Let's Make Robots!

laser pointer and a 38khz sensor

would it be possible to make a laser flicker at 38khz?

I was thinking; if I had a modified laser that gave me a red dot that pulsed at 38Khz. If a robot was made to go towards a 38Khz beacon...

I thought this might function as a intuitive remote control.

The robot is programmed to do whatever, map its surrounding, search for metal or filming the girls gymn locker room. But when the laser is pointed anywhere in its vicinity it'll start following the red dot until the laser is switched of again. then it will continioue its original task.

Think of a custom officer and his K9 drug sniffing robot. the robot is rummaging through some suitcase when the office spots a suspicios looking fellow. The officer could guide the robot to the suspect simply by pointing, and when the robot arrives, he just turns of his pointer and the robot starts sniffing for drugs again at the new location.

Is i doable? Not the drug sniffing part, but the laser ray as a IR 38Khz beacon that a robot follows part?

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The only reason I suggested a laser was because it gives the operator a visual feedback, so he knows when the remote control is on, and where he's pointing it. The laser might just as well be an extra indicator while the robot acually focuses on anather invisible beam sent along the same path..

But yes, I was hoping that the bot would follow the reflection, and not the actual light source in the controllers hand. this would require the operator to point the control device slightly besides the bot, and not directly at it.

Red laser pointers do emmit some IR that can be detected by an IR receiver but it is only a small portion of the light output so for your system to work you would need an IR laser. A red laser pointer can also be used so you can see where the IR laser is pointing.

Yes you can modulate your laser beam, by using the picaxes IR out command and connecting your laser to the output pin you should be able to send a signal as long as the laser will work at 5V. Since many of the laser pointers run on 3V or 4.5V you may need to put some diodes in series to drop the voltage. Each diode will drop about 0.6V if your laser needs more than 25mA then consider using a transistor to drive the laser.

You want to detect the reflection of the laser? You want your bot to "see" the laser dot in its environment. That would require a very sensitive detector (array). Perhaps a camera.

Why the 38 kHz? You also want to encode some commands in the beam? Or simply to avoid the very sensitive detector from following just any laser dot in the area? Or anything bright for that matter.

The IR receivers used with picaxe are very sensitive but require a 38Khz modulated signal. You can use other frequencies but the picaxe software is written for a 38Khz reciever.

I think your best option would be to use a laser to "paint" the target. This is a technique the military uses for guiding missles, but you can probably adapt it for your uses.


Only one small issue the laser has to work in the IR wavelenghth so the IR 38kHz detector can "see" it in the first place. I do not think a red pointer laser is usable since lasers are usually tuned for a specific wavelength. Once this requirement is met I see no reason why you could not pulse the laser at 38kHz but you would not see the blinking point without a camera:). 

Plus IR lasers are dangerous exactly because thay cannot be seen.