Color Acoustical Holography

Abstract

Holographic acoustical imaging of complicated object fields, such as those that may be found in medical diagnosis and geophysical applications, is likely to lead to some difficulties in the identification of objects. This difficulty may be alleviated by taking advantage of the differential responsivity of the various parts of the object field to different acoustic frequencies. This can be accomplished by making two or more acoustical holograms of the same scene at different acoustic frequencies and superimposing their reconstructed images as different colored images to produce a multicolored acoustical hologram. Experiments are described in which a color acoustical hologram image of a silhouette object letter “R” was produced with red, yellow, and blue components of the image corresponding, respectively, to the 15-, 18-, and 21-kHz acoustic frequency components. The results of experiments at several acoustic frequencies using the diffusely reflecting object letters “ARL” are also described.