Polaroid Sun 660 AF
The Polaroid Autofocus 660 was a square-bodied instant camera in Polaroid's 600-series. It was the first in the range to use Polaroid's patented Sonar Autofocus device. The distance to the subject was calculated by emitting an sonar (ultrasonic) pulse which then was captured again. The time difference between the sent versus received pulse gave the distance measurement. The sonar emmiter/receiver is the big gold disk next to the lens.