FEI Quanta FEG 250, Руководство пользователя

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Operating Procedures: Detector Types and Usage
5-17
Obtaining Image in BSE Mode
1. Install one of the diodes and select the corresponding Detector.
2. Close the chamber door and pump down the chamber.
When the BSED / GAD diode is installed,
No Accessory / GAD
cone must be selected in the PLA Configuration dialogue when
this appears.
3. When the Vacuum is ready, switch on the accelerating voltage and
slowly increase the contrast and brightness to obtain an image.
Note:
Whenever the BSED or GAD is selected, the optical quad is paused
(because the CCD camera infra-red LEDs are switched off not to emit
the photons supersaturating the detector diode).
LARGE FIELD DETECTOR (LFD)
This detector is used with the standard insert. The field of view is
unrestricted and the magnification range is identical to that of HiVac
mode (assuming no other pole-piece accessory is mounted).
The signal from the LFD contains more BSE information than the
GSED signal. The detector is ideal for general imaging; it is also the
only gaseous SE detector that can be used simultaneously with a
BSED Detector.
FIGURE 5-5 LFD AND ITS CONFIGURATION
Installing and Setting the LFD
The LFD plugs into the signal connector behind the conical lens. In some
cases the user is prompted for the PLA size. Select No Accessory in the
PLA Configuration dialogue or appropriate Cone if installed.
Note:
After inserting the LFD, Preferences… / ESEM tab / Purge mode
changes to Automatic despite any previous selection. This ensures
that the proper chamber environment is achieved (see Chapter 4).
THE CCD CAMERA
enables to view the inner space of the specimen chamber (an optical
quad). It assists with an overall sample orientation and during a stage
movement to prevent its collision with the lens pole. IR LEDs are used
to light the specimen chamber interior.