Investigation of smooth wave fronts using SLM-based phase retrieval and a phase diffuser

A phase retrieval technique using a spatial light modulator (SLM) and a phase diffuser for a fast reconstruction of smooth wave fronts is demonstrated experimentally. Diffuse illumination of a smooth test object with the aid of a phase diffuser (maximum phase shift, Df = 0.85p) results in a significant diversity in the intensity measurements which, in turn, is beneficial for a non-stagnating iterative phase reconstruction. The use of the SLM enables accurate and fast speckle intensity recording and active correction of misalignments in the setup. The effectiveness of the technique is demonstrated in the optical testing of lenses.Comment: The paper has been presented in 1st EOS Topical Meeting on Micro-and Nano-Optoelectronic Systems, Bremen, Germany, 7 - 9 December 201

3D capture, processing, display, and perception with digital holography: results from a European-funded project

“Digital holography for 3D and 4D real-world objects’ capture, processing, and display” (acronym “Real 3D”) is a research project funded under the Information and Communication Technologies theme of the European Commission’s Seventh Framework Programme, and brings together nine participants from academia and industry (see www.digitalholography.eu). This three-year project contributes to a long-term effort to facilitate the greater presence of digital holography in the three-dimensional capture and display markets. At the end of its third year, the aims and results of the project are summarized

Roadmap on holography

From its inception holography has proven an extremely productive and attractive area of research. While specific technical applications give rise to 'hot topics', and three-dimensional (3D) visualisation comes in and out of fashion, the core principals involved continue to lead to exciting innovations in a wide range of areas. We humbly submit that it is impossible, in any journal document of this type, to fully reflect current and potential activity; however, our valiant contributors have produced a series of documents that go no small way to neatly capture progress across a wide range of core activities. As editors we have attempted to spread our net wide in order to illustrate the breadth of international activity. In relation to this we believe we have been at least partially successful.This work was supported by Ministerio de Economía, Industria y Competitividad (Spain) under projects FIS2017-82919-R (MINECO/AEI/FEDER, UE) and FIS2015-66570-P (MINECO/FEDER), and by Generalitat Valenciana (Spain) under project PROMETEO II/2015/015

Optical In-Process Measurement: Concepts for Precise, Fast and Robust Optical Metrology for Complex Measurement Situations

Optical metrology is a key element for many areas of modern production. Preferably, measurements should take place within the production line (in-process) and keep pace with production speed, even if the parts have a complex geometry or are difficult to access. The challenge for modern optical in-process measurements is, therefore, how to simultaneously make optical metrology precise, fast, robust and capable of handling geometrical complexity. The potential of individual techniques to achieve these demands can be visualized by the tetrahedron of optical metrology. Depending on the application, techniques based on interferometry or geometrical optics may have to be preferred. The paper emphasizes complexity and robustness as prime areas of improvement. Concerning interferometric techniques, we report on fast acquisition as used in holography, tailoring of coherence properties and use of Multiple simultaneous Viewing direction holography (MultiView), self reference used in Computational Shear Interferometry (CoSI) and the simultaneous use of several light sources in Multiple Aperture Shear Interferometry (MArS) based on CoSI as these techniques have proven to be particularly effective. The use of advanced approaches based on CoSI requires a transition of the description of light from the use of the well-known wave field to the coherence function of light. Techniques based on geometric optics are generally comparatively robust against environmental disturbances, and Fringe Projection (FP) is shown to be especially useful in very demanding measurement conditions

3D Display System Based on Spherical Wave Field Synthesis

We present a novel concept and first experimental results of a new type of 3D display, which is based on the synthesis of spherical waves. The setup comprises a lens array (LA) with apertures in the millimeter range and a liquid crystal display (LCD) panel. Each pixel of the LCD creates a spherical wave cutout that propagates towards the observer. During the displaying process, the curvature of the spherical waves is dynamically changed by either changing the distance between LA and LCD or by adapting the focal lengths of the lenses. Since the system, similar to holography, seeks to approximate the wavefront of a natural scene, it provides true depth information to the observer and therefore avoids any vergence–accommodation conflict (VAC)

Visualization 1: Holographic display system for dynamic synthesis of 3D light fields with increased space bandwidth product

Holographic reconstruction of the test object from different viewing angles showing parallax effects Originally published in Optics Express on 27 June 2016 (oe-24-13-14393