NVD has a history of over 40 years. These products can be divided into several generations. Every major breakthrough on the road to NVD technology leads to a new generation of products.

Earliest Generation - The earliest night vision systems were developed by the U.S. military. They were used on the battlefields of World War II and the Korean War. These NVD systems used active infrared technology. This means that an emitting unit called an infrared radiation source must be attached to the NVD. The unit emits a beam of near-infrared light, similar to the beam from a normal flash. Such beams cannot be seen by the naked eye, they bounce off objects and return to the NVD's lens. This system connects the anode to the cathode to accelerate the electrons. The problem with this approach is that the electron acceleration distorts the image and greatly reduces the life of the tube. When this technology was first used in the military, there was an important problem: the enemy was able to copy the system in a short time, which allowed enemy soldiers to use their NVD system to observe the infrared beam emitted by the device. .

night vision goggles

1st generation - This generation of NVDs abandoned active infrared technology in favor of passive infrared technology. This NVD can use ambient light from the moon and stars to amplify the reflected infrared rays around it, so it was once called starlight by the U.S. military. This means they do not require an infrared emitting source. This also means they don't work very well on cloudy or moonless nights. The first generation of NVDs used the same image intensifier tube technology as the 0th generation, also relying on the cathode and anode for electron acceleration, so there are still problems with image distortion and shorter tube life.

Second Generation - Significant advances in image intensifier tube technology gave rise to the second generation of NVDs. They have higher resolution, better performance, and better reliability than first-generation devices. The biggest takeaway from the second-generation technologies is their ability to generate images in extremely low-light conditions, such as on a moonless night. Sensitivity is increased due to the addition of a microchannel plate to the image intensifier tube. Because MCP increases the number of electrons rather than just accelerating the original electrons, the degree of image distortion is significantly reduced, and the brightness is also higher than that of previous generations of NVDs.

Third Generation - The U.S. military currently uses third-generation technology. Although its principle is not fundamentally different from that of the second generation, the resolution and sensitivity of this generation of NVDs are better. That's because its photocathode is made of gallium arsenide, a substance that helps improve the efficiency of converting photons into electrons. In addition, the MCP is also covered with an ion barrier layer, which can effectively increase the pipe life.

night vision goggles in movies

Fourth-generation technology - The fourth-generation technology we usually refer to is also called "no film threshold" technology. Generally speaking, the performance of this generation of systems has been greatly improved in both strong and low-light environments.

MCP removes the ion barrier added by the third-generation technology, so the background noise is reduced, and the signal-to-noise ratio is improved. Removing the ion film actually allows more electrons to be amplified, so the image is significantly less distorted and brighter.

The introduction of an automatic threshold power supply system enables the voltage of the photocathode to be switched on and off rapidly, allowing the NVD to respond instantly to fluctuations in lighting conditions. Advances in this technology are critical for NVD systems, with the ability to quickly move from bright light to low light (or vice versa) without the image producing any bumps. As an example, imagine a ubiquitous movie scene: an agent who uses night vision goggles will "blind" if someone turns on a nearby light. With the latest threshold power technology, changes in light conditions do not have such consequences, and the improved NVD system can respond immediately to changes in the light environment.

Many so-called "cheap" night vision goggles use Gen 0 or Gen 1 technology, and if you have high expectations for the sensitivity of professional equipment, you may be disappointed. Second-, third-, and fourth-generation NVDs are generally more expensive, but can last longer if properly maintained. Another point is that any NVD system can benefit from using an IR radiation source in locations that are extremely dim or even where ambient light is barely captured.

An image intensifier tube undergoes rigorous testing to see if it meets the standards set by the military. Compliant tubes are classified as MILSPEC. Even if only one of the indicators does not meet the military standard, the tube will be classified as a common specification (COMSPEC).