Night vision glossary

Amplifies available light using an image-intensifier tube. It still needs some light; it cannot produce a scene in total darkness without illumination.

Displays a camera image on a screen. Check whether IR illumination is needed, as well as latency, frame rate and battery life.

Detects infrared radiation emitted by objects to form a thermal image. It works differently from a device that amplifies visible light.

FOM is signal-to-noise ratio multiplied by resolution in lp/mm. It is one indicator, not a complete measure of the view. Low-light performance, blemishes and optics also matter.

These describe the phosphor screen colour. White phosphor does not automatically mean better performance; specifications and individual tubes matter.

Rapidly controls tube operation to help handle changing light levels. It does not make unrestricted daylight use or pointing at the sun or intense light sources safe.

Gain controls image amplification; an iris controls the amount of light entering the lens. A manual iris is not the same as manual tube gain.

These refer to tube technology or generation. Compare actual specifications rather than assuming performance from the generation label alone.

Dark spots may come from tube characteristics or contamination in the optics; cleaning cannot remove all spots. Check whether performance data is measured for your specific tube or is a batch reference.

The angular width of the scene you can see at once. Field of view and magnification are different measurements.

Adjust the eyepiece diopter for your eyesight and the objective focus for viewing distance. Do not confuse adjustment rings with parts used for disassembly.

A compatible helmet and mount are the starting point. Some devices also need an arm or adapter. The L4G24 name alone does not establish compatibility with every setup.

Provides infrared illumination in dark conditions. It may be visible through other night-vision devices. Check the specifications of your particular device.

Similar shapes do not mean the same voltage or charging requirements. A 1.5V AA primary cell is not equivalent to a 3.7V rechargeable 14500. Use only the specified battery and charger; never recharge primary cells.