The Video Gauge noncontact extensometer from Imetrum (Bristol, UK) reportedly is the only device of its kind to achieve the exacting requirements of ISO 527-1: 2012 ASTM D638 equivalent. The system, which has undergone rigorous, independent testing, is capable of determining tensile modulus by measuring a change of gauge length to 1% accuracy of the relevant value. In tests, Imetrum was able to achieve between 0.2 and 0.3 µm for all gauge lengths using the same camera and lens combination. This exceeds by a factor of three the accuracy required by ISO 527 for a 50-mm gauge length.
Designed for use with tensile testing machines, the system comprises a controller with Video Gauge software, one or more high-resolution digital video cameras, and application-specific lens. Also included is a voltage output module for interfacing with traditional strain channels, lighting, tripod, and a rugged case for storage and transportation. The system is straightforward and intuitive to use and has many distinct advantages over traditional contact methods, such as clip-on extensometers and strain gauges, according to the company.