A distance measuring apparatus controls a forward laser beam to scan a detection area. The personal certificate includes the digital watermark embedded in an authentic image such as a facial photograph, a retinal scan, or a fingerprint. Further, the present invention relates to methods for using information in T2 plots, combined with knowledge of the microstructure of a wood sample surface, to find pith location andor ring curvature. For this purpose, the side bars of at least some members comprise supporting elements that project outward beyond the remaining areas of the outer face of the respective side bar when having a substantially linear relative position to an adjacent member. , thus giving rise to a second slurry formed of calcium sulfate hemihydrate crystals; and, within the second slurry, separating a produced phosphoric acid, having a free SO3 content that is less than 2%, and a calcium sulfate hemihydrate filter cake.