Subject:
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Re: Autonomous Robot
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 9 Aug 2000 22:39:54 GMT
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Viewed:
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563 times
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in article Fz036w.F10@lugnet.com, Ian Warfield at ipw47@hotmail.com wrote on
8/8/00 6:08 PM:
> How exactly do the retroreflectors work? I was under the impression that you
> couldn't selectively reflect light unless you had a parabolic dish - and then
> it would all focus on one point. Do your reflectors have a convex mirror, or
> some other arrangement?
Here's a picture of a marine radar reflector.
http://www.oceanmark.com/manufacturers/safety_manuf/Safety-Davis.html
The back of a bicycle reflector is a hexagonal array of little triangular
right-angle pyramids packed edge to edge. Seen from the front, each pyramid
looks like an inside corner of a radar reflector.
Incidentally (pun!) this is why bicycle reflectors only reflect within 45
degrees of their surface - the corner reflectors only spread out 90 degrees,
which is 45 degrees off of perpendicular in any direction.
The white reflective road paint uses little spherical glass beads mixed into
the paint. The surface of the paint is covered in glass spheres half buried
in paint and half exposed. The light enters the exposed part, bounces
around inside, and exits roughly in the direction it entered.
I don't know how reflective tape works.
>
> --Ian
--
Doug Weathers, http://www.rdrop.com/~dougw
Portland, Oregon, USA
Don't spam me - I know how to use http://www.spamcop.net
"On a clear disk you can seek forever"
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Message has 1 Reply:
 | | Re: Autonomous Robot
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| (...) But they seem (in practice) to splatter reflections in all sorts of weird directions (as well as the direction you want). That might not matter in some applications. The corner reflector ought not to suffer from *that* problem - but it looks (...) (24 years ago, 10-Aug-00, to lugnet.robotics)
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Message is in Reply To:
| | RE: Autonomous Robot
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| I had a similar idea, but I was picturing a funnel-shaped mirror above a light sensor so that no matter what angle you hit it at the light is reflected down at the sensor. -----Original Message----- From: Ian Warfield [mailto:ipw47@hotmail.com] (...) (24 years ago, 8-Aug-00, to lugnet.robotics)
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