The reflective object characteristics are also important factors to be considered and ultimately the goal is to maximize the amount of reflected energy received by the detector. The size and shape of the object determines how much of the emitter’s beam width is reflected and the shape determines the angle of reflection. In addition, surfaces have small irregularities that may reflect or scatter the IR energy. For example, a polished surface reflects better because the amount of irregularities on the surface is small compared to a surface that may be rougher. In either case there are typically two types of reflections, specular and scatter. The specular reflection is the reflection that provides the highest intensity of the emitted energy due to the angle of incidence of the object. Another consideration is the absorption of the object. In many applications the human hand is the reflective object which can absorb some of the IR energy.