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Reflectors, etc.
> From: mengerin at cs_utexas.edu
...
> > figures to back it up. Another thing to consider which you may have
> > observed is that white surfaces reflect light in a diffuse manner. That
> > is, the light striking the reflector at a given angle is reflected in
> > several directions.
...
> Yes, this was understood, but that the light intensity, though
> scattered was nearly as intense. Eric Olson was the person reference
> for this one. Eric, you still about?
I was going to reply first to George's quote, then to Wade, but
figured I didn't have any new info to contribute (everyone else was
doing a fine job!). One thing I'll say is that my initial post (8/96)
was in reference to reflectivity only, because my big NASA balloon
payload merely had to direct light away from the payload, not in any
particular direction. I have found white paint to be very effective
on top of otherwise darker surfaces (wood, black acrylic, etc), and
depending on the gloss of the paint, it can be smooth enough for you to
direct light (I can see myself faintly in a shoplight).
Others have confirmed this qualitatively; George even backed this up
with his "classic" intensity measurements. Do a search of the APD
archives using "white paint" for comments from others.
At the time of my original post, the alternative was (I beleive) using
a mirror or a brushed aluminum sheet, both of which have lower
reflectivities (think about it, metal sheets get hot!). Aluminized
mylar from the hobby shops could have a slight improvement over white
paint, because it has a slightly higher reflectivity AND it can be
directed better.
I would note, that sitting here in my office, though there is a
specular aluminum thingy in the fixtures above, the majority of the
reflection seems to be from the white painted surface behind the
fixture!
- Erik
---
Erik Olson
eriko at wrq.com