Refractive index &amp;amp; physical thickness distributions measurement and consideration of dependence of measurement accuracy on scanning interval using low-coherence digital holography

Watanabe, Kaho; Nomura, Takanori

doi:10.1109/sii.2013.6776608

Cited by 4 publications

(1 citation statement)

References 17 publications

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“…We have proposed the system to obtain refractive index and thickness distributions from Fresnel holograms recorded by a temporally low-coherent light source. 1,2 On the other hand, spatially incoherent holography has been widely studied in recent years. [3][4][5][6][7] In the methods, a hologram of the spatially incoherent object (incoherently illuminated or self-luminous object) can be recorded.…”

Section: Introductionmentioning

confidence: 99%

Reconstruction of incoherent Fresnel-like hologram by a rotational shearing interferometer

Watanabe

Nomura

2015

SPIE Proceedings

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The systems to record incoherent holograms using a rotational shearing interferometer is demonstrated. The systems can record incoherent holograms by self-interference of the two coherent object points created by the beam splitter from one object point. In general, the rotational shearing interferometer cannot reproduce any depth information. The proposed rotational shearing interferometer has the advantage of obtaining depth information by the reconstruction owing to lenses for the shear which is parallel to the optical axis. A preliminary experiments were performed. The object images at some reconstruction distances were reconstructed numerically. The experimental results confirm the proposed system.

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Section: Introductionmentioning

confidence: 99%

Reconstruction of incoherent Fresnel-like hologram by a rotational shearing interferometer

Watanabe

Nomura

2015

SPIE Proceedings

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Digital holography for non-invasive quantitative imaging of two-dimensional materials

Ghosh

Noble

Sebastian

et al. 2020

Journal of Applied Physics

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Digital holography has found applications in many walks of life, from medicine to metrology, due to its ability to measure complex fields. Here, we use the power of digital holography to quantitatively image two-dimensional Transition Metal Dichalcogenides (TMDs) such as MoS2 and WS2 placed on a SiO2/Si substrate and determine their complex refractive indices or layer thicknesses. By considering the different refractive indices of the TMDs as they are thinned down from bulk to monolayers and by holographically capturing both the amplitude and the phase of reflected light, single atomic layers of TMDs, about 0.7 nm thick, can be resolved. Using holography, we also predict the number of layers contained within a thick TMD flake, which shows agreement with results obtained using Atomic Force Microscopy (AFM). A Bland–Altman analysis was performed to compare our experimental results with the standard AFM measurements, yielding a limit of agreement <5 nm for samples with thicknesses ranging from 15 to 60 nm. Our technique is non-contact, non-invasive, does not require scanning, and produces a field of view of a few hundred micrometers by a few hundred micrometers in a single capture. To further our study, we also perform simulations to demonstrate how the thickness of the SiO2 layer and the laser wavelength are critical in optimizing the amplitude and phase response of a two-dimensional material. These simulations can be used as a roadmap to determine the ideal wavelength and SiO2 layer thickness that should be used to accurately determine the refractive index or thickness of any given sample.

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Recording spatially incoherent hologram using rotational shearing interferometer with a lens for the parallel shear

Watanabe

Nomura

2015

2015 14th Workshop on Information Optics (WIO)

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Refractive index & physical thickness distributions measurement and consideration of dependence of measurement accuracy on scanning interval using low-coherence digital holography

Cited by 4 publications

References 17 publications

Reconstruction of incoherent Fresnel-like hologram by a rotational shearing interferometer

Reconstruction of incoherent Fresnel-like hologram by a rotational shearing interferometer

Digital holography for non-invasive quantitative imaging of two-dimensional materials

Recording spatially incoherent hologram using rotational shearing interferometer with a lens for the parallel shear

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