Hiedemann patterns at very high frequencies

Abstract

Diffraction patterns in liquids have recently been produced in this laboratory by using ultra-sonic waves of frequencies above 100 Mc./sec., and certain interesting features of such patterns have been studied. With a 2-mm. tourmaline plate, frequencies up to 103 Mc./sec. are now communicated to a glass slab as sound waves and the corresponding diffraction patterns obtained by allowing light to pass through the glass slab, as was first done by Hiedemann, but at much lower frequencies. The thickness of the glass slab used in our investigations is such that at these frequencies it oscillates at about its 300th harmonic.