On 4 Dec, 16:53, NT wrote:
On Dec 4, 12:47*pm, sm_jamieson wrote:



I have fitted a rigid sunpipe (300mm) in the roof of my extension to
brighten a dark corner, which it is doing, but the diffuser that fits
on the end of the tube is multi-directional - as you'd expect from a
diffuser. The diffuser is polycarbonate with random angled facets to
spread the light in all directions.
Now, a diffuser is needed to protect the eyes when the sun is
reflected directly in the tube (and to seal the bottom of the tube),
but I'd like something that sends all the light in one broad
direction, i.e. towards a 45 degree sector of the sphere, so no light
is being sent back towards the windows
and being "wasted".
Anyone come across such a thing, such as on some fancy light fitting ?
I could seal the end of the tube and have some mirror type arrangement
below, but that would be inefficient and look ugly.
Cheers,
Simon.

The light that's come down the tube is exiting the tube at an
assortment of angles. One simple way is to put some reflective sheet
inside the interior diffuser such that the light all goes to one side
of the diffuser. More exact control gets more complex, a fresnel lens
won't do it because the light's multidirectional.

NT

What you really need is a diffuser as I described before, but with all
the little facets
pointing in the same direction. I could just put a piece of tubing
that extends beyond
the bottom on one side. Trouble is, that would only catch shallow
angle light.
Simon.