Simultaneous measurement of refractive index and thickness of multilayer systems using Fourier domain optical coherence tomography, part 2: implementation

Rajai, Payman; Schriemer, Henry; Amjadi, Ahmad; Munger, Réjean

doi:10.1117/1.jbo.22.1.015003

Cited by 4 publications

(1 citation statement)

References 44 publications

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“…[13][14][15][16] Both spectrometer-based spectral-domain (SD-OCT) and swept-source OCT (SS-OCT) realizations are similar from a theoretical point of view because the measured spectrum discretized by the CCD pixels can be interpreted the same as the timemultiplexed output of the balanced detector in SS-OCT configuration. 12,17,18 The method used in this work and the experimental results are based on SD-OCT configuration, but a similar approach can be utilized for SS-OCT devices.…”

Section: Methodsmentioning

confidence: 99%

Developing a New Dimension for Fourier Domain Optical Coherence Tomography Images by Simultaneous Measurement of the Refractive Index and Thickness

et al. 2021

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Introduction: Fourier domain Optical coherence tomography (OCT) is a widely used high-resolution optical imaging technique. It is useful for various applications in medical imaging, such as ophthalmology (e.g. retinal imaging for diagnosing complications like glaucoma or macular degeneration), dermatology, oncology, and cardiology. The ability to noninvasively measure both the refractive index and thickness of biological tissues could have various medical applications and enable earlier disease detection. For example, observing changes in the refractive index can help distinguish between tissues with normal or abnormal function. Methods: In this study, the theoretical framework for simultaneous measurement of the refractive index and physical thickness of multilayer systems is proposed and tested for two different samples, each having three layers, a glass/NaCl solution/glass sample and a glass/sugar solution/glass sample. The whole signal processing procedure and the experimental setup are described. Results: The refractive index and thickness of salt water and sugar water samples in the Fourier-domain OCT (FD-OCT) system were obtained. The resulting data were compared with reference measurements and showed a deviation of about 1% for the samples. Conclusion: We tested the proposed framework for the simultaneous extraction of the refractive index and thickness of multilayer systems of salt water and sugar water from its FD-OCT data. We showed that the measured parameters were in agreement with reference amounts.

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Section: Methodsmentioning

confidence: 99%

Developing a New Dimension for Fourier Domain Optical Coherence Tomography Images by Simultaneous Measurement of the Refractive Index and Thickness

et al. 2021

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Dual-angle optical coherence tomography for index of refraction estimation using rigid registration and cross-correlation

Photiou

Pitris

2019

J. Biomed. Opt.

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The index of refraction (n) of materials and/or tissues depends on their physical properties and serves as a source of optical contrast in imaging. The variations of the index of refraction have also been investigated for diagnostic purposes in various fields, such as hematology, oncology, etc., since they can signify disease and cell dynamic changes. Optical coherence tomography (OCT) has been used in the past to measure the index ex vivo. However, most methodologies described in the literature are not appropriate for in vivo imaging since they require either a mirror below the sample or a complicated imaging setup and algorithms. We describe a technique that uses two images, obtained at different angles, to estimate the index of refraction and can, thus, also be applied in vivo. The index of refraction is calculated from the path-length difference observed by the OCT beam at the two different angles. When a reflector is not available, the path-length difference can be estimated using image registration and the cross-correlation of adjacent A-scans. The proposed technique was validated experimentally using both clear and scattering samples. The resulting values of the index of refraction were within ∼1% of the expected. The main limitation of this technique is the effect of misalignment on the results, requiring the precision provided by an angular-resolved OCT system. These very promising results provide evidence that the dual-angle method should be further investigated and validated on human tissues so that it can be developed into a clinically useful diagnostic tool in the future.

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Application of optical coherence tomography and optical path length method for monitoring corneal thickness and refractive index change during corneal cross-linking

et al. 2019

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Simultaneous measurement of refractive index and thickness of multilayer systems using Fourier domain optical coherence tomography, part 2: implementation

Cited by 4 publications

References 44 publications

Developing a New Dimension for Fourier Domain Optical Coherence Tomography Images by Simultaneous Measurement of the Refractive Index and Thickness

Developing a New Dimension for Fourier Domain Optical Coherence Tomography Images by Simultaneous Measurement of the Refractive Index and Thickness

Dual-angle optical coherence tomography for index of refraction estimation using rigid registration and cross-correlation

Application of optical coherence tomography and optical path length method for monitoring corneal thickness and refractive index change during corneal cross-linking

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