The Light ray transform for pseudo-Euclidean metrics

We study the ray transform $L$ over null (light) rays in the pseudo-Euclidean space with signature $(n',n'')$, $n'\ge2$, $n''\ge2$. We analyze the normal operator $L'L$, derive an inversion formula, and prove stability estimates. We show that the symbol $p(\xi)$ is elliptic but singular at the light cone. We analyze $L$ as an Fourier Integral Operator as well. Finally, we compare this to the Minkowski case.