This is a mounted light outside my bedroom door that takes away whatever night vision they have. I operate it from my bedroom with the door closed. They can't come down the hallway without me hearing it and the light hits them from the backside, will generally make them turn that direction. I then turn the light off, and with my night vision intact, can open the door and take whatever action I need to.
This works to some degree. Back in the 1980's, I had a problem with "certain" people who enjoyed showing up at my rented trailer home late at night and banging on the door trying to wake me up to go out and do crazy things with them.
Jerks like this, and burglars too, hate being exposed in the light because it makes them more vulnerable. Here is what I did:
I installed two very bright spot lights on the top of a 25 foot electric company utility pole. I aimed them right at my front door. I put a "panic switch" on the wall right next to my bed. This switch also activated a small, red, light bulb in my bedroom, so I could simultaneously find my way around the room if need be. One night, they showed up again, drunk, laughing and banging on my door at around 2 a.m..
I pushed the button, and they got very quiet. I think the bright lights suprised them more than it blinded them though. I then grabbed my shotgun and went out the BACK door. When I crept up on them and looked into their eyes, it was obvious that the bright lights were affecting their vision and annoying them. I wouldn't go so far as to say they were "blinded," but I was able to surpise them by coming up on them from the darkness. All I said was, "What do you want?" And all they said was, "We're going fishing, wanna come?" BUT, this type of thing NEVER happened again. I was pleased that I was able to ruin their
"game" with simple technology and some creative thinking.
I agree with Wizard that darkness and PLANNING create a tremendous advantage for a potential victim. The more, the better. I think it's a better game if the homeowner pinpoints the entry points into their home in advance, and plans shooting angles in advance. Granted, there are situations where using a flashlight can be helpful, but in an armed shootout no. The whole concept of blinding an armed felon with a high intensity flashlight installed on the defense gun completely falls to pieces in the majority of armed, home intrusion, shootout scenarios.
The marketing genius' would actually have one believe that shining a bright light at a potential shooter somehow causes some type of "paralysis" enabling you to shoot them first. They shouldn't be doing this, even though it does help sell a bunch of flashlights.
I think that motion sensing flood lights at entrances are a real good idea also. They are very inexpensive (again at Walmart) and will help ruin night vision. They also prevent people from seeing "through" our windows. They send a message/warning that the homeowner at least "thinks" about home security and just might be ready for them - a good deterrent IMHO.
So how do you ID your target in a dark room? One person suggested saying "Freeze," and waiting for a reply which would certainly come to you if it was a child, spouse, etc. I'd be a concerned that the reply might be gunfire, so I'm not so sure about this method. What do you think?