Last updated: Sat Jan 11 2003

Rotation of Linear Polarized Light in Sugars
White Light in Fructose
l-fructose

Linearly polarized white light scattered by a column of disolved fructose (l-fructose or levulose).
Three views of the same column. taken approx. 45 degrees apart, showing a clear right helix.

Light from a mini-maglite passes through a linear polarizer film, enters the tube from the bottom and creates a beautiful color helix that turns to the right, clockwise.

If the column were ordinary water, we would only see darker and brighter zones, purely vertical, alternating every 90 degrees.
And if the polarizer film were absent we would only see white light, actually pale blue, emitted homogeneously in all directions.

Here, because of the l-fructose, the vertical brighter bands become separated into their constituent colors and rotated progressively more as the light travels up the tube. When looking down the tube, the polarization directions (each color has its own) are actually turning to the *left* or anticlockwise. For any given color, the polarization direction is the direction of maximum intensity of its complementary color. The l- prefix (levus) indicates "left".