A laser diode shares a commonality with incandescent bulbs -- they both use electricity to generate a light. Test the integrity of a laser diode by constructing a laser pointer using a battery supply. A few items from a laser service supply will be needed, as will some tools most homes have on hand. Follow the steps listed to test a laser diode for its functionality.
Stand the soldering iron on a work surface. Plug the solder iron’s power cord into a wall socket for power. Let the soldering iron heat up for 10 minutes.
Take the exposed end of the black wire and solder it so that is attached to the laser module onto the negative-labeled contact on the battery pack. Let the solder cool for a minute.
Solder the exposed end of the red wire that is attached to the laser module onto the positive-labeled contact on the battery pack. Let the solder cool for a minute. Unplug the soldering iron.
Unscrew the front cap from the laser module. Stand the laser module on the work surface with the open end facing up. Rotate the open end so that the the hole to the side of the two vertical holes is facing to the right.
Grip the laser diode by the base with the tweezers. Insert the shorter of the two pins connected to the bottom of the diode into the hole that is to the side of the two vertical holes. Insert the longer of the two pins connected to the bottom of the diode into the hole to the left and above the hole that the shorter pin is inside of.
Insert one of the two batteries into the battery pack -- lining up the positive and negative contacts on the battery with the text labeled the same on the battery pack.
Install the other battery into the battery pack -- lining up the positive and negative contacts on the battery with the text labeled the same on the battery pack. Watch the laser diode emit a beam of laser light. Remove one of the two batteries from the battery pack to cause the laser diode to cease functioning.
Wear laser safety glasses when applying power to the laser diode. Do not allow children or pets nearby when you are trying out the laser diode to check if it will project a laser beam.