An approach to improve the image quality by aperture synthesis in generalized phase-shifting interferometry is proposed. The aperture of the holographic system is enlarged by increasing the recording area to receive a more diffusive spectrum by moving a singular CCD. The sub-object wave fronts are combined with the index of their intensities. This method can avoid the negative effect of environmental disturbance and improve the synthesis efficiency by hundreds of times. The optical experiments have shown that it is simple and robust to stitch the complex object wave front accurately and to improve the imaging quality greatly, especially for the recording of large scale objects.

An accurate aperture synthesis method in generalized phase-shifting interferometry is suggested to improve the quality of the reconstructed object wavefront by stitching both the phase and the real amplitude of the object wave on the recording plane. Since the phase distribution affects the reconstruction of the original object wavefront, phase stitching is also important in aperture synthesis. Double correlations are used to find the proper relative locations and correct the phase error of subwavefronts on the recording plane. By using phase correction, the phase distributions of subwavefronts are combined perfectly. Corresponding optical experimental results have verified the effectiveness of this method, which can stitch not only the real amplitudes but also the phases of the complex amplitudes of the object wave on the recording plane and improve the quality of the reconstructed object image.

A phase shift selection method is proposed to design algorithms immune against phase shift errors in two-step generalized phase-shifting interferometry. A general formula for wavefront reconstruction error is derived, and its specific expressions for two common errors are also given. Calculation results suggest that the proper range of phase shift for general application is about from 0.5 to 2.0 rad for both the fixed and linear phase shift errors. Computer simulations have demonstrated the effectiveness of this phase shift selection method by decreasing the wave reconstruction errors to one-fifth.

An advanced phase-shifting interferometry approach with a spherical wavefront reference is proposed to improve the quality of the holographic image by avoiding errors caused by noncollimated reference and lowering the resolution of the recording device. By considering not only the real amplitude but also the phase distribution of a spherical wavefront reference, a singular object-wave reconstruction formula is deduced. The suggested method here can work without using the collimator in the reference wave and can then remove all the errors incurred by it. Computer simulations demonstrate that this technique is more convenient in the recording process and can improve the precision of the reconstructed wavefront by more than one order of magnitude after considering the real reference amplitude. Optical experiment results show the feasibility and effectiveness of this method.

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