L ABORATORI N AZIONALI DI F RASCATI SIS – Pubblicazioni LNF–08/26 (IR) November 24, 2008 OPTICAL FAR FIELD DIFFRACTION PATTERN TEST OF LASER RETROREFLECTORS FOR SPACE APPLICATIONS IN AIR AND ISOTHERMAL CONDITIONS AT INFN-LNF A.Boni, C. Cantone, S. Dell’Agnello 1 , G. O. Delle Monache, M. Garattini, N. Intaglietta, C. Lops, M. Martini, L. Porcelli Laboratori Nazionali di Frascati dell’INFN, Via E. Fermi 40, Frascati, I-00044, ITALY Abstract We describe the INFN-LNF standard procedure for the optical Far Field Diffraction Pattern (FFDP) test of cube corner laser retroreflectors (CCRs) for space applications, when these CCRs are in air and in isothermal conditions around (22 ± 2) o C. This procedure was developed in 2007 and 2008, using prototype GLONASS CCRs lent to LNF by IPIE of Moscow and a GPS-2 flight model CCR array lent to LNF by the University of Maryland at College Park (all using Al-coated fused silica retroreflectors of 27 mm diameter). This was done in the context of the INFN experiment ETRUSCO 2 . The modeling of FFDP measurements is performed with a commercial software, CodeV by O.R.A. Inc., and it has been cross-checked against two independent software programs developed by other two members of the ILRS “Signal Processing Working Group”, D. Arnold and T. Otsubo, finding very good agreement among the three. In summer 2008 this procedure has been validated by performing the FFDP test of the LAGEOS “Sector”, an engineering prototype on loan from NASA-GSFC, equipped with 37 uncoated, fused silica retroreflectors of 38 mm diameter. We report test results for the GLONASS and LAGEOS CCRs. Details of the test procedure and CodeV simulations are given for the particular case of the LAGEOS Sector. 1 Member of the Signal Processing working group of the International Laser Ranging Service (ILRS). 2 ETRUSCO (Extra Terrestrial Ranging to Unified Satellite Constellations) is dedicated to characterization and the improvement of the satellite laser ranging of GNSS constellations [1].