UV McGizmo = bee-sting preventer?

I have a cousin who's deathly allergic to bee stings, and when I was hanging out with him the other day the bees simply would not leave him alone. I happened to have my UV Mule with me, so we went in a dark room and I shined the UV light on him. His shirt lit up like a glow-stick. Turns out he'd been using a detergent with "optical brighteners" in it, and they were making an otherwise muted color much more UV-responsive than expected. He changed into another shirt that didn't fluoresce and went back outside, and the bees left him alone for the rest of the day.

A UV Sundrop might make a good gift for someone who's allergic to bees, and it costs less than a single trip to the ER. Something to think about.

Bees like fluorescence. Flowers fluoresce to attract bees. Hence, shirts that fluoresce also attract bees. Detergent companies like to add fluorescent dye to their detergents because it makes colors look "brighter", which makes them appear to be more "effective" or something.

Yeah, it's supposed to counteract the fading effect of washing. But anyway, the light worked like a charm for the purpose I just invented.

So, basically, the UV light would be usefull to make sure that person doesn't wear fluorescent clothes is that right ?

Bluette is pure optical brightener, IIRC

tino_ale said:

So, basically, the UV light would be usefull to make sure that person doesn't wear fluorescent clothes is that right ?

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The UV light is useful to make sure they don't wear clothes that strongly reflect UV light. It's not always obvious if UV light is being reflected, if there is lots of visible light in the area.

fyrstormer said:

It's not always obvious if UV light is being reflected, if there is lots of visible light in the area.

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I think it's safe to say that it is never obvious that UV light is being reflected unless you use a UV light to check.

Only the longer wavelengths of UV light are visible to humans, and those are easily overpowered by any light in the rest of the visible spectrum. Traditional UV bulbs are tinted to filter out any normal light and only let the UV light escape so that it will be visible. Honestly, though, I'm not sure how UV LEDs achieve the affect.

The die composition of the LED emits a certain wavelength of light when energized, it can be adjusted to emit different wavelengths. Most white LED's are Violet-Ultra Violet wavelengths which energize a phosphor that emits relatively white light.

jag-engr said:

I think it's safe to say that it is never obvious that UV light is being reflected unless you use a UV light to check.

Only the longer wavelengths of UV light are visible to humans, and those are easily overpowered by any light in the rest of the visible spectrum. Traditional UV bulbs are tinted to filter out any normal light and only let the UV light escape so that it will be visible. Honestly, though, I'm not sure how UV LEDs achieve the affect.

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well, between 360nm and 405nm leds work fine, anything lower you either have super expensive leds, or simple fluorescent. afaik there are no leds on the market that are capable of emitting wavelenth to use as bacteria killing germicidal lights. OTOH fluorescent are installed in almost every new water cooler and cost very little.

65535 said:

The die composition of the LED emits a certain wavelength of light when energized, it can be adjusted to emit different wavelengths. Most white LED's are Violet-Ultra Violet wavelengths which energize a phosphor that emits relatively white light.

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I thought the LED's were still blue for the most part. Nichia had some UV based samples they showed at a SAE conference a few years back but the rep told me the concern was about any damaged LED's that might then leak the UV directly. Apparently there is much less shift in wave length with a UV source so it's easier to get a stable white over a range of temperatures and Vf.

As for knowing if UV light is being reflected, I would think you would need a device to measure it since it is invisible to the naked eye?!?! If clothing fluoresces does that necessarily mean that it is more reflective in the UV bands as well? :shrug:

A fluorescent object doesn't convert all of the UV light striking it into visible light, any more than any other object converts all of the visible light striking it into infrared. There is always at least a tiny amount of light that gets reflected at its original wavelength.

Anyway, I can't say for sure exactly how much UV a fluorescent shirt reflects as compared to a non-fluorescent one, but the bees certainly noticed the difference. I'm inclined to say if the Nichia UV emitters have anywhere near the output of other power LEDs these days, then the percentage of UV being converted to visible wavelengths is less than half of the total output.

I thought bees saw UV light, under which flowers display patterns that aren't present in visible light, whether fluorescing or not. I think you may have come to a premature conclusion.

http://photographyoftheinvisiblewor...5/bidens-ferulifolia-bee-vision-one-step.html

http://www.sciencealert.com.au/news/20073105-15942-3.html

"...Bees see ultra-violet colour as well as blue and green, while humans see a mix of blue, green, and red colours." Dr Dyer said.

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TorchBoy's post is in accord with the point I was trying to raise.

If Bees are attracted to specific colors or wave lengths of light then their presence would be the source of attraction. There is plenty UV light in sunlight but most objects absorb this light and don't reflect much of it. Since we can't see UV, I base this last statement on suspicion more than anything else. Using a UV light on some fabric and discovering that it fluoresces more than otherwise due to some detergent additive certainly indicates that its nature of responding to light has been altered. Perhaps it appears brighter because it is more reflective and more reflective in both visible (to us) as well as invisible light. That could explain the bee's interest.

Many materials are enhanced to endure UV exposure and I know there are additives for coatings that boost UV protection. I wonder if the nature of this protection is based on enhancing the reflectivity of UV so that this energy is bounced off the surface as opposed to being absorbed with resultant degradation? :shrug:

We see some pretty incredible colors in fluorescent objects subjected to UV as well as under ambient sunlight. The iridescent colors in a hummingbird or peacock or some of the fish I see here in the ocean come to mind. There are some pretty exotic paint jobs now that change in color based on the angle of incidence and reflection of light. A bird, bee or other creature that can see a wider band of light than us may be treated to even more interesting sights. We have our rods and cones which integrate information of light reaching them and provide us a visual impression which we in turn process as information. I dare say bees see things differently.

A UV light source can identify for us that an object is different in nature. Perhaps bees do respond to the fluorescent response of some surfaces and they are much more sensitive to this than we (A UV source is needed to bring this to our attention). On the other hand, if it is the presence of reflected UV light that they respond to then we are blind to this attribute which they key on. :shrug: