This invention is scanning microwave ellipsometry. It contains a test head that rotates the electric microwave field relative to the sample without rotating the sample; a test head mounted onto a 6-axis robotic arm; and an algorithm that fits the microwave ellipsometry data. This a new tool and method to characterize carbon fiber alignment and measure materials for inline quality assurance or for verification of alignment in 3D parts. This implementation uses a polarized electric microwave field and measures the reflection of that field off a sample under test as a function of angle.