▁sample , ▁it ▁is ▁possible ▁not ▁just ▁to ▁determine ▁the ▁position ▁of ▁defect s ▁but ▁also ▁to ▁determine ▁the ▁type ▁of ▁defect ▁present . ▁If ▁the ▁sample ▁is ▁orient ed ▁so ▁that ▁one ▁particular ▁plane ▁is ▁only ▁slightly ▁t ilt ed ▁away ▁from ▁the ▁strong est ▁diff ract ing ▁angle ▁( known ▁as ▁the ▁B rag g ▁Ang le ), ▁any ▁dist ort ion ▁of ▁the ▁cry stal ▁plane ▁that ▁locally ▁til ts ▁the ▁plane ▁to ▁the ▁B rag g ▁angle ▁will ▁produce ▁particularly ▁strong ▁contrast ▁variations . ▁However , ▁defect s ▁that ▁produce ▁only ▁disp lacement ▁of ▁atoms ▁that ▁do ▁not ▁t ilt ▁the ▁cry stal ▁to ▁the ▁B rag g ▁angle ▁( i . ▁e . ▁disp lac ements ▁parallel ▁to ▁the ▁cry stal ▁plane ) ▁will ▁not ▁produce ▁strong ▁contrast . ▁ ▁Ph ase ▁contrast ▁ ▁Cry stal ▁structure ▁can ▁also ▁be ▁investig ated ▁by ▁high - resol ution ▁transmission ▁electron ▁micro sc opy ▁( HR TE M ), ▁also ▁known ▁as ▁phase ▁contrast . ▁When ▁using ▁a ▁field ▁emission ▁source ▁and ▁a ▁spec imen ▁of ▁uniform ▁thick ness , ▁the ▁images ▁are ▁formed ▁due ▁to ▁differences ▁in ▁phase ▁of ▁electron ▁waves , ▁which ▁is ▁caused ▁by ▁spec imen ▁interaction . ▁Image ▁formation ▁is ▁given ▁by ▁the ▁complex ▁mod ulus ▁of ▁the ▁incoming ▁electron ▁be ams . ▁As ▁such , ▁the ▁image ▁is ▁not ▁only ▁dependent ▁on ▁the ▁number ▁of ▁electrons ▁hitting ▁the ▁screen , ▁making ▁direct ▁interpretation ▁of ▁phase ▁contrast ▁images ▁more ▁complex . ▁However ▁this ▁effect ▁can ▁be