Analysis of amplitude and phase characteristics of two-dimensional optical fields using the modulation-spectrum method

A solution to the phase problem in optics is considered within the contest of the registration and analysis of two-dimensional stationary optical fields transformed by an object under study or fields forming an image. The modulation-spectrum method put forward by the authors is used for obtaining information on the amplitude and phase distributions of a light field. To solve the problem, the intensity distribution is directly detected for the spatial spectrum or the image of a signal and for those additionally modulated in a special way. The modulation should provide a visualization of the phase information. The intensity distributions obtained make it possible to calculate the two-dimensional structure of the initial signal. It is essential that the method require no iteration procedures in solving the problem. This allows one to expect speeding up of the processing and analyzing of the information. Three variants of optical schemes for the analysis of light fields are considered in the paper. The first one uses an additional spatial modulation in the plane of the investigated field, the spectrum of spatial frequencies being recorded. In the second case, the spatial modulation is performed at the input of the processing scheme, the spatial spectrum being registered likewise. In the third variant of the scheme, the spatial modulator is placed at the plane of spatial frequencies, and the image is registered.