How night vision cctv works

BASICS: How does a night vision device work

To be able to see at night is still a touch of magic in these high-tech times, but we can reassure you, it's not rocket science, only technology involved. And this is not even a particularly new technology; the first models were available as early as the 1940s. But now to explain how a night vision device works.

All residual light amplifiers work on the basis of the multiplication of light in the visible and near infrared range up to approx. 1400 nm. In the more distant IR range, the thermal imaging devices are then at home, which let you see the temperature in a “magical way”. The night vision device consists of a lens, image intensifier tube, power source and an eyepiece. The heart of a night vision device is thus the image intensifier tube.

Schematic sketch of a generation 2 image intensifier tube

The existing ambient light (residual light) is emitted by the observed object and reaches the lens. Similar to a camera, an image is projected onto the photocathode through the lens. Photoelectrons emerge from each point of the photocathode illuminated in this way due to the external photo effect and are accelerated by a high electrical voltage (typically 10 to 17 kV) over the distance to the luminescent screen (phosphor layer). There they use cathodoluminescence to create a light spot at the point of impact, the brightness of which is proportional to the entrance lighting. A monochrome, mostly green-yellow, intensified image of the object can be viewed on the output side. This corresponds to the functionality of a generation 1 device.

Generation 2 and 3 image intensifier tubes have an additional component in the vacuum area between the photocathode and the phosphor screen, the microchannel plate (MCP). This multiplies the electrons emitted by the photocathode many times over, making the image brighter and more detailed. We want to go into the structure of Generation 2 and Generation 3 tubes in an extra BASICS article.

An exciting fact is that a dessert device is an analog technology. The only analog technology that was able to prevail against the previous digital ones. The only question is how much longer, because the digital is catching up - keyword SIONYX.

We have introduced the new SPARTANAT BASICS category for you. With this we introduce you to the basics that you always wanted to know how they work.

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