Abstract: An experiment series to determine the ability of laser vibrometers to receive and process echoes from the water surface culminates in a 28 inch by 28 inch aperture synthesis. Highly resolved three dimensional imagery of a submerged three liter beverage bottle, suspended in the free field is presented. Excitation is accomplished by a submerged acoustic source transmitting a swept FM pulse near 70 kilohertz with a 10 kilohertz sweep. The receive laser head is suspended 19 inches above the water surface, and moved by an inverted x-y positioning table to create a three dimensional synthetic aperture. Temporal oversampling and common trigger for transmitter and data acquisition system are used to establish coherence. In an effort to better resolve the target, the aperture is made larger than previous attempts. Experimental results are reported. !3
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