Tecnai on-line help manual -- Options - UT Southwestern

<strong>Tecnai</strong> on-line help Options 113Options Software version 28 TEM Free Lens Control (FP5458/00)8.1 IntroductionFree Lens Control allows control over individual lenses of the <strong>Tecnai</strong> microscope. The followinglimitations apply.Safety• The spot size (first condenser lens or C1) cannot be taken lower than the value for spot size number1.• On 200 kV systems the spot size (first condenser lens or C1) cannot be taken lower than the valuefor spot 5 when the high tension is higher than 120 kV and no holder is present in the CompuStage.• On 200 and 300 kV systems the spot size (first condenser lens or C1) and intensity (secondcondenser lens or C2) are blocked when the gun is in conditioning.Operation• All lens settings range from 0 to 100%, except for the first condenser lens which has a minimumvalue as decribed above and the minicondenser lens which ranges from -100 to 100%.• The changes in lens settings are not persistent. If microscope settings are changed that affect lenssettings (e.g. the switch between Microprobe mode and Nanoprobe mode), the Free Lens settingsare overruled. In order to avoid interference as much as possible, the relevant knobs on the ControlPads of the microscope are disconnected. Thus the Intensity knob is disconnected when C2 ischanged, the Focus knob when the objective lens is changed, and the Magnification knob when oneof the projection system lenses(Diffraction, Intermediate, Projector 1, Projector 2) is changed. Theseknobs are reconnected when Free Lens Control is deactivated. There are, however, many controlsthat can interfere with Free Lens Control and not all can be blocked.• As long as a particular lens has not been changed through Free Lens Control, its particularmicroscope control is not disconnected. Thus, if you only change settings of the projection system,the control of the condenser system (spot size, intensity) can still be done with the normalmicroscope controls.