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Laser Beam Receptor

Discussion in 'Electronic Design' started by [email protected], Feb 11, 2006.

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  1. Guest

    Hello, I may not be a techie in this field so if my question is too
    basic or not clear, please bear with me.

    I am looking for a device - a light receptor - that can receive the
    laser pointer's light and then send signals/bytes as output.

    Any ideas?
  2. Steve

    Steve Guest

    You don't say what if any information is coded onto that laser light
    beam. Is it just an on/off laser pointer you are talking about? If
    so what "bytes" do you expect to see as receiver circuits output? Or
    do you just want a high/low signal from your circuit dependent on
    whether it detects laser light? A component suitable to detect the
    laser light is a photodiode, which you will need to couple to some
    sort of amplifier unless you get one with integral ampifier, there are
    many that have such integral amplification which makes the job easier.

  3. Guest

    In fact I am looking for a laser trip circuit so that if anything comes
    between the pointer and receiver, the circuit alarms and then I can do
    the coding on my computer.
  4. Ken Taylor

    Ken Taylor Guest

    Buy a commercially available door sensor with a relay output and use that
    contact closure as your computer input.

  5. Steve

    Steve Guest

    For the most basic setup all you need is a photodiode with integral
    amplifier, this is likely supplied with +5V and will give you a
    voltage output on an OP pin when it detects the laser. Look in an
    electronics catalogue in the optoelectronics section. Some issues
    though. Ambient (room) lighting if high could affect the diode, how
    important is 100% function of this circuit? If you need it very
    reliable you will get into significant electronics here, and
    commercial kit might be the way to go! A basic method to reduce the
    false trigger issue might be to use a window comparator circuit to
    trip your output on off at certain voltage (light) levels. If you
    want to be pretty sure that the light you are detecting is from *your*
    beam then you need to modulate the sender's beam in some way that you
    can recognise and decode at the other end, at it's most basic using
    modulation at a particular frequency that you can filter out in the
    receiver. Reliable systems of this type are likely to use dual beams
    of light, spaced significantly apart - reduces false triggers due to
    atmospheric effects eg insects in the beam, particles whatever. I
    think if you want something very basic it might be OK make something
    yourself, but there are many commercial break beam detectors out there
    you'd do well to consider, including some cheap ones for domestic
    alarm circuits.

  6. Guest

    I did something like that. Basically set up a circuit to detect the
    beam break, then it signals my PC via the serial port. It is pretty
    easy to do. I have a circuit and sample code at:

  7. Rich Grise

    Rich Grise Guest

    It's almost trivial, which is why I've crossposted this to the .basics
    group. I haven't set followups yet, because googlegroupies probably don't
    know how to find followups on other NGs anyway.

    Go to the other side of google, and search on "photoreceptor",
    "photodiode", and "phototransistor" - that should keep you occupied for
    awhile. :)

    Have Fun!
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