The modified Beer–Lambert law revisited

Kocsis, László; Hermán, Péter; Eke, András

doi:10.1088/0031-9155/51/5/n02

Cited by 510 publications

(342 citation statements)

References 13 publications

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“…Typically, two or a few more discrete wavelengths are used in NIRI, and the MBLL equations are evaluated at these selected wavelengths (Delpy et al, 1988;Kocsis et al, 2006). In broadband NIRI, however, light from a continuous portion of the spectrum is required in order to obtain the continuous absorption spectrum of the diffuse reflectance (Diop et al, 2009;Kashyap et al, 2007;Tisdall et al, 2007).…”

Section: Light Sources For Fniri Instrumentsmentioning

confidence: 99%

A review on continuous wave functional near-infrared spectroscopy and imaging instrumentation and methodology

Scholkmann¹,

Kleiser²,

Metz³

et al. 2014

NeuroImage

1,523

1,394

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This year marks the 20th anniversary of functional near-infrared spectroscopy and imaging (fNIRS/fNIRI). As the vast majority of commercial instruments developed until now are based on continuous wave technology, the aim of this publication is to review the current state of instrumentation and methodology of continuous wave fNIRI. For this purpose we provide an overview of the commercially available instruments and address instrumental aspects such as light sources, detectors and sensor arrangements. Methodological aspects, algorithms to calculate the concentrations of oxy-and deoxyhemoglobin and approaches for data analysis are also reviewed. From the single-location measurements of the early years, instrumentation has progressed to imaging initially in two dimensions (topography) and then three (tomography). The methods of analysis have also changed tremendously, from the simple modified Beer-Lambert law to sophisticated image reconstruction and data analysis methods used today. Due to these advances, fNIRI has become a modality that is widely used in neuroscience research and several manufacturers provide commercial instrumentation. It seems likely that fNIRI will become a clinical tool in the foreseeable future, which will enable diagnosis in single subjects. This year marks the 20th anniversary of functional near-infrared spectroscopy and imaging (fNIRS/fNIRI). As the vast majority of commercial instruments developed until now are based on continuous wave technology, the aim of this publication is to review the current state of instrumentation and methodology of continuous wave fNIRI. For this purpose we provide an overview of the commercially available instruments and address instrumental aspects such as light sources, detectors and sensor arrangements. Methodological aspects, algorithms to calculate the concentrations of oxy-and deoxyhemoglobin and approaches for data analysis are also reviewed. From the single-location measurements of the early years, instrumentation has progressed to imaging initially in two dimensions (topography) and then three (tomography). The methods of analysis have also changed tremendously, from the simple modified Beer-Lambert law to sophisticated image reconstruction and data analysis methods used today. Due to these advances, fNIRI has become a modality that is widely used in neuroscience research and several manufacturers provide commercial instrumentation. It seems likely that fNIRI will become a clinical tool in the foreseeable future, which will enable diagnosis in single subjects. Contents

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Section: Light Sources For Fniri Instrumentsmentioning

confidence: 99%

A review on continuous wave functional near-infrared spectroscopy and imaging instrumentation and methodology

Scholkmann¹,

Kleiser²,

Metz³

et al. 2014

NeuroImage

1,523

1,394

View full text Add to dashboard Cite

show abstract

“…However, with the present instrumentation both the initial light intensity and the scattering properties of the tissue remain unknown and a quantification of absolute hemoglobin concentrations is therefore impossible. The Beer-Lambert law and its application in in-vivo nearinfrared spectroscopy is discussed in [4]. By properly choosing λ 1 and λ 2 one ensures that the condition number of the linear system of equation which is constituted by the Beer-Lambert law is as favorable as possible and hence disturbance of the results by measurement-and computation-accuracy errors is minimized.…”

Section: Theorymentioning

confidence: 99%

Wireless miniaturized in-vivo near infrared imaging

Muehlemann¹,

Haensse²,

Wolf³

2008

Opt. Express

145

108

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Our group measures tissue oxygenation and the cortical hemodynamic response to sensory stimuli applying continuous wave near-infrared imaging (NIRI). To improve the method's quality and applicability and to explore new fields in clinical practice and research, we developed a miniaturized wireless NIRI system. It was validated by measuring muscle oxygenation in a blood-flow occlusion experiment and brain activity in adults. Abstract: Our group measures tissue oxygenation and the cortical hemodynamic response to sensory stimuli applying continuous wave nearinfrared imaging (NIRI). To improve the method's quality and applicability and to explore new fields in clinical practice and research, we developed a miniaturized wireless NIRI system. It was validated by measuring muscle oxygenation in a blood-flow occlusion experiment and brain activity in adults. Wireless miniaturized in-vivo near infrared imaging

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“…However, this law is no more applicable while measuring the absorbance of media for which transmittance is either very high, or too weak, under certain conditions. Thus, there are important operational conditions under which the Beer-Lambert law cannot be applied without modification [2] [4] [5] [6] [7] [8].…”

Section: Introductionmentioning

confidence: 99%

Structured Imagery Processing Strategies for Spectroscopic Measurement in Dense Solutions

Koffi¹,

Regnima²,

Bosson³

et al. 2017

OJAppS

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Absorbance measurement in dense media via conventional optical spectroscopy techniques leads to inaccurate results. This is mainly due to multiple scattering phenomena that contribute to the overall light extinction in the interrogated sample. This limitation imposes the use of dilute solutions for absorption spectroscopy. However, depending on the polarity of the solvent used, the absorption spectrum may vary over a given solution. Structured illumination technique offers an alternative to this problem, and provides the ability to calculate in-situ optical properties in dense media. In this paper, we propose two processing methods applied to images acquired by structured laser illumination planar imaging (SLIPI) technique to extract extinction coefficients µ of probed solutions: The first is based on the implementation of principal component analysis (PCA) and the second, on the calculation of Mean Value. In practice, two kinds of studies were carried out: one quantitative set of measurements within chlorophyll liquid solutions and a second set with concentrated coffee solutions, with controlled proportion and concentrations for each sample. These two proposed analytical techniques are advantageous because they are very easy to implement and provide a much simpler alternative to the previous one. Both methods offer satisfactory results, similar to those obtained with the original method which is based on 1D Fourier transform.

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The modified Beer–Lambert law revisited

Cited by 510 publications

References 13 publications

A review on continuous wave functional near-infrared spectroscopy and imaging instrumentation and methodology

A review on continuous wave functional near-infrared spectroscopy and imaging instrumentation and methodology

Wireless miniaturized in-vivo near infrared imaging

Structured Imagery Processing Strategies for Spectroscopic Measurement in Dense Solutions

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