A hybrid temporal and spatial speckle-suppression method for laser displays

Deng, Qing; Lin, Bor-Shyh; Wu, Pei Jung; Chiu, Kuan Yao; Fan, Ping; Chen, Chien Yue

doi:10.1364/oe.21.031062

Cited by 13 publications

(7 citation statements)

References 16 publications

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“…Actually, the objective speckle contrast can be reduced down to 1.36%, 3.93%, and 1.44% corresponding to the wavelength of 450, 532, and 638 nm, respectively, during LD lighting by using SA-L-2/3 as the diffuser (Figure 3i and Figure S21, Supporting Information). These values are lower than the speckle contrast that can be recognized by the human eye (4%) [18] and comparable to speckle contrast reduction by using dynamic optical elements, [19] a static Hadamard matrix diffuser, [20] and a hybrid system, [21] all those require complicated and precise devices. Hence, silica aerogel with elaborate tuning of its building block sizes can be used for laser-driven lighting.…”

Section: Resultsmentioning

confidence: 86%

Elaborate Size‐Tuning of Silica Aerogel Building Blocks Enables Laser‐Driven Lighting

Zhang

2021

Advanced Materials

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Silica aerogels with accurate building‐block control are realized by adjusting the surfactant concentration during the synthesis process. The resulting silica‐aerogel monolith with spherical building blocks of ≈24–40 nm, together with a deliberately created hole along the incident light direction, shows an incredibly promising application in monochromatic laser‐driven lighting. The resulting coefficient of illuminance variation is as low as 8.1%, significantly outperforming commercially available ground‐glass diffusers (139.0%) and polymer diffusers (249.1%); the speckle contrast is lower, as well as better, than that can be recognized by the human eye (4%), and the illuminance uniformity in the range of 0.770–0.862 is much better (higher) than that indoor workplace lighting required by the International Organization for Standardization. Lighting with any color in the visible spectrum, including white, can be obtained by using three primary color lasers (450, 532, and 638 nm) with different powers simultaneously as the light source. The resulting silica aerogel, which has excellent thermal stability, high laser‐damage threshold, outstanding mechanical performance, and superhydrophobicity, can be further applied to long‐distance and noncontact laser‐driven lighting in rain or underwater without any additional encapsulation components.

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Section: Resultsmentioning

confidence: 86%

Elaborate Size‐Tuning of Silica Aerogel Building Blocks Enables Laser‐Driven Lighting

Zhang

2021

Advanced Materials

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“…Fortunately, this complexity can be solved by using a single color emitter coupled with an appropriate phosphor material. Phosphor‐converted near‐UV or blue LDs have been developed to generate white light with high luminance, low cost, and free of speckle noise . Extensive research and commercial areas are opening toward white laser light applications, such as automobile headlamps, laser TVs, cinema projectors, and high‐end home theaters …”

Section: Introductionmentioning

confidence: 99%

Color Conversion Materials for High‐Brightness Laser‐Driven Solid‐State Lighting

Wang

Hirosaki

et al. 2018

Laser & Photonics Reviews

273

191

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Solid‐state lighting is advancing toward higher power, higher brightness, and smaller size to cope with the market competitiveness, and laser‐driven solid‐state lighting technology is springing up owing to its super‐high brightness and compactness. These developments put forward new requirements for color conversion materials (i.e., phosphors). Here, the state‐of‐art achievements in laser phosphors are summarized, and the topics of luminescence saturation, light extraction efficiency, and light uniformity encountered in laser lighting technology are discussed. Several typical types of color converters, such as single crystal, phosphor ceramics, phosphor‐in‐glass, phosphor films, and quantum‐well light‐emitting diodes, are comparatively overviewed and discussed. The cutting‐edge applications of high‐brightness white laser light in lighting, displays, healthcare, and communications are summarized. The challenges and outlook in laser‐driven solid‐state lighting and some empirical rules for designing novel laser phosphors are highlighted.

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“…When incident laser light has a certain divergence angle, internal reflections will occur within the lightpipe and generate virtual images. These virtual images are overlap with each other at the end facet of the light pipe and provide a more uniform light field [15]. More internal reflections will generate more virtual images and thus provide better uniformity [16].…”

Section: Lightpipementioning

confidence: 99%

Speckle Reduction by Optimized Multimode Fiber Combined With Dielectric Elastomer Actuator and Lightpipe Homogenizer

Kitai

et al. 2016

J. Display Technol.

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Speckle, due to the interference of coherent light having random phases, can seriously degrade image quality in a laser based projection system. The speckle is even worse when the diode pumped solid state (DPSS) lasers are used as light sources since the laser linewidth from the DPSS lasers is usually very narrow. In this paper, a de-speckle system consisting of a multimode fiber (MMF), a dielectric elastomer actuator (DEA) and a lightpipe is proposed and demonstrated, which can reduce speckle significantly. The speckle reduction components used in the system are optimized, taking into account speckle reduction ability and optical efficiency. The proposed de-speckle system is low in cost and easy to set up. It features a low optical power penalty and is compatible with large venue laser projection for applications such as digital cinema. In the proposed de-speckle system, test images captured by a camera with a setup following the recently proposed speckle measurement standard can achieve a speckle contrast ratio as low as 4.7%. By adding a voice coil motor (VCM) to vibrate the MMF to generate temporal diversity, the speckle contrast ratio can be further reduced to 3.7%.

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A hybrid temporal and spatial speckle-suppression method for laser displays

Cited by 13 publications

References 16 publications

Elaborate Size‐Tuning of Silica Aerogel Building Blocks Enables Laser‐Driven Lighting

Elaborate Size‐Tuning of Silica Aerogel Building Blocks Enables Laser‐Driven Lighting

Color Conversion Materials for High‐Brightness Laser‐Driven Solid‐State Lighting

Speckle Reduction by Optimized Multimode Fiber Combined With Dielectric Elastomer Actuator and Lightpipe Homogenizer

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