In this paper the multibeam reflection in a Fabry-Perot optically acti
ve etalon has been studied in the case of total reflection of one boun
dary. The formulae for the intensity of the reflected beam are obtaine
d. The mathematical modelling shows that the multiple reflection reinf
orced by total reflection in optically active isotropic medium increas
es the intensity of the reflected waves and causes strong effects such
as the polarization transformation and the splitting of the interfere
nce maxima.