http://www.bbc.co.uk/news/science-environment-18181201
Despite the completely absurd sounding title, scientist did in fact discover a method that would allow them to "trap a rainbow". This investigation came about as a result of research into cloaking techniques, or in other words, finding a way to produce an invisibility cloak up to Harry Potter's standards. In order to produce the appearance of invisibility, light must either be guided around an object or cancelled by the material. As stated by the article, the intensive study of light principles has applications that go far beyond invisibility. Researchers claim that by arranging several tiny cloaks in a grid pattern they may develop a technology with functionality in bio-medicine, sensing, and traditional camouflage. So far, the design has not been perfected, but one accomplishment mentioned above was the feat of capturing a rainbow. As interesting as the process is, its not quite as enthralling as the notion of men in lab coats chasing after rainbows, but none the less the technological process goes as such; a micro-lens array only 50 millionths of a metre across is coated with gold and placed on a gold coated sheet of glass. When light was shone through the side it produced a cloaked region in the center of each lens, and slowed the light down as well. The light, in an effect akin to that of a prism, is scattered into its constituent colors producing the "rainbow". From this experiment, scientists have drawn encouragement and they are excited to see how broad the technology can extend across all fields.