The 1st generation is the simplest and also the most reasonably priced version of night vision devices. These devices work as described above and amplify residual light. In addition, they have an infrared illuminator which only needs to be used when it is completely dark. With this, an infrared beam is cast into the darkness which the human eye, with a sensitivity at 550 nanometres, cannot perceive.
Unlike the human eye, the night vision device can detect the infrared light wavelength range. Thus, vision is possible even in absolute darkness. The disadvantage, however, is that this feature cannot be used for very long distances. The 1st generation devices amplify light around 1.000 times.
The image appears green because the blue portion of the light is shifted into the green spectrum and the red portion is shifted into the infrared. When you look through a night vision device, you notice a static that appears as a structure streaked with fine grains. With use, the green visual impression slowly disappears until the image is completely black again. As a rule, 1st generation devices offer 2,000 hours of operation.