Paper
12 November 2003 Impact of light coherence on depth of focus of wearable retinal displays
Marc von Waldkirch, Paul Lukowicz, Gerhard Troester
Author Affiliations +
Abstract
This paper discusses the impact of light coherence on the defocusing properties of a novel retinal projection display. The display is based on a liquid crystal display (LCD) illuminated by partially coherent light from a LED which projects the LCD-image directly onto the eye's retina. It is shown that the increase of the coherence level of the illumination light enhances on the one hand the contrast of a defocused image. On the other hand, however, the perceived image quality is affected by the occurrence of intermediate defocusing peaks as well as by coherence effects, such as edge-ringing. Measurements of both the modulation transfer function (MTF) and of the text readability when defocusing are presented using a bench model of the display system. The experimental results reveal that for text readability the best DOF can be achieved not for fully coherent illumination, but for partially coherent light of a coherence level σ ≈ 0.35-0.5. Further, it is shown that the optimum σ-level depends slightly on the targeted text size.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Marc von Waldkirch, Paul Lukowicz, and Gerhard Troester "Impact of light coherence on depth of focus of wearable retinal displays", Proc. SPIE 5186, Design of Efficient Illumination Systems, (12 November 2003); https://doi.org/10.1117/12.505814
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Cited by 1 scholarly publication.
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KEYWORDS
LCDs

Modulation transfer functions

Eye

Image quality

Coherence (optics)

Spatial frequencies

Speckle

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