Spectroscope rvfm sep 205a p the really intriguing aspect of this device is the use of a common place cd or dvd replacing either an expensive prism or specially made diffraction grating the performance of this ultra low cost spectroscope is comparable with instruments typically costing 163 80 p p it clearly shows fraunhofer lines in the spectrum arising from natural light and distinctive emission bands from artificial sources such as sodium lamps differences between fluorescent lighti