Water feature - LEDs & internal reflection (not urology related...)

[Rob]

Well it's sort of on topic.

Anyone played around with building a swimming pool or outdoor water
feature - in particular embedding a narrow emission angle high brightness
LED in a water jet (along the axis of flow)? Perhaps a led coupled into some
plastic fibre in the flow path.

I guess the light escapes when the critcal angle is exceeded and that when
and where this happens will vary as the water stream moves around. Might
look ok if the effect lasts more than a few inches from the jet exit point.

comments / flames / ideas??
rob

 

[Kryten]

Sounds a valid idea.

ISTR a demo of total internal reflection using a laser shone through water
pouring sideways out of a largish hole. The beam reflected several times.

A simple plastic fibre inside the flow will be surrounded by water instead
of air, so the critical angle will be different. Proper optical fibre will
have the reflection done at an internal layer and will work as well as it
does in air.

I notice fountains need a lot of pressure to create a tall jet.
You might create fake tall jets by pumping the water up a transparent tube.
This does look nice.
I saw an amusing one with a brass tap stuck on the end:
the water appeared to be pouring out of a tap in mid air

Anyway, you could shine the LED light up the transparent tube.

Have fun, and put the photo on the net!

K.

 

[Rich Grise]

Well it's sort of on topic.

Anyone played around with building a swimming pool or outdoor water
feature - in particular embedding a narrow emission angle high brightness
LED in a water jet (along the axis of flow)? Perhaps a led coupled into some
plastic fibre in the flow path.

I guess the light escapes when the critcal angle is exceeded and that when
and where this happens will vary as the water stream moves around. Might
look ok if the effect lasts more than a few inches from the jet exit point.

comments / flames / ideas??

The stream will stay in "one piece" longer if you can arrange for it
to have a "laminar flow". Get ahold of some of those little teeny tiny
straws that they put in cocktails at bars, and stick a bunch of them
into a piece of PVC pipe, and run your water through it. That makes
the flow less turbulent, and the stream won't break up so soon. Plus,
you could put your light on the "upstream" side, and it should be
gorgeous. ;-)

Here ya go:
http://www.google.com/search?q="laminar+flow"+fountain

Good Luck!
Rich

 

[Rob]

The stream will stay in "one piece" longer if you can arrange for it
to have a "laminar flow". Get ahold of some of those little teeny tiny
straws that they put in cocktails at bars, and stick a bunch of them
into a piece of PVC pipe, and run your water through it. That makes
the flow less turbulent, and the stream won't break up so soon. Plus,
you could put your light on the "upstream" side, and it should be
gorgeous. ;-)

Here ya go:
http://www.google.com/search?q="laminar+flow"+fountain

Good Luck!
Rich

Hi Rich, Kryton, thanks for the replies - I'm more enthused now, I think
I'll give it a go.
regards
rob

 

[Rich Grise]

Hi Rich, Kryton, thanks for the replies - I'm more enthused now, I think
I'll give it a go.

Be sure and keep us all up-to-date, preferably with pictures! ;-)

Good Luck!
Rich