Method and apparatus for testing material joints or material compounds

A method for testing material joints or material compounds, the method comprising:

• providing an arrangement to be tested, the arrangement comprising at least two components connected via at least one material joint or material compound;
• exciting, with laser pulses from a laser light source, of acoustic waves in at least one component in the provided arrangement to be tested;
• detecting ultrasound waves in an air or gaseous layer adjacent to the provided arrangement to be tested with at least one membrane-free optical microphone;
• evaluating the ultrasound waves detected with the at least one membrane-free optical microphone by determining an acoustic pressure variation of the ultrasound waves;
• and
• evaluating the at least one material joint or material compound based on acoustic standing waves at resonant frequencies in the material joint or material compound.

A test apparatus for testing of material joints or material compounds comprising:

• at least one membrane-free optical microphone;
• a laser light source for emitting laser pulses;
• and
• an evaluation device, the evaluation device being at least designed to evaluate ultrasound waves detected with the at least one membrane-free optical microphone by determining an acoustic pressure variation of the ultrasound waves, and to evaluate material joints or material compounds based on an occurring mode conversion of a symmetrical mode with a first out-of-plane deflection into an asymmetrical mode with a second out-of-plane deflection.