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Optical Heterodyne Measurement In Non-destructive Flaw Detection In Applied Research

Posted on:2007-02-16Degree:MasterType:Thesis
Country:ChinaCandidate:L G LiFull Text:PDF
GTID:2208360185955761Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Optical nondestructive testing as a kind of the nondestructive testing techniques is introduced and compared with the traditional nondestructive testing techniques like RT, UT and ET, et al. Its applied merits generalized illustrate that the shortages of nondestructive testing techniques can be covered by the optical techniques to a great degree, which indicates that the optical nondestructive testing has great advantages and application prospects in industrial testing area.The application of optical heterodyne measurement in nondestructive testing is mainly researched and a nondestructive testing system employing optical heterodyne and ultrasonic techniques is introduced. The testing principle of the system is explained and the two components of the system including the optical heterodyne measurement system and the system of ultrasound pulse generated by a laser pulse are introduced.The theory of the optical heterodyne measurement system is expounded and the principle and merit of ultrasound pulse generated by a laser pulse are analyzed. The signal-to-noise ratio of the nondestructive testing system employing optical heterodyne and ultrasonic techniques is analyzed and calculated from two aspects including phase matching of optical heterodyne measurement in nondestructive testing and the effects of beam incidence on the intensity of heterodyne signal and signal beam. The research on phase matching is ascribed to the analysis of the effects of 6 factors on the heterodyne efficiency .The calculations of heterodyne efficiency show the results as following.The heterodyne efficiency will be reduced as the optical path difference between signal beam and local beam increases. When the optical path difference is a constant, the relative position of detector has an optimum value and by which the heterodyne efficiency can be increased up to a maximum. The area of the photo-sensitive surface for the detector has an optimum value, accordingly the heterodyne efficiency can be increased up to a maximum. The focal lens in the optical system has crucial effects on the heterodyne efficiency, which leads to a narrow range of the focal length allowed,...
Keywords/Search Tags:nondestructive testing, optical heterodyne measurement, phase matching, heterodyne efficiency, fitting
PDF Full Text Request
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