Deformation Measurement by Phase-shifting Digital Holography

Abstract

ABSTRACT--The out-of-plane displacement of a cantilever is measured by phase-shifting digital holography. From four phase-shifted holograms of a cantilever recorded by a CCD image sensor, a complex amplitude at each pixel of the CCD plane is obtained using the conventional phase-shifting method. The complex amplitude of a cantilever is reconstructed from the complex amplitude of the CCD plane using the Fresnel diffraction integral. The phase difference distribution on the cantilever before and after deformation, i.e., the out-of-plane displacement distribution, is calculated. In order to decrease the effect of speckle noise, a new method using divided holograms is proposed. The theory and experimental results are shown.KEY WORDS-~Phase-shiffing digital holography, holographic interferometry, displacement measurement, out-of-plane displacement, speckle noise reduction

Optimal noise suppression in Fresnel incoherent correlation holography (FINCH) configured for maximum imaging resolution

“…Yet, the least-squares solution can be approximated using the Moore-Penrose pseudoinverse [6]. In contrast to other noise reduction methods [7][8][9][10][11][12][13][14][15][16], these proposed noise suppression methods are motionless and do not make use of any postprocessing operations, such as filtering of the reconstructed images. The optimal setup and the noise suppression techniques are discussed in the following sections.…”

Partially coherent digital in-line holographic microscopy in characterization of a microscopic target

“…In Gabor interferometry, the magnification changes as a function of sensor-pinhole distance; therefore, for the lateral measurements to be accurate, the axial positions of the objects need to be known. As stated previously, the reconstructed quantitative phase can be used in accurate depth calculations [21][22][23]; however, if it is not usable, the depth extraction analysis can be conducted on the amplitude/intensity reconstructions.…”

Stochastic digital holography for visualizing inside strongly refracting transparent objects

“…For a few years, digital holography has become a very stimulating topic for the scientific community working in this area. Spectacular applications have been demonstrated, such as microscopy (also known as quantitative phase imaging or interferometric phase microscopy) [4][5][6][7][8][9][10][11][12][13][14], material properties [15], surface shape [16], polarization imaging [17], displacement field measurements [18,19], or vibrations [20][21][22][23]. In addition, an increasing number of applications rely on the possibilities of using digital color holography to record and reconstruct colored objects at high precisions by using a simple optical setup [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41].…”