Everhart Thornley Detector (Etd); Low Vacuum Detector (Lvd) - Thermo Scientific Apreo User's Operation Manual

Everhart Thornley Detector (ETD)

The Everhart Thornley Detector is a scintillator photo-multiplier
type detector that collects electrons generated by the primary
beam interaction with the specimen surface. It is permanently
mounted in the chamber over and to one side of the sample. It
works in Modes:
• Secondary Electrons (SE)
• Backscattered Electrons (BSE)
• Custom
ETD Settings
The Detector Settings / Mode list box enables choosing an SE /
BSE mode (the Grid Voltage is set to +250 V / -150 V) or a Custom
mode, for which the Grid Voltage can be set by the adjuster in a
range from -240 to +260 V. When the voltage is negative (use a
range of -25 to -240 V), SE are repelled from the ETD detector
and only BSE are detected.

Low Vacuum Detector (LVD)

This detector is standard and optimal for general imaging in Low
Vacuum mode over the entire pressure range from 10 – 500 Pa
(0.08 to 4 Torr). Its signal contains both secondary and
backscattered electrons. The LVD detector limits the field of view
to about 1 mm at the 10 mm working distance. The minimum
working distance is limited to about 3 mm.
Low Vacuum Detector (LVD)
FIGURE 5-7:
LVD Settings
After the pump down and purge processes, switch on the
accelerating voltage. The modified Detectors module / Bias slider
is automatically activated.
Adjust Bias if necessary to increase the signal or to stop possible
discharges. At the lowest possible magnification, adjust the
Contrast and Brightness, if necessary, until the bright circle of the
LVD cone can be seen in the center of the image. Increase
magnification and adjust Contrast and Brightness more precisely.
5-18 User Manual
Operating Procedures: Standard Detectors
C O N F I D E N T I A L – limited rights
Feb 2018 Revision A