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Bright Light Cut-Off (Analog NV) | Optics Trade Debates

Welcome to Optics Trade debates. In each episode, we talk about a different topic and try to answer the most common questions we receive about it. Today we are going to talk about bright light cut-off on analog night vision optics.

Bright light cut-off is a term which is only used with analog night vision devices. Analog night vision devices are all devices that feature an analog cathode to amplify light.

Digital NV devices have a similar function called automatic brightness control, which can cause confusion. Some manufacturers even use one term on both types of night vision devices.

On older models that didn't include this function, users could hurt their eyes when a powerful light source came into the field of view. The analog cathodes amplify all light sources in the same way, so a powerful light source could overwhelm the user's eye. When pupils are hit with a bright light, they contract, and with contracted pupils, the user could not continue to observe because they wouldn't gather enough light.

The bright light cut-off mode enables the device to amplify differently bright objects in different ratios. So the difference of brightness is much smaller in the image.

Analog night vision devices can get damaged if they're pointed at a powerful light source. Some are protected better than the others. The bright light cut-off function also helps protect the device.

This function is not necessary for use in dark environments where there are no artificial light sources. But these kinds of environments are rare so for use in more populated areas we would recommend an analog NV optics with the bright light cut-off function.

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Explanation of the term on our website:

The newer generation and newer night vision devices have build in special electronics that lower the power or reduce image brightness when sensors detect sudden bright light such as flashlights, car headlights and other devices that causes bright light. Otherwise, without bright light cut-off possibility sudden appearance of bright light could damage the image tube and shorten its lifespan.  

Second and third generation of night vision devices also have a built-in automatic image brightness. This possibility enables automatic adjustment when an even smaller amount of sudden bright light occurs and also enhances the device's lifespan. It also helps to protect of the sudden appearance of bright light and prevent damage of night vision device.


Source: Careflight (NV with no BSP and with BSP)

Products mentioned:
NV optics:


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