions, a grazing incidence angle \(\theta_{in}\) of a few mrads provides a sufficiently small z-component kinetic energy \(E_z\), perpendicular to the surface (fig.1).
 Recently, the quantum reflection of a thermal atomic beam has been reported at a grazing incidence angle [28-31]. Under grazing incidence condition which is another way to enhance the wave nature of the particle, the vertical component of the wave vector for a particle is decreased and corresponding de Broglie wavelength becomes larger. Hence, when an incident matter-wave propagates almost parallel to a surface, even fast atoms can be coherently reflected from the surface. In such circumstances, the reflectivity from a solid surface can reach 1 as grazing incidence angle goes to 0, which is an important requisite for the practical matter-wave mirror. In other words, those fast atoms without complex preparation steps like trapping or cooling processes can ///complement/// the ultra-cold atoms as the proper matter wave sources for the atomic mirror.////
 Furthermore, under the above-mentioned condition, resolved diffraction peaks have been observed from micro-fabricated reflection-gratings [ref]. Figure 1a and 1b show the schematics of matter-wave scattering from a transmission grating with the period of 100 nm and a square-wave grating whose period is 400 um, respectively. For the sake of convenience, the incidence angle \(\theta_{in}\) and the diffraction angle \(\theta_n\) of the nano-transmission grating are defined with respect to the normal line while those are determined by the angle between the incident beam and the grating-surface plane at the square-wave grating. A sign of the diffraction order is defined in a way that diffraction angles of positive orders are larger than negative orders./// In order to see the difference between two gratings, \(n\)-th-order diffraction angles over certain ranges of incidence angles from each grating are calculated by grating equation [2008-19] in Fig 1c and 1d, respectively. Here, matter-wave de Broglie wavelength is fixed at 136 pm. Assuming the angular resolution of the atomic beam is around 100 urad, up to 5th order diffraction peaks can be observed at grazing incidence angles from the micro-fabricated reflection-grating as it can be from a nano-transmission grating at a normal incidence condition. Considering the fact that the reflection and diffraction efficiencies are increased as incidence angle goes smaller from the reflection-type grating, diffraction efficiencies from square-wave gratings are expected to be higher as much as those efficiencies from transmission grating. Therefore, micro-fabricated structures can act as a matter-wave-grating and it appears important for the generality of matter-wave elements due to its lower price and size-limit than nano-fabricated structures like the nano-transmission grating. Thus, micro-fabricated solid structures can be a good candidate for practical matter-wave optical instruments as exploiting grazing incidence condition.