Abstract：As SSYtype extensometer of high precision, good stability, it is widely used in the crustal deformation observation.The use of new diaphragm has greatly increased the displacement calibration repetition accuracy and constant precision of extensometer. However for such a diaphragm calibration device a comparative measurement traceability has not yet made up to date. Diaphragm we use the laser interference technique to recalibrate the calibration device through the line, the laser energy source, therefore, the diaphragm after such a calibration calibrator is accurate and reliable.
