Basics

The elec­tro­mag­net­ic spec­trum of vis­i­ble light as we could see it in a rain­bow reach­es from vio­lett over blue, green, yel­low to red. The spec­trum below this area is called ultra­vi­o­let, above this spec­trum it is called infrared. As you might know, sun­light con­sists of all parts of the spec­trum not only the vis­i­ble part.