To akidonicki (If I spelt that right),A couple points:
I myself actually have the EXACT same problem. Very very often. I also can't do anything about it. (Coincidentally, As I write this, it is happening. Again.) There are things which you may try to do about it, which I cannot in my own situation. For instance, I can't move away from where I live due to lack of money.
Build a solid gate/fence, to block it out, or pay someone else to do this; for there are *few* restrictions upon how high anyone is allowed to build a gate or a fence.
Keep a diary about it, as precise as you can - what, when, where, who, how long, effects, and such. This is for the LAW, to present a case if you can. In law, this is called "Light Pollution", and the business is similar to "Noise Pollution", and is treated with as much respect by the law... which I cannot comment upon... (Some other things which you state may count as "Stalking"'.)
I have taken many photographs much like yours, and so I know what you mean there. Stand in place, and take one photo with the "flash" ON, and then another with the flash off... and if you can, try to take some in daylight when the light is still on, or get any close-ups showing the exact light fixture (to show that it is pointed at your property)... something like that... which relates to this last suggestion...
Buy yourself a bright light and do the same to them...?? (Make certain that it shines upon no-one else at all.) Find out how *they* themselves next deal with it - in LAW - ...and then state your own case. Whatever you do, please tell us what happens - but also please do not do anything in haste (bad), if you know what I mean.
To akidoniki again...Just re-reading other things which you write... this is definitely "Harrasment" in law, and I would like to read any advice that NAS might give you. Keep very precise records, and ask your children to do the same if they can.
Buy yourself a bright light and do the same to them...?? (Make certain that it shines upon no-one else at all.) Find out how *they* themselves next deal with it - in LAW - ...and then state your own case.
Do not do this, to not retaliate or take aggravating actions, this will weaken your case and if legal action is taken against you you're on the back foot, the courts don't really like the argument of "but he did it as well".