Leica DMi8 A - Startup; Adjusting the diaphragms for the incident light illuminator

6. Instrument setup– AdjustIng the dIAphrAgms
6. Startup
6.1 Adjusting the diaphragms
for the incident light illuminator
The following procedure is provided for incident light-bright
field illumination.
• Select an objective with moderate magnication (10x–
20x) and adjust the image.
• Activatetheincidentlightaxisifnecessary.
• SwitchontheBF(=brighteld)orSmithreector.
• Placeaspecimenonthestage.
•Bringthespecimenintofocusandadjustthelightinten-
sity.
Adjusting the field diaphragm
• Closetheilluminatedelddiaphragmuntiltheedgeofthe
diaphragm appears in the specimen plane.
•Ifthelimitsoftheelddiaphragmarenotinthecenterof
the field of view, move the position of the field diaphragm
to the center with the two centering screws (Fig. 52.1) on
the right side of the stand using a 3 mm Allen key. When
centering, observe the position of the field diaphragm
through the eyepieces.
•Openthelightelddiaphragmuntilitjustdisappearsfrom
the field of view.
•Thissettingoftheelddiaphragmremainsthesameforall
objectives.
It is necessary to readjust the field diaphragm only when
using eyepieces with different field numbers or when
changing the magnification using a magnification chang-
er, and for photography and TV imaging. Narrowing the
field diaphragm normally improves the contrast.
2
1
Fig. 52: Adjusting the diaphragms (incident light)
1 Adjusting screws for moving the field diaphragm
2 Adjusting screws for moving the aperture diaphragm
Adjusting the Aperture Diaphragm
• Useaatspecimenwithgoodreectiveproperties,anda
glass plate (specimen carrier) if necessary.
• Removeoneeyepiece (the right one, for example).
• Close the aperture diaphragm until the edge of the dia-
phragm appears in the exit pupil of the objective (aper-
ture diaphragm plane).
• Iftheimagedoesnotappearinthemiddleoftheeldof
view, the aperture diaphragm must be moved into the exit
pupil using the centering screws (Fig. 52.2).
• Opentheaperturediaphragmuntilthespecimentappears
in good contrast.
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