DETERMINATION OF STRAIN FIELDS OF DIFFUSE OBJECTS BY DIGITAL HOLOGRAPHIC INTERFEROMETRY WITH A STEP-BY-STEP PHASE SHIFT
V. I. Guzhov, E. N. Denezhkin, S. P. Ilinykh, G. A. Pozdnyakov, D. S. Khaidukov
Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: digital holography, step-by-step phase shift method, holographic interferometry, mathematical hologram, Fresnel transform, laser, wavelength
Abstract
A modification of the digital holographic interferometry method for determining the deformations of an object with a diffuse surface by comparing the complex wave fronts reflected from it in two different states is discussed. The difference between the proposed method and the classical methods of digital holography lies in the fact that digital holograms used for image reconstruction have complex values determined by the method of phase shifts (“complex” hologram), while the classic digital holograms have only real values. In addition, the reconstruction of digital holograms is performed with due allowance for inhomogeneity of the reference beam intensity, which increases the quality of reconstruction. For this purpose, a tunable neutral optical filter is introduced into the reference arm of the optical scheme of the interferometer. An experimental verification of the method is performed.
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