Kiessig fringes

Kiessig fringes are a pattern of light and dark stripes that appear when light reflects off a thin film, such as soap bubbles or oil on water. This phenomenon occurs due to interference, where light waves bouncing off the top and bottom surfaces of the film combine. Depending on the film's thickness and the angle of light, some light waves reinforce each other (creating bright fringes) while others cancel out (creating dark fringes). These patterns can provide valuable information about the film's properties, such as its thickness and uniformity, making them useful in scientific and industrial applications.