fluorescence microscopy
barrier filters should not ...
absorb the fluorescent wavelength
what chemical should you use with optics
alcohol, such as ethanol
why is a powerful light source needed
because fluorescence has a low yield and the microscope collection efficiency is low
why must you use extreme care when cleaning with chemicals
can migrate into internal areas or could remain in contact with the surface for too long
mechanical maintenance my include
dirty body, loose nose piece, sticky stage, sticky focus / condenser / diaphragm
what results in fluorescent microscopes
fluorescing areas shines brightly against a dark background
dirt that is non adherent may be removed from less delicate surfaces by ...
gently brushing with a clean camelhair brush
what are the three main features of an vertical illuminator
heat filter, neutral density filters, and a filter cube
what is a safer alternative to xylene
histolene and histoclear
what is the basic task of a fluorescence microscope
illuminate the specimen and separate the much weaker emitted fluorescent light from the brighter excitation light and make it visible to the viewer
why is damaged cement bad?
it is irreparable and must be discarded
the darker the material, the ....
more efficient the instrument
what should you never do with cleaning a microscope
never disassemble an objective, don't clean objective back focal lens, don't apply force, and keep acids/bases away
can barrier filters filter out reflected UV light
no
can excitation filters produce fluorescence
no
what is the forensic application with fluorescent microscopy
not used to identify, only used as a comparative tool
what is fluorescence
optical phenomenon in which certain materials absorb a short wavelength, high energy photon, and re-emits it as a lower energy photon with a longer wavelength
dust, lint, and smudges on the optical components contribute to ...
overall degradation of microscope performance
example of primary fluorescence
paint or fiber
do you need to stain the samples?
possibly, some items fluoresce by itself, like scorpions
what is one danger with solvents and cleaning opticals
potential to dissolve the cements
why do we cover microscopes
prevent the microscope from being exposed to airborne contaminants protect against scratches and spills protect against damage
what is an abrasive slurry
saliva and dirt
how can you remove dust from a microscope
small vacuum, cleaner, blower, or dabbing with moist papertowel
example of secondary fluorescence
staining
all optical components should be ...
stored in some form of container to avoid getting contaminated
primary/autofluorescence
substances that show fluorescence in their natural form
secondary fluorescnce
substances that will show fluorescence only after treated with chemicals capable of fluorescing
why are excitation and barrier filters found in sets
they were designed to function together
if the background it white, the yield would be ...
to small and we wouldn't be able to see the fluorescent
if we wanted to see the emitted light in the visible region, then the excitation light has to be in the ...
ultraviolet region
the emitted light is much ___ than the excitation light
weaker (lower intensity)
what are some typical covers for microscopes
wooden, plastic, metal box, vinal, and textile
what chemical is good for removing oil and old grease
xylene
is fluorescence subjective?
yes, therefore K&Q on comparison microscope
how does a dichromatic beamsplitter mirror work
- not allowing short wavelengths through and reflects back to sample - when it comes back again, it reflects back toward the lamp - allows long wavelengths to pass though - hits barrier filter and filters again so the only thing you see is fluorescent light