Doris, you are an expert.
I was thinking outdoor range.
Indoor than things could be different.
Most TV remote control is done by IR light that blinks at 40000 times per second. The transmitters and receivers are very common and low cost. (the parts to make them)
So "down range" there are many IR transmitters. (infer red light)
Normally the receivers have a very wide field of view. If the receiver was back inside a tube it could only see light from a very limited direction.
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Another thought:
On my shotgun I have a light source that spreads light out in about the same pattern as the spread on the gun. For night hunting; when light hits the target then shot will hit the target. The light could be converted to invisibale light. I think this is backwards but the gun/target could know if the gun was pointed in about the right direction.
I was thinking outdoor range.
Indoor than things could be different.
Most TV remote control is done by IR light that blinks at 40000 times per second. The transmitters and receivers are very common and low cost. (the parts to make them)
So "down range" there are many IR transmitters. (infer red light)
Normally the receivers have a very wide field of view. If the receiver was back inside a tube it could only see light from a very limited direction.
------------
Another thought:
On my shotgun I have a light source that spreads light out in about the same pattern as the spread on the gun. For night hunting; when light hits the target then shot will hit the target. The light could be converted to invisibale light. I think this is backwards but the gun/target could know if the gun was pointed in about the right direction.