Switched Gradient Impulse Response Measurement with Uniform Excitation of Eigenmodes

For pulsed field gradient experiments, it is important to characterize gradient switching to correct for errors in measured diffusivity and velocity resulting from imbalances in the gradient time integrals. Accurate characterization of the system requires the time derivative of the test gradient pulse mimic that of an impulse function which excite all the gradient eigenmodes uniformly. We introduce a new test pulse, called the Fresnel pulse whose derivative is a chirp function, which has a uniform spectrum like the impulse function. We also introduce a MR imaging based method to measure the spatiotemporal magnetic fields generated after the test pulse.