Beam shaping using liquid crystal-on-silicon spatial light modulators for laser ultrasound generation

The application of laser ultrasound for nondestructive testing of carbon fiber–reinforced plastics (CFRP) and carbon fiber–reinforced thermoplastics (CFRTP) is shown. Laser-generated excitation creates a three-dimensional, thermoelastic zone which emits ultrasound waves during expansion and contraction. In order not to exceed the damage threshold of the material to be tested usually only a low-energy density and therefore a weak excitation of ultrasound waves can be achieved. For instance, the use of a YAG laser type with a wavelength around 1 spatial light modulator to laser ultrasound allowing for tailored spatial energy distributions for efficient nondestructive excitation of ultrasound waves within CFRP or CFRTP.