Improving the reconstruction quality with extension and apodization of the digital hologram

Zhang, Yancao; Zhao, Jianlin; Fan, Qi; Zhang, Wei; Yang, S.

doi:10.1364/ao.48.003070

Cited by 16 publications

(9 citation statements)

References 9 publications

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“…If we consider multiplying equation (6) with equation (4) and subsequently dividing the result by the reference beams’ amplitude , then we obtain the following:Equation (7) is therefore a corrected hologram containing only the information of the x or y components of the modulated beam. If necessary, we can insert a numerical smooth mask, i.e., an apodized window function, in front of the corrected digital hologram to reduce fringing in the reconstruction plane 31, 32 . Finally, we use a computer to perform the numerical reconstruction of equation (7) within the framework of the angular spectrum method 19 .…”

Section: Resultsmentioning

confidence: 99%

Complex beam shaping based on an equivalent q-plate system and analysis of its properties using digital holography polarization imaging

Yang

Fuh

2017

Sci Rep

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In this study, we generate various complex beams carrying angular momentum (AM) by using a programmable beam shaping system to mimic typical q-plates. When a circularly polarized wave is incident onto the system, the emerging beam reverses its spin handedness and obtains a spatial phase factor. This phase factor can be engineered by designing a computer-generated hologram (CGH) and applying it to a spatial light modulator (SLM) to produce a beam with controllable spatially distributed orbital angular momentum (OAM) density. To determine the properties of the generated fields, we combine digital holography (DH) with the beam shaping system to yield visualizations of the beam intensity, phase, and AM distributions over the transverse plane at different propagation distances. Comparisons of the theoretically and experimentally obtained results show good qualitative agreement. This study advances our understanding and interpretation of AM characteristics produced by a programmable q-plate-like system.

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Section: Resultsmentioning

confidence: 99%

Complex beam shaping based on an equivalent q-plate system and analysis of its properties using digital holography polarization imaging

Yang

Fuh

2017

Sci Rep

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“…To reduce the aperture diffraction during numerical reconstruction, it is proposed [21][22] to apodize the hologram aperture. This method is applied to smoothly bring a sampled signal down to zero at the edges of the sampled region.…”

Section: Suppressing Aperture Diffraction By Apodization Of the Hologrammentioning

confidence: 99%

Speckle noise reduction for computer generated holograms of objects with diffuse surfaces

et al. 2016

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Digital holography is mainly used today for metrology and microscopic imaging and is emerging as an important potential technology for future holographic television. To generate the holographic content, computer-generated holography (CGH) techniques convert geometric descriptions of a 3D scene content. To model different surface types, an accurate model of light propagation has to be considered, including for example, specular and diffuse reflection. In previous work, we proposed a fast CGH method for point cloud data using multiple wavefront recording planes, look-up tables (LUTs) and occlusion processing. This work extends our method to account for diffuse reflections, enabling rendering of deep 3D scenes in high resolution with wide viewing angle support. This is achieved by modifying the spectral response of the light propagation kernels contained by the look-up tables. However, holograms encoding diffuse reflective surfaces depict significant amounts of speckle noise, a problem inherent to holography. Hence, techniques to improve the reduce speckle noise are evaluated in this paper. Moreover, we propose as well a technique to suppress the aperture diffraction during numerical, viewdependent rendering by apodizing the hologram. Results are compared visually and in terms of their respective computational efficiency. The experiments show that by modelling diffuse reflection in the LUTs, a more realistic yet computationally efficient framework for generating high-resolution CGH is achieved.

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“…In fact, window functions have been applied to DH for diffraction suppression 10,11 , in order to improve the lateral resolution of the intensity image. But as far as we know, their impacts on phase image and the associated axial dimension measurement are still not investigated and unknown.…”

Section: Objective and Backgroundmentioning

confidence: 99%

The phase error reduction using window functions in digital holography

Yan

Asundi

2015

SPIE Proceedings

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Digital holography (DH) is a 3D imaging technique with a theoretical axial accuracy of better than 1-2 nanometers. However, practically, the axial error has been quoted to be tens of nanometers which is much larger than the theoretical value. Previous studies of the axial error mainly focused on the phase error introduced by lens. However, it is found that CCD aperture size is also an important contributors to axial error by our group. It is necessary to investigate the reduction approach of such axial error. The most possible connection between the limited CCD aperture size and the axial error is the diffraction effect. Window functions once have been applied to digital holograms for diffraction suppression and improve the lateral resolution of the intensity image. However, their impacts on phase image and the associated axial dimension measurement are still unknown. In this paper, window functions are applied to digital holograms for phase/axial error reduction. Both simulation and experiment are performed. Moreover, the relation between axial error and window functions is also illustrated by the mathematical formulas derived in the theory. And all the results validate that the window functions can reduce the axial error of digital holography.

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Improving the reconstruction quality with extension and apodization of the digital hologram

Cited by 16 publications

References 9 publications

Complex beam shaping based on an equivalent q-plate system and analysis of its properties using digital holography polarization imaging

Complex beam shaping based on an equivalent q-plate system and analysis of its properties using digital holography polarization imaging

Speckle noise reduction for computer generated holograms of objects with diffuse surfaces

The phase error reduction using window functions in digital holography

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