CD Spectroscope in a Box, Spectrograph

Step 2 Construction

Glue a cardboard plate 70mm from the top and keep it horizontal, Especially from side to side! This is just to support the CD which you may hot glue or tape in place. If you place the plate lower than the recommended 70 mm, the CD must be a little farther from the far edge of the box and the viewing hole must be proportionalely farther from the front edge. Try to keep the angles correct. The incident angle is about 13 degrees from perpendicular and the viewed angle is about 47 degrees from perpendicular or 43 degrees from the horizontal. Note that the angle of the diffracted light is NOT the same as the angle of the source (incident)light.
A hole 10 mm x 20 mm is cut far enough from the front edge to allow taping two razor blades in place 1 mm apart or less. A viewing hole 25mm square is cut 95 mm from the slit. This hole can be slightly oversize for ease of viewing. The light guard is not essential but it is definitely helpful. Hot glue was used in much of the construction. Again, it is not essential but made things easier.