Bending light experiment

For the Long Night of Science in Erlangen, I have prepared an experiment where light is being bend by propagating inside a gradient refractive index media. Here is the recipe:

1. Prepare saturated sugar solution:
Dissolve 6 kg of sugar in 3 l of water => Will produce more than 7 liters of sugar solution (keep in mind for beaker size). Fill beaker with water, use magnetic stirrer and heat solution to about 50 °C. Pour in sugar, small amounts at a time. Try to avoid having a layer of sugar on the bottom, this will burn and produce caramel (which might taste good but is not helpful here).

2. Experiment:
Fill an empty fish tank with the saturated sugar solution. Use a tube to fill it carefully with water (maybe 20 or 25 liters, about 5 times the sugar solution) on top of the sugar solution. Try to avoid that the solutions mix. Diffusion will produce the sugar concentration gradient within a couple of hours. Shine with a laser from the side to see several bounces from the bottom glass.