| 摘要 |
PROBLEM TO BE SOLVED: To provide a non-contact extensometer capable of eliminating error factors such as the thickness fluctuation or the like of a test piece and effectively improving the measurement accuracy. SOLUTION: First and second cameras 1 and 2 for respectively picking up the images of two reference lines R1 and R2 attached to the test piece are set to a prescribed interval D, the focus distance is fixed and the image of one of the reference lines R1 and R2 is picked up respectively. Then, a distance L to the surface of the test piece is measured corresponding to the positions P1 and P2 of reference line images in images respectively picked up by the respective cameras 1 and 2, the interval D of the cameras 1 and 2 and the focus distance F and the focus distance (visual field angle) of the respective cameras 1 and 2 is adjusted (optimized) corresponding to the measured distance.
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