Zeiss GeminiSEM Series Instruction Manual

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3 Product and Functional Description | 3.3 Optional Components and Accessories ZEISS3.3.1.10 aSTEM DetectorPurpose The optional aSTEM (annular Scanning Transmission Electron Microscopy) detector consists of anelectron detector underneath an ultrathin specimen.The aSTEM unit is equipped with diodes that are switched on or off in order to allow dark fieldand bright field imaging.123Fig. 35: aSTEM detector1 Incident electron beam (primary elec-trons)2 Thin specimen3 aSTEM detectorInfoRisk of malfunction: The diode segments are sensitive to the light that is used for illuminationin TV mode (infrared and white).When you use a diode detector, always make sure that the TV illumination is switched off. Ifthe CCD Mode is set to Auto Detect, then the TV illumination is automatically switched offwhen a diode detector is used.Function The aSTEM detector is a pneumatically retractable multi-mode detector with a 12-stub specimenholder for bright-field and dark-field detection.The diodes of the aSTEM detector collect transmitted electrons below the ultrathin specimen.A special arrangement of the diodes allows a parallel detection of bright field (BF), oriented darkfield (ODF), annular dark field (ADF), and high angle annular dark field (HAADF). There are onebright field segment (S1), two dark field segments (S2 and S3), one annular dark field segment(S4), and one high angle annular dark field segment (S5).Two different models are available:§ The aSTEM4 allows detection of four channels in parallel.§ The aSTEM1 only collects one signal at a time.58 Instruction Manual ZEISS GeminiSEM series | en-US | Rev. 2 | 349500-8138-000