COLOURS OF LIGHT EMITTED BY H3 LIGHT SOURCES
The colour of the light emitted emitted by GTLS (Gaseous Tritium Light Source) devices is
determined by the phosphur used to coat the inner surface of the glass tube. The resulting
colour can be any specified colour of the visual spectrum but the human eye's perception
in darkness has maximum sensitivity to green and yellow. For this reason, GTLS sources in
green are the most usual colour used with luminous watch dials etc. The following table
|Intensity Relative To Green
Where a GTLS device requires the use of two colours, green and orange are usually paired for
their easily recognised contrast.
Although red and blue are relatively weaker (25% of the perceived brightness of green), they
have advantages in situations requiring undisturbed night vision of the eye (i.e. dark
adaption) - for example with astrononomers.
Self-illuminated watches used by professional and recreational divers at greater depths tend
to have blue (rather than green) GTLS sources because blue is the only (last) colour still
visible beyond a certain depth due to light refraction under water.