Interference colors are formed when there is an obstruction or an interference between two reflected light rays that can be fast or slow, and when light is passing through an anisotropic surface (Roddaro 2707). Because of the perceived obstruction, different colors are produced depending on the wavelength of the light and the thickness of the surface. Inference colors refer to those colors that are visible when a thin section placed between two polarizing film pieces are rocked (Roddaro 2709). In essence, interference colors offer a wide range of reflective features when viewed from diverse angles. Correspondingly, Interference colors result due to the differences recorded in the refractive index of light, light speed, thickness of the anisotropic material and the retardation processes (Roddaro 2710).
The interpretation of interference colors is carried out using a variety of color charts found in most standardized books and related articles (Roddaro 2711). The reoccurrences of Interference colors is common depending on the thickness of the reflective surface. Birefringence is a term used to describe the dissimilarities that exists between the refractive indices of two reflected rays and is therefore not an observable property (Sun and Yinlong 64). As a result, interference colors are the only observable indicator of birefringence that uses primarily the polychromatic lights. Other scientists will also argue that Interference colors are a product of inequality in the transmission of the white light reflected under the anisotropic minerals (Sun and Yinlong 64). Briefly, the occurrence of Interference colors primarily depends the thickness of the mineral component (anisotropic), the refractive differences that exists between two light indices (Birefringence) and the alignment of the crystals in relation to the polarized surfaces.
Reasons why bubbles have colors
Contrary to the various perceptions majority of the people have concerning colors in rainbows or soap bubbles, the observed colors are primarily attributed to the concept of light reflection and refraction (Boys and Charles 23). For example, a bubble always reflects the color of the surrounding explaining the reasons for the many colors in it. This happens when a light wave strikes the surface of bubbles resulting into reflection of some of the light to the eyes of the viewer. Notably, the white light is a combination of all the colors observed in rainbows explaining why there are many colors observed in the reflected light (Boys and Charles 27).
As the two reflected lights travels back, they further obstruct each other leading to the formation of colors. As the two waves strengthen each other, the formed color becomes more intensified until the waves cancel each other out resulting into an almost colorless interface (Boys and Charles 28). With time, the walls of the bubbles get narrower, primarily due to gravitational forces or from weak solutions, the distance separating the inner and outer surface of the bubbles narrows down.
The colors that make up the white light are of different wavelengths and, therefore, as the bubble film thickness narrows, the distance traveled by light changes significantly. Therefore, when the bright light strikes a bubble, the film is quickly reflected into a light of a particular hue that changes with the thickness of the film (Boys and Charles 29). The light strikes the bubbles from diverse angles explaining why the bubbles are often so colorful. Similarly, depending on the wavelength of the reflected light, different colors are observable on the bubbles.
Boys, Charles Vernon. Soap bubbles and the forces which mould them. Doubleday Anchor Books, 2009.
Roddaro, S., et al. “The optical visibility of graphene: Interference colors of ultrathin graphite on SiO2.” Nano letters 7.9 (2007): 2707-2710.
Sun, Yinlong, et al. “Deriving spectra from colors and rendering light interference.” IEEE Computer Graphics and Applications 19.4 (2006): 61-67.