Recent experiments in high-power lasers show that they modulate of the density of air at long ranges, up to filamentation
in a restricted volume. There are two effects: light concentration and plasma filamentation, depending on the laser
power. Two such laser-heated volumes can scatter stellar light into a central station, where they are made to interfere in
speckled fringes. Usually the density modulations deflect the light only slightly, so the maximum baseline is not
extended. However, if either the modulation of the density of air is strong, or its spatial frequency is high, then the stellar
beam deflection is significant. In such a case, the scattering volumes can be further off to the sides, and baselines of
hundreds of meters can be envisaged.