A new approach to vector scattering: the 3s boundary source method

Coupland, John N.; Nikolaev, N. I.

doi:10.1364/oe.27.030380

Cited by 9 publications

(7 citation statements)

References 18 publications

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“…However, from these results we cannot entirely understand why the measured grating's PV height and surface height variation are amplified in cases II and III. A fully 3D rigorous CSI model that considers polychromatic incoherent illumination, based on the recently reported boundary source method surface scattering model 31 , is required (an extension of the 2D rigorous CSI model 25 ).…”

Section: Resultsmentioning

confidence: 99%

Optical topography measurement of steeply-sloped surfaces beyond the specular numerical aperture limit

Thomas

Su²,

Groot³

et al. 2020

Optics and Photonics for Advanced Dimensional Metrology

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Engineered functional surfaces often feature varying slopes on macro-and micro-scales. When surfaces are mirror-like, the highest surface slope that can be measured by a far-field 3D imaging optical surface measuring instrument is the arcsine of the numerical aperture (NA) of the objective lens, i.e. the acceptance angle of the lens. However, progress in instrument design has allowed for measurement of non-specular surfaces with slopes steeper than this "traditional" NA limit. Nonetheless, there is currently a lack of understanding about the instrument response to surfaces with steep slopes beyond this limit. It is unclear over what surface spatial frequencies we can expect to accurately report fine surface-feature details.Here we present results demonstrating the capability of a commercial coherence scanning interferometer for measuring surface topography of a roughened flat and a blazed grating with tilt angles greater than the NA slope limit. We show that the surface form, i.e. the tilted plane, can be measured correctly. But, while surface texture information that can appear useful is also obtained, tilting significantly influences the measurement accuracy of micro-scale texture, and for asymmetric gratings, can depend on the tilting direction. A simplified surface scattering model suggests that the loss of scattered power captured by the instrument and a low signal-to-noise ratio causes the reduction of measurement accuracy. However, a rigorous three-dimensional instrument model is needed for a full understanding; we will develop this in our future work.

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Section: Resultsmentioning

confidence: 99%

Optical topography measurement of steeply-sloped surfaces beyond the specular numerical aperture limit

Thomas

Su²,

Groot³

et al. 2020

Optics and Photonics for Advanced Dimensional Metrology

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“…Due to the recent completion of the 3-D BEM-like surface scattering model, 42 the current 2-D CSI model can be directly extended to a full 3-D CSI model.…”

Section: Discussionmentioning

confidence: 99%

“…Since the current BEM model is only 2-D but the experimental instrument generates 3-D images, comparison between simulation and experiment is intended only to be qualitative, not quantitative. A novel fully 3-D BEM-like model has recently been developed to overcome these limitations 42 and will be used in the future to extend the proposed CSI model to 3-D.…”

Section: Introductionmentioning

confidence: 99%

Modeling of interference microscopy beyond the linear regime

Thomas

Nikolaev

et al. 2020

Opt. Eng.

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Coherence scanning interferometry (CSI), a type of interference microscopy, has found broad applications in the advanced manufacturing industry, providing high-accuracy surface topography measurement. Enhancement of the metrological capability of CSI for complex surfaces, such as those featuring high slopes and spatial frequencies and high aspect-ratio structures, requires advances in modeling of CSI. However, current linear CSI models relying on approximate surface scattering models cannot accurately predict the instrument response for surfaces with complex geometries that cause multiple scattering. A boundary elements method is used as a rigorous scattering model to calculate the scattered field at a distant boundary. Then, the CSI signal is calculated by considering the holographic recording and reconstruction of the scattered field. Through this approach, the optical response of a CSI system can be predicted for almost any arbitrary surface geometry. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…( 7)-( 10)) for the main part of the transmitted radiation, and without application of more complicated diffraction theory methods (e.g. [35][36][37][38]). The similar approach (based on exact analytical solutions of the boundary problems) was…”

Section: Statement Of the Problem And Analytical Modelmentioning

confidence: 99%

Features of transmission of electromagnetic waves through composite nanoresonators including epsilon-near-zero metamaterials

Starodubtsev

2020

EPJ Appl. Metamat.

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Transmission of electromagnetic waves through nanometric multilayers (nanoresonators) including a main composite layer made of two alternating strips of low-absorbing dielectrics that is sandwiched between epsilon-near-zero (ENZ) or metallic spacer layers has been modeled. Analytical models are based on exact solutions of electromagnetic boundary problems. The spacers with the definite properties lead to extreme dependences of amplitude transmission coefficients on the system parameters and drastic increase in phase difference of the transmitted waves. These effects are most pronounced for subwavelength multilayer thicknesses due to multibeam interference features in the nanoresonator, and they can be amplified when the main layer and (or) the whole system thicknesses decrease. The investigated transmission features take place under variations of the system parameters such as anisotropy of the main layer materials, non-ideal realization of ENZ materials, oblique incidence of the exciting radiation (for small incidence angles). The obtained results can have applications in development of ultra-thin nanophotonics devices using phase transformation of transmitted waves.

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A new approach to vector scattering: the 3s boundary source method

Cited by 9 publications

References 18 publications

Optical topography measurement of steeply-sloped surfaces beyond the specular numerical aperture limit

Optical topography measurement of steeply-sloped surfaces beyond the specular numerical aperture limit

Modeling of interference microscopy beyond the linear regime

Features of transmission of electromagnetic waves through composite nanoresonators including epsilon-near-zero metamaterials

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