Determining the difference between night vision devices is not an easy task. What is it / how does it work? Night vision allows the user to see objects and surroundings even under the darkest conditions without additional illumination. The heart of night vision is an image intensifier tube (IIT) which amplifies the ambient light by many thousands a times. In addition to visible light, this tube is sensitive to infrared radiation. That means that you can use invisible infrared illuminator to add luminescence to the objects. The unit collects light from all possible sources (stars, moon, distant urban illumination, built-in or add-on infrared flashlight, etc.) and projects an image on the screen. Do's and Do Not's · NEVER take the unit apart. This device contains high voltage, which may be hazardous to your health! · NEVER expose the opened objective lens of a unit to daylight or bright artificial light. (Note: 1st generation devices remain active for a few minutes after switching off). You can turn the unit on during the day, but the caps must cover objective lenses. There is a tiny hole in the lens caps to provide enough light for daytime operation. · NEVER aim active units at intense light sources (i.e. lights, headlamp, campfires, the moon, etc.) It will not make you blind like in the movies, but it will harm the unit. · NEVER reverse the polarity of a battery · NEVER connect the unit to external power sources · ALWAYS keep the objective lenses covered when not in use · ALWAYS store in a warm dry place when not in use · ALWAYS remove battery when not in use for a long period of time. Glossary of terms: Image Intensifier Tubes: Collects and amplifies light, which is then displayed on the display. Binoculars vs. Monoculars: A night vision monocular is designed for use with one eye and contains one image intensifier tube. A night vision binocular is designed for use with both eyes and contains two image intensifier tubes. The hybrid of binocular and monocular is called bi-ocular. It splits the image projected by a single tube into two channels. This construction is as convenient as an ordinary binocular, but twice less expensive. However, it doesn't provide stereo vision and twice less brightness than a normal binocular. Generations: The quality of different night vision systems is graded by generations. Simply put, Gen 1 was developed long ago, but is still in production because its performance is sufficient for the consumer applications and the cost is affordable. Gen 2 came next considerably increasing the quality of the image intensifier tube. Gen 3 followed with an even better image. As the technical answer to American Gen. 3 design, the European companies decided to develop the Gen 2 technology. Gen 2+ or Supergen, can be consistently compared on par with Gen 3. Infrared illuminator: I/R illuminators emit light with wavelengths of about 800 nanometers. This range is perfectly accepted by night vision equipment of all generations. At the present time, all night vision have built-in infrared diodes. Designated hand-held or stationary illuminators are also available. This equipment increases the night vision functionality allowing it to work even in total darkness. Normally illuminators are completely eye safe, but with power increasing and stepping from infrared LED to infrared laser the devices may become not eye safe and potentially hazardous. This parameter is one of the most important to know when you buy the illuminator. I/R emitting devices are almost invisible from the opposite side unless your probable rival also has night vision equipment. This is why the information about whether I/R is on or off is very important for combatant operations. Infrared aimer: This device is very similar to the previous one, but it emits a very narrow beam. The task of the aimer is not to light the terrain but to spot the target only. Usually aimers are used with different weapons. Resolution: Measured in line pairs per millimeter (lp/mm), this is the clarity or quality of the image seen on the screen. The higher the number, the better the image quality is. However, buyer beware, these numbers are often inflated by some companies because it is impossible for the average customer to test this parameter without special, very expensive equipment available only at factories. Magnification in Night Vision: Higher is not always better, and this is one of the cases. Higher magnification means lower brightness and poorer visibility. Normally night vision magnification is 1x-2x. Good Gen. 2+ and 3 devices can have 4x-5x magnification. Higher magnifications are useless unless these are very professional units with huge and heavy optics, which cost thousands of dollars itself.