Abstract: Processing of electrical signals representative of incident and reflected acoustic signals generated by underwater explosion and comprising primary and secondary impulse, or bubble pulse, peaks. Acousto-optic diffraction and optical Fourier transform of the primary or explosive incident signal is performed and photographically recorded to provide a bubble pulse spatial filter. The filter is used in performing subsequent acousto-optic diffraction and optical Fourier transforms to derive impulse response, bottom loss, and an output electrical signal representative of the reflected signal, without the bubble pulse.