Browsing by Subject "Acoustic microscopy."
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Item Open Access Characterization and imaging of single layered materials by the Lamb wave lens(1991) Değertekin, F. LeventThe Lamb wave lens, which was introduced earlier as a new kind of lens for scanning acoustic microscope, is analyzed theoretically. A simulation program capable of handling single layered materials with different material parameters and bonding conditions is developed. The validity of theory is investigated by comparing the simulation results with the experimented ones for speciidly prepared samples. Parameter sensitivity of V{f) curves are used to test the characterization ability of the lens in layered materials. Sul)surface imaging ability of the Lamb wave lens is also investigated by forming amplitude and peak frequency images of some samples.Item Open Access Data acquisition system design for acoustic microscopy(1996) Baştürkmen, Nadir ZaferConventional acoustic microscopes suffer from the complexity and low speed of their scanning mechanisms. The frame rates of these instruments are low, while their cost are high. In this work, a data acquisition system for acquiring raster image data at precise positions was designed for an acoustic microscope which uses a high speed, simple, and hence low cost scanning mechanism. The design is based on a data acquisition integrated circuit which is specifically designed to be used in this system. The implementation was done in sucha way that the system can be mounted to a standard personal computer. It is possible to obtain acoustical images on the monitor of the personal computer at rates as high as 50 lines per second, using this system.Item Open Access Material characterization by using high velocity modes(1994) Yaralıoğlu, Göksen GökseninAcoustic microscopy is one of the most powerful tools for non-destructive material characterization. Excited modes on the materials are responsible for the high contrast obtained in the images. However, conventional lenses suffer from multi-mode excitation. Lamb wave lens proposed earlier overcomes this difBculty. It insonifies material surface at only one incidence angle. In this thesis, material characterization ability of high velocity modes for loaded single layered materials by using Lamb wave lens is investigated. The validity of the theory is checked by comparing simulated and measured V(z) curves obtained from specially prepared sample.