Anisotropic strain induces a partial linear polarization of the photo-luminescence (PL) emitted by cubic semiconductor crystals such as GaAs or InP. This paper thus presents a polarimetric PL microscope dedicated to the characterization of semiconductor devices. The anisotropic strain is quantified through the determination of the degree of linear polarization (DOLP) of the PL and the angle of this partial linear polarization. We illustrate the possibilities of this tool by mapping the anisotropic strain generated in GaAs by the presence of a stressor film at its surface, that is, a microstructure defined in a dielectric thin film (SiNx) that has been deposited with a built-in stress and shaped into a narrow stripe by lithography and etching. Our setup shows a DOLP resolution as low as 4.5×10 on GaAs.