A surface inspecting method for inspecting a flaw of a test object using a surface wave and estimating a depth of the flaw of the test object from an attenuation ratio of a frequency of a generation wave, the surface inspecting method including calculating a power spectrum of generation wave generating...http://www.google.com/patents/US8094297?utm_source=gb-gplus-sharePatent US8094297 - Laser-based maintenance apparatus for inspecting flaws
