When the arc lamp is turned on, and the slide/specimen is placed in position on the stage,
illumination of the sample from the objective lens will be readily apparent. The slider, black and
marked L on left side and R on right side, can be used to block / interrupt the illumination beam
path (move to far right position) when not viewing the sample to prevent photobleaching. The
green filter/middle position slightly filters the light, but the open position (far right) is probably
best when examining the sample.
*Note:
in fluorescence microscopy, the less exposure of the sample / fluorophore to excitation
light, the less photobleaching and subsequent loss of fluorescence and intensity of signal.
The fluorescence reflector or tiller slider [large horizontal black metal box between ocular and
objective lenses] has 4 positions for fluorescence that contain
various excitation filter / dichroic
mirror / emission
filter sets
, from right to left:
// ~450-490 um ex.
(green em.)
// ~510-560 nm ex
. (red em.)
// ~450-490 nm ex.
(green/yellow em)
// ~300-390 nm ex.
(blue em.)
Decide which filter set is appropriate/best for exciting and
detecting the fluorophore(s) being used, and move the filter slider
to that position. [See fluorescence reflector slider sheet for filter set details.]
*Note:
It should not be necessary to change/adjust the illumination beam, however, the
following controls affect the diameter and centering of the light. Levers for adjusting the
luminous field diaphragm
(upper, left and right side) — move by pushing or pulling levers
to
the right to reduce and to the left to increase
the illuminated area [“normally," the area of light
should just fill the field of view, as for the halogen lamp beam with light microscopy]. Use
the
two silver centering screws
(lower, left and right side) to position the luminous field diaphragm
- to move and align the light beam, alternate twisting both screws.
