Subject:
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Re: detecting goal objects at a distance
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 31 Dec 1999 00:02:44 GMT
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Viewed:
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1380 times
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Mario Ferrari wrote:
> Does any of you have suggestion on what kind of IR led is more appropriate
> to make such an object? Do I need any additional circuit, or just a LED and
> a battery (and the proper resistor) are enough?
I imagine that - even if using such an IR LED as a beacon - roomlight etc. will
still be the major problem.
So, I'm pretty sure that a quite simple means at the detector side would
simplify such a project dramatically: an optical IR filter. This would greatly
enhance the original S/N coming from the sensor. The filter could either be a
bandpass type or a highpass type ("high" refering to wavelength, not to
frequency).
I have no concrete source at hands at the moment, but I'm sure such filters
exist. Probably, a bandpass filter is expensive, but I think a simple highpass
would be good enough. In the best case, it might even not be necessary to buy a
commercial filter, since probably many materials exhibit the required spectral
transmission characteristics. (For instance, a piece of silicon wafer will
transmit IR but block any visible light. But, maybe wafer pieces are not easy to
obtain, too :-) We have to look around for something suitable that is easy to
get and cheap. If you decide to follow this way, I can offer to help locating
such materials.
[I just started playing with RIS, and so I have no experience yet whatsoever
with making own sensors etc. However, my profession is related with optics, so I
know what I'm talking about (well, roughly:-)).]
Further, refering to Ben's other question, yes, I think a kind of lens will be
needed. I think even a very simple lens will be clearly much better than no lens
at all. So, although the lens may not be perfect and may be hard to adjust well
(since the signal is not visible by eye), it will help much. Without any such
kind of "directional filter", things will be hard. (An alternative to a lens
might be a simple arrangement of two aligned pinholes, but that wastes a lot of
signal.)
Uwe
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Message has 1 Reply:
 | | Re: detecting goal objects at a distance
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| (...) Well, I do now! I bought three last night. I got a GaAs IR LED that was clearly made for a remote control application. The good news is that when it is pointed at the LEGO light sensor it pegs at 100%! Unfortunately it's higly directional (it (...) (25 years ago, 31-Dec-99, to lugnet.robotics)
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Message is in Reply To:
| | Re: detecting goal objects at a distance
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| (...) it (...) a (...) systematically) (...) darkened (...) barely (...) target in (...) on (...) make (...) This is a thing I'm interested in too. Those of you who were at the mindfest might remember the soccer playing robots. The bots were really (...) (25 years ago, 30-Dec-99, to lugnet.robotics)
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