As for phase unwrapping along a rhombus-shaped path,the rhombus phas e unwrapping algorithm is very popular because it has the features of rapid expanding,easy understanding and so on.However,it is error prone and the error will accumulate to form lines or islands when unreliable poi nts are encountered on the unwrapping path.Therefore,an improved rhombus phase unwrapping algorithm is pr oposed.First,a basic mask is made by binarization of the deformed pattern′s modulation based on Otsu and the poles are found on the wrapped phase in the corresponding area to the nonzero area of the basic mask,so a pole mask can be formed by locating the pole coordinates.Second,according to basic mask and pole mask,the pole an d unreliable points in the wrapped phase can be isolated,then the reliable wrapped phase can be unwrapped efficiently.Finally,according to the principle of phase continuity,phase approximation and interpolation fitting are used to correct the phase at the unreliable point,so that complete and realistic phase unwrapping results can be obtained.The experimental results show the feasibility and validity of the proposed algorithm.It reveals that the improved rhombus phase unwrapping algorithm can effectively avoid the line-like and the island-like p hase errors.