(ω, φ) X-ray Diffraetometry is a method of XRD based on two independent variables, ω–the rotation of the sample around an axis contained in the plane of the sample and normal to the incident beam, and-the rotation of the sample in its own plane. Each crystallographic plane has an φ peak position, i.e. diffracted intensity is a maximum at a particular ω position for a given φ position. The incident X-ray beam is considered to be parallel, (a divergence of 0.1 degrees or less is accepted), very narrow (the width of the beam is not critical, a width of 0.1 mm or less is accepted), and monochromatic. The position of the detector is not a necessary variable in this system. Its open X-ray sensitive area collects the photons from the diffracting planes at different positions on that sensitive area. Using the method, the diffraction angles 2θ of different crystallographic planes can be determined without the need for knowing the position of the detector, which is a large area detector, free of slits between the sample and the area sensitive to the X-ray photons. Consequently the detector can be placed in a favorable position such as close to the sample.

The method can be applied to any crystal symmetry. If the symmetry of the crystal is known then a theoretical ω(φ) curve can be generated and compared with the experimental data. The difference between these two curves can be easily computed and attributed to the crystallographic lattice distortions of the sample.