Figure 0 - Build a long range laser night vision illuminator
Build a long range laser night vision illuminator

Infrared LEDs are the most widely used source of infrared radiation for night vision illuminators because they are inexpensive, easy to connect, and possess no safety hazards because they are human eye safe and do not radiate much heat. The drawback to LED based night vision illumination systems is that they are not really useable at distances of more than 100 feet no matter how many LEDs you use in the array. Filter based night vision illuminators that change visible light into infrared light are capable for much greater distances, but they suffer from huge energy losses due to massive heating of the filter material and because of this, require massive amounts of current and are only suitable for outdoor use. A laser on the other hand, is capable of extremely long distance illumination and is probably the most energy efficient source of bright light possible.

The main problem with using infrared lasers to create night vision illuminations systems is that there are safety issues that must be addressed, especially when using lasers with a rating higher than Class IIIa, or lasers that have an output power of more than 5mW (milliwatts). Class IIIb and Class IV lasers can output as much as 500 mW, and they are certainly not eye safe, especially when highly focused. A laser that outputs only 50 mW may seem like nothing, but be aware that instant eye damage could occur if you hit your retina with a focused beam. Using infrared lasers makes this situation so much more dangerous because you cannot see the beam, and your blink reflex will not help save your vision in the event of an accidental exposure to the laser beam.

Do not continue with any of these experiments unless you are well aware of the dangers involved and have proper laser safety equipment and experience in using higher powered lasers. You can still create a useable short range laser illuminator using a lower power 5mW infrared laser diode or module, so consider starting with a Class IIIa laser if you want to experiment with laser night vision illumination.

Figure 1 - Laser pointers are now available that output infrared radiation
Figure 1 - Laser pointers are now available that output infrared radiation

Not that long ago, an infrared laser with enough power to burn wood was the size of a shoe box and taken hundreds of watts of power. But today you can purchase a laser pointer for under $100 from many online distributors with enough power to pop a balloon at 20 feet and burn electrical tape. Make no mistake though - these lasers are not toys. Your first mistake will also be your last as a single shot into your eyes will likely permanently damage your vision. If you intend to work with high power lasers, purchase a set of laser safety goggles and wear them in your lab when experimenting with these lasers.

The two laser pointers shown in Figure 1 are both extremely high power Class IIIb lasers, capable of outputting 50 mW and 250 Mw of infrared laser radiation. Calling these lasers "pointers" is really a bad term to use as they are completely invisible and not safe for pointing at objects. The laser shown in the top of Figure 1 will burn any black object from up to 20 feet away, and has a rated output power of over 250 milliwatts. The laser shown at the bottom of Figure 1 will output about 50 milliwatts of power and has been converted for infrared operation by changing the original visible red laser diode with one from a DVD burner. Both of these lasers work very well as long range night vision illuminators once their beam has been spread by some type of lens.

If you are looking to purchase a laser pointer style laser for night vision experimentation, then choose one that allows the collimating lens to be adjusted of fully removed. The goal will be to spread the beam out to an area of several feet in diameter at a distance of several hundred feet.

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