MTS Series LX Laser Extensometer - Manual (Page 16)

LX Laser Extensometer Introduction 16
The laser extensometer uses a unique scanning laser beam technique to measure
elongation entirely from one side of the specimen. Two tiny retro-reflective
targets are attached to the specimen at the desired gauge length and the beam is
scanned along the specimen in the direction of elongation. Reflections from these
targets are then processed by the laser extensometer to provide measurement of
elongation (strain). This approach eliminates the need for a separate Scan
Receiver Unit mounted on the opposite side of the specimen.