Absolute Measurement of the Refractive Index of Water by a Mode-Locked Laser at 518 nm

Meng, Zhaopeng; Zhai, Xiaoyu; Wei, Jianguo; Wang, Zhiyang; Wu, Hanzhong

doi:10.3390/s18041143

Cited by 10 publications

(5 citation statements)

References 44 publications

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“…The Stokes shift of Nile red can be related to the Lippert–Mataga polarity parameter Δ f : , where ε is the dielectric constant of the solvent and n is the refractive index of the solvent. The Stokes shift (Δ v ) is proportional to Δ f , and hence, we can write The dielectric constants and refractive indexes for distilled water and PMAA are 78.5, 10 and 1.34, 1.43 respectively. ,− The Stokes shift of Nile red in water (Δ v water ) was measured to be 2.8 × 10 3 cm –1 (Figure SI7). At pH = 6, the experimental value of the Stokes shift is 2.8 × 10 3 cm –1 , which indicates that the Nile red is completely solvated by water under these conditions.…”

Section: Resultsmentioning

confidence: 99%

RAFT Emulsion Polymerization: MacroRAFT Agent Self-Assembly Investigated Using a Solvachromatic Dye

2020

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Polymerization-induced self-assembly (PISA) and amphiphilic-macroRAFT-mediated emulsion polymerization are commonly used approaches for synthesis of well-defined polymers and sophisticated particle morphologies. One aspect of these systems that remains relatively unexplored is the conformational state of macroRAFT agents in aqueous solution. To redress this deficiency, we have used fluorescence spectrometry experiments to conduct detailed investigations of the coil conformation across a wide range of pH values for a series of poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) macroRAFT agents with different Z-groups (-S-(CH 2 ) 2 -COOH, -S-(CH 2 ) 3 -CH 3 , and -S-(CH 2 ) 11 -CH 3 ), as well as amphiphilic macroRAFT agents (PMAA-b-poly(methyl methacrylate)-(PMMA) and PAA-b-polystyrene(PS)). The critical aggregate concentrations (CAC) or critical micelle concentrations (CMC) for all systems ranged from 7.48 × 10 −7 to 2.57 × 10 −3 mol L −1 . Overall, an extensive library of CAC/CMC values has been compiled for PAA-and PMAAbased macroRAFT agents at different pH conditions, providing important information related to the mechanistic understanding and optimization of macroRAFT-assisted emulsion polymerization.

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Section: Resultsmentioning

confidence: 99%

RAFT Emulsion Polymerization: MacroRAFT Agent Self-Assembly Investigated Using a Solvachromatic Dye

2020

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“…phase contrast microscopy [1,2], digital holography microscopy [3,4], optical coherence tomography [5,6], etc. [7][8][9][10]) are intrinsically indirect as they rely on the knowledge, assumption, or measurement of the spatial dimensions of the sample. Even when optical path delay and thickness of the sample are well characterized, we can only obtain the average refractive index along the beam propagation axis.…”

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confidence: 99%

Direct Three-Dimensional Measurement of Refractive Index via Dual Photon-Phonon Scattering

2019

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We developed a microscopy technique that can measure the local refractive index without sampling the optical phase delay of the electromagnetic radiation. To do this, we designed and experimentally demonstrated a setup with two co-localized Brillouin scattering interactions that couple to a common acoustic phonon axis; in this scenario, the ratio of Brillouin frequency shifts depends on the refractive index, but not on any other mechanical and/or optical properties of the sample. Integrating the spectral measurement within a confocal microscope, the refractive index is mapped at micron-scale three-dimensional resolution. As the refractive index is probed in epi-detection and without assumptions on the geometrical dimensions of the sample, this method may prove useful to characterize biological cells and tissues.When light propagates inside a material, the phase of the electromagnetic wave is sensitive to the optical path, which fundamentally couples the geometrical path and the local index of refraction. Thus, methods to map the refractive index of a material (e.g. phase contrast microscopy [1,2], digital holography microscopy [3,4], optical coherence tomography [5,6], etc. [7-10]) are intrinsically indirect as they rely on the knowledge, assumption, or measurement of the spatial dimensions of the sample. Even when optical path delay and thickness of the sample are well characterized, we can only obtain the average refractive index along the beam propagation axis. This fundamental issue has important practical ramifications as it prevents performing spatiallyresolved measurements of the index of refraction. Mapping the distribution and variations of the local refractive index is potentially crucial to analyze mass density behavior in cell biology [11][12][13][14], cancer pathogenesis [13,15,16], and corneal or lens refraction [17][18][19].Several techniques in the past years have emerged to circumvent the coupling of geometrical path and refractive index in 3D samples using a tomographic approach, i.e. performing multiple measurements from different angles to reconstruct the internal refractive index distribution [20][21][22][23][24]. Tomographic phase microscopy enabled spatiallyresolved measurements of refractive index for the first time. However, as the individual measurements are still based on optical path delay, known geometrical boundary conditions and/or reference refractive index values are needed as well as access to the sample from at least two sides. In addition, even under these conditions, the measurements are subject to artifacts due to phase wrapping when phase variations inside the sample are not smooth [1,2,13].Here we present a novel microscopy technique that probes the refractive index of materials relying on photon-phonon interactions, not optical path delays, and thus decouples optical from geometrical path. The technology is based on measuring two inelastic Brillouin scattering interactions in confocal configuration, probing the same acoustic phonon axis so that the refractive index is the ...

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“…The core idea of the wave optics measurement method is that the phase difference of coherent light is related to the refractive index, and the refractive index is calculated by measuring the phase difference based on interference effect [7,8]. The commonly used wave optics measurement methods are digital holography method [9], surface plasmon method [10], and optical frequency comb method [11]. When a light beam passes through the liquid, the total reflection occurs at the interface with the air to produce a shading effect, forming a circular shading pattern, and its radius is related to the refractive index of the liquid [12,13].…”

Section: Introductionmentioning

confidence: 99%

Smartphone-based system for measuring liquid refractive index

Deng,

Yu,

Wang

et al. 2023

AOPC 2023: Optical Sensing, Imaging, and Display Technology and Applications; And Biomedical Optics

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Absolute Measurement of the Refractive Index of Water by a Mode-Locked Laser at 518 nm

Cited by 10 publications

References 44 publications

RAFT Emulsion Polymerization: MacroRAFT Agent Self-Assembly Investigated Using a Solvachromatic Dye

RAFT Emulsion Polymerization: MacroRAFT Agent Self-Assembly Investigated Using a Solvachromatic Dye

Direct Three-Dimensional Measurement of Refractive Index via Dual Photon-Phonon Scattering

Smartphone-based system for measuring liquid refractive index

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