Interference off a Dewdrop

In addition to supernumeraries there were these white light fringes, reminiscent of bands in a strong fogbow. They were a bit harder to find and seemed to be due to reflection off a distorted drop, perhaps where it joined a blade of grass. A simple reflection of the sun in the sperical surface wouldn't do this, as shown at the bottom.

White light interference fringes Reflection interference fringes off a water drop

A good example of the white light fringes.

Rather like a fogbow with coloured supernumaries.

Guttation drops on grass Inteference fringes from a water drop

The bright spot in the upper drop was the source -

- for this set of fringes.

Specular reflection off a guttation drop Out of focus specular reflection off a drop

A simple reflection of the sun on a spherical drop -

- doesn't produce the fringes.

Canon EOS 20D   April 2007

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