Photofabrication of random achromatic optical diffusers for uniform illumination

Mendez, Eugenio Rafael Mendez; García-Guerrero, E. E.; Escamilla, Heéctor M.; Maradudin, A. A.; Leskova, T. A.; Shchegrov, Andrei V.

doi:10.1364/ao.40.001098

Cited by 36 publications

(23 citation statements)

References 10 publications

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“…44,70 L͑z͒ tends to 0 as the real part of its argument goes to 0 in the upper half of the complex plane ͓Im͑z͒ Ͼ 0͔. With Re ⌫ϰ1/ h ͱ ͉ 2 ͉, relation (29) therefore implies that the derived BRDF converges to the incoherent solution ͑AM r cos 2 s ͒ / 2 ␤ for surfaces with sufficiently narrow autocorrelation or sufficiently large roughness. Referring to Eq.…”

Section: ͑29͒mentioning

confidence: 90%

“…In particular, surface profiles with discontinuous derivatives are formally inadmissible under the tangentplane approximation, although pyramidal features with facet dimensions ϳ10 have been accurately described by the Beckmann model. 29 Extensions of the Beckmann model in the field of computer-graphic design have contributed treatments of polarization and shadowing effects. 30 The Stratton-Chu-Silver integral 31 was applied to optical scattering by Leader, 32,33 with the surface fields also determined under the tangent-plane approximation.…”

Section: Introductionmentioning

confidence: 99%

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Coherence solution for bidirectional reflectance distributions of surfaces with wavelength-scale statistics

Hoover

Gamiz

2006

J. Opt. Soc. Am. A

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The scalar bidirectional reflectance distribution function (BRDF) due to a perfectly conducting surface with roughness and autocorrelation width comparable with the illumination wavelength is derived from coherence theory on the assumption of a random reflective phase screen and an expansion valid for large effective roughness. A general quadratic expansion of the two-dimensional isotropic surface autocorrelation function near the origin yields representative Cauchy and Gaussian BRDF solutions and an intermediate general solution as the sum of an incoherent component and a nonspecular coherent component proportional to an integral of the plasma dispersion function in the complex plane. Plots illustrate agreement of the derived general solution with original bistatic BRDF data due to a machined aluminum surface, and comparisons are drawn with previously published data in the examination of variations with incident angle, roughness, illumination wavelength, and autocorrelation coefficients in the bistatic and monostatic geometries. The general quadratic autocorrelation expansion provides a BRDF solution that smoothly interpolates between the well-known results of the linear and parabolic approximations.

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Section: ͑29͒mentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Coherence solution for bidirectional reflectance distributions of surfaces with wavelength-scale statistics

Hoover

Gamiz

2006

J. Opt. Soc. Am. A

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“…Assuming a relatively fast f/2 projection lens, as used in current LED-based pico-projector architectures 19 with x = 7 mm, gives f = 15 mm. An engineered diffuser with scattering angle of θ = 15°provides an acceptable balance between optical efficiency and speckle reduction 20,21 and this results in a source angular subtense of 40 mrad. If the projection system has a diagonal throw ratio r t and forms an image with aspect ratio r a , then the horizontal and vertical projection angles θ h and θ v are given by (8) Current laser-based imaging pico-projectors operate at a diagonal throw ratio r t = 0.77, 22 providing horizontal and vertical throw angles of θ h = 37°and θ v = 21°, respectively, assuming an aspect ratio of 16:9.…”

Section: Imaging Projector Analysismentioning

confidence: 99%

Eye‐safety analysis of current laser‐based LCOS projection systems

Buckley¹

2010

J Soc Info Display

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A laser safety analysis for liquid-crystal-on-silicon (LCOS) based imaging projection systems utilizing laser light sources is presented. It is shown that a typical laser-based imaging projector is capable of providing a D65 white-balanced luminous flux in excess of 20 lm while remaining Class 1 eye safe. By considering a Class 2 classification, it is shown that the same architecture is capable of providing several hundred lumens, a performance level which could potentially be applicable to a new class of high-brightness miniature projection systems.

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“…1,2 They are widely used in imaging systems, LED displays, and barcode scanners to provide uniform light exposure and eliminate high-intensity spots. [3][4][5][6][7] Depending on the incorporated light scattering method, optical diffusers are classified as the volumetric or surface relief types. 8 Volumetric diffusers scatter the light via transparent microscopic beads and/or fillers trapped inside the surface that cause the light to diverge as it is transmitted through the material.…”

Section: Introductionmentioning

confidence: 99%

Laser inscription of pseudorandom structures for microphotonic diffuser applications

et al. 2018

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Optical diffusers provide a solution for a variety of applications requiring a Gaussian intensity distribution including imaging systems, biomedical optics, and aerospace. Advances in laser ablation processes have allowed the rapid production of efficient optical diffusers. Here, we demonstrate a novel technique to fabricate high-quality glass optical diffusers with cost-efficiency using a continuous CO2 laser. Surface relief pseudorandom microstructures were patterned on both sides of the glass substrates. A numerical simulation of the temperature distribution showed that the CO2 laser drills a 137 μm hole in the glass for every 2 ms of processing time. FFT simulation was utilized to design predictable optical diffusers. The pseudorandom microstructures were characterized by optical microscopy, Raman spectroscopy, and angle-resolved spectroscopy to assess their chemical properties, optical scattering, transmittance, and polarization response. Increasing laser exposure and the number of diffusing surfaces enhanced the diffusion and homogenized the incident light. The recorded speckle pattern showed high contrast with sharp bright spot free diffusion in the far field view range (250 mm). A model of glass surface peeling was also developed to prevent its occurrence during the fabrication process. The demonstrated method provides an economical approach in fabricating optical glass diffusers in a controlled and predictable manner. The produced optical diffusers have application in fibre optics, LED systems, and spotlights.

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Photofabrication of random achromatic optical diffusers for uniform illumination

Cited by 36 publications

References 10 publications

Coherence solution for bidirectional reflectance distributions of surfaces with wavelength-scale statistics

Coherence solution for bidirectional reflectance distributions of surfaces with wavelength-scale statistics

Eye‐safety analysis of current laser‐based LCOS projection systems

Laser inscription of pseudorandom structures for microphotonic diffuser applications

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