With these instruments, the backlight incorporates an optical filter which reduces the overall brightness and minimizes blue and green spectrum light. This helps preserve the eye's natural night vision in dark conditions.
Additionally, Night Vision backlights are also much dimmer than a standard backlight, making it more difficult to detect with the naked eye in night operations - a useful feature for military personnel. This backlight appears soft greyish pink, not red, and is still in the visible spectrum, so is not compatible with night-vision equipment.
It takes 30 to 45 minutes for the average eye to adapt to darkness and maximize night vision. Even a short burst of white, yellow, green or blue light "bleaches out" the rod cell photoreceptors in the eye and causes night blindness until the entire adaptation process can take place again. Light in the red spectrum does not cause this "bleaching out", preventing night blindness and night vision fatigue.
All the other features of the Kestrel Night Vision instruments are just the same as their more colourful counterparts.
For NSN for specific Kestrel models - please click here.