What makes night vision equipment wary of bright light?
There are many kinds of night vision devices, but they are basically composed of optical system, image-changing tube or micro-light tube, power supply and power supply system. Of course, the active infrared night vision device must also be equipped with infrared searchlights, among which the image-changing tube or low-light tube is the "heart" of the night vision device. The image-changing tube can convert the invisible infrared image into a visible image, and the micro-light tube can enhance the weak light by tens of thousands or even hundreds of thousands of times, so that the human eye can perceive it. Night vision devices are afraid of strong light because the image converter and low light tube are afraid of strong light. Taking the image transformation tube as an example, when the infrared light is irradiated on the photocathode of the image transformation tube, the photocathode emits electrons, and the electrons are accelerated to the fluorescent screen under the action of a high-voltage field (16-21 kV) and an electronic lens, so that the fluorescent screen Displays the visible target image. The more light signals received by the imaging tube, the more electrons are emitted, the stronger the light signals sent by the fluorescent screen, and the brighter the image seen. They are basically proportional. However, if the external light is too strong, the number of electrons emitted by the photocathode will not increase to a certain extent, that is, saturation will occur, and the target will not be seen clearly. If too strong light suddenly shoots over, it may also burn out the photocathode of the tube, so that electrons cannot be emitted, and of course nothing can be seen.
Although the night vision device has taken certain anti-glare measures, its effect is limited, so it must be operated strictly according to the regulations. When encountering strong light or targeting during the day, put on the objective lens cover or turn off the power switch. Proper use of the night vision device can prolong its service life and avoid unnecessary damage, so as to give full play to the role of the night vision device.
