We introduce a single-exposure widefield system of producing phase gradient images by dividing the illumination and detection apertures into two oblique complementary components and encoding them using polarization. A Wollaston prism splits the images formed by the two respective aperture halves to allow both components to be simultaneously imaged by a single camera. By producing images characteristically similar to differential interference contrast while using a darkfield illumination scheme, sensitivity to weak phase gradients is improved.