Diffraction of light by ultrasonic waves

Ix a series of interesting papers, Sir C. V. Raman and N. S. Nagendra Nath I have developed a theory for the diffraction of light by high frequency sound waves, the essential idea being the diffraction of the corrugated form of the transmitted wave-front of light. Their theory has been able to explain many of the experimental results of R. B/it * and of Debye and Sears? In Part II of their theory they have very satisfactorily explained the curious phenomenon of the wandering of the intensities of the various orders observed first by Debye and Sears on tilting the trough containing the liquid. Their theory also explains ttae disappearance of the diffraction effects at greater angles of obliquity. The standpoint developed by them in Parts IV and V of their series, based~ on the wave-equation governing the propagation of light in a medium filled with sound waves explains the asymmetry in the diffraction pattern. In this paper the author presents detailed results of investigation with regard to the asymmetry observed in the diffraction spectra. The asymmetry in the diffraction spectra was observed, simultaneously and independently by Lucas and Biquard, 4 and by Debye and Sears in their earliest papers, and later by the author while carrying out determinations of ultrasonic velocities in various organic liquids. I t has been recently investigated in_ detail by Biir 5 also.