- Variable resistor laser driver outputting 3 volts
- Momentary switch
- Wire cutters
- Narrow-gauge copper wire
- Soldering iron and solder
- 7.2-volt power supply
- Voltage meter
- Eyeglasses screwdriver
- 3-volt infrared laser diode
Infrared lasers generally emit laser light between 700 and 1,100 nanometers — at this length, if the laser dot is visible at all, it's as a red glow. IR lasers are commonly used by the military to help track targets, but they have civilian applications as well — for example, in laser cutting or laser rangefinding. You can make a do-it-yourself infrared laser by adapting an IR laser diode in the same sort of circuits common to visible lasers.
Set the variable resistor laser driver and the momentary switch on the breadboard. Press the legs through the holes to secure them in place. Use the wire cutters to snip off a length of copper wire long enough to connect the laser driver and the momentary switch.
Solder the input leg of the laser driver to one end of the copper wire. Make sure not to use so much solder that you accidentally create a short circuit across the laser driver. Solder the other end of the copper wire to one terminal of the momentary switch.
Cut a length of copper wire long enough to connect the momentary switch with the 7.2-volt power supply. Solder one end of the copper wire to the free leg of the momentary switch, and solder the other end to the positive terminal of the 7.2-volt power supply.
Turn on the voltage meter. Touch the positive probe to the output leg of the laser driver and the negative probe to the negative terminal of the 7.2-volt power supply. Confirm that the meter registers exactly 3 volts. You may need to use the eyeglasses screwdriver to adjust the variable resistor of the laser driver.
Place the 3-volt infrared laser diode on the breadboard. Cut a short length of copper wire to connect the laser diode to the laser driver. Solder the positive leg of the laser diode to one end of the wire, and solder the other end of the wire to the output leg of the laser driver. Be careful when soldering the laser diode because laser diodes are particularly susceptible to high heat.
Cut a length of copper wire long enough to connect the laser diode to the 7.2-volt power source. Solder one end of the wire to the negative leg of the laser diode, and solder the other end of the wire to the negative terminal of the power supply.
Be very careful when using your infrared laser. Because the laser is not visible, you could accidentally damage something or injure yourself before you know what's happening.