Abstract: A non-contact, laser strain extensometer for use in materials testing utilizes a revolving laser beam to measure the separation of benchmarks placed on the specimen to be tested. The reflection of the laser beam from the benchmarks is focused on a photosensor to generate electronic pulses. The time duration between these pulses can be precisely measured using electronic counters. This time duration correlates with the distance separating the benchmarks. The revolving beam can be generated either by rotating polygonal mirror or an oscillating mirror.