## 4 Results and Discussions
### Computer Simulation of the Scattering Process of an Incident Beam
(**a**) The beam is incident at a right angle; (**b**) the beam is incident at an obtuse angle; (**c**) the beam is incident at an acute angle. The arrow shows the direction of beam incidence. When a beam is incident at an obtuse or acute angle on a surface with a mono-periodic structure, the nature of the reflection is also scattered, but scattering occurs in sectors lying in the region of the angles of incidence and reflection of the beam (Figure 8b,c). This study shows that applying a transparent coating can improve the scattering of the reflected beam due to the effect of multiple reflections of the beam from the inner boundary of the transparent coating. However, when the beam is reflected from a flat surface, this significant positive effect is not observed. If a beam of light falls on a flat surface with a coating normal to the surface, its reflection occurs in the opposite direction, without a significant tendency to scatter, despite the presence of an additional coating on the reflecting surface (Figure 9a). When a beam is incident at an obtuse or acute angle on a flat surface with a coating, the nature of the reflection is also without a significant tendency to scatter (Figure 9b,c). The reflected beam is not sufficiently diffused and tends to travel in one direction. This means that, despite the presence of an additional coating, the studied surface glares in a beam of directed light. Figure 9: The incident beam scattering pattern: the reflection from a flat surface with the transparent outer coating. (**a**) The beam is incident at a right angle; (**b**) the beam is incident at an obtuse angle; (**c**) the beam is incident at an acute angle. The arrow shows the direction of beam incidence. In the case of reflection of a beam from a surface with a complex two-periodic structure, the nature of the reflection has a clearly defined scattered character (Figure 10). This is very different from the case of reflection from a flat coated surface or from a flat surface with a transparent coating. With normal angle incidence of the beam on a surface with a complex two-periodic structure, the nature of the reflection has a clearly defined scattered character (Figure 10a). When a beam is incident at an obtuse or acute angle on a surface with a complex two-periodic structure, the nature of the reflection also has a clearly defined scattered character (Figure 10b,c), as in all cases of reflection from the presented surface. Thus, from a series of calculations performed, we can conclude that the presence of an additional coating on a flat surface does not improve its scattering properties and does not eliminate glare. The reflected beam is weakly scattered and the angle of reflection remains identical to the angle of incidence, which reduces the secrecy of the reflecting surface in the visible wavelength range. In the event that a complex two-periodic structure is formed  
Figure 10: The incident beam scattering pattern: the reflection from a structured two-periodic surface with the transparent outer coating. (**a**) The beam is incident at a right angle; (**b**) the beam is incident at an obtuse angle; (**c**) the beam is incident at an acute angle. The arrow shows the direction of beam incidence. on the reflective surface and the coating surface, the nature of the reflection has a clearly defined scattered character, regardless of the angle of incidence of the light beam. This study shows the feasibility and effectiveness of forming a two-periodic structure on the surface in order to give it stealth characteristics and reduce visibility. It should be noted that models of the reflection process describe the surface as a relief formed by a set of craters having a regular axisymmetric shape in accordance with the Gaussian normal distribution and a smooth surface of the bottom and walls (Figure 1c). In this case, the additional influence on the nature of scattering of small (chaotic, LIPSS and other) elements of the microstructure (Figure 4 pos.