Electronic image formation in high-voltage TEM by sequential pixel acquisition

We describe a complete hybrid imaging system for the electronic detection and manipulation of high-voltage TEM images. The system includes a recently incorporated two-dimensional beam deflector for dissecting the image into pixels by displacing it in a raster in front of an aperture leading to an electron detector. The characteristics of images thus formed by sequential pixel acquisition and displayed on a CRT are discussed and illustrated. Absorption or thickness profiles are also obtained by displaying the scanned pixel intensity in Y-modulation. Similarly, the displacement of an entire diffraction pattern allows the intensities of individual diffraction spots to be quantitated directly over a wide dynamic range. The direct splitting of the image into electronically controlled pixels can be applied to local mass measurements and to energy-loss analysis by means of a simple magnetic prism that can also provide energy filtering in lieu of a more elaborate electron-optical, image-preserving system.