Electro-optical Design, Laser Ultrasonic Nondestructive Testing System

Nondestructive testing has been widely used in the material testing area, because it don't destroy the physical futures and characteristics of the materials. As the developments of the finish machining and the space technology in our country, many kinds of new materials had been used. The complexities of these materials induce the appearance of various disfigurements. And these disfigurements can badly influence the characteristics and the security of the materials. So the accuracy of the nondestructive testing becomes higher. For this aim, the principle of the nondestructive testing is researched and the laser ultrasonic nondestructive testing system is designed.The laser ultrasonic nondestructive testing technology is a new technique which developed at the end of the 20 century. It bases on the laser interference technique, can accurately locate the disfigurements of the materials. The laser ultrasonic nondestructive testing system include detecting of the light signal, amplification, demodulation and signal processing. The light path, the amplifier and the demodulator are design in this thesis.The background, the application, the development of the project are introduced in the first chapter of this thesis. The two kinds of laser ultrasonic testing system in common use– confocal F-P interference testing system and the laser heterodyne interference testing system are compared, the design of the light path and the motivation methods and the requests of the ultrasonic are described in the second chapter. The design of the amplifier is described in detail and the noise in the circuit is calculated in the third chapter. Several demodulating methods are compared and the design of the demodulator is described in detail in the fourth chapter. The experiment work has been done, and the error rate of this system is calculated in the fifth chapter. The theoretic research and the experimental results of the whole research stage are concluded in the last chapter.The laser ultrasonic nondestructive testing technology came true 20 years ago, but it is also stay in the developing stage because of its high cost and insecurity. Most laser ultrasonic nondestructive testing systems are based on the heterodyne principle, but the laser ultrasonic nondestructive testing system which is based on the homodyne principle...