Coloured Fluorescent Lighting.

[AdamW]

You see, coatings are the reason that fluorescent tubes are so energy efficient: light bulbs put out a lot of energy in the IR and UV parts of the spectrum. Tubes (and energy saving bulbs) don't put much out in the IR hence they are quite cool to the touch), and convert UV light into visible light through the phosphorescent coating.

The chosen gas IS responsible for the colour of "neon" tubes, as they are usually clear rather than coated.

Some light is invisible to the eye because it is outside the frequency range of the retina. Just think of it like your ears: most people can hear between 20Hz and 20KHz. Just as you can't hear a whale's mating call (too low frequency) you can't see IR. And just like you can't hear a dog whistle (too high frequency) you can't see UV.

Interestingly, not all animals see in 3 primary colours. Most birds see 4 primary colours, one of these being UV, plus they can detect the polarisation of light. So blackbirds might look pretty colourful to each other!

 

[Stod]

There are two types of UV "fluorescent" tubes.

The ones with a plain glass or quartz tube i.e. with no phosphors. These emit hard UV radiation, peaking at 270 nanometers or so. Kills bugs and can mess up your eyesight. You can get them from hairdressers' suppliers.

The others are the "blacklight" tubes, which have UV fluorescent phosphors radiating "soft" long wave UV. These do not harm your eyesight although if you look at the tube directly it will make the fluid in your eyball fluoresce.

 

[breezer]

the claer uv lamps stod refers to are used in "clarifiers" for ponds, see here

 

[kendor]

The chosen gas IS responsible for the colour of "neon" tubes, as they are usually clear rather than coated.

That is wrong to say that the gas alone determines a colour output, Argon produces blueish purple colour, Neon is used a lot and produces reddish orange there is a long list of other gases and mixes more than i can remember off the top of my head.
I mentioned that if you wanted to just see the colour of a particular gas then the tube would be clear, you are wrong to say they are usually clear, coated tubes are used extensively in signage especially in the "safer" neons used these days (the old HT signs had a lot of regulations going along with their use).
as i stated before the coating will define the tubes colour output, you can get white ,yellow......the list goes on and on, merely using blue gas(for example) with appropriately coated tubes you can get all sorts of colours depending on what gas and coatings are used.

 

[kendor]

Some light is invisible to the eye because it is outside the frequency range of the retina. Just think of it like your ears: most people can hear between 20Hz and 20KHz. Just as you can't hear a whale's mating call (too low frequency) you can't see IR. And just like you can't hear a dog whistle (too high frequency) you can't see UV.!

Call me picky but when you refer to visible light the general accepted terminology used is Wavelength(Electro magnetic wave) as opposed to Frequency which is what i said in my post. when you mention frequency you talk in Hertz, when you talk in Wavelengths you talk in measures of a metre, regarding light, visible light is in the range 0.7-0.4 micro metres(is there any way on here to produce symbols? it doesn't seem to accept unicodes),
you can use any of these terms wavelength or frequency but it is generally accepted that the visible light spectrum of an electromagnetic wave is talked about in wavelengths.
as i mentioned before it is the properties of the coatings ability to work within a certain wavelength and it is that particular wavelength that stimulates the receptors at the back of the retina into telling the brain what particular colour you are seeing. when we are talking Neons there seems little point in talking about the invisible ranges of the spectrum as we want to be able to "see" the signs.

 

[AdamW]

Call me picky

OK picky!

You are right, usually when talking about optical devices we physicists talk about the wavelength. But seeing as you are keyed up on the EM spectrum I am sure you realise that wavelength and frequency are inversely proportional, that is any frequency has an associated wavelength.

c = nu*lambda (i.e. speed of light = frequency * wavelength)

So, any EM wave can be referred to by its frequency or wavelength.

However, the wavelength of light is usually given in nanometres rather than micrometres (ah, fond memories of my trusty 650nm laser), but that is me being REALLY picky

when we are talking Neons there seems little point in talking about the invisible ranges of the spectrum as we want to be able to "see" the signs

But UV is great cos white things glow and you can see ladies' bras and that.

 

[kendor]

ok you are really picky and completely right! I must have been eating Micro Chips for lunch or something, actually i let a wrongly legended chart sway me, i had originally worded it nM but the chart suggested micro see:
here
also: here which shows both nm and micro and I quoted the figures as 0.4 and 0.7 instead of 400 and 700 ( It's all got to do with the decimal point as to what you call it) and we should use the correct terminology now i've gone and started it!
regarding the UV part I was stating that for neon signs there would be no point in using the invisible part of UV light or for that matter the visible part as you ain't gonna be able to look at it

As for seeing ladies bras and such, It proves that not all physicists are boring old men

 

[ban-all-sheds]

But UV is great cos white things glow and you can see ladies' bras and that.

Personally I prefer the effect it has on thongs....

 

[securespark]

Spot the perv!!