We had four nights in January and, for the first time, a clear, calm night to phase the two telescopes. The phasing took some time but we finally achieved interference late on the first night. We looked by changing the path-length difference between the beams while monitoring the flux of the star. As the path difference became less than the coherence length we saw a random fluctuation in intensity that was a maximum when the paths were equal. This random fluctuation is caused by atmospheric turbulence creating path-length differences between the beams. The two movies below show sequences of short exposure frames capturing the stars at constructive and destructive interference.

The top image is R Leo the bottom image is alpha Orionis (Betelgeuse). Both have surrounding dust clouds which are detectable once the star light is cancelled out.

The frames in which the starlight cancels out are saved and later added together to achieve a high signal-to-noise image of any circumstellar material.