Night vision goggles don't have to be high-tech. With a little ingenuity and some inexpensive parts, you can also enter the weird and wacky world of the infrared. The human eye actually can see light in the infrared range to a certain degree, but usually the incoming visible light upstages the incoming infrared "messages." However, if visible light is blocked from the eye, and the available infrared light is boosted, the eye's sensitivity to the infrared range is greatly improved. You can use homemade filters and LED lights to transform common welding goggles into night vision goggles.
Unscrew the lens assembly from both "eyes" of the goggles.
Remove the dark green lenses. (Leave the clear plastic lenses in place.)
Make red and blue filters for the goggles. Simply trace the shape of the lenses onto gel sheets and cut them out with a utility knife. Make two blue filters and two red filters.
Insert a blue filter and a red filter into each eyepiece. If needed, attach with a dab of glue.
Solder a row of four LEDs together in a series and attach this row to the right side of the goggles with silicone glue. Do the same for the left side.
Use a three-volt battery to complete the circuit and light up the LED lights. Connect one wire to each side of the battery and secure each with a small piece of duct tape. Then attach the battery to the goggles with silicone glue. Do this for both right and left "eyes" of the goggles. If the lights don't come on once wired to the battery, reverse the wires and try again.
Test your goggles. Walk around in a dark room or outside at night. The human eye cannot detect the infrared light the LEDs emit, so you will be somewhat "invisible." To turn off the goggles, peel back the duct tape from top side of the battery and disconnect the wire.
When you need to replace a battery, use a straightedge razor blade to cut through the silicone glue that attaches it to the goggles. Remove the duct tape on both sides of the battery to free the LED wires.
Don't look into the sun with these goggles. Because the filters block light in the visible spectrum, your pupils are open wide, leaving your eyes unprotected from the sun's infrared rays.