Weronika Zaperty

Wide angle holographic display system with spatiotemporal multiplexing.

This paper presents a wide angle holographic display system with extended viewing angle in both horizontal and vertical directions. The display is constructed from six spatial light modulators (SLM) arranged on a circle and an additional SLM used for spatiotemporal multiplexing and a viewing angle extension in two perpendicular directions. The additional SLM, that is synchronized with the SLMs on the circle is placed in the image space. This method increases effective space bandwidth product of display system data from 12.4 to 50 megapixels. The software solution based on three Nvidia graphic cards is developed and implemented in order to achieve fast and synchronized displaying. The experiments presented for both synthetic and real 3D data prove the possibility to view binocularly having good quality images reconstructed in full FoV of the display.

Synthetic aperture Fourier holography for wide-angle holographic display of real scenes

A novel approach for wide-angle registration and display of digital holograms of static 3D scenes is presented. The registration setup design combines Fourier holography with the synthetic aperture technique, which results in recording performance of a wide spherically curved detector. The coherent object wavefield extracted from the synthetic exposition has a simple Wigner distribution function (WDF) representation and can serve as input for a variety of processing tools necessary to adopt the captured data for display in a chosen configuration. Here we use WDF diagrams for optimization of the 3D imaging space and as a basis for development of an aliasing-free numerical algorithm for adjustment of the magnification and axial position of the reconstructed image. The influence of the pixel size and wavelength mismatch between the registration and reconstruction systems is also discussed within the paraxial regime. For experimental tests we take a 60 megapixel synthetic aperture hologram of a bulk object recorded by use of a single spherical reference wave with divergence angle reaching 16°. The display system consists of six reflective liquid crystal on silicon spatial light modulators working in pure phase mode and illuminated by a single collimated beam.

Capture and display mismatch compensation for real-time digital holographic interferometry.

Optical holographic interferometry (HI) is realized by two well-known techniques: double exposure holographic interferometry (DEHI) and real-time holographic interferometry (RTHI). However, the digital version of HI is typically realized numerically by DEHI. The main problem in digital implementation of RTHI is the lack of commercially available cameras and spatial light modulators with the same pixel size. This mismatch results in lateral and transversal magnifications of an object wavefront reconstruction. In real-time digital HI the reconstruction of an object in an initial state has to be superimposed on top of the loaded object. In this work, we present and analyze five approaches to overcome the mismatch problem, and the performance of these procedures is numerically quantified and compared. The experimental suitability of these approaches is investigated.

Spatiotemporal multiplexing method for big images observation in wide angle holographic display

In the paper a holographic display system with extended viewing angle and capability to reconstruct images with no size limitation is presented. The display is constructed from three spatial light modulators (SLM) arranged on a circle. For gap disposal in reconstructed images a beam splitter is used. The presented spatiotemporal multiplexing technique based on sequential illumination from different direction allows us to double their number. In experimental setup we have obtained a continuous holographic reconstruction in 2.5 times bigger viewing angle comparing to a single SLM utilization.

Multi SLMs holographic display with inclined plane wave illumination

Holography can store full wide angle information about a registered object, since during registration process information about amplitude and phase of an optical wave scattered from an object is captured. Because of this unique feature people put hope in holography as the method which can be utilized in a 3D imaging display. In the paper we present the design of a wide viewing angle display system utilizing multiple Spatial Light Modulators (SLMs). The system is capable of displaying objects from both virtual and real worlds. In our system we are using phase only reflective SLMs based on liquid crystal on silicon (LCoS). There are designed to work with normal illumination. However in order to simplify an optomechanical system of the display here the SLMs are used with an inclined plane wave illumination. Therefore in the paper at first we focus on determination of a tilt depended SLM calibration, so thus SLM even with highly off axis inclined illumination is capable of an accurate wave reproduction. Then we focus on obtaining high quality reconstruction of objects from virtual world. We present an algorithm based on Gerchberg-Saxton scheme and diffraction computing between tilted and parallel planes. All of the paper discussions are accompanied with experimental results obtained in the multi SLMs display.

Spatiotemporal multiplexing method for visual field of view extension in holographic displays with naked eye observation

Abstract In this paper we propose a method which allows to overcome the basic functional problems in holographic displays with naked eye observation caused by delivering too small images visible in narrow viewing angles. The solution is based on combining the spatiotemporal multiplexing method with a 4f optical system. It enables to increase an aperture of a holographic display and extend the angular visual field of view. The applicability of the modified display is evidenced by Wigner distribution analysis of holographic imaging with spatiotemporal multiplexing method and by the experiments performed at the display demonstrator.

Wide-angle color holographic 3D display with multi-source-based holographic content

In this paper we present a wide viewing angle multi SLMs color holographic 3D display. An extended viewing angle is provided by the use of circular setup configuration. To ensure best utilization of spatial bandwidth of a single SLM a temporal multiplexing method for a color reconstruction is applied. Averaged in time modulated component wavefronts overlap in space and create a real color 3D image. We present the display implementation resulting in color reconstruction of computer generated objects and multi-view 2D real object stereogram converted into holographic representation. The applicability of this approach to allow holographic display of big 3D scenes and the future possibilities to extend the spatio-temporal bandwidth of color holographic displays are discussed.

Full and horizontal parallax Fourier holography with laser capture and LED display

The digital holography and holographic display constitute the best framework of 3D imaging as they aim to recreate the complete optical field emitted by a recorded scene. In this paper, we present two techniques of Fourier holographic imaging of real world objects. The first solution is an end-to-end full color Fourier holographic imaging approach, which involves standard RGB holographic recording an LED-driven viewing window display. It gives possibility of almost undistorted orthoscopic reconstruction of large real objects. Second architecture uses the same digital holographic content and horizontal parallax rainbow holographic display, which has reduced space bandwidth product requirements.

Numerical model of diffraction effects of pixelated phase-only spatial light modulators

In this work, we investigate numerical models of selected spatial light modulators (SLMs) to provide an accurate simulation of diffractive effects present in optoelectronic hologram reconstruction, i.e. DC term and higher orders. We focus on reported most influential parameters: (a) fill factor, (b) amplitude modulation of dead space (effect of surface structure between adjacent pixels), (c) phase of dead space (phase modulation profile between adjacent pixels), (d) spatial influence of adjacent pixels on phase modulation value, and (e) number of phase quantization levels. The impact of each factor on modeled diffraction efficiency and orders distribution is investigated. We consider phase-only reflective models of LCoS SLMs on the basis of commercially available architectures. Additionally, the pixelated SLM model is tested on the example of two practical cases.

Fourier RGB synthetic aperture color holographic capture for wide angle holographic display

In this work we present a high pixel count color holographic registration system that is designed to provide 3D holographic content of real-world large objects. Captured data is dedicated for holographic displays with a wide-viewing angle. The registration in color is realized by means of sequential recording with the use of three RGB laser light sources. The applied Fourier configuration of capture system gives large viewing angle and an optimal coverage of the detector resolution. Moreover, it enables to filter out zero order and twin image. In this work the captured Fourier holograms are transformed to general Fresnel type that is more suitable for 3D holographic displays. High resolution and large pixel count of holographic data and its spatial continuity is achieved through synthetic aperture concept with camera scanning and subpixel correlation based stitching. This grants an access to many tools of numerical hologram processing e.g. continuous viewing angle adjustment, and control of 3D image position and size. In this paper the properties of 1D synthetic aperture (60000 x 2500 pixels) are investigated. Each of the RGB 1D SA holograms is composed of 71 frames, which after stitching result in approx. 150 Megapixel hologram pixel count and 12° angular field of view. In experimental part high quality numerical reconstructions for each type of the hologram are shown. Moreover, the captured holograms are used for generation of hybrid hologram that is assembled from a set of RGB holograms of different color statues of height below 20 cm. In the final experiment this hybrid hologram as well as RGB hologram of a single object are reconstructed in the color holographic display.