Sunrise to seafloor
Solid state lasers are made by growing a crystals and then processing to form the individual lasers, like sculpting. This involves taking away material, and adding others. When liquids are applied to the structure, they are not always uniformly. When their thicknesses differs, their color changes.
Each of the six rectangular mesas represents a separate laser being fabricated. They were etched in a GaN wafer with a chlorine reactive ion etch. BCB (B-staged divinylsiloxane-bis- benzocyclobutene) was spun onto the wafer. However, due to a contaminant on the surface of the wafer altering the flow pattern of the BCB, the final thickness was not uniform and the "wave-like" pattern is seen. This image was taken with an optical microscope.