(A) (B) (C) Optic axis Optic axis Tilted Optic axis incident Reflecting Incident Reflecting Incident beam plane beam plane beam 20=angle of tilt of incident beam specimen specimen specimen 20 20 Objective Objective lens lens Direct Diffracted Direct Diffracted Diffracted Direct beam beam beam beam beam beam Objective Objective aperture aperture 0 Optic Objective Optic Objective Optic Objective axis aperture axis aperture axis aperture Direct beam Diffracted beam Diffracted beam Direct Diaphragm Diaphragm beam Bright field(BF)imaging Dark field (DF)imaging Centered dark field imaging 7 from Fig.9.14 D.B.Williams and C.B.Carter,Transmission electron microscopy(2nd edition)7 Bright field (BF) imaging Dark field (DF) imaging Centered dark field imaging from Fig. 9.14 D.B. Williams and C.B. Carter, Transmission electron microscopy (2nd edition)