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8.
Cleaning Objectives
It is critical that the front lens of each objective is kept clean and free of contamination. Any
dust or dried immersion oil will seriously affect the image quality attainable with that
objective. If contamination is suspected then the easiest way to confirm this is by removing
the objective lens and examining the front lens using the eyepiece. To do this take out one
of the eyepieces, turn it around so that you are looking the wrong way through it and move
it towards the front of the objective until you can focus on the front lens. This will clearly
show any contamination. To remove dirt and oil a lens cloth, lens tissue or cotton bud
dampened with industrial alcohol can be used. A spiral motion starting from the centre of
the lens moving to the outside is the best way of achieving a thoroughly clean surface
9.
Centring the Objectives
The lowest power objective is mounted in a fixed position and therefore centration of this
particular lens is not user adjustable.
All other powers are mounted in positions with adjustment screws fitted into the nosepiece
above to enable the end user to make adjustments to the alignment of the objective lens. To
re-align an objective which is obviously misaligned with the centre of rotation, as indicated by
the crossline in the eyepiece the following procedure should be followed.
Insert the two supplied centring keys into the adjustment screw sockets above the objective
in the knurled ring of the nosepiece. Rotate the stage and observe that part of the specimen
upon which the specimen appears to rotate. If necessary move the specimen until the centre
of rotation coincides with a feature in the specimen that is easily recognised.
Now by means of the centring screws move the feature until it coincides with the
intersection of the crossline in the eyepiece. The stage must remain stationary while the
objective is being centred. Once the identifiable feature has been aligned with the crossline
rotate the stage to check that the axis of rotation is now coincident with the intersection of
the crossline.
P r i o r L u x P O L
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