The Fresnel equations describe how much light is reflected and transmitted (refracted) when it encounters the boundary between two different media, such as air and glass. These equations are fundamental in understanding optical behavior at surfaces.
What They Describe:
When a light wave strikes a boundary between two media with different refractive indices, part of the wave is reflected back and part continues into the second medium but changes direction (refraction). The Fresnel equations give the exact proportions of reflected and transmitted light, depending on:
- The angle of incidence.
- The refractive indices of the two media.
- The polarization of the light (whether it is parallel or perpendicular to the plane of incidence).
Key Outcomes:
- Reflection Coefficient (R) – Tells what fraction of light is reflected.
- Transmission Coefficient (T) – Tells what fraction of light is transmitted.
- At normal incidence, reflection depends only on the difference in refractive indices.
- At certain angles (like Brewster’s angle), reflected light can be completely polarized.
Applications:
- Anti-reflection coatings (like on camera lenses and glasses).
- Fiber optics, where light transmission must be maximized.
- Optical design in solar panels, sensors, and display technologies.
- Understanding laser reflections and minimizing power losses.
Why It Matters:
The Fresnel equations are essential for precise control of light in optical systems. They are critical in designing devices that manage reflection and transmission, helping optimize performance in everything from microscopes to solar cells.