Speckle Noise Evaluation and Reduction of an Edge-Lit Backlight System Utilizing Laser Diodes and an Optical Fiber

Fujieda, Ichiro; Kosugi, Takao; Inaba, Yusuke

doi:10.1109/jdt.2009.2027612

Cited by 19 publications

(3 citation statements)

References 13 publications

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“…LEDs are devices with a much smaller spatial and temporal coherence than lasers and, consequently, LED light projected on rough surfaces exhibits no speckle. Additional features making the use of LEDs attractive are their longevity, low cost, reduced size, high radiant power, and electrical and optical performance [12], [18].…”

Section: Introductionmentioning

confidence: 99%

LED-Based Collimating Line-Light Combining Freeform and Fresnel Optics

et al. 2018

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Illumination for line-scan machine vision systems is required to produce a highly asymmetric elliptical beam pattern, to maximize system speed and accuracy. The use of LED emitters with symmetric Lambertian emission patterns is challenging in this context, requiring significant beam reshaping. A design for a collimated line-light, with long working distance, utilizing LEDs with symmetric Lambertian emission patterns, is presented. Using a combination of Fresnel lenses and total internal reflection (TIR) optics, an elliptical beam with a high degree of collimation is achieved. TIR elements are designed based on an adaptation of a freeform lens design method published by Chen et al. [Opt. Express 20, 10 (2012)]. Practical performance of the design is verified experimentally using a prototype unit. In addition, the design is compared, using ray tracing software, to line-lights constructed using commercially available symmetric and elliptical TIR lenses, and its superior performance is confirmed. The optical design described is fully manufacturable and suitable for both smalland large-scale production.

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Section: Introductionmentioning

confidence: 99%

LED-Based Collimating Line-Light Combining Freeform and Fresnel Optics

et al. 2018

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“…where K denotes the convolution operator on clean image v . And the noise level  varies in different conditions, which includes Gaussian, salt-and-pepper noise, speckle noise [3] and other distortion situations [4][5] [6] [7]. For recovering more edges and textures or improving the stability of the restoration procedure, some regularization terms [10] are developed to obtain a favorable solution.…”

Section: Introductionmentioning

confidence: 99%

Image Deblurring via Adaptive Proximal Conjugate Gradient Method

Pan¹,

Jing²,

Li³

et al. 2015

KSII TIIS

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It is not easy to reconstruct the geometrical characteristics of the distorted images captured by the devices. One of the most popular optimization methods is fast iterative shrinkage/ thresholding algorithm. In this paper, to deal with its approximation error and the turbulence of the decrease process, an adaptive proximal conjugate gradient (APCG) framework is proposed. It contains three stages. At first stage, a series of adaptive penalty matrices are generated iterate-to-iterate. Second, to trade off the reconstruction accuracy and the computational complexity of the resulting sub-problem, a practical solution is presented, which is characterized by solving the variable ellipsoidal-norm based sub-problem through exploiting the structure of the problem. Third, a correction step is introduced to improve the estimated accuracy. The numerical experiments of the proposed algorithm, in comparison to the favorable state-of-the-art methods, demonstrate the advantages of the proposed method and its potential.

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“…The vibration rapidly changes phase retardation in the optical fiber, and the interference patterns are averaged out. 12 At present, however, the cost associated with LDs seems to be an inhibiting factor for direct-view applications. The quantum dot backlight technology 13,14 might be an interim solution toward a wide-gamut LCD.…”

Section: Introductionmentioning

confidence: 99%

Backlight units based on light extraction from a curved optical fiber

et al. 2014

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A backlight unit is constructed by laying out a plastic optical fiber (POF) in a curved trench fabricated in a light-guide plate. First, the light leaks out of the POF at curved sections and enters the plate. Next, the light is extracted from the plate by some microstructures fabricated on the surfaces of the plate. Coupled to a laser diode, its optical power can be efficiently and uniformly delivered over a large area via the POF. In this experiment, we fabricated a 10 cm × 10 cm × 3 mm prototype unit with off-the-shelf components. It becomes seethrough when the space around the POF is filled with index-matching oil. One can build an arbitrary-shaped planar light source by tiling multiple cells and connecting them by a POF. The light inside the POF is depleted as it propagates downstream. This can be compensated by decreasing the radii of curvature. Microstructures on the light-guide plate can distort the passage of ambient light. For a see-through unit, we can distribute them sparsely and/or use absorbers. A see-through backlight unit is a relatively unexplored device, and it might pave the way for new applications.

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Speckle Noise Evaluation and Reduction of an Edge-Lit Backlight System Utilizing Laser Diodes and an Optical Fiber

Cited by 19 publications

References 13 publications

LED-Based Collimating Line-Light Combining Freeform and Fresnel Optics

LED-Based Collimating Line-Light Combining Freeform and Fresnel Optics

Image Deblurring via Adaptive Proximal Conjugate Gradient Method

Backlight units based on light extraction from a curved optical fiber

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