Hg Arc - Lamp change on a Nikon Diaphot microscope - T.H. Hogan
NB:Read the manual before attempting the following:
(These pictures and comments are not a substitute for reading the manual)
Note: - Avoid getting fingerprints on the lamp ! I would advise wearing rubber surgical gloves, or at least using
a "Kimwipe" type lintless tissue to handle the arc lamp tube ! \&;
Fingerprints could cause the lamp to shatter when it heats up.
- These lamps are shortlived (200 or 300 hours for certain extended life bulbs)! After this time, brightness suddenly
decreases and the lamp is prone to explosion. It is a good practice to always keep track
of lamp usage with a log book. Then you will know when to replace the lamp and avoid
the trouble of clean up and safety issues.
- Have a replacement lamp ready to be installed. For this particular Nikon Diaphot, the catalog number is: HBO 100 W/2
Make certain that the electricity is off and the power supply is unplugged from the mains !
Close up view of the thumbscrews on the Nikon Diaphot Mercury Arc Lamp Housing.
The small thumbscrews on 45 degree angle (yellow arrows) must be removed to change the lamp.
The other thumbscrews are for centering the lamp and do not need to be adjusted until
after the new lamp is installed.
Once you have removed the lamp holder
there is another thumbscrew on the chrome electrical connector at the end of the lamp tube.
Remember to wear gloves when handling the arc lamp tube ! Never get fingerprints on it; doing so may cause it to shatter when it heats up.
Fill out the logbook by noting the number on the little counter in the upper left corner
of the power supply. Write the number down before you turn it on and after
you turn it off ! It's the only
certain way to keep track of microscope and mercury arc lamp usage.
Remember: if you turn it off then don't turn it on again
for twenty minutes (allow it to cool off before restarting).
Re-insert the lamp holder with the new lamp. Place the old lamp in the cardboard box.
Mercury Arc lamps are expensive and do not last more than a few hundred
hours.
Order a new one as soon as possible. Request pickup by the safety department. They will know how to get this mercury recycled.
Often fluorescence microscopy is conducted
in a darkened room to allow the microscopist's eyes to "dark adapt" so
that faint fluorescence can be seen. In "dark adaptation"
the pupils dilate and the retina's pigment epithelium retracts. This is
especially useful when "picking clones" that are expressing green
fluorescent protein (GFP).
There can be significant amounts of ultraviolet light pollution where
mercury-arc illumination is being used. In the "dark-field" photo of the microscope at
left, invisible ultraviolet light was recorded as purple. This unseen ultraviolet light can
affect exposures and decrease the quality of your images. Ultraviolet light can also contribute
to cataracts, sunburn, snowblindness, and skin cancer. These effects are cummulative and you
should take all safety precautions.
Make sure that sources
of ultraviolet light such as germicidal mercury vapor lamps are turned
off. Wear utraviolet protective safety goggles/glasses if possible.
List of useful microscopy sites
-
Zeiss Apo Tome :
NEW! Select Apo Tome in Quick Links !
-
Confocal Introduction Washington/Keck
-
Microscopy Primer Objectives
-
An "E-zine" resource: Microscopy
Online
-
Commercial Dichroic Mirrors ("Filters") / GFP Chroma
-
Commercial Fluorescent Labels Molecular
Probes
-
Commercial Fluorescent Labels Clontech
-
UltrafastSensors ... Ultrafast Sensors