We propose to study extended emission of intermediate mass
 pre-main sequence stars. We have selected a sample of nearby
 Herbig Ae/Be stars. We will investigate the contribution
 of individual dust populations (large grains, small graphites,
 PAH) to the overall energetics of the halo. For this end,
 the well known mid IR excess of the objects will be
 imaged at different CVF positions.
 The detailed picture of the circumstellar environment will be
 used to disentangle the luminosity of the disk and envelope.
 Our radiative transfer models will be constrained by far IR maps.
 Out of these maps we will derive physical parameters such as far IR
 sizes,  colour temperatures, total dust mass, density distributions
 and opacities.