METHOD AND APPARATUS FOR MEASUREMENT OF PLASTIC STRAIN RATIO BY LASER ULTRASONIC METHOD

摘要

PROBLEM TO BE SOLVED: To provide a method and an apparatus in which a plastic strain ratio is measured by a laser ultrasonic method in which it is not required to bring the apparatus close to an object to be inspected and in which the value (r) (the plastic strain ratio) of the object to be inspected can be found with high precision even when the distance between the apparatus and the object to be inspected is not kept constant. ;SOLUTION: A laser beam [at an optical frequency of (f)] which is radiated from a laser 11 for ultrasonic observation is divided into three beams by two polarization beam splitters (PBS's) 16, 17, and the respective laser beams are shifted to optical frequencies f₀, f₁, f₂ by corresponding acousto-optic elements 18, 19, 20. The laser beam at f₀ is made incident perpendicularly to the surface of an object 1 to be inspected. The laser beam at f₁ is made incident at an angle of θ₁ from the x-axis inside the x-z plane. The laser beam at f₂ is made incident at an angle of from the y-axis inside the y-z plane. A position which is irradiated with the respective laser beams is identical to a point O which is irradiated with a laser beam for ultrasonic generation.;COPYRIGHT: (C)1999,JPO