We propose to perform a detailed comparison between infrared and
X-ray high spatial resolution images on two selected bright X-ray
regions in the Cygnus Loop supernova remnant (SNR). We will be
able to determine down to which scale infrared and X-ray emission
are linked, and to derive direct implications for the grain
processing in the hot gas of SNRs. Correlation with the optical
emission will also be carried out. The morphological differences
between optical and X-ray emission will permit to decompose the
infrared emission into two components : one arising from the
collisionnaly heated dust in the hot gas and the other from dust
heated within cooler optically emitting filaments.
 X-ray spectra with a good spectral resolution (ASCA satellite)
strongly support a large underabundance of elements in the Cygnus
Loop SNR. Depletion of the these elements from the gas phase is
usually invoked. A map of the infrared silicate band, compared
to the X-ray emission should clarify this point and show if the
X-ray missing material is still in the grain phase.
 Images in the 10.7-12 microns range will show if the carriers
of unidentified infrared features survive or not the passage of the
shock and if they do, how they are linked to the optical and X-ray
emission.