Everyone knows that Gen2+ IIT outperforms Gen1 without braking a sweat. This is due to the fact that in devices starting from Gen2+ you have MCP (Micro-channel plate) which amplifies electrons in addition to having better optics than Gen1.
But it is not a known fact that high-end Gen2+ IITs like Photonis 4G can even outperform a new and high FOM (2100+) Gen3’s in some environments!
What are the parameters to look for in NVD devices?
Resolution
The ability of an image intensifier or night vision system to distinguish between objects close together. Image intensifier resolution is measured in line pairs per millimeter (lp/mm). Typically, the higher the line pair, the better the image resolution. Both higher quality Gen2+ and Gen 3 tubes generally have a resolution between 62 to 72 lp/mm, therefore line pair measurement does not indicate the generation of the tube.
Photocathode Sensitivity
Photocathode sensitivity is a measure of how well the image intensifier tube converts light into an electronic signal so it can be amplified. The measuring units of photocathode sensitivity are micro- amps/lumen (?A/lm) or microamperes per lumen.
Signal-to-Noise Ratio (SNR)
A measure of the light signal reaching the eye divided by the perceived noise as seen by the eye. A tube’s SNR determines the low light resolution of the image tube; therefore, the higher the SNR, the better the ability of the tube to resolve objects with good contrast under low-light conditions. Because SNR is directly related to the photocathode’s sensitivity and also accounts for phosphor efficiency and MCP operating voltage, it is the best single indicator of an image intensifier’s performance.
Figure of Merit (FOM)
Image Intensification tube specification designation, calculated on line pair per mm x signal to noise. (FOM=lp/mm * SNR).
Autogated
Autogated offer the tube better protection and preventing resolution loss in high light conditions.
Black & White Image (White Phosphor, WP)
By using a different kind of phosphor (P45) the image looks like a black & white picture in high definition. For some people these seem to work better than for others. Personal preference.