Olive oil fluorescence — 3 lasers
The blue, green and red line spectra above show the fluorescence of extra-virgin olive oil excited by lasers of 404nm, 532nm and 633nm respectively. The relative strengths of the laser peaks and the main chlorophyll peak at 678nm give an approximate measure of the ratio of molecular scattering to chlorophyll fluorescence ('false' to 'true' dispersion in the language used by Sir George Stokes in his 1852 papers). The grey line is the transmission spectrum of the olive oil (pathlength 1cm).
The four images below show the laser beams entering a glass bottle of the olive oil from the right. The laser wavelengths are, clockwise from the top left: 404nm, 532nm, 633nm, high power 532nm. All of these lasers excite the red fluorescence but the fainter spectral features shortward of the 633nm laser peak are different. This will be shown in a later post.