Noise immune unwrapping based on phase statistics and self-calibration

Unwrapping is an important step for precise phase measurement in an interferometric technique. Due to the effects of noises and speckles, an accurate unwrapping has been quite difficult. To address this issue, a new phase unwrapping method is proposed. The new method uses the wrapped phase statistics together with the limited smoothness characteristics of the interference phase. In this method, statistical parameters of the wrapped phase are firstly obtained. The step is then followed by a self-calibration process to identify and correct corrupted data points to obtain preliminary unwrapped phases. Finally, a phase revision step is taken to remove the effects of the residual errors. A computational testing was carried out to demonstrate the performance of the proposed method at six different levels of noise injection. An experimental test was also carried out using a lateral shearing interferometer. The success and the precision achieved using the proposed algorithm show that the method is quite effective and accurate for phase recovery under the condition of noise contaminations. (C) 2002 Elsevier Science Ltd. All rights reserved.