A Simple CD ROM Spectroscope - Step-by-Step

Joachim Köppen Kiel/Strasbourg/Illkirch Spring 2007

  1. In the bottom of your cardboard box (from muesli or cereals) cut a small hole which will serve as the viewing opening
  2. make a larger hole for the entrance aperture. Both the sizes and the separation of these holes are not critical.
  3. Take a strip of cardboard to make the holder for the CD ROM piece: Its height should snugly fit the interior of the muesli box, and it should be broader than the CD ROM piece, that is, it should be larger than one half diameter of a CD ROM. The flaps at the top and bottom are for glueing it to the box, and can be any dimension you prefer.
  4. Cut the CD ROM: Take a good pair of scissors, hold the CD firmly, and simply cut it from the outer rim to the centre in one go with even pressure. The silvery foil of the CD is the most important part, as it contains the grooves. It often comes off at the cut edges. It is a good idea to pass a hot soldering iron or a plastic cutting tool over the "top" side in order to fix the silvery foil by melting it to the plastic body. An even better way is to use a soldering iron or a hot-wire plastic cutter to cut the CD.
  5. Do not glue the CD ROM with its "top" side (which contains the lettering etc) directly to the cardboard holder. Instead, attach strips of sticky tape to the clear "bottom" side (into which you would look) and fix the tape strips to the cardboard.
  6. Placing and positioning the CD ROM in the box is the most delicate part of the construction. After some initial trials to get a rough idea at which position and which orientation you best see the spectrum of a test light source (a small penlight held to the entrance opening helps!), apply glue to the top and bottom flaps of the holder, and fix it in the box at the desired position. While the glue is still not dry, you can then adjust its orientation until you get the best view. If your room has fluorescent lights, they serve well because of their distinct spectrum of bright emission lines!
  7. The slit is made from a suitably sized piece of the silver plastic cover of yoghurt containers (or white cheese ...). With a good pair of scissors, make a straight, clean cut across the middle. The two pieces then are placed side by side ...
  8. ... on a flap cut from cardboard which will cover the spectroscope's entrance hole. A narrow gap (half a mm or less) is left between the two yoghurt strips.

| Top of the Page | to Main Page | to my Home Page |