Magnetic field vector retrieval with the Helioseismic and Magnetic   Imager
  We investigate the accuracy to which we can retrieve the solar photospheric magnetic field vector using the Helioseismic and Magnetic Imager (HMI) that will fly onboard of the Solar Dynamics Observatory (SDO) by inverting simulated HMI profiles. The simulated profiles realistically take into account the effects of the photon noise, limited spectral resolution, instrumental polarization modulation, solar p modes and temporal averaging. The accuracy of the determination of the magnetic field vector is studied considering the different operational modes of the instrument. 
J.M. Borrero, S. Tomczyk, A. Norton, T. Darnell, J. Schou, P.   Scherrer, R. Bush, Y. Liu