Measuring probes which the three-coordinate measuring machines are equipped with are mainly contact trigger probes in the past. After application experience for more than 20 years, the industry has found that the applicability of such probes has its limits. It is more suitable for regular-shaped workpieces, which are generally composed of basic geometric shapes (such as planes, cylinders, arcs),  to be measured by such probes. However, for the dimensional measurement of curved workpieces, the limits of such probes have always been proposed and discussed. With the advent of non-contact scanning systems, the limits of trigger probes have been solved, and the measurement speed of curved workpieces has also been greatly improved. With the non-contact scanning system, it is possible to process the scanned data directly without subsequent data processing. However, the contact sensing probes must overcome the tool radius compensation problem, and so it is necessary to perform subsequent data processing. The reason why the non-contact scanning technology can thrive is precisely because it has the following two factors that the three-coordinate measuring machine does not possess:

(1) No defective deformation caused by contact scanning

(2) High-speed and accurate scanning effects.