The fluorescent tube as we know it
today has in fact been around for a very long time indeed. A
number of experiments relevant to the invention of the fluorescent tube
as we know it today have been undertaken dating back to the very dawn
of electric lighting at the end of the 19th century.
It
was really in the 1920s however that more intensive research into the
commercial introduction of such a lamp started as all of the necessary
components were there. Cheaply produced glass tubing, phosphors
which emit visible light when excited by shortwave UV, proven electrode
designs, and the means to create the necessary control gear.
While it's hard to pin down a precise date without doing further
research - which one day I probably will - it appears that it was
somewhere in the early 1930s that mainstream production of fluorescent
lamps as we recognise them today would have started.
Since
then there have been innumerable improvements to the electrode, ballast
and phosphor designs which have improved both the overall system
efficacy and the colour rendering abilities of the lamps, the overall
design hasn't changed much however - if you were to look at a tube from
the 40s, you would still most recognise it as a fluorescent tube.