Phase-shifting Holography Research Articles

Two-step-only quadrature phase-shifting digital holography

Conventional methods of quadrature phase-shifting holography require two holograms and either intensity distribution of the reference wave or that of the object wave to reconstruct an original object without the zero order and the twin-image noise in an on-axis holographic recording setup. We present a technique called two-step-only quadrature phase-shifting holography in which solely two quadrature-phase holograms are required. Neither reference-wave intensity nor an object-wave intensity measurement is needed in the technique.

Reconstruction of sectional images in holography using inverse imaging

This paper discusses the reconstruction of sectional images from a hologram generated by optical scanning holography. We present a mathematical model for the holographic image capture, which facilitates the use of inverse imaging techniques to recover individual sections. This framework is much more flexible than existing work, in the sense that it can handle objects with multiple sections, and possibly corrupted with white Gaussian noise. Simulation results show that the algorithm is capable of recovering a prescribed section while suppressing the other ones as defocus noise. The proposed algorithm is applicable to on-axis holograms acquired by conventional holography as well as phase-shifting holography.

Phase-sensitive Fourier space imaging of optical Bloch modes

We present a phase-shifting holography method in k space that allows us to investigate the phase and amplitude of optical Bloch waves. The method is based on a Fourier space imaging technique combined with a Mach-Zehnder interferometer. Using a W3 photonic crystal waveguide as a model system, we determine, with high accuracy, both the intensity and the phase of the envelope function of the Bloch modes propagating in such waveguides. We show that local variation of the dielectric map as low as 20 nm can be clearly observed from the part of the angular spectrum of field located inside the light cone.

Tomographic diffractive microscopy of transparent samples

We report a tomographic diffractive microscope, which permits imaging non-labelled transparent or semi-transparent samples. Based on a combination of microholography with a tomographic illumination, our set-up creates 3-D images of the index of refraction distribution within the sample. One acquires successively interferograms, rotating the illumination (the specimen being static) and using phase-shifting holography. Within the first Born approximation, each interferogram is interpreted as a subset of the Fourier transform of the specimen index of refraction distribution. The reconstruction is therefore similar to synthetic aperture imaging: one recombines the information in the Fourier space, and a final Fourier transform gives a 3-D image of the specimen. First recalling the theoretical foundations, we then describe our experiment, and show initial results obtained on biological samples.

Noise and aliases in off-axis and phase-shifting holography

We have compared the respective efficiencies of off-axis and phase-shifting holography in terms of noise and aliases removal. The comparison is made by analyzing holograms of a USAF target backlit with laser illumination, recorded with a charge-coupled device camera. We show that it is essential to remove the local oscillator beam noise, especially at low illumination levels.

Phase-shifting real-time holographic interferometry applied to load transmission evaluation in dried human skull

Phase-shifting real-time holography with photorefractive Bi(12)SiO(20) crystal as holographic recording medium applied to load transmission evaluation and tension dissipation on a dried human skull under loading is presented. The applied loading stands as a simulation of isolated contraction (SIC) of some masticatories muscles. The four-frames phase-shifting technique and the unwrapping branch-cut technique were used to obtain the phase map. The quantitative results show the feasibility of the employed system in the study of microdisplacements in the skull structure provided by SIC.

Digital holography with ultimate sensitivity

We propose a variant of the heterodyne holography scheme that combines the properties of off-axis and phase-shifting holography. This scheme makes it possible to filter off numerically the zero-order image alias and the technical noise of the reference. It is then possible to record and reconstruct holographic images at an extremely low signal level. We show experimentally that the sensitivity of the method is limited only by the quantum nature of photons.

Mapping of dopant concentration in a GaAs semiconductor by off-axis phase-shifting electron holography

This letter presents a method to map dopant concentration in compound semiconductors by off-axis electron holography. Using the microsampling technique of a focused ion beam, the authors prepared a cross sectional test specimen with n+(3.0×1018cm−3), n−(1.3×1016cm−3), and p gallium arsenide thin films. A phase map was obtained by off-axis phase-shifting electron holography, and the dopant distributions across a p-n junction are clearly observed. Furthermore, the low and high dopant concentration regions are remarkably distinguished in high contrast.

Surface contouring by phase-shifting real-time holography using photorefractive sillenite crystals

This work proposes to obtain surface contouring by phase-shifting real-time holography using photorefractive sillenite crystals which provides the surface contouring from a change in phase of wavefront of the object illumination beam. The real-time holography using the photorefractive Bi 12 SiO 20 crystal and the four-frame phase-shifting technique was used to obtain the phase map, this map was filtered by an anisotropic sin/cos filter and the unwrapping process used was the cellular-automata technique. We obtained experimental results of the surfaces of the large objects with real discontinuities, and these results agree with the dimensions of the object.

High precision phase-shifting electron holography

Today's information-oriented society requires high density and high quality magnetic recording media. The quantitative observation of fine magnetic structures by electron holography is greatly anticipated in the development of such new recording materials. However, the magnetic fields around particles <50 nm have not been observed, because the fields are too weak to observe in the usual way. Here we present a highly precise phase measurement technique: improved phase-shifting electron holography. Using this method, the electric field around a charged polystyrene latex particle (100 nm in diameter) and the magnetic field around iron particles (30 nm in diameter) are observed precisely. A precision of the reconstructed phase image of 2pi/300 rad is achieved in the image of the latex particle.

Development And Applications Of Highly Precise Phase Measurement Technique Using Phase-Shifting Electron Holography

Today's information-oriented society requires high-density, high-quality magnetic recording media. For the development of such new recording materials, the quantitative observation of magnetic fine structures by electron holography is eagerly awaited. However, the magnetic fields around particles smaller than 50 nm have not been observed because they are too weak to be observed in the usual way. Here, we report a highly precise phase measurement technique, improved phase-shifting electron holography. Using this method, we observed weak electric and magnetic fields precisely. The precision of the reconstructed phase image was as good as 2π/300 rad.In phase-shifting electron holography, the phase images are reconstructed from a series of electron holograms whose interference fringes are shifted relative to one after another. The shifting of interference fringes is achieved by tilting the incident electron beam, which corresponds to shifting the initial phase of the incident electron waves in a specimen plane.

Principle and application of phase-shifting electron holography

Electron holography using an improved phase-shifting (fringe-scanning) interferometric technique is described. The improvements it makes in phase measurement, in spatial resolution of reconstructed images and in hologram formation are clarified and demonstrated with three experiments: (1) quantitative detection of atomic surface steps on molybdenite crystal film, (2) topographic measurement of gold platelets epitaxially grown on a molybdenite substrate, and (3) sensitive observation of a bacterial flagellum filament.