Nondestructive testing

Nondestructive testing (NDT) encompasses those analysis techniques for inspection of structures, materials, or assemblies which neither cause damage nor impair their future usefulness. Nondestructive testing of historic structures is used in architectural archaeology, structural stability analysis, and materials characterization. Four types of physical probes are available: sound, penetrating radiation, visible light, and electromagnetism. Each of these can be utilized in several ways. Additional options involve hybrid techniques that combine probe methods.

Methods and techniques
NDT is divided into various methods of nondestructive testing, each based on a particular scientific principle. These methods may be further subdivided into various techniques. The various methods and techniques, due to their particular natures, may lend themselves especially well to certain applications and be of little or no value at all in other applications. Therefore choosing the right method and technique is an important part of the performance of NDT.
 * Electromagnetic testing (ET)
 * Alternating current field measurement (ACFM)
 * Eddy-current testing (ECT)
 * Hardness testing
 * Infrared and thermal testing
 * Laser testing
 * Electronic speckle pattern interferometry
 * Holographic interferometry
 * Profilometry
 * Optical microscopy
 * Radioscopy
 * Radiography
 * Computed radiography
 * Digital radiography (real-time)
 * Neutron radiographic testing (NR)
 * SCAR (Small Controlled Area Radiography)
 * X-ray computed tomography (CT)
 * Scanning electron microscopy
 * Ultrasonic testing (UT)
 * Electro Magnetic Acoustic Transducer (EMAT) (non-contact)
 * Laser ultrasonics (LUT)
 * Internal rotary inspection system (IRIS) ultrasonics for tubes
 * Phased array ultrasonics
 * Visual inspection