(a) Observable excited area in the equatorial plane for φ = 0°, with x, y and z (pointing out of the page) being the instrumental orthogonal coordinates system. The accessible areas of reciprocal space are dark grey in all insets. (b) Ewald construction in Laue geometry in the equatorial plane for typical high-pressure data collections using the mini-DAC. (c) Ewald construction in Laue geometry in the vertical instrumental yz plane (with x pointing out of the page) given a reorientation by ±120°, as possible with the mini-DAC. In this instance, the blind regions can be attributed to the erasing lamps, the incident- and transmitted-beam holes are ignored. Note that covered areas in (b) and (c) could be reflected through the origin, according to Friedel's law. However the figures would be much more cluttered and therefore their reflections are omitted for the sake of clarity. (d) Ewald construction in monochromatic geometry in the equatorial plane for typical high-pressure data collections using a DAC with an opening half angle = 39° (cell axis is along y), assuming that the cell body is shielded. Entry of the incident beam from both sides of the cell is shown.