Effect Of The Aperture Diameter On The Image - JEOL JSM-IT200 Instructions Manual

6.1.4 Effect of the aperture diameter on the image

Standard (MAP1)
The OL aperture prepares of two types: 25μm diameter and 50μm diameter. It can get the most suitable
image quality and analysis accuracy if OL aperture is fitted to use purpose and used properly.
Selects the 30μm diameter for observing general or high resolution. Selects the 50μm diameter when a
large current is necessary with analysis. (The 25μm diameter aperture is mounted at the time of factory
shipping.)
Option (MAP3)
The objective lens aperture (movable aperture) provided in this instrument consists of three steps of size: 20,
30 and 100 µm diameter. To obtain high resolution, you must select an optimum aperture diameter.
However, because the image in this instrument requires not only the fineness of the electron beam, but also a
sufficient amount of signals to form an image, you cannot reduce the aperture diameter more than is
necessary. Select 20 µm diameter at the high-resolution observation, 30 µm diameter at the normal
observation and the EDS analysis, and 100 µm diameter at the case when a large current is required such as
the analysis using the WDS.
6-3
No.ISMIT200-1E