Detecting laser beam break

Discussion in 'The Projects Forum' started by smashdk, Jul 29, 2010.

  1. smashdk

    Thread Starter New Member

    Jul 22, 2010
    Guys I am having an issue trying to detect the laser beam break with my microcontroller. I am a newbie. This issue is with the detection:

    the sensor is reading .3v before laser hit and only climbing to .5v when it does hit. I need it to climb to atleast 1 volt when it hits the sensor. any suggestions would be great.

    i have a laser circuit built with this laser:

    I am trying to detect the laser presents with this sensor:

    Last edited: Jul 29, 2010
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    It's not going to work. Look at the laser output (630-645 nm) and the sensor sensitivity (850 nm). You either need to get a laser that outputs in the IR or a sensor that can see 630 nm.
  3. TrevorP

    Active Member

    Dec 8, 2006
    While the system you have might give you small voltage changes in the presence of laser light it might also be easily affected by ambient light. Making sure that the receiver and transmitter are near in the same wavelength will allow for better ambient light protection.

    That being said your .3V to .6V is more than workable, amplify and filter it to the full scale of the ADC channel on the microcontroller and it should work well enough. You could also try a Schmitt trigger to produce a clean 0 - 5V.
  4. BMorse

    Senior Member

    Sep 26, 2009
    If you use a small solar cell, and use a voltage to current amplifier, you can get a more usable reading from it....

    Here is a circuit I designed for detecting a Laser beam from up 200 feet, if you look at the Thread called Fast Horses, you will see the rest of the circuit and lenses that were used to construct this device and it is used to trigger a timer when a horse goes through to start the activities such as barrel racing...

    B. Morse


    and here is another circuit used to test output power of small lasers....