A Photographic Method for Displaying Sound Wave and Microwave Space Patterns
01 July 1951
In analyzing the performance of an acoustic or microwave radiator'it is helpful to know the way in which the waves proceed as they emerge from the source. It is desirable in some cases to have a photographic record of the distribution of intensity in the field generated by the radiator. This paper describes a simple mechanical scanning method for accomplishing this result. For acoustic analysis, a probe microphone is moved back and forth through the sound field to be explored and a small lamp is affixed to the microphone. When the output of the microphone is connected to the lamp through an amplifier, the intensity of the light varies in accordance with the sound level encountered by the probe microphone. A camera set at time exposure records the variations of light intensity. In this way the desired picture is built up by scanning the sound field somewhat after the manner in which a television image is formed. 1 For analyzing microwave fields the microphone is replaced with a microwave pickup probe. EXPERIMENTAL