Table 2.

Comparison of pulse thermal excitation.

Method	Advantage	Disadvantage	Application
Flash	High power, high efficiency and high detection accuracy	Cumbersome volume, depth of detection	Metals, nonmetals and composites
Laser	High energy density, very uniform light intensity and high detection accuracy	Large volume, complex system and image time correction	Metals, nonmetals, composites and crackle
IR-Lamp	Wide wavelength range, stable power and portable	The depth of detection is low	Metals, nonmetals and composites
Hot air	Small size, easy to carry, cheap	The depth of detection is low and the energy is low	Less material for light absorption coefficient