Differential Imaging Polarimetry with Adaptive Optics

Marshall Perrin (UCLA)

While AO imaging now routinely provides very high angular resolution,
obtaining high contrast sensitivity to faint circumstellar matter 
remains a challenge due to the extended PSF halo of AO-uncorrected 
light. One technique which has proven very powerful in this regard 
is differential polarimetry, which exploits the polarization of 
scattered light to distinguish true circumstellar material, such as 
disks and envelopes, from extended PSF artifacts. This approach has 
been used to obtain high contrast images of disks around many young 
stars, and is increasingly being used as a tool for better 
understanding the physical composition of these disks. I will present 
the basic physics behind imaging polarimetry, describe the instrumental 
and observational techniques used, and highlight a few recent science 
results before closing with a look ahead at the planned imaging 
polarimetry modes of the next generation high-contrast AO systems, 
GPI and SPHERE.