yes, in ENVI it's possible, but I have to create an IDL script wich do some operation on N1 Meris Files, if I cannot open the file, I cannot work wih IDL

ENVISAT files are not HDF files.  They have their own format and ENVI has created a special reader to read in these files.  You could use ENVI's routine ENVI_OPEN_DATA_FILE with the /ENVISAT keyword to open the file.  IDL does not have a specific routine to read in ENVISAT files.  You could also get the BEAM software and convert the MERIS data files to HDF or other format that IDL can read directly.  Or you could create your own reader in IDL to read in the datafiles using the ENVISAT file specification.