World's Eye
Michael Sha
Award: Top 100
School: stanford online high school
Teacher: marie hamaoui
Category: Contrived
Photo #19308
World's Eye
This macro photograph captures the phenomenon of thin-film interference in a soap bubble. It has been rotated from its original horizontal position to create visual similarities to an eye.
The visible colors arise due to the constructive and destructive interference of white light reflecting off the front and back surfaces of the soap film, which has a thickness on the order of hundreds of nanometers. As light encounters the bubble, part of it reflects off the outer surface, while the rest transmits through the film and reflects off the inner surface. The two reflected waves recombine, and their phase difference (dependent on the film's variable thickness and the wavelength of light) determines whether they interfere constructively (bright color) or destructively (dark).
Thus, color bands correspond to variations in the local thickness of the film, which is not uniform due to the effects of gravity and surface tension. The dark "pupil" at the edge occurs where the film has become extremely thin, approaching the limit where destructive interference eliminates visible reflection. In the lower right region, the vein-like flowing patterns are Marangoni flows, caused by surface tension gradients due to temperature or concentration differences in the film. These patterns are dynamically generated and can evolve rapidly.
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