A speckle-interferometric setup for contactless measurements of the velocity of rayleigh ultrasonic waves
Alexander P. Vladimirov, Горкунов Эдуард Степанович, P. S. Eremin, Sergey M. Zadvorkin, M. V. Shadrin, K. E. Solov’ev · Instruments and Experimental Techniques · 2010
The velocity of a Rayleigh wave was determined by measuring its propagation time between two Iaser-illuminated small areas of a rough surface. It is sh own that, if a Rayleigh wave passes over these areas, a photodiode twice detects signals proportional to the surface displacement in the speckle overlap region. In contrast to the previous variant, signal-distorting reflections are eliminated in the instrument. A sample holder excluding adjustment of the interferometer upon a change in the object size has been manufactured. A new technique for determining the time interval between two signals is used. The instrument operates at a frequency of 5 MHz, and the distance between the areas is adjusted in the range 5–100 mm. The rms deviation of the velocity from the average value for ten measurements is 8 × 10–4.