Image rotation from lensing

Forthcoming radio surveys will include full polarisation information, which can be potentially useful for weak lensing observations. We propose a new method to measure the (integrated) gravitational field between source and observer, by looking at angle morphology of galaxy orientation polarisation. For this we use fact that, while photon is parallel transported along geodesic, infinitesimal shape source, e.g. its principal axis in case an ellipse, Lie transported. As example, calculate rotation vector with respect direction generated distribution foreground Schwarzschild lenses. galaxies, intrinsic morphological polarised emission are correlated. It follows that observing both provides information on unlensed potential line sight.