MadSci Network: Physics

Re: Is it posible to see UV lights without a black light bulb?

Date: Tue Jul 5 10:42:30 2005
Posted By: Guy Beadie, Staff, Optical sciences, Naval Research Lab
Area of science: Physics
ID: 1119985823.Ph

Hello, Oleg.

It sounds like you’re a little confused about what black light is and how UV glasses might work. I’ll be happy to try and clear that up for you.

The light that you can see with your eyes is, of course, visible light. You can see the colors of a rainbow from red to blue. What we associate with color is the wavelength of light; the longer the wavelength the redder the light, and the shorter the wavelength the bluer the light.

Light, however, extends far beyond our ability to see. Radio waves and microwave radiation are also “light”, but at wavelengths far, far longer that we can see with our eyes. Similarly, X-rays and gamma rays are light at far shorter wavelengths that we can see.

Ultraviolet light (UV light) represents light at wavelengths just a bit shorter than we can see. A black light shines brightly at these wavelengths, so it is a convenient source when working with UV light. We can’t see it, but the light energy is there. Some animals can see in the UV (several bird species, for example) and to them a black light would look as bright as a normal light bulb would look to us.

We can only see UV light indirectly, by getting something to emit visible light when exposed to the UV. This is what UV glasses would do – convert a scene illuminated by UV light to a “false-color” image in the visible.

Now to get to your first question, “Is it possible to make UV glasses so you don't need a black light bulb to use?” If you had UV glasses then they would work whether or not you had a black light bulb. However, you need to get UV light from somewhere. A sunny day will provide you with UV light, but you don’t really need UV glasses for that. Some fluorescent light bulbs emit UV light, but they’ve got the same drawback as the sun: they’re bright in the visible, too. That’s why you typically need a black light bulb. An alternative would be a UV light-emitting diode (LED). These are just coming on the market, so if you do a Google search you could easily find a vendor.

I hope I’ve already answered your last question, “I want to know more how it works.” I interpreted it to mean, “What is UV light and how would UV glasses make this light visible?” On the other hand, I do not know of any UV glasses that actually exist. So, if you’re asking about details on how a real pair of glasses work then I cannot help you.

Keep asking questions!


Basic black light info:

Ultraviolet light

Black light tips

Madsci post about infrared glasses:

Re: what is the difference between night vision 'goggles' and thermal imaging?

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