UV leds

[e44-72]

Hello

I know ultraviolet light has a shorter wavelength (higher frequency) than the visible light of the elctromagnetic spectrum and is closest to violet in the same way IR is closest to red in the vissble light.
Therefore it is invisble to our eyes, so howcome we can see light from UV leds?

Thanks for any answers or help.

 

[ronsimpson]

so howcome we can see light from UV leds?

Really?
I have many different types of IR LEDs. Some are very close to "red". Those LEDs look like a very dim red to my eyes. I built some IR lights for night time cameras. The LEDs that glowed dim red were rejected because you could tell if the camera was on.

There are many different 'colors' of IR LED. There is also a spectral purity number where the LED may have a very wide or narrow color output.

I assume the UV LEDs are the same.

 

[KJ6EAD]

LEDs aren't coherent light sources (lasers). Look at the data sheet for any of them and you'll see a "peak emission" wavelength as well as a range of wavelengths that may be emitted and often a graph showing a spectral curve indicating the amount of energy emitted at wavelengths on each side of the peak.

The term "ultraviolet" as used in marketing literature somewhat loosely describes a range of wavelengths, some of which are partially visible as with the example above involving infrared emitters. For example, Lumex offers six different wavelength options under the heading ranging from 355nm to 415nm. The longer of these will obviously have a significant visible component.

 

[WTP Pepper]

Be very careful indeed. Just because you cannot see the the IR/UV and are merely looking at what appears to be a dim voilet/red source does not mean it is not burning your eyes out.
Too much exposure and we are talking cataracts/blindness.

What you are seeing are side effects from your retina being saturated along with the device saturating and leaking visible light despite the high power source appearing invisible. You need proper goggles.

Despite not being able to hear high volumes of ultrasound as the brain won't recognise it doesn't mean it's not killing the eardrum.