It sounds to me that he is indicating that he employed police laser (aka police lidar) to obtain your alleged speed.
Were you driving with a radar detector (which can also detect police lidar)?
If it were police laser, targeting distances in the evening can be pretty extreme (above 1500-2000 feet away). If he was sitting on the side or in the median dark, it would be awfully hard to pick him out at that distance in the evening.
If LIDAR were used, it wouldn't be estimated, it would be precise (perhaps even into the 10th of mph).
Was a distance indicated on your citation?
If you are unfamiliar with police lidar, may I suggest this online guide to police lidar