For the next year, every night after sunset, an enormous rainbow will appear on one of the arched windows of Amsterdam’s Central Station. The rainbow is a project designed by artist Daan Roosegaarde, but it requires plenty of technology to make it happen.
The artist worked with an optics company and academic researchers to develop a special filter to make the rainbow. The filter is made of a thin film of liquid crystal. It transforms white light from a 4,000-watt spotlight into the rainbow, both splitting the light into its component colors and creating the arched shape.
Among the technical challenges the team overcame were ensuring the colors were rich and strong, spacing the colors so viewers could see ROYGBIV clearly, and ensuring little light leaked from the spotlight elsewhere. The team didn’t want to blind train operators or passengers. The engineers who worked on the project also develop filters that work for optical telecom switches and instruments that detect exoplanets, Roosegaard’s website explains.