Scattering from reflective diffraction gratings: the challenges of measurement and simulation

Kroneberger, Monika; Fray, Sebastian

doi:10.1515/aot-2017-0032

Cited by 4 publications

(2 citation statements)

References 1 publication

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“…Because the grating pitch is very small, the quality of the electrical signal is affected by the manufacturing process and collimation of the light source. Some researchers had analyzed the effect of scattering on Moiré fringe formation [18][19][20] and proposed some optimized schemes [21,22]. However, because the effect of the light source on measurement is not the main reason and the collimation of the light source is very limited [23,24], the measurement accuracy of the grating still relies on the precision of the grating manufacturing process.…”

Section: Introductionmentioning

confidence: 99%

A High Precision Time Grating Displacement Sensor Based on Temporal and Spatial Modulation of Light-Field

Zhu

et al. 2020

Sensors

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A new displacement sensor with light-field modulation, named as time grating, was proposed in this study. The purpose of this study was to reduce the reliance on high-precision measurements on high-precision manufacturing. The proposed sensor uses a light source to produce an alternative light-field simultaneously for four groups of sinusoidal light transmission surfaces. Using the four orthogonally alternative light-fields as the carrier to synthesize a traveling wave signal which makes the object movement in the spatial proportion to the signal phase shift in the time, the moving displacement of the object can be measured by counting time pulses. The influence of the light-field distribution on sensor measurement error was analyzed in detail. Aimed to reduce these influences, an optimization method that used continuous cosinusoidal light transmission surfaces with spatially symmetrical distribution was proposed, and the effectiveness of this method was verified with simulations and experiments. Experimental results demonstrated that the measurement accuracy reached 0.64 µm, within the range of 500 mm, with 0.6 mm pitch. Therefore, the light-field time grating can achieve high precision measurement with a low cost and submillimeter period sensing unit.

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Section: Introductionmentioning

confidence: 99%

A High Precision Time Grating Displacement Sensor Based on Temporal and Spatial Modulation of Light-Field

Zhu

et al. 2020

Sensors

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“…For an easy fit procedure this function is approximated by a Harvey-Shack function (see Figure 1-1) and fitted to the measured BRDF of the grating at the peak of the diffraction order at which the grating is designed to operate. (detailed discussion see [7] and [9]). The fitted Harvey-Shack function is then compared to the Harvey-Shack function resulting from the requirement for compliancy.…”

Section: Introductionmentioning

confidence: 99%

Straylight of curved gratings: an interlaboratory comparison

Kroneberger

Tomuta

Mezger

2019

International Conference on Space Optics — ICSO 2018

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The accurate simulation of stray light is essential for the verification of the contrast requirements in optical instruments. In a spectrometer, the scattering from reflective gratings is difficult to characterize while contributing significantly to the overall system stray light and reduction of the spectrometer contrast.Curved gratings also introduce higher straylight and difficulties in the verification of their straylight compliance. Scatterometers have to be adapted to the grating curvature and thus loose some of their performance.While measuring a curved sample, this becomes part of the optical system of the scatterometer. For the AlbatrossTT and the CASI the system considering the curved sample has to be adapted to refocus the beam onto the detector. Additional aberrations modify the near angle limit, i.e. the smallest angle where the measured BRDF is higher than the system signature. Theoretical analysis of the scatterometer becomes necessary because the signature of the system is no longer directly measureable.In addition, 2D BRDF measurement is adequate for characterization of a high polished optical surface or black coatings but deems to be insufficient to characterize all features of the grating scatter function.3D measurement is essential to verify compliancy in all angular directions.Small errors in the measurement procedure or measurement setup can lead to different results. Also every scatterometer setup has its own design driven limitations effecting near angle limit and resolution. To create reasonable results those limitations have to be carefully considered.We present a set of measurements in two different laboratories with different scatterometers.

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Diffuse scattering due to stochastic disturbances of 1D-gratings on the example of line edge roughness

Heusinger¹,

Michaelis²,

Flügel-Paul³

et al. 2018

Opt. Express

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Scattering from reflective diffraction gratings: the challenges of measurement and simulation

Cited by 4 publications

References 1 publication

A High Precision Time Grating Displacement Sensor Based on Temporal and Spatial Modulation of Light-Field

A High Precision Time Grating Displacement Sensor Based on Temporal and Spatial Modulation of Light-Field

Straylight of curved gratings: an interlaboratory comparison

Diffuse scattering due to stochastic disturbances of 1D-gratings on the example of line edge roughness

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