In a previous paper (1) we presented exper imenta l da ta concerning the l inear polar izat ion of 150 ~ e V photons. We obta ined these da ta by measur ing the asymme t ry in electron pair product ion at cer ta in angles, in an conver ter . This method is not feasible when the photon energy is larger than ~ 500 MeV, because the angle of emission of the pair part icles, wi th respect to the p r imary photon, becomes too small . In this le t te r we propose a me thod for measur ing the l inear polar izat ion based again on a s y m m e t r y in pair product ion , bu t t ak ing into account the pair par t ic les emi t t ed at any angle in a th in crystal conver te r (2). The l imi ta t ions in the use of this me thod are also examined . L e t us consider a h igh-energy photon b e a m of m o m e n t u m k/c (c is the ve loc i ty of the light) l inear ly polar ized in the direct ion 9 and s tr iking a single crys ta l at a small angle 0 (~ 0.1 rad) wi th a reciprocal la t t ice axis b 1. We choose two o ther axes b 2, b3 perpendicular to each o ther and to b 1, in order to have a reference f rame. We s ta r ted f rom MAY'S (3) e lectron pair product ion differential cross-section f rom l inear ly polar ized photons in the field of a nucleus and we used the same calcula t ion technique employed in o ther works (L4.5). We considered the electron pair product ion cross-section da~l and do• for e para l le l and perpendicular , respect ively, to the p lane (k, bl), de tecmined by the direct ion of the incident photons and the axis b 1. doll and do• are differential in the energy E_ of the electrons and in tegra ted over the emission angles of the pair electrons.