Nikon ECLIPSE 80i Manual de instrucciones - Página 33
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Selecting Fluorescent Filters
18
A filter cube is comprised of the following three
optical components: an excitation filter (EX filter),
a barrier filter (BA filter), and a dichroic mirror
(DM). Select a combination of filter cubes
appropriate for the specimen characteristics,
fluorescent pigment, and the purpose intended.
Keep in mind the following:
• Different combinations of excitation and
barrier filters may be selected for the same
excitation method.
• Other types of excitation filters, barrier filters,
and dichroic mirrors can be purchased
separately.
• Excitation filters are exposed to strong light
during operations and tend to age rapidly.
Replace the excitation filter at frequent
intervals.
Selecting excitation filters (EX filters)
18.1
Excitation filters allow selective transmission of
light (excitation light) in the waveband required for
fluorescent light emissions from the specimen,
blocking light of all other wavelengths. The range
of wavelengths allowed to pass through a filter is
referred to as bandwidth.
The range of the bandwidth of the excitation filter
determines the brightness of the fluorescent image,
the generation of self-fluorescence (fluorescence
resulting from substances other than fluorescent
pigments), and degree of fading. The broader the
bandwidth, the greater the amount of excitation
light irradiated onto the specimen, increasing
brightness. However, this also increases the
amount of self-fluorescence and causes faster color
fading. Narrow bandwidth reduces the amount of
excitation light striking the specimen and causes
the image to appear darker, but reduces
self-fluorescence and fading. For specimens with
pronounced self-fluorescence, use excitation filters
that pass a narrow bandwidth (note that this will
make the fluorescent image darker).
Excitation filters are exposed to strong light during
operations and tend to age rapidly. Replace the
filter at intervals determined by usage.
Individual Operations
18 Selecting Fluorescent Filters
31
Excitation
filter
Dichroic mirror (inside the cube)
EX filter
0
Wavelength
Barrier filter
Bandwidth