Polarizers have, in fact, been in use for a very long time - the Vikings used a “sunstone” (now thought to have been composed of the mineral cordierite, a natural polarizing material) to observe the location of the sun on foggy or overcast days.  Since scattered sunlight is highly polarized compared to light coming along the direction to the sun, the distribution of the sky’s brightness could be observed through the sunstone and hence the sun’s position could be localized and, if the time of day were known, the compass directions.
In 1920, F. Weigert discovered that the fluorescence from solutions of dyes was polarized.  Specifically, he looked at solutions of fluorescein, eosin, rhodamine and other dyes and noted the effect of temperature and viscosity on the observed polarization.  Wiegert discovered that polarization increased with the size of the dye molecule and the viscosity of the solvent, yet decreased as the temperature increased.  He recognized that all of these considerations meant that fluorescence polarization increased as the mobility of the emitting species decreased.
Polarizers II