Fluorescence of white geranium flower

Right: white (Sun) light image
Middle: UV (368nm) LED + UG2 filter
Left: UV (368nm) LED + UG2 filter with yellow camera filter

This shows that the petals fluoresce with a beautiful pure blue colour. Such pure blues (with no red component) are very rare amongst plant 'pigments' - here of course, the colour is not the result of a pigment but derives from the UV-excited fluorescence of molecules within the petal.

The green image on the left is a test I did to ensure that the camera is not directly seeing any of the exciting UV light.

Note that the centre and left images are taken in complete darkness except for the UV source. The illuminated background is fluorescence from the wooden (beech) table.

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