Device for testing coins or other flat objects

摘要

Two optical barriers (L1,L2) are sepd. by a distance (L) along a track inclined at an angle (theta) to the horizontal (H). The coin (M) rolling down the track starts a timing operation at the first barrier and terminates it at the second. From the durations of occultation at the two barriers and of transit between them, the length of a chord (B) of the rolling coin at a max. distance from its edge equal to the distance (h) of the barriers from the track is calculated on the assumption of approximately constant acceleration.