Great question about the angle actually. There's previous work by an applied physics group [1] that shows the detectable field-of-view from the camera is about 20 degrees. Our experiments also confirm that.
We also think using the smartphone flashlight (if that's what you mean) is the best way forward. That's already very helpful (and recommended) for humans to find hidden cameras, and it should be a useful extra modality for our work too.
You don't have to answer but, I'm assuming by the phone's API you can steer the beam/have an exact precision known of the minimum angle you can sample? That's pretty cool tech to work with.
Unfortunately we can't steer the ToF beam, so the user has to move the phone around to multiple positions (a 2D grid of positions, basically). The app provides pretty clear guidance on where to move the phone to cover all possible spots, though.
We also think using the smartphone flashlight (if that's what you mean) is the best way forward. That's already very helpful (and recommended) for humans to find hidden cameras, and it should be a useful extra modality for our work too.
[1] https://ieeexplore.ieee.org/document/8790792