Detecting extrasolar planets with sparse aperture masking

Extrasolar planets are directly detected most easily when they are young and can have contrasts only a few hundred times fainter than their host stars at near- and mid- infrared wavelengths. However, planets and other solar-system scale structures around solar-type stars in the nearest star forming regions require the full diffraction limit of the world's largest telescopes, and can not be detected with conventional AO imaging techniques. I will describe the recent successes of long-baseline interferometry in detecting planetary-mass companions, focusing on the transitional disk system LkCa 15. I will outline why aperture-masking has been so successful in its resolution and sensitivity niche, and will outline the algorithms needed to calibrate the primary observable of closure/kernel phase to the level needed for extrasolar planet detection.