▁used ▁to ▁an ▁advantage , ▁as ▁it ▁can ▁be ▁manip ulated ▁to ▁provide ▁more ▁information ▁about ▁the ▁sample , ▁such ▁as ▁in ▁complex ▁phase ▁retr ieval ▁techniques . ▁ ▁D iff raction ▁ ▁As ▁previously ▁stated , ▁by ▁adjust ing ▁the ▁magnetic ▁l enses ▁such ▁that ▁the ▁back ▁foc al ▁plane ▁of ▁the ▁l ens ▁rather ▁than ▁the ▁imag ing ▁plane ▁is ▁placed ▁on ▁the ▁imag ing ▁appar atus ▁a ▁diff raction ▁pattern ▁can ▁be ▁generated . ▁For ▁thin ▁cry st all ine ▁samples , ▁this ▁produces ▁an ▁image ▁that ▁consists ▁of ▁a ▁pattern ▁of ▁d ots ▁in ▁the ▁case ▁of ▁a ▁single ▁cry stal , ▁or ▁a ▁series ▁of ▁rings ▁in ▁the ▁case ▁of ▁a ▁pol yc ry st all ine ▁or ▁am orph ous ▁solid ▁material . ▁For ▁the ▁single ▁cry stal ▁case ▁the ▁diff raction ▁pattern ▁is ▁dependent ▁upon ▁the ▁orientation ▁of ▁the ▁spec imen ▁and ▁the ▁structure ▁of ▁the ▁sample ▁ill umin ated ▁by ▁the ▁electron ▁beam . ▁This ▁image ▁provides ▁the ▁investig ator ▁with ▁information ▁about ▁the ▁space ▁group ▁symmet ries ▁in ▁the ▁cry stal ▁and ▁the ▁cry stal ' s ▁orientation ▁to ▁the ▁beam ▁path . ▁This ▁is ▁typically ▁done ▁without ▁using ▁any ▁information ▁but ▁the ▁position ▁at ▁which ▁the ▁diff raction ▁sp ots ▁appear ▁and ▁the ▁observed ▁image ▁symmet ries . ▁ ▁D iff raction ▁patterns ▁can ▁have ▁a ▁large ▁dynamic ▁range , ▁and ▁for ▁cry st all ine ▁samples , ▁may ▁have ▁intens ities ▁greater ▁than ▁those ▁record able ▁by ▁C CD . ▁As ▁such