a clip-regulator (4). The glass tube and the funnel were attached to the holder. The
standard scheme consisting of a He–Ne laser (5), a pinhole (6), and a convergent lens
(7) was used to create a parallel beam of 2 cm diameter. The beam is declined by the
optical mirror (8), so that its direction is changed from horizontal to vertical, and then
it enters into the beaker.
The light beam crosses the interface, containing the investigated“salt finger” cells,
and then it reGects again from the secondoptical mirror (9). Now it propagates in the
horizontal direction and passes through the second imaging lens (10) with the focus
length F = 5 cm. The obtained image produced by the lens is recorded by means of
the CCD camera.
When the beaker was filled with two solutions, we observed(at the appropriate
concentrations of the solutions) a distinct separation between the solutions and the
process of the double-diffusive convection, due to the T–S (sugar–salt) instability owing
to the different values of the salt and sugar diffusivities. We saw the ink-dyed “salt
fingers” cells (see Fig. 2) that descended from the top layer to the bottom layer with