Recent developments in photoacoustic imaging and sensing for nondestructive testing and evaluation

Visual Computing for Industry, Biomedicine, and Art

Table 1 Summary of PA technologies used for NDT/E

PA technology for NDT/E	Lateral resolution^a	Advantage	Ref.
1. Modulated CW laser for PA wave excitation	Approximately micron	Cost-effective light sources	[10, 15,16,17,18,19,20,21,22,23,24,25]
2. Pulsed laser for PA wave excitation
2.1 PA Aline and simple imaging	Approximately millimeter	Useful information in PA Aline	[27,28,29,30,31,32,33,34,35,36,37]
2.2 PACT	Hundreds of micron		[38, 39]
2.3 PAM	Tens of micron (AR-PAM); approximately micron (OR-PAM)	High lateral resolution	[9, 11, 40,41,42,43,44,45]
3. PA-generated US waves as sources	Approximately micron	Broad bandwidth for generated US waves; miniature size of PA transmitters	[46,47,48,49,50,51]
4. All-optical PA wave excitation and detection	Approximately micron	Broad bandwidth, wide acceptance angle, and noncontact for PA wave detection	[10, 19, 31, 34, 35, 48]