On 24.05.2024, the Lange Nacht der Forschung (Long Night of Research) commenced in Austria. Lorenz, Rahul, and Sebastian from iStOMPS participated in this fantastic event with an exhibit at the main building of the University of Vienna. Together with members of the Backus group (laser spectroscopy), they presented a hand-built, do-it-yourself-style absorption spectrometer for visible light. We (and the visitors) had lots of fun in discovering how colors work. There even was a detective story about the ominous Prof. U. V. Vis for the kids to solve!
The spectrometer consists of easily available parts: an LED torchlight, a reading lens, two playing cards, a simple optical grating, a strip of white paper, and a webcam. The parts are arranged on a plywood frame with some 3D-printed mounts and contained in a black cardboard box that can be closed. When the torchlight is turned on, its light falls on the grating and is split into a rainbow on the paperstrip. The webcam sends pictures of the rainbow to a connected laptop that visualizes the absorption spectrum of colorful foils or table scatter gemstones.