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The extremely low magnetic field of the GEMINI® column, compared to single pole FESEM instruments, allows distortion-free high resolution imaging of magnetic materials at short working distances.
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| | Excellent efficiency detection of the secondary electron (SE) signal is another benefit of the GEMINI® lens concept. The low energy, secondary electrons generated at the impact point of the primary electron beam are intercepted by the weak electrical field at the sample surface, then accelerated to a high energy by the field of the electrostatic lens and focussed on the annular In-lens detector inside the beam booster located above the objective lens.
The GEMINI® column used with the SUPRA™ range of FESEMs now benefits from the 3rd generation of In-lens detectors with increased signal to noise ratio, improved dynamic range and no aging effect on the detection material. While the In-lens detector provides the best high resolution information, a lateral SE detector in the specimen chamber provides optimum topographical information. Signals from both detectors may be mixed to deliver optimum image quality.
For the variable pressure (VP) instruments a unique VPSE detector was developed to enable SE imaging at pressures in the 2 to 133 Pa range combined with the standard Everhart-Thornley detector for imaging in high vacuum (HV) mode.
The GEMINI® column allows optimum detection of backscattered electrons (BSE) because of the absence of an immersion field of the objective lens. Classical FE columns tend to condense the BSE on the optical axis in the same way as it condenses the primary electrons. With the GEMINI® column a high probe current can be focussed on a small spot, even at low beam energies, allowing BSE images and X-ray mapping with much better resolution than ever before.
The GEMINI® objective lens concept allows optimum detection of all signals generated at the specimen. |