تباعد الشعاع Beam divergence https://en.wikipedia.org/wiki/Beam_divergence https://en.wikipedia.org/wiki/Beam_divergence beam divergence http://en.wikipedia.org/wiki/Beam_divergence (en) تباعد الشعاع low-divergence beam diverge Divergência de feixe Beam divergence [الإنجليزية] Beam divergence English