Double-integrating-sphere system for measuring the optical properties of tissue

Pickering, John W.; Prahl, Scott A.; Wieringen, N. Van; Beek, Hans van; Sterenborg, Henricus J. C. M.; Gemert, Martin J. C. van

doi:10.1364/ao.32.000399

Cited by 426 publications

(284 citation statements)

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“…Since hemispherical reflectance depends on the angle of incidence (and therefore on the diffuse/direct character of the illumination), modeling the reflectance measured by DUFFISSS requires the estimation of the amount of diffuse light hitting the snow. The photon distribution in an ideal integrating sphere evolves as a Markov process (Pickering et al, 1993). We adapted the simple yet accurate Markov model presented and evaluated in Hidović-Rowe et al (2006) to our experimental geometry.…”

Section: Reflectance Modeling At 1310 Nmmentioning

confidence: 99%

“…spectral albedo), depends on snow grain size and therefore on snow SSA (Warren, 1982;Grenfell and Warren, 1999). By using the term "hemispherical reflectance", we refer to the terminology recommended by Schaepman-Strub et al (2006). Here hemispherical reflectance therefore means reflectance integrated over 2π steradians, regardless of the geometry of the incident illumination.…”

Section: Introductionmentioning

confidence: 99%

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Measurement of the specific surface area of snow using infrared reflectance in an integrating sphere at 1310 and 1550 nm

et al. 2009

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Abstract. Even though the specific surface area (SSA) and the snow area index (SAI) of snow are crucial variables to determine the chemical and climatic impact of the snow cover, few data are available on the subject. We propose here a novel method to measure snow SSA and SAI. It is based on the measurement of the hemispherical infrared reflectance of snow samples using the DUFISSS instrument (DUal Frequency Integrating Sphere for Snow SSA measurement). DUFISSS uses the 1310 or 1550 nm radiation of laser diodes, an integrating sphere 15 cm in diameter, and InGaAs photodiodes. For SSA<60 m 2 kg −1 , we use the 1310 nm radiation, reflectance is between 15 and 50% and the accuracy of SSA determination is 10%. For SSA>60 m 2 kg −1 , snow is usually of low density (typically 30 to 100 kg m −3 ), resulting in insufficient optical depth and 1310 nm radiation reaches the bottom of the sample, causing artifacts. The 1550 nm radiation is therefore used for SSA>60 m 2 kg −1 . Reflectance is then in the range 5 to 12% and the accuracy on SSA is 12%. We propose empirical equations to determine SSA from reflectance at both wavelengths, with that for 1310 nm taking into account the snow density. DUFISSS has been used to measure the SSA of snow and the SAI of snowpacks in polar and Alpine regions.

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Section: Reflectance Modeling At 1310 Nmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Measurement of the specific surface area of snow using infrared reflectance in an integrating sphere at 1310 and 1550 nm

et al. 2009

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“…The integrating-sphere technique is a classic indirect measurement setup (Pickering et al, 1993). The simplest model for such measurements is based on the Kubelka-Munk theory.…”

Section: Measurement and Modeling Techniquesmentioning

confidence: 99%

Diffuse Optical Imaging

Nissilä

Noponen

Heino

et al.

Advances in Electromagnetic Fields in Living Systems

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Diffuse optical imaging is a functional medical imaging modality which takes advantage of the relatively low attenuation of near-infrared light to probe the internal optical properties of tissue. The optical properties are affected by parameters related to physiology such as the concentrations of oxy-and deoxyhemoglobin. Instrumentation that is used for optical imaging is generally able to measure changes in the attenuation of light at several wavelengths, and in the case of time-and frequency-domain instrumentation, the time-of-flight of the photons in tissue.Light propagation in tissue is generally dominated by scattering. Models for photon transport in tissue are generally based on either stochastic approaches or approximations derived from the radiative transfer equation. If a numerical forward model which describes the physical situation with sufficient accuracy exists, inversion methods may be used to determine the internal optical properties based on boundary measurements.Optical imaging has applications in, e.g., functional brain imaging, breast cancer detection, and muscle imaging. It has the important advantages of transportable instrumentation, relatively high tolerance for external electromagnetic interference, non-invasiveness, and applicability for neonatal studies. The methods are not yet in clinical use, and further research is needed to improve the reliability of the experimental techniques, and the accuracy of the models used. In this chapter, we describe the interaction between light and tissue, light propagation models and inversion methods used in optical tomography, and instrumentation and experimental techniques used in optical imaging. The main applications of optical imaging are described in detail, with results from recent literature.

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“…Using established theory [15], the attenuation can be accurately predicted also for double integrating sphere arrangement with diffusor sheets in between. .…”

Section: Energy Ratio Monitoring Investigationsmentioning

confidence: 99%