Experimental characterisation of CCD cameras for HREM at 300 kV

The modulation transfer function, noise transfer function and detection qua ntum efficiency of both 1k(2) and 2k(2) cameras attached to the same 300 kV FEGTEM have been measured. The results show that both the MTF and the DQE of the 2k(2) camera are lower than for the 1k(2) camera at frequencies abov e a third of the Nyquist limit. This lower per-pixel performance of the 2k( 2) camera is primarily a result of the use of a thicker phosphor scintillat or. However, MTF and DQE of the 2k(2) camera operated as an effective 1k(2) camera by using 2x(2) pixel binning are superior to the 1k' camera in the medium spatial frequency range. (C) 2000 Elsevier Science B.V. All rights r eserved.