Three-dimensional profile measurement of the blade based on multi-value coding

As the blade must have precise size and accurate shape, three-dimensional (3D) profile measurement of the blade is very important. 3D profile measurement method based on multi-value coding is proposed. This method designs a multi-value coding stripe pattern combined with the four-step phase-shifting method. Two kinds of fringe patterns are projected onto the object respectively, one is sinusoidal intensity distribution used for wrapped phase, the other is multi-value coding fringe pattern for phase unwrapping. Because this encoding method is simple, and easy to implement, the absolute phase can be quickly implemented. Experimental results demonstrated that the proposed method can achieve a high precision, high speed and low cost 3D profile measurement of the blade.