Asymmetries in transition disks: high angular observation with aperture masking

Aperture masking offers a new tool to observe transition disks right where it matters: between a few to a tenth AUs. This 
superior angular resolution, not yet reached by coronagraph or differential techniques, immediately offered ground-breaking 
results: from the orbiting companion of T Cha, to the possible planet formation signature around LkCa 15. During this talk, 
these old results, as well as new ones, will be discussed.