Fresnel’s equations help calculate how much light is reflected when it strikes the boundary between two different materials, like air and glass. The amount of reflected light depends on the angle at which the light hits the surface and the materials’ optical properties.
To calculate the reflected intensity using Fresnel’s equations, you first determine how the electric field of the light behaves at the boundary. Light can be polarized in different ways—either perpendicular or parallel to the surface—and each type reflects differently. Fresnel’s equations provide specific reflection factors for each polarization.
These reflection factors represent how much of the electric field is reflected. Since the intensity of light is related to the strength of its electric field, you find the reflected intensity by squaring these factors. If the light is unpolarized, meaning it contains both polarizations equally, you take the average of the two reflection values.
Finally, you multiply this result by the original light’s intensity to get the actual reflected intensity. This method is used in optics to predict how bright a reflection will be from surfaces like lenses, windows, or water, and it’s essential in designing things like anti-reflective coatings or optical sensors.