deuteron-nucleus tensor interaction.
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Introduction
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Various methods for carrying out $S$-matrix to potential inversion are now available, see for example [@chadan; @balaton], but, until recently, it has been possible only for cases with channel-spin zero or 1/2. However, there have been many accurate experiments involving spin-one polarised particles and these provide a powerful motivation to develop an efficient technique for inversion in cases with higher channel spin, i.e. coupled-channel scattering. With such a technique, one can exploit the very large volume of polarisation data which has accumulated. This includes vector and tensor analysing powers and polarisation transfer observables.

Over the years, we have developed a practical and widely generalisable procedure, the iterative perturbative, IP, method [@early; @kalinin; @ketal1; @zuev; @candm] and we recently [@prl] demonstrated an extension to spin-1 projectiles for the first time. Ref. [@prl] demonstrates the method in one specific application, but does not give details or a derivation of the method. In this paper we present details of our extension of the IP $S$-matrix to potential inversion method to the coupled-channel case of spin-1 projectiles and present further evaluation of it. We also test and evaluate an important extension of the IP method, single step data-to-potential 