Debye-Sears Effect (Ultrasound Experimental Set 5)

With the devices and materials in this set one can conduct experiments as an introduction into acousto-optics and the use of continuously emitted ultrasonic waves (continuous waves – cw). The focus here is upon the Debye-Sears effect and the imaging of a standing ultrasonic wave field using laser light.With the cw generator SC600 ultrasonic waves of different frequencies can be generated in a water bath. The ultrasonic waves act like the elements of a diffraction grating, the grating constant of which depends on the wavelength of the ultrasound. When parallel laser light passes through, it is diffracted. A classic diffraction pattern, the Debye-Sears effect, results. By using different ultrasound frequencies and red and green laser light, the dependence of the interval of the orders of diffraction on the acoustic and optical wavelengths can be shown. If divergent laser light is used, a direct optical projection of the acoustic wave field can take place. By means of an acoustic absorber, the differences between travelling and standing ultrasonic waves can be demonstrated.By supplementing the set with a photodiode receiver, it can be expanded into an ultrasound resonance cell. This is primarily used in measuring concentrations.