ohutkalvointerferenssi

Ohutkalvointerferenssi, or thin‑film interference, is a wave phenomenon that occurs when light reflects off the boundaries of a very thin layer of material, such as oil, soap film, or a metal coating. The film’s surfaces act as two partially reflecting interfaces. When a beam of light is incident, part of it is reflected at the top surface, while the rest passes through, reflects off the bottom surface, and travels back out through the top. Because the optical path length of the second beam is longer, it can interfere constructively or destructively with the first, depending on the film thickness, the wavelength of the light, and the angles of incidence.

The constructive or destructive interference modifies the intensity of the reflected light for each wavelength, producing vivid colors that change with viewing angle and film thickness. This effect is responsible for the rainbow patterns observed in soap bubbles, oil slicks, and the iridescence of some insects and feathers. In technology, thin‑film interference is exploited in anti‑reflective coatings on eyeglass lenses, place‑neutral photonic crystals, and metal‑film antireflective structures on solar panels. Precise control of film thickness allows for coatings that selectively transmit or reflect specific wavelengths, enhancing optical system performance. The underlying physics can be described by the Fresnel equations and phase shifts upon reflection, and it is a key concept in optics, materials science, and nanophotonics.