Research On Key Technologies Of Laser Ultrasonic

Ultrasonic nondestructive testing technology is widely used inindustrial andmedical fields.The development of industry needs the nondestructive testing technology to have higher precision,effectiveness and reliability.Laser ultrasonic, as a new technology in ultrasonic nondestructive testing field, compared with the traditional piezoelectric ultrasonic technology, has the advantages of high accuracy, high sensitivity, high resolution and no dead zone, which can also realize the non-contact detection.But one of the disadvantages of laser ultrasonic nondestructive testing technology is low energy conversion efficiency of laser ultrasonic low. In order to obtain enough amplitude of ultrasonic signal, the laser power will be increased higher than the damage threshold of the sample. Therefore, research on the improvement of the energy conversion efficiency of laser ultrasonichas becomes a hotpot.Based on laser ultrasonic theory, this paper carries out a laser induce ultrasonic structure through absorbing layer constraint to analyze the influence of laser and sample characteristics to laser induce ultrasonic. This kind of structure can improve the efficiency of energy conversion to obtain ideal ultrasonic signal amplitude without any damage occurred on the sample. The paper also deduces the improved multiple of energy conversion efficicency of this structure compared with laser inducing ultrasonic directly on the object. According to the laser ultrasonic model and the parameters of existed device, simulation on ANSYS and experiments have been done to verify different schemes.Based on the schemesdiscussed above, a design of backward mode detection of laser-induced ultrasonic with optiacoustic transducer has been carried out, details in material choice, physical dimension, processing technic have been discussed.Experimental results show powerful supportto this structure of laser induce ultrasonic, which can improve the efficiency of energy conversion.Deep research on energy conversion efficiency and design of backward mode detection of laser-induced ultrasonic with optiacoustic transducer provide the technicaland theoreticalbasis for laser ultrasonic scanning and imaging.