In general, interferometry is used to measure surface shape, including thin-film thickness [1]. It is a powerful means to measure a surface using light's interference phenomenon. The thickness can be measured by the phase difference of the interferograms generated on the upper and lower surfaces of the thin film [2].

What does an interferometer do?

Because of their wide application, interferometers come in a variety of shapes and sizes. They are used to measure everything from the smallest variations on the surface of a microscopic organism, to the structure of enormous expanses of gas and dust in the distant Universe, and now, to detect gravitational waves.

What causes thin film interference?

Thin film interference occurs when light waves reflecting off the top and bottom surfaces of a thin film interfere with one another. This type of interference is the reason that thin films, such as oil or soap bubbles, form colorful patterns.