UV Bikelight

Quoted message said:

I recently passed close to a blacklight in my flourescent commuting
attire and was stunned by just quite how visible I was. The effect is
dramatic, even with faded / dirty material.

That got me thinking about swapping the LEDs in a light for UV LEDs
and pointing it not away from my bike, but instead towards my
flourescent jacket (e.g. on a rack, shining at my back). It probably
wouldn't make a great deal of difference when hit by a car's
headlight, but at dusk the effect could be quite dramatic. Using the
light on a flashing cycle could be effective too.

Has anyone tried this? I'm tempted to give it a go.

I haven't, but let us know how you get on. Sounds interesting.

Quoted message said:

I recently passed close to a blacklight in my flourescent commuting
attire and was stunned by just quite how visible I was. The effect is
dramatic, even with faded / dirty material.

That got me thinking about swapping the LEDs in a light for UV LEDs
and pointing it not away from my bike, but instead towards my
flourescent jacket (e.g. on a rack, shining at my back). It probably
wouldn't make a great deal of difference when hit by a car's
headlight, but at dusk the effect could be quite dramatic. Using the
light on a flashing cycle could be effective too.

Has anyone tried this? I'm tempted to give it a go.

It would be valuable to have one pointing at your front, as drivers pulling
out from side roads are not pointing their headlights at you. I seem to
remember someone inventing a bike light that shone both forwards and at his
chest for this reason, and I thought that there would be a problem with
glare for the rider. How visible are these UV LEDs? I didn't know they
existed until I saw your post.
ps, if your cycle flashes you would be visible anyway, or is it a cycle that
you use for flashing purposes? If so, you would need to stain your skin with
fluoresceine.
--

Martin Bulmer

On Apr 2, 8:53 am, "Martin Bulmer" <[email hidden]>

Quoted message said:

ps, if your cycle flashes you would be visible anyway, or is it a
cycle that you use for flashing purposes? If so, you would need
to stain your skin with fluoresceine.

Get your teeth crowned and remember to keep smiling at night.

--
Dave...

Quoted message said:

That got me thinking about swapping the LEDs in a light for UV LEDs
and pointing it not away from my bike, but instead towards my
flourescent jacket (e.g. on a rack, shining at my back). It probably
wouldn't make a great deal of difference when hit by a car's
headlight, but at dusk the effect could be quite dramatic. Using the
light on a flashing cycle could be effective too.

Has anyone tried this? I'm tempted to give it a go.

It might be an interesting experiment, but my guess is that using UV leds
will make you appear no more illuminated than white LEDs.

Anthony

Anthony Jones said:

Quoted message said:

That got me thinking about swapping the LEDs in a light for UV LEDs
and pointing it not away from my bike, but instead towards my
flourescent jacket (e.g. on a rack, shining at my back). It probably
wouldn't make a great deal of difference when hit by a car's
headlight, but at dusk the effect could be quite dramatic. Using the
light on a flashing cycle could be effective too.

Has anyone tried this? I'm tempted to give it a go.

It might be an interesting experiment, but my guess is that using UV leds
will make you appear no more illuminated than white LEDs.

Anthony

There are three things to consider here:

a) lumens per watt. You should be able to estimate whether the light
output from a uv-illuminated vest/jacket/whatever would or would not be
greater than that from a "normal" white LED. It's possible that uv-LED's
are much more efficient, so much more that the inevitable efficiencly loss
when the uv is down-converted by the materials in the vest is more than
overcome - but I doubt it.

b) visual subtended angle. There is some data, I believe, that shows that
a larger area of illuminated retina is better attended to than a smaller
one, even if the total illumination is equal. (Again from memory) I think
this was found for night vision, and so could well have application in this
case.

c) pattern recognition. Using such an LED-and-vest system might allow
motorcar drivers to determine that the thing they are seeing is a cyclists
- perhaps to a better degree than normal LED - or other forms - of cycle
illumination. Wethere or not this is seen as a good thing rather depends
on the result that this knowlege has on the bahaviour of the driver;
perhaps a uv-LED and a vest with block-lettering spelling "POLITE" might be
a good solution.

_ said:

Quoted message said:

It might be an interesting experiment, but my guess is that using UV leds
will make you appear no more illuminated than white LEDs.

There are three things to consider here:

a) lumens per watt. You should be able to estimate whether the light
output from a uv-illuminated vest/jacket/whatever would or would not be
greater than that from a "normal" white LED. It's possible that uv-LED's
are much more efficient, so much more that the inevitable efficiencly loss
when the uv is down-converted by the materials in the vest is more than
overcome - but I doubt it.

It wasn't clear from my post, but I was actually thinking in terms of
pointing the white LEDs at the jacket in the same way as the UV ones. So b)
and c) aren't really relevant in that case, and a) is roughly what I had in
mind. The question is: does the jacket appear brighter with some number of
UV LEDs, or the same number/power of white LEDs? This would very easy to
test.

Anthony

Anthony Jones said:

_ said:

Quoted message said:

It might be an interesting experiment, but my guess is that using UV leds
will make you appear no more illuminated than white LEDs.

Quoted message said:

There are three things to consider here:

Quoted message said:

a) lumens per watt. You should be able to estimate whether the light
output from a uv-illuminated vest/jacket/whatever would or would not be
greater than that from a "normal" white LED. It's possible that uv-LED's
are much more efficient, so much more that the inevitable efficiencly loss
when the uv is down-converted by the materials in the vest is more than
overcome - but I doubt it.

It wasn't clear from my post, but I was actually thinking in terms of
pointing the white LEDs at the jacket in the same way as the UV ones. So b)
and c) aren't really relevant in that case, and a) is roughly what I had in
mind. The question is: does the jacket appear brighter with some number of
UV LEDs, or the same number/power of white LEDs? This would very easy to
test.

Anthony

I think you're probably right, in terms of actual illumination I
suspect UV LEDs won't be any more effective that white ones. In fact,
probably less so since they won't have much effect on non-UV reactive
colours. I haven't looked into the relative outputs.

However, a flashing UV light shining against a yellow vest (for
example) would create a flashing effect on just the vest and nowhere
else. The contrast this provides might make the (flahsing) vest more
noticable than just a white LED. I suspect this probably won't be the
case, but it's certainly worth trying.

Where it might find the most useful application is in dusk riding -
when the light is poor enough to dull and merge normal colours, but
bright enough for a white self-illumination not to have much effect.
These are the sort of conditions when flourescent colours seem (to me)
to be most effective, because they really stand out against the
background noise. In such conditions, UV illumination could make
flourescent colours stand out in a way that normal UV light might not.

I won't have chance to try this for a few weeks, but I'll report back
when I have.

Thanks for the feedback!

Quoted message said:

However, a flashing UV light shining against a yellow vest (for
example) would create a flashing effect on just the vest and nowhere
else. The contrast this provides might make the (flahsing) vest more
noticable than just a white LED. I suspect this probably won't be the
case, but it's certainly worth trying.

Also useful if you want to illuminate your jacket from the front without
blinding youself. 😉

Anyway, let us know how it turns out.

Anthony