Journal article

Spectral cola or how to turn green laser light red

A green laser pointer shone through a glass of cola will appear red when looking from above the glass. Lowering the laser so that it is deeper in the cola, the colour will vary from orange to deep red. Fluorescence and absorption spectra were recorded consistent with the reddening of the laser. The depth dependence of the colour of the immersed laser is attributed to a more significant absorption of the short wavelengths by the cola, making the laser look redder as it is lowered deeper into the cola. To confirm this hypothesis, we simulated the fluorescence spectrum we would get at various depths by applying the Lambert law on our measured fluorescence spectrum. These spectra were then converted into red, green and blue (RGB) values. These values were compared to those measured on images of the immersed laser beam at corresponding depths.


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