Coherent noise reduction in digital holographic interferometry by slightly rotating object

The coherent noise degrades the imaging quality and resolution in digital holographic interferometry. A method to reduce coherent noise by the way of slightly rotating object is proposed. Firstly, a series of digital holograms with different coherent noise patterns were recorded by slightly rotating object. Secondly, the different holograms were reconstructed individually, and the differences between the reconstructed complex amplitudes due to the rotation of the object were removed by using phase compensation and image registration algorithms. Thus, multiple identical retrieved images of object with different coherent noise distributions were obtained. Finally, the coherent noise was reduced by a proper averaging process for amplitude and phase images. Moreover, Non-correlation between two speckle patterns can be achieved by rotating very small angle proven by means of computing the correlation between the circle speckle spots. The experimental results and evaluations are given to confirm the proposed method.