International round-robin experiment for angle-resolved light scattering measurement

Abstract

An international round-robin experiment has been conducted to test procedures and methods for the measurement of angle resolved light scattering. ASTM E2387-05 has been used as the main guide, while the experience gained should also contribute to the new ISO standard of angle resolved scattering currently under development (ISO/WD 19986:2016). Seven laboratories from Europe and the USA measured the angle resolved scattering from Al/SiO 2 coated substrates, transparent substrates, volume diffusors, quasi volume diffusors, white calibration standards, and grating samples at laser wavelengths in the UV, VIS and NIR spectrum. Results were sent to Fraunhofer IOF that coordinated the experiments and analyzed the data, while ESA-ESTEC, as the project donor, defined conditions and parameters. Depending mainly on the sample type, overall good to reasonable agreements were observed, with largest deviations at scattering angles very close to the specular beam. Volume diffusor characterization unexpectedly turned out to be challenging. Not all participants provided measurement uncertainty ranges according to GUM, often, a single general scatterometer-related measurement uncertainty value was stated. Although relative instrument measurement uncertainties close to 1% are sometimes claimed, the comparison results did not support these claims for specular scattering samples as mirrors, substrates, or gratings.

Tailoring Patterned Visible-Light Scattering by Silicon Photonic Crystals

“…In our case with the Si samples, the reflection mode was used. The scattered radiation intensity is recorded by a detector at the scattering angle θ s from 0 to 85° with the sample rotation angle φ s from 0 to 360°. , …”

“…The scattering pattern in the scattering angle range of 0° ≤ θ S ≤ to 85° and the sample rotation angle range of 0° ≤ φ S ≤ 360° was measured. The angle-resolved scattering intensity can be described by where ARS­(θ S , φ S ) is the scattering intensity, θ S is the polar scattering angle, φ S is the azimuthal scattering angle, Δ P S (θ S , φ S ) is the scattering power in solid angle range ΔΩ s , and P i is the incident light power. , …”

A breakthrough instrument for wide-range wavelength and angle resolved light scattering measurements of high performances optical coatings

“…Many instruments have been proposed for this metrology but most of them use laser lines to reach sufficient power and measure scattering at discrete wavelengths in the UV, visible or infrared [8], [9]. The configuration of the setup presented in this paper overcomes this limitation and owns a continuous spectral range.…”

Trapped light scattering within optical coatings: a multilayer roughness-coupling process

“…Light scattering has been extensively studied in multilayer optics [1][2][3][4][5][6][7][8], and today it is possible to predict and measure total losses (integrated in whole space) less than a few ppm (1 ppm = 10 −6 of the incident flux) in the whole continuous spectral range (400 nm-1.7 µm) [9,10]. Such accuracy is crucial for applications in high precision optics, including space applications (rejection rates in sensor matrices), mirrors for gyro-lasers (blind zones) and detection of gravitational waves [11][12][13] (see LISA/LIGO/Virgo projects).…”