We demonstrate how a simple optical setup based on the incoherent self-imaging phenomenon can be used to capture two-dimensional phase maps of transparent (phase) objects. We prove that the derivative of the object’s phase map can be extracted from the self-image. Simulations of self-images from a semi-spherical transparent object confirm the theoretical results. As proof-of-principle examples, experimental phase profiles obtained for water droplets on glass, and also a hydrophobic substrate are presented and compared. The phase maps are extracted from a single self-image, using the Fourier analysis, that makes this technique favorable for real-time measurements on dynamic samples.
A common-path spatial phase shifting digital speckle pattern shearing interferometry setup is introduced for simultaneous measurement of in-plane and out-plane strain components under dynamic loading using two laser beams with different wavelengths that symmetrically illuminate the test object and a single detector. The simplicity, stability, and efficiency of the arrangement are provided by using a glass plate as a shearing device, which is capable of tuning the sensitivity continuously. The phase is recovered from a single frame by the Fourier method. In this setup, the spatial carrier frequencies can be adjusted independent of the amount of the lateral shear. Ultimately, the desired field of view can easily be achieved by simple imaging optics. To validate the feasibility and the flexibility of our technique, the proposed setup is used to evaluate the in-plane and out-plane strain maps of an aluminum plate, which is deformed under dynamic stress in its plane. The temporal phase stability of the proposed system is also investigated.
The spatial phase shifting digital speckle pattern shearing interferometry (DSPSI) system has been widely used to determine map of deformation. In this paper a common-path DSPSI setup is introduced for in-plane strain measurement under dynamic loading, using two laser beams with different wavelengths that symmetrically illuminate the test object, and a single detector. The simplicity, stability and efficiency of the arrangement are provided using a glass plate as a shearing device which is capable of tuning the sensitivity continuously. The phase is recovered from a single frame by the Fourier method. In this setup the spatial carrier frequencies can be adjusted independent of the lateral shearing amount. Ultimately, the desired field of view can easily be achieved by simple imaging optics. To validate the feasibility and the flexibility of our technique, the proposed setup is used to evaluate the strain map of an aluminum plate which is deformed under dynamic stress in its plane. Experimental results are presented and discussed.
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