Inuences of geometrical shapes on infrared signatures for anisotropic emitting point targets

The paper applies the anisotropic emission behavior of materials to the point-source infrared (IR) detection research. The target-to-detector IR transmission model is established via the Monte Carlo method, and the effects of the anisotropic emission patterns of the target surface upon the target's IR signatures for four simple geometrical objects are investigated. It is concluded that the sensitivity of point-source signals to anisotropic emission behavior is related to the target's geometrical shapes and the emission angular patterns of the target surface. As the hemispherical emissivity is kept constant, the signals are highly sensitive to the near-normal emission patterns with narrow radiant angular widths, and increasing the normal emissivity can enhance the total energy intensity. In addition, compared with the ellipsoid, cylinder and cone, the sphere is the least sensitive to anisotropic emission patterns, which signifies that the angular distribution of emission has the minimal impacts upon the sphere.