(a) A three-dimensional illustration of GTSAXS and GISAXS geometries. The incident beam (red arrow) impinges on the sample at a grazing angle of and the scattered beam is collected by an area detector. The direct incoming beam (orange dotted line) goes through the origin of the qr–qz reciprocal space. In the scattering image, the solid line  marks the surface horizon, which divides the whole scattering image into the GTSAXS and GISAXS regimes. The dotted line corresponds to the direct beam (qz = 0). (b) A two-dimensional Ewald sphere illustration of the GTSAXS, GISAXS and TSAXS regimes. The rather large grazing incident angle shown is for illustrative purpose. In GISAXS measurements is close to grazing incidence and in TSAXS the range is typically °.