| Abstract [eng] |
The most promising new phase imaging techniques are digital holography (DH) and quadri-wave lateral shearing interferometry (QWLSI) allowing both amplitude and phase to be simultaneously observed. The main purpose of this research project was to compare DH and QWLSI methods for both static and dynamic phase objects. This work is the first research study directly comparing DH and QWLSI. The thickness of the etalon crater was measured using both methods and gave very similar results. In either case, the measurement was less than 1,5 % away from the universally recognized profilometer value. Thus, it can be stated that both methods are appropriate for measuring static phase objects. Moreover, we measured that the spatial resolution is higher than 2 μm for both the DH and QWLSI methods. It was identified that in DH using 20 times enlarging microscope objective, the maximum field of view is 250 μm. The reasons are the zero and first order diffraction maximums that appear in off-axis digital holography. Meanwhile, QWLSI is only limited by the size of diffractive grating and sensor. Time-resolved pump-probe experiments were performed on fused silica and hafnium dioxide coating. The measurement results of the two methods diverged for dynamic phase objects. A possible explanation for different results is the signal distortion in QWLSI due to scattering, plasma, and radiance of noncoherent thermal excited material. These distortion factors in DH case are eliminated. In order to find the actual reasons for the different results, further studies are needed. |
