Test piece heat expansion measurement - using laser beam interferometry to measure test piece dependent path length change

摘要

The test piece is mounted in one of two grooves in a suitable carrier element, and a reflective quartz crystal is used to mark one end of the test piece in one groove and the other end in the other groove. A gas laser generated light beam is divided into two parallel beams, one down each groove. Each of these is reflected by the appropriate quartz crystal and directed to an inferometer by a semi-reflective mirror element. The interferometry patterns are then used in the usual way to detect path length changes, and thus to measure any expansion of the test piece.