Electron Optical System in TEM

Electron Optical System lens System Electrongun Aperture placed b/w wondersor $ of objective lens Thermionic emission (TE) gun Eurbeam passing through the wndenson lens illuminates the Heating of filament (cathode) aporture Thermodectron beam Aporture allows part of the e beam to reach the O. lens Focussed into anode Objective lens focuses and Wennett electrode determines the final foursed C beam - Crossover. diameta of the I beam Speciman stage Stably Supports the specimen and moves smoothly Performs the following movements. Honzontal movement : for Selection of field View Vertical movement: for change of Image resolution and depth of four. Titting Rotation

2 - Donor For detecting I 2° is emitted from the specimen Suntillator on the detector tip with a high Voltage 2° electrons generate light on hitting the suntillar Directed to PMT Converted to is Amplified as an electric signal Image Display and Recording Unit Brightness variation appears on the monitor screen on - the display unit forms a SEM Image. Olden days: CRT Recent days LCD. - fast Scan Speed: for observation. Slow Scan Speed: for Saving of Image Rewriting : Digital format - electronic file. ,