Actions
Forum Thread Details
  • Replies 5 replies
  • Subscribers 30 subscribers
  • Views 566 views
  • Users 0 members are here
Related

Build Idea - RGB Touchpad Controlled Handheld Laser

Former Member

Hey Ben,

 

 

I've been a member over at Laser Pointer Forums for a little while now. When you join you are drilled about laser safety and ensuring that proper safety glasess. I've seen countless Youtubers posting videos with lasers but without saying anything about laser safety. Those same YouTubers are burning matches and other things with no safety glasses on. No one should have to be told not to point lasers at airplanes, but you see it on the news. I'm afraid that persons who enjoy lasers in a safe and responsible way are about to lose their hobby. All of that said I would like to create a Handheld RBG laser. The innovative part will be the option to control the 3 individual diodes output power with a touchpad from a laptop. I might be able to get the parts machined and I might be able to use potentiometers to control each, but I want to take it one step higher. I'm assuming I could do this with the Arduino Nano, but I don't know how I could vary the mA output of the driver with the arduino. Then I have to figure out how to use the x,y coordinates to control each Constant current driver. This is just above my skillset. Not only would I like to combine the beams in a small semi hand held format, I would like to hack a laptop touchpad to control the rgb output. Maybe center is white, I'm not quite sure. That would take some brain storming. I think this would be a really cool build as well as an opportunity to speak out about laser safety and that they are not toys. I would like to be able to continue to enjoy the hobby.

 

 

Thanks,

Ben

(Trendkilla254 on Laserpointerforums.com)

  • Hi Ben,

     

    I just became a member here and saw your build idea. Now I am not an expert but I think a good starting point for this project is studying PWM or Pulse Width Modulation.

    This is something already build in every Arduino. Most digital pin's can be assigned as PWM and it's often used to control the speed of a motor or the intensity of a LED!

    On a given time interval the pin goes from low to high then stays in that state for a given percentage of the interval and after that goes low until the next interval. The interval stays constant but the period of time the pin stays high (called the Pulse Width) you can vary. This Pulse Width controls the percentage of the period the pin is high. This percentage is called the Duty Cycle. Imagine a LED is set on for the Duty Cycle of the period and let's say the total amount of time per Pulse is two milliseconds. This means the LED is set on 500 times a second. When the Duty Cycle is set to 10% the LED will blink 500 times a second of which it stays on 10 percent of time every blink and is off 90% of every blink. You can imagine the amount of light send out is much less then when the LED is on 90% of every blink. So varying the Pulse Width dims the light intensity the more when you decrease the Pulse Width.

     

    The lasers I've seen and used had a pin on the CC driver to turn them off when set to high and turn them on when set to low so that's usable for PWM.

    Each laser gets it's own PWM pin on the Arduino and varying their Duty Cycles gives more or less of the individual R, G and B.

     

    I've added a picture from the web to clarify the theory behind PWM.

     

    I hope this helps.

    Regards,

    Nico.

    image

  • PWM does not control the output in mA. It pulses which makes it appear less bright. I need analoug modulation.

  • Sorry I didn't have much time to post earlier. I don't want to use PWM. The issue with PWM is that if I decide to use galvos it isn't optimal because the laser will actually blink at a very rapid rate. This isn't an issue so much until you start to record your laser shows. Instead of a pure line you have a dotted line.

  • Hi Ben,

     

    If analog instead PWM is a must, probably you could use a DAC connected to the arduino, and connet its output to an V-I converter buit with op amp.

     

    Hope that helps,

  • in reply to gihu

    I'm not terrible with wiring, but I have no experience with arduino, dacs or op-amps. The only thing I have programmed is through AutoIT for a video games. This sounds about right though. I suppose I will start research on how to use a dac with arduino. Thank you.