The relaxation of strain in compositionally step‐graded InxGa1−xAs layers grown on GaAs(001) has been examined with cathodoluminescence (CL) wavelength and linearly polarized imaging approaches. A polarization anisotropy in CL is found, and this correlates with spectral shifts in the peak positions of excitonic luminescence. Varying asymmetries in misfit dislocation densities from transmission electron microscopy are found to be consistent with the &mgr;m‐scale spatial variations in strain that is deduced from the CL. ©1995 American Institute of Physics.