A technique for MRI or the like employs optimized orthogonal gradients. For a device having a peak physical magnetic field gradient strength G0, the gradients are optimized if, in physical space, one gradient has a value −0.5G0 while the two gradients orthogonal thereto have the value G0. That is equivalent to an optimized orthogonal gradient space in which one gradient has a value 1.5G0 while the two gradients orthogonal thereto have the value zero. The gradients are cycled over a sequence of six gradient pulses to provide enough data to calculate the diffusion tensor.