68
Brightness of fluorescence image
Occurrence of self-fluorescence
Degree of fading
Narrow
Bandwidth of excitation filter
Wide
Dark
Bright
Less frequent
Frequent
Small
Large
23
Filter Cube for Fluorescence Observation
The LV-UEPI2A can accommodate up to two filter cubes for the
epi-fl microscopy.A filter cube consists of three types of optical
components: an excitation light filter (EX filter), a barrier filter
(BA filter), and a dichroic mirror (DM). Taking the following as a
guideline, select a combination of filters that is suitable for your
purpose and for the characteristics of the specimen and the
fluorophore.
•
Even in the same excitation method, a variety of combination
of the excitation light filter and the barrier filter can be selected.
•
Each excitation light filter (EX filter), barrier filter (BA filter),
and dichroic mirror (DM) can be purchased separately.
•
The excitation light filter is exposed to strong lights. Therefore it may deteriorate under use. It is
recommended to replace it at a proper interval.
•
See Page 84, “IV. Assembly” for the filter cube installation method.
Light source for the epi-fl microscopy
To perform the epi-fl microscopy, the standard light source (a halogen lamp) may not be able
to provide the sufficient brightness. In such case, use an external light source for the
episcopic illumination that is suitable for the excitation method.
* Please take note that if an external light source is attached onto this microscope, the
microscope system will not be treated as a UL-listed product. Nikon recommends that the
light source to be installed onto this microscope should have been tested by a safety
certification organization.
Selecting the excitation light filter (EX filter)
An excitation light filter transmits lights selectively and
blocks other lights. The transmitted lights are called excitation
lights. They are used to excite the fluorophore in the specimen
and fluorescent lights are emitted from the specimen. The
wavelength range of lights that can pass through the filter is
called the bandwidth.
The bandwidth of the excitation light filter determines the
brightness of the fluorescent image, the occurrence of autofluorescence (fluorescence resulting from
substances other than the fluorophores), and degree of fading. When the filter has a wide
bandwidth, a large amount of excitation lights will be irradiated on the specimen. In this case, the
image becomes bright but the amount of autofluorescence becomes large and fading of the
specimen occurs soon. On the contrary, when the filter has a narrow bandwidth, a small amount of
excitation lights will be irradiated on the specimen. In this case, the image becomes dark but the
amount of autofluorescence becomes small and fading of the specimen occurs late. For specimens
with pronounced autofluorescence, use an excitation light filter with a narrow bandwidth. (The
resulting fluorescent image will be darker, however.)
The excitation light filter is exposed to strong lights. Therefore it may deteriorate under use. Please
replace it at a proper interval based on the hours used.
UV-2A
EX 330
-380
DM 400
BA 420
Barrier filter
Excitation filter
Dichroic mirror
(housed inside)
0
Wavelength
EX filter
Bandwidth
Spectr
al
tr
ansmittance