Computer-Generated Phase-Only Holograms for Real-Time Image Display

Buckley, Edward

doi:10.5772/18709

Cited by 7 publications

(7 citation statements)

References 75 publications

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“…Rather than modulating amplitude in the image plane, holographic displays modulate phase in the Fourier plane. Therefore, a fraction as high as 88% 19 of the initial luminous flux can be arbitrarily re-directed into a selected number of image points. 20 This plays a crucial role for AR and MR devices, which have an inherently small image coverage.…”

Section: Achieving High Brightness and Efficiency Using Diffractive Holographic Displaymentioning

confidence: 99%

An intrinsically eye safe approach to high apparent brightness augmented reality displays using computer‐generated holography

et al. 2021

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Achieving the luminance of real‐world scenes is a challenge for many display technologies. Computer‐generated holography offers a number of advantages, due to both the high optical efficiency and the ability to redistribute available luminous flux to individual points. This is important while displaying sparse content that needs to be clearly perceived against a bright background in augmented reality. In this work, we consider a range of optical architectures and analyze the impact of each element on the overall display luminance. We conclude that the range of holographic projector efficiencies can vary from 50% to 0.05%, with the average of 3%. An example holographic projector with 2% efficiency is built to evaluate the analysis. Using a low‐power RGB laser module, outputting 1.78 mW, a mean luminance of 30,000 cd/m2 has been attained. In the presence of sparse content, peak luminance exceeding 300,000 cd/m2 is demonstrated. Both the calculation and the measurements confirm that by using holography, it is possible to achieve a display that is sufficiently bright to be clearly viewable in daylight, in a manner that can be intrinsically eye safe. The image is projected against daytime sky and appears several times brighter, hence adding visual validation to the analysis.

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Section: Achieving High Brightness and Efficiency Using Diffractive Holographic Displaymentioning

confidence: 99%

An intrinsically eye safe approach to high apparent brightness augmented reality displays using computer‐generated holography

et al. 2021

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“…Moreover, in the real world, display devices are incapable of modulating light continuously, and being limited to a number of discrete levels results in quantization artifacts, which have an adverse effect on image quality. 26 During this process, the information stored in the interference pattern will be reduced, leading to a degradation in image quality.…”

Section: Downgrade Of the Replay Field Image Qualitymentioning

confidence: 99%

Hardware implementations of computer-generated holography: a review

et al. 2020

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Computer-generated holography (CGH) is a technique to generate holographic interference patterns. One of the major issues related to computer hologram generation is the massive computational power required. Hardware accelerators are used to accelerate this process. Previous publications targeting hardware platforms lack performance comparisons between different architectures and do not provide enough information for the evaluation of the suitability of recent hardware platforms for CGH algorithms. We aim to address these limitations and present a comprehensive review of CGH-related hardware implementations.

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“…Since the noise variance and speckle contrast both vary as N s 1/2 , where N s is the number of subframes, 24 acceptable uniformity and speckle performance requires the display of N s = 16 subframes per video frame 25 ; for a video frame rate f r , this requires a microdisplay refresh rate of f rs = 3N s f r for frame-sequential color. (In practice we can assign the subframes arbitrarily and could, for example, choose to assign more subframes to the red and green channels to exploit the significantly reduced spatial-resolution sensitivity at the blue wavelengths.)…”

Section: Microdisplaymentioning

confidence: 99%

“…In addition to photothermal limits, the Class 1 classification procedure asserts photochemical power limits for the green and blue wavelengths λ g and λ b by including the weighting function C 3 where (23) To determine a radiometric power figure that satisfies the Class 1 classification requires that the photochemical power at the output of the projector for blue and green wavelengths, and the photothermal power summed across all wavelengths, are less than the respective limits. Expressed mathematically, if the photochemical limits at blue and green wavelengths are P ph (λ b ) and P ph (λ g ), respectively, and the photothermal output power limit is P th , then to achieve a Class 1 the following must simultaneously hold: (24) and (25)…”

Section: Class 1 Analysismentioning

confidence: 99%

Eye‐safety analysis of phase‐only holographic projection systems

Buckley¹

2011

J Soc Info Display

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Recently, laser-safety analyses have been presented for scanned-beam and LCOS imaging projectors. A third class of projection technology, based on the properties of phase-only diffraction, is differentiated from scanned-beam and LCOS counterparts in its ability to provide a significantly higher effective luminous flux for video style images. In this paper, this desirable property is recognized by the definition of the "video lumen" and a detailed design for a hypothetical holographic projector and corresponding laser safety analysis is presented. As in the case of conventional amplitude-modulating LCOS projectors, a holographic projector is capable of delivering several hundred white lumens in Class 2; an appropriately specified holographic projector can also provide several tens of video lumens while maintaining a Class 1 classification.

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Computer-Generated Phase-Only Holograms for Real-Time Image Display

Cited by 7 publications

References 75 publications

An intrinsically eye safe approach to high apparent brightness augmented reality displays using computer‐generated holography

An intrinsically eye safe approach to high apparent brightness augmented reality displays using computer‐generated holography

Hardware implementations of computer-generated holography: a review

Eye‐safety analysis of phase‐only holographic projection systems

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