Images　of　Ga+-implanted　amorphous　silicon　layers　in　a　110　n-type　silicon　substrate　have　been　collected　by　a　range　of　detectors　in　a　scanning　electron　microscope　and　a　helium　ion　microscope.　The　effects　of　the　implantation　dose　and　imaging　parameters　(beam　energy,　dwell　time,　etc.)　on　the　image　contrast　were　investigated.　We　demonstrate　a　similar　relationship　for　both　the　helium　ion　microscope　Everhart-Thornley　and　scanning　electron　microscope　Inlens　detectors　between　the　contrast　of　the　images　and　the　Ga+　density　and　imaging　parameters.　These　results　also　show　that　dynamic　charging　effects　have　a　significant　impact　on　the　quantification　of　the　helium　ion　microscope　and　scanning　electron　microscope　contrast.　Lay　description　The　helium　ion　microscope　(HIM)　is　a　recent　development　in　the　family　of　charged-particle　microscopes　and　it　operates　on　similar　working　principles　to　those　of　the　conventional　scanning　electron　microscope　(SEM).　We　investigated　the　effects　of　imaging　parameters　on　HIM　and　SEM　images　using　a　Ga+　focused　ion　beam　implanted　silicon　sample.　Our　results　highlight　the　similarity　and　difference　between　the　two　microscopes　and　also　show　that　imaging　parameters　as　well　as　specimen　properties　have　a　significant　impact　on　the　quantification　of　HIM　and　SEM　metrology.