  We obtain an expression for the probability density function (PDF) of
partially developed speckles formed by light with an arbitrary degree of
polarization. From the probability density we calculate the detection threshold
corresponding to the 5sigma confidence level of a normal distribution. We show
that unpolarized light has an advantage in high contrast imaging for low ratios
of the deterministic part of the point spread function (DL PSF) to the halo,
typical in coronagraphy.

Instrumentation and Methods for Astrophysics