Zero In On Meaning

(idiomatic) To aim precisely at a target

Example:   The pilot zeroed in on the bunker and launched a guided missile.
To successfully narrow down a search
  We have zeroed in on the source of the problem.
  See if you can zero in on the caller.
To concentrate or focus one's attention on at task
  One member of the check fraud team will zero in on the fingerprints.
To converge on something
  At the spring sale, everyone zeroed in on the bargain clothes.