Motic Instruments Inc. Canada
October 06, 2006
25
3.16 Aligning the mercury arc lamp
DO NOT
perform the lamp centering procedure with the UV filter cube in the optical path
as harmful UV radiation from the lamp may enter the eyes, possibly resulting in loss of
vision.
Please note: A UV excitation filter cube cannot be used in this instance since an arc
image will not appear in the window of the centering tool.
The mercury lamp consists of two electrodes sealed in a glass bulb under high pressure,
which contains mercury. When the power supply is turned on, a high voltage pulse is
sent to the electrodes, which in turn ionize the gas in the bulb, igniting the lamp. These
ions, under low voltage, carry the current that generates the light between the
electrodes. The lamp gets very hot during the vaporization of the mercury; creating high
pressure inside the glass bulb. Avoid applying mechanical force that might cause the
lamp to explode.
The average lifetime of a mercury arc lamp varies between 200 and 400 hours,
depending upon design specifications, burns and the switch cycle.
Avoid touching the lamp with bare fingers as the oils from the fingers may etch the glass
surface resulting in light loss.
When the lamp has been allowed to stabilize it gives off high intensity light concentrated
at certain discrete wavelengths (e.g. 365, 400, 440, 546 and 580nm) making it an ideal
source of illumination for fluorescence microscopy.
