Extensions of the scattering-object function and the pulser-receiver impulse response in the field II formalism

The pulse-echo impulse-response format in the Field II formalism is generalized to separately located transmitter and receiver. To first order in sound velocity and density perturbations, identical results for the scattering-object function are obtained for the Morse-Ingard and the Chernov formulation in both the temporal and frequency domains: fs = −[2Δc/c + (Δρ/ρ)(1 − cos θ)] where for ultrasonic pulse-echo or transmission modality, cos θ ≈ −1 or +1, respectively.