STEVE LOCK
44
|
FALL 2014
Different species of marine life display
fluorescence differently. This moray
eel is revealed predominantly in green
emission colors.
Seeing the Reef in a New Light
Fluorescence night diving
B Y L Y N N M I N E R
D
ivers, who are inquisitive by nature,
are always looking for new ways
to experience the wonders of the
underwater world. One increasingly
popular diving technique, called
fluorescence (fluo) night diving, gives divers the ability
to observe marine creatures in brilliant, glowing colors
invisible to the naked eye.
Fluo diving relies on the property of some marine
life to emit longer wavelengths of visible light when
illuminated with shorter-wavelength blue light. The
term “emission” is very important to understanding
the physics of fluorescence. The emission of light
differs from the reflection of light that happens when,
for example, you take your white light torch on a
night dive. In traditional night diving, white light is
reflected off of the reef or organism and bounced back
to your eyes. Emission light, however, is light that the
organism creates and emits back to you. The process
is similar to bioluminescence in that the organism
creates its own light; however, in bioluminescence the
light, which is generated by chemical reaction, requires
no excitation light.
To view biofluorescence, fluo divers equip themselves
with blue-light torches and barrier filters for their masks
(and cameras, if they are doing photography). The
barrier filter’s function is to block the blue light that
is reflected back to the observer from the organisms
on which the light is shining. All that would be visible
without the barrier filter is a very bright blue light,
but the filter is designed to cut off all or most of the
wavelengths in the blue part of the spectrum. The
intensity of the emission light from the organism
is very dim — so dim, in fact, that it is completely
overwhelmed by the blue light; but if you block the
blue, all you will see are the emission colors.
RESEARCH, EDUCATION & MEDICINE
//
A D V A N C E D D I V I N G
