incidentlicht

Incidentlicht, or incident light, refers to the portion of electromagnetic radiation that travels toward and strikes a surface or boundary. It is defined by its direction, spectral content, intensity, and polarization. The angle between the incident ray and the surface normal is the angle of incidence. When incident light meets a boundary between two media, part of it is reflected back into the original medium and part is transmitted into the second medium (refraction). The law of reflection states that the angle of incidence equals the angle of reflection, while Snell’s law governs refraction, relating the incident and transmitted angles to the refractive indices of the two media.

The interaction of incident light with a boundary depends on polarization. Reflection and transmission coefficients differ for light polarized parallel (p) and perpendicular (s) to the plane of incidence. The Fresnel equations describe these dependencies and determine how much light is reflected versus transmitted at a given angle and wavelength. If some light is absorbed by the surface, this contributes to the material’s absorptance.

Key quantities associated with incident licht include irradiance, the incident power per unit area (measured in W/m²), and the spectral distribution of the incident field. These concepts are important in a range of applications, such as photography, solar energy, optical coatings, and sensing.

Applications include analyzing optical systems, designing anti-reflective coatings, calculating solar panel input, and characterizing surface properties in metrology. The concept of incident light is foundational in optics, providing a basis for understanding how light interacts with boundaries, surfaces, and materials.