Re: infrared wall to detect an object

Hernán Sánchez wrote:
Hi.

For a project that I'm building, I need an object detector that signals
when something "cross" the virtual wall of light.

I create a virtual wall using a laser and two mirrors (one in front the
other). The laser goes to the front mirror, it reflects the light back
to the other mirror that is behind the laser, and it reflects back the
light and so on. An the end, a photorresistor sense the laser light.
When an object cross thru the light, the photorresistor change and a
comparator signals that something is passing thru the virtual wall.

The problem is the photorresistor that it is sensible to natural light
and of course the laser... it is dangerous for the eyes (an accident
can happen). Another problem is with the mirrors, they need to be
complete aligned to each other.

I want to change it to infrared light and a IR detector.. like those
used in remote controls. But I need some IR leds with a small
apperture to create a virtual wall.

I don't have any information on a IR emitter, but suggest you look at modulating the beam. By using a narrow filter on the detector, you should be able to filter out ambient light changes and use a lower power.

--
Thad
.

Relevant Pages

  • Re: infrared wall to detect an object
    ... For a project that I'm building, I need an object detector that signals ... I create a virtual wall using a laser and two mirrors (one in front the ...
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  • infrared wall to detect an object
    ... when something "cross" the virtual wall of light. ... I create a virtual wall using a laser and two mirrors (one in front the ...
    (comp.arch.embedded)