In many a sci-fi, the villains (and sometimes the good guys) have glowing lenses attached to their gas masks to help both identify them and provide a useful target for the protagonists. The obvious reason any (kinda) moderately sane military would do this was stated before hand, identification. However, I feel that it is far too obvious of a identifier since the enemy would also know where you are.
Intimidation? Sure, but looks aren't stopping a bullet from spewing your brains out once people adjust to the look, especially if they're professional soldiers.
One other possibility is that they are infrared lights for inbuilt cameras to detect. The issue is that infrared is normally invisible and doesn't require such large lens in the first place. Just a single infrared LED would do.
So with all this in mind, why would militaries have glowing lenses for their troops?
- Need to be visible to regular people
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