Well, this is disappointing and surprising. I put
frosted window film on the DI10 hoping it would scatter the IR a little better. I can't say that I see much difference with or without the film on it. Still a huge hotspot on the ground despite it being aimed upward as best as it can be.
If that is the unit on the post on the right side of the image, I'm not sure there is much you can do with the device in that location. It's physics....... You'll never get "even" coverage when some of the yard is 5' from the device and some of the yard is 25' from the unit. That's a 5:1 ratio (meaning the front is going to be 5 times brighter than the rear - not accounting for the natural falloff of the light which will make it an even higher ratio in real life)
The best solution is to mount the unit on a higher pole and/or move the unit farther back from the edge of the yard. If you mounted it on a 20' pole, then the front of the yard would be 20' from the unit and the back of the yard would be about 32' from the unit. That produces about a 1.5:1 ratio and it will be much easier to get "even" coverage then. (I realize you probably don't want to mount it on a 20' pole - I'm just using that exaggerated height to help prove my point).
Even if you left it on the 5' pole, but moved the pole 10' from the edge of the yard (farther to the right), then the front part of the yard will be 11' or so from the device will the rear part of the yard will be 35' from the yard. That a 3:1 ratio which is still likely to produce a hot spot, but it is better than the 5:1 ratio as currently installed.
The ultimate solution might be a combination of the two. If neither of those options works, then you really need to cut the output of the IR. I'd suggest getting a lower power unit, but adding a neutral density filter would work too. You still won't have even coverage, but at least you get rid of the hot spot.