Efficiency certificate for TE, TM, and NP polarizations of -1st order of a resonant subwavelength G185M grating, investigated in the VUV—NUV range. Efficiency calculated for the best model using the average AFM border profiles before & after coating Cr/Al/MgF2 and RIs taken from Palik’s tables (Al) and the best fit of the calculated efficiency data to experimental ones (MgF2).