Volume 3, Number 1

January 2004

 

 

INBOX

 

Q.	Which industry uses laser NDT? What type of defects are found?
A.	The term laser method may be confusing because several NDT methods use lasers. Lasers provide coherent (single wavelength, in-phase) electromagnetic radiation (for example, light or microwaves) at various wavelengths. When the wavelength is in the infrared part of the spectrum, it’s considered a technique of the infrared and thermal method. Lasers are also used to generate and detect acoustic waves in several advanced techniques of ultrasonic testing. Ultrasonic laser techniques have been the subject of research for many years but are not widely used in industry. Lasers usually operate in the visible part of the spectrum, and the best known group of laser techniques (shearography, profilometry, and holography) are used for surface testing. These three NDT methods all work by measuring variations on surfaces to find discontinuities such as impact damage, corrosion, and warping. The phrase laser NDT is sometimes used to refer exclusively to the shearographic and profilometric methods. Among other applications, shearography is used to detect dents on airplanes and profilometry is used to detect deposits in heat exchanger piping.

 

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[ The NDT Technician ]

 

 

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