I guess "Deflector Screens" are called "screens" because one of their main functions is to deflect or "screen" out dust particles and micro meteorites. Just like a fly screen on your window screening out flies?
You wouldn't want to hit a fly at full impulse power!
I'm not sure .. but are the deflector shields used when traveling at warp? Or only with Impulse/Sub Light speeds?
If they are .. are they necessary? (during warp)
Do dust and micro meteorites exist in that bubble of "Warp space" surrounding the ship?
Is the "warp bubble" alone sufficient to push small objects away that are in normal space?