| 摘要 |
Procedure for examining in materials in the solid state of aggregation, such as metals, their surface defects, surface cracks or equivalent, the properties of coatings or the surface quality of paper. A special application of the procedure of the invention is measurement of the thickness of the surface hardening layer of steel. With a view to preventing the rapid levelling out of the temperature differences produced on the surface of the material under examination, on the material (25) under examination is directed a pulsed light beam (21) in the visible light wavelength range, whereby at least part of said light beam (21) is absorbed on the surface of the material (25) under examination and causes elevation of the surface temperature of the material (25) under examination. The surface of the material (25) under examination that has been heated by effect of the periodic temperature variation produced emits a pulsed infra-red radiation (26), which is received with a means (27) sensitive to infra-red radiation. |
