1.
optical
Symptoms
Causes
Countermeasures
Darkness at the preiphery,
or uneven viewfield
brightness
Revolving nosepiece not in click
stop position ( objective not
centered in optical path )
Revolve to click-stop position
( switch the objective
correctly into optical path )
Filament image not in center
Centering
Dirt or dust on the lens
( condenser, objective, eyepiece
or collector )
Cleaning
Dirt or dust in the viewfield
Dirt or dust on the lens
( condenser, objective, eyepiece
or collector )
Cleaning
Dirt or dust on the slide
Cleaning
Condenser position too low
Correct position
Poor image quality ( low
resolution poor contrast )
No cover glass on the specimen
Attach cover glass
Cover glass too thick or thin
Use cover glass of specified
thickness ( 0.17mm )
Slide upside-down
Turn over the slide
Immersion oil on dry objective
( especially 40X )
Cleaning
No immersion oil used on
immersion objective
Use immersion oil
Dirt or dust on the lens
( condenser, objective, eyepiece
or collector )
Cleaning
Air bubbles in immersion oil
Remove air bubbles
Unspecified immersion oil used
Use specified immersion oil
Condenser aperture and field
diaphragm opened too far
Close properly
Dirt or dust on the entrance lens
Clearing
Condenser position too low
Raise to the position where
the field diaphragn image in
focus
Condenser not in the center of
the view field or condenser
inclined
Reinstallation condenser and
carefully adjust with center
screw
Image shifts on one side
Revolving nosepiece not in click
stop position
Adjust the nosepiece and
centering
Floating specimen
Fasten securely
Image shifts during focus
Specimen rise from stage
surface
Place it stable
Revolving nosepiece not in click
stop position
Revolving to click-stop
position
