Light reflection and transmission simulation. Thin Film Interference model investigates reflection and transmission of light through a thin film. The user can change the thickness and index of refraction of the thin film as well as the incident light wavelength.

With this simulation, you can explore thin-film interference. When light traveling in one medium is incident on a thin film of material that is in contact with another medium, some light reflects off the top (or front) surface of the film, and some light goes through the film, reflects off the bottom (or back) surface of the film, and emerges back into the original medium. These two reflected waves then interfere with one another. The interference can be constructive, destructive, or something in between, depending on the thickness of the film.

Note that, in the simulation, the incident wave is shown on the left. The wave that reflects off the top surface of the film is moved horizontally to the right, so we can see it easily without it being on top of the incident wave. The wave that reflects off the bottom surface of the film is moved even farther to the right. Look at the interference that occurs between the two waves traveling up in the top medium.
We can start our analysis by thinking about the path-length difference that occurs for the two waves. One wave just bounces off the film, while the other wave goes through the film, reflects, and travels through the film again before emerging back into the first medium. If the film thickness is t, then the second wave travels an extra distance of 2t compared to the first wave. The path-length difference, in other words, is 2t.

Requirements:
* Java

The license of this software is Freeware, you can free download and free use this graphing software.