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Non-contact scanning at small source-detector separation enables imaging of cerebral and extracranial signals at high spatial resolution and their separation based on early and late photons accounting for the related spatio-temporal characteristics.

A combined optical coherence tomography (OCT)-Raman probe was designed and built into a spectral domain OCT head, and its performance was evaluated and compared to the most common Raman probe setups, based on a fiber bundle and confocal free space optics. Due to the use of the full field of view of an OCT scanning lens, the combined probe has a superior performance within maximum permissible exposure limits, compared to the other two probes. Skin Raman spectra, recorded in vivo, further prove the feasibility of the OCT-Raman probe for the future in vivo clinical applications in skin cancer screening. © 2017 Author(s).

Evanescent wave cavity ring-down spectroscopy (EW-CRDS) has been applied to study, in situ, the deposition kinetics of commercially available gold colloids on functionalized silica surfaces from quiescent solution. Neither 5 nor 20 nm citrate-stabilized nanoparticles were observed to adsorb on clean silica surfaces. Adsorption on a poly-l-lysine-functionalized surface, however, occurs readily and irreversibly with the kinetics of adsorption differing markedly for the two particle sizes studied. 5 nm particles adsorb to form a highly disperse submonolayer of individual particles with atomic force microscope images showing no evidence of aggregation. The controlled growth of multilayer nanoparticle/polyelectrolyte films is demonstrated by alternately depositing colloidal particles and poly-l-lysine films. The deposition of multilayer nanoparticle films increases the sensitivity of the functionalized surface to changes in the solvent refractive index. The adsorption kinetics of the 20 nm colloid is more complex than that of the smaller colloid with adsorbed particles acting as nucleation sites for subsequent aggregation with the result that the interfacial absorbance continues to increase indefinitely with time.

Evanescent wave cavity ring-down spectroscopy (EW-CRDS) has been used to study the interaction of the tris(2,2'-bipyridine)ruthenium(II) complex, [Ru(bpy)(3)](2+), at both native silica surfaces and surfaces modified with polyelectrolyte films. Both poly-l-lysine (PLL) and PLL/poly-l-glutamic acid (PGA) bilayer functionalized interfaces have been studied. Concentration isotherms exhibit Langmuir-type adsorption behavior on both silica and PGA-terminated surfaces from which equilibrium constants have been derived. The pH-dependence of the [Ru(bpy)(3)](2+) adsorption to silica and the PLL/PGA film has also been investigated. For the latter substrate, the effective surface pK(a) of the acid groups was found to be 5.5. The effect of supporting electrolyte was also investigated and was shown to have a significant effect on the extent of [Ru(bpy)(3)](2+) adsorption. A thin-layer electrochemical cell arrangement, in which a working electrode was positioned just above the substrate, was used to change the solution pH in a controlled way via the potential-pulsed chronoamperometric oxidation of water. By measuring the optical absorption using EW-CRDS during such experiments, the desorption of [Ru(bpy)(3)](2+) from the surface has been monitored in real time. Experiments were carried out at different cell thicknesses and at various pulse durations. By combining data from the EW-CRDS experiments with fluorescence confocal laser scanning microscopy (CLSM) to determine the pH at the substrate surface, the pK(a) of the PLL/PGA film could be ascertained and was found to agree with the static pH isotherm measurements. These studies provide a platform for the further use of electrochemistry combined with EW-CRDS to investigate dynamic processes at interfaces.

Comparison of optical coherence tomography and high frequency ultrasound B-Scans and a H&E stained histology of a melanocytic nevus. A reliable, fast, and non-invasive determination of melanoma thickness in vivo is highly desirable for clinical dermatology as it may facilitate the identification of surgical melanoma margins, determine if a sentinel node biopsy should be performed or not, and reduce the number of surgical interventions for patients. In this work, optical coherence tomography (OCT) and high frequency ultrasound (HFUS) are evaluated for quantitative in vivo preoperative assessment of the skin infiltration depth of melanocytic tissue. Both methods allow non-invasive imaging of skin at similar axial resolution. Comparison with the Breslow lesion thickness obtained from histopathology revealed that OCT is slightly more precise in terms of thickness determination while HFUS has better contrast. The latter does not require image post-processing, as necessary for the OCT images. The findings of our pilot study suggest that non-invasive OCT and HFUS are able to determine the infiltration depth of lesions like melanocytic nevi or melanomas preoperatively and in vivo with a precision comparable to invasive histopathology measurements on skin biopsies. In future, to further strengthen our findings a statistically significant study comprising a larger amount of data is required which will be conducted in an extended clinical study in the next step.

Melanoma skin cancer has one of the highest mortality rates of all types of cancer if not detected at an early stage. The survival rate is highly dependent on its penetration depth, which is commonly determined by histopathology. In this work, we aim at combining optical coherence tomography and optoacoustic as a non-invasive all-optical method to measure the penetration depth of melanoma. We present our recent achievements to setup a handheld multimodal device and also results from first in vivo measurements on healthy and cancerous skin tissue, which are compared to measurements obtained by ultrasound and histopathology. © 2016 SPIE.

An evanescent wave variant of broadband cavity enhanced absorption spectroscopy using a supercontinuum light source has been used to detect electrogenerated species at the silica-water interface. In proof-of-concept experiments [IrCl6]2− was produced by electro-oxidation of [IrCl6]3− in a thin layer electrochemical cell. Diffusion of the Ir(IV) across the cell to a silica interface was monitored yielding real-time concentrations within an evanescent field region at the interface. The optical response was compared with the electrochemical response during chronoamperometric step and cyclic voltammetric experiments and both were simulated by finite element modeling. The experiment is highly sensitive to interfacial processes and its wide spectral width and fast time resolution make it a potentially powerful tool for in situ spectroscopic monitoring of processes and intermediates in dynamical electrochemistry. Keywords: Spectroelectrochemistry, Interfacial absorbance, Broadband cavity enhanced absorption, Supercontinuum radiation

We present a system for non-contact time-resolved diffuse reflectance imaging, based on small source-detector distance and high dynamic range measurements utilizing a fast-gated single-photon avalanche diode. The system is suitable for imaging of diffusive media without any contact with the sample and with a spatial resolution of about 1 cm at 1 cm depth. In order to objectively assess its performances, we adopted two standardized protocols developed for time-domain brain imagers. The related tests included the recording of the instrument response function of the setup and the responsivity of its detection system. Moreover, by using liquid turbid phantoms with absorbing inclusions, depth-dependent contrast and contrast-to-noise ratio as well as lateral spatial resolution were measured. To illustrate the potentialities of the novel approach, the characteristics of the non-contact system are discussed and compared to those of a fiber-based brain imager.

The application of evanescent wave cavity ring-down spectroscopy (EW-CRDS) in monitoring electrogenerated species within a thin-layer electrochemical cell is demonstrated. In the proof-of-concept experiments described, ferricyanide, Fe(CN)6(3-), was produced by the transport-limited oxidation of ferrocyanide, Fe(CN)6(4-), in a thin-layer solution cell (25-250 microm) formed between an electrode and the hypotenuse of a fused-silica prism. The prism constituted one element of a high-finesse optical cavity arranged in a triangular ring geometry with light being totally internally reflected at the silica/solution interface. The cavity was pumped with the output (approximately 417 nm) of a single-mode external cavity diode laser, which was continuously scanned across the cavity modes. The presence of electrogenerated ferricyanide within the resulting evanescent field, beyond the optical interface, was detected by the enhanced loss of light trapped within the cavity, as measured by the characteristic cavity ring down. In this way, the EW-CRDS technique is sensitive to absorption in only the first few hundred nanometers of solution above the silica surface. The cavity ring-down response accompanying both cyclic voltammetric and step potential chronoamperometry experiments at a variety of electrode-surface distances is presented, and the results are shown to be well reproduced in modeling by finite element methods. The studies herein thus provide a foundation for further applications of EW-CRDS combined with electrochemistry.

A fast Fourier transform (FFT) method for analysis of ring-down decays from a cavity ring-down (CRD) spectrometer has been tested and compared with alternative fitting methods. The ring-down times derived from the FFT method are obtained with a precision close to that of the Levenberg–Marquardt non-linear least-squares method, but the fitting algorithm is ~100 times faster, allowing real-time fitting of individual ring-down traces on a personal computer. Advantages of the FFT method are discussed, and the method is demonstrated for the measurement of NO2 partial pressures equivalent to mixing ratios of 150 pptv and above in laboratory air, using a CRD spectrometer based on an external cavity diode laser operating at wavelengths around 410 nm. The absorption by NO2 is distinguished from other cavity losses either by using synthetic (zero) air reference samples, or by diverting the sampled laboratory airflow through an NO2 chemical scrubber consisting of hydroxyapatite on a TiO2 substrate. Typical mixing ratios of NO2 in the laboratory air are ~25 ppbv.

The detection of NO2 at sub part per billion by volume (ppbv) concentrations has been demonstrated using a cavity ring-down spectrometer with a blue diode laser operating at wavelengths close to 410 nm. Measurements at peaks in the absorption spectrum at wavelengths of 410.4955 and 410.3533 nm demonstrate a minimum detectable number density of NO2 of 9.8×109 molecules cm−3, which would correspond to 0.4 ppbv under atmospheric conditions in the lower troposphere. Additional experiments performed with a pulsed, tuneable dye laser system provide absorption cross-sections for NO2 over the restricted wavelength ranges of 408.5–410.5 and 435.0–435.5 nm, but at a resolution of ∼ 0.06 cm −1 that is higher than previously reported and close to the Doppler broadening limit at 295 K. These spectra show considerably more structure than is evident in published Fourier transform (FT) spectra obtained at lower resolution, but yield cross-sections that are in quantitative agreement with the FT measurements.

A new multimodal system for rapid, noninvasive in vivo skin cancer screening is presented, combining optical coherence tomography (OCT) and optoacoustic (OA) modalities to provide precise tumor depth determination with a Raman spectroscopic modality capable of detecting the lesion type and, thus, providing diagnostic capability. Both OA and Raman setups use wide field skin illumination to ensure the compliance with maximum permissible exposure (MPE) requirements. The Raman signal is collected via the OCT scanning lens to maximize the signal-to-noise ratio of the measured signal while keeping radiation levels below MPE limits. OCT is used to optically determine the tumor thickness and for volumetric imaging whereas OA utilizes acoustic signals generated by optical absorption contrast for thickness determination at potentially higher penetration depths compared to OCT. Preliminary results of first clinical trials using our setup are presented. The measured lesion depth is in good agreement with histology results, while Raman measurements show distinctive differences between normal skin and melanocytic lesions, and, moreover, between different skin areas. In future, we will validate the setup presented for reliable detection of pathophysiological parameters, morphology and thickness of suspicious skin lesions.

We propose a simple and reliable solid phantom for mimicking realistic localized absorption changes within a diffusive medium. The phantom is based on a solid matrix holding a movable black inclusion embedded in a rod. Translating the rod parallel to the phantom surface, the inhomogeneity can be positioned beneath the source-detector pair (perturbed case) or far from it (unperturbed case). Examples of time-resolved transmittance measurements and time-resolved reflectance scans are shown to demonstrate the properties and the versatility of the phantom.

We developed a novel scanning system that relies on gated detection of late photons at short source-detector separation, enabling the recording of absorption changes in deep tissue compartments. The tissue was scanned by a galvanometer scanner from a distance of more than 10 cm, with a fixed separation of the illumination and the detection spot of a few mm. The light source was a supercontinuum laser with an acousto-optic tunable filter that was used to rapidly switch between two wavelength bands centered at 760 nm and 860 nm. A fast-gated single-photon avalanche diode was employed to eliminate the intense early part of the diffusely remitted signal and to detect photons with long times of flight with improved signal-to-noise ratio. A second detection channel contained a non-gated detector. The gated and non-gated time-of-flight distributions of photons were recorded by imaging time-correlated single photon counting synchronized with the movement of the scanner. A tissue area with dimensions of several cm was scanned with 32×32 pixels within a frame time of 1 s. Sensitivity and spatial resolution of the system were characterized by phantom measurements. In-vivo tests included functional brain activation by various tasks and demonstrated the feasibility of non-contact imaging of hemodynamic changes in the cerebral cortex.

The nEUROPt protocol is one of two new protocols developed within the European project nEUROPt to characterize the performances of time-domain systems for optical imaging of the brain. It was applied in joint measurement campaigns to compare the various instruments and to assess the impact of technical improvements. This protocol addresses the characteristic of optical brain imaging to detect, localize, and quantify absorption changes in the brain. It was implemented with two types of inhomogeneous liquid phantoms based on Intralipid and India ink with well-defined optical properties. First, small black inclusions were used to mimic localized changes of the absorption coefficient. The position of the inclusions was varied in depth and lateral direction to investigate contrast and spatial resolution. Second, two-layered liquid phantoms with variable absorption coefficients were employed to study the quantification of layer-wide changes and, in particular, to determine depth selectivity, i.e., the ratio of sensitivities for deep and superficial absorption changes. We introduce the tests of the nEUROPt protocol and present examples of results obtained with different instruments and methods of data analysis. This protocol could be a useful step toward performance tests for future standards in diffuse optical imaging. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.

We present the experimental implementation and validation of a phantom for diffuse optical imaging based on totally absorbing objects for which, in the previous paper [J. Biomed. Opt. 18(6), 066014, (2013)], we have provided the basic theory. Totally absorbing objects have been manufactured as black polyvinyl chloride (PVC) cylinders and the phantom is a water dilution of intralipid-20% as the diffusive medium and India ink as the absorber, filled into a black scattering cell made of PVC. By means of time-domain measurements and of Monte Carlo simulations, we have shown the reliability, the accuracy, and the robustness of such a phantom in mimicking typical absorbing perturbations of diffuse optical imaging. In particular, we show that such a phantom can be used to generate any absorption perturbation by changing the volume and position of the totally absorbing inclusion. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.

A multi-center study has been set up to accurately characterize the optical properties of diffusive liquid phantoms based on Intralipid and India ink at near-infrared (NIR) wavelengths. Nine research laboratories from six countries adopting different measurement techniques, instrumental set-ups, and data analysis methods determined at their best the optical properties and relative uncertainties of diffusive dilutions prepared with common samples of the two compounds. By exploiting a suitable statistical model, comprehensive reference values at three NIR wavelengths for the intrinsic absorption coefficient of India ink and the intrinsic reduced scattering coefficient of Intralipid-20% were determined with an uncertainty of about 2% or better, depending on the wavelength considered, and 1%, respectively. Even if in this study we focused on particular batches of India ink and Intralipid, the reference values determined here represent a solid and useful starting point for preparing diffusive liquid phantoms with accurately defined optical properties. Furthermore, due to the ready availability, low cost, long-term stability and batch-to-batch reproducibility of these compounds, they provide a unique fundamental tool for the calibration and performance assessment of diffuse optical spectroscopy instrumentation intended to be used in laboratory or clinical environment. Finally, the collaborative work presented here demonstrates that the accuracy level attained in this work for optical properties of diffusive phantoms is reliable. © 2014 Optical Society of America.

Novel protocols were developed and applied in the European project “nEUROPt” to assess and compare the performance of instruments for time-domain optical brain imaging and of related methods of data analysis. The objective of the first protocol, “Basic Instrumental Performance”, was to record relevant basic instrumental characteristics in a direct way. The present paper focuses on the second novel protocol (“nEUROPt” protocol) that was devoted to the assessment of sensitivity, spatial resolution and quantification of absorption changes within inhomogeneous media. It was implemented with liquid phantoms based on Intralipid and ink, with black inclusions and, alternatively, in two-layered geometry. Small black cylinders of various sizes were used to mimic small localized changes of the absorption coefficient. Their position was varied in depth and lateral direction to address contrast and spatial resolution. Two-layered liquid phantoms were used, in particular, to determine depth selectivity, i.e. the ratio of contrasts due to a deep and a superficial absorption change of the same magnitude. We introduce the tests of the “nEUROPt” protocol and present exemplary results obtained with various instruments. The results are related to measurements with both types of phantoms and to the analysis of measured time-resolved reflectance based on time windows and moments. Results are compared for the different instruments or instrumental configurations as well as for the methods of data analysis. The nEUROPt protocol is also applicable to cw or frequency-domain instruments and could be useful for designing performance tests in future standards in diffuse optical imaging.

Using Monte Carlo simulations we demonstrate that a realistic absorption inhomogeneity embedded in a diffusive medium can be effectively mimicked by a small black object of a proper volume (Equivalence Relation). Applying this concept we propose the construction of simple and well reproducible inhomogeneous phantoms.

We present a simple and efficient Monte Carlo model to predict the scattering coefficients and the influence of multiple photon scattering with increasing concentration of scattering centers from optical coherence tomography (OCT) data. While the model reliably estimates optical sample parameters for a broad range of concentrations, it does not require inclusion of more complex phenomena such as dependent scattering. Instead, it relies on a particular weighting function which is introduced to describe various orders of multiple scattering events. In weakly scattering homogeneous media the measured scattering coefficient depends linearly on the concentration of scattering centers. In the case of strong scattering, the dependence becomes nonlinear. Our model is able to accurately predict this nonlinearity and can be applied to extend the OCT studies of biological tissue towards determination of optical properties in the future.

We report on the development and proof-of-principle tests of a scanning non-contact tissue imaging system for time-domain NIRS applications. The system is based on the null source-detector separation approach and a state-of-the-art fast-gated SPAD.

To facilitate the design and optimization of instruments for time-domain optical brain imaging within the European project "nEUROPt", the performance of various instruments is assessed and compared. This type of instruments relies on picosecond lasers with high repetition rates, fast detectors and time-correlated single photon counting. The first step of the assessment included a number of basic tests that are related to parameters of the source, to the differential nonlinearity of the timing electronics and to the temporal instrument response function (IRF). An additional test has been devised to measure the responsivity of the detection system, i.e. the overall efficiency to collect and detect light emerging from tissue. Dedicated solid slab phantoms have been developed and quantitatively spectrally characterized to provide sources of known radiance with nearly Lambertian angular characteristics. The wavelength-dependent transmittance factor of these phantoms was of the order of 10 20 /(W s m 2 sr). Measurements of the responsivity of the detection systems of three time-domain optical brain imagers tested yielded similar values of the order of 0.1 mm 2 sr.

We report on the development of a scanning non-contact brain imager, based on a novel technique in time-resolved near-infrared spectroscopy, i.e. the null source-detector distance approach. Our concept is designed to image an area of about 10 cm2 with small adjustable scanning steps, i.e. a high density of mapping points can be realized. The feasibility of the proposed method was tested with a single-point confocal optical setup without beam scanning so far. A set of test measurements was performed on a liquid phantom with a small black polyvinyl chloride (PVC) cylinder as a target, which was translated in X direction to emulate the optical scanning and estimate lateral spatial resolution, and in Z direction to estimate the depth sensitivity of the instrument. The problem of dominance of early photons at null source- detector separation was solved by applying a fast time-gated detector to detect late only photons. Two fast-gated detectors, a newly developed state-of-art time-gated single-photon avalanche photodiode (tgSPAD) and commercially available fast-gated intensified CCD (iCCD) camera, were compared against each other. It was shown that, due to its better dynamic range, the tgSPAD is capable to detect later photons than the iCCD camera, and hence, a scanning system equipped with the time-gated SPAD has better depth sensitivity. Thus the time-gated SPAD is the detector of choice for further development of the non-contact confocal brain scanner.

A multi-laboratory study for the accurate calibration of diffusive liquid phantoms based on Intralipid and Indian ink has been performed. Different techniques, instrumental set-ups and analysis methods led to compatible values for optical properties.

Performance assessment of instruments devised for clinical applications is of key importance for validation and quality assurance. Two new protocols were developed and applied to facilitate the design and optimization of instruments for time-domain optical brain imaging within the European project nEUROPt. Here, we present the "Basic Instrumental Performance" protocol for direct measurement of relevant characteristics. Two tests are discussed in detail. First, the responsivity of the detection system is a measure of the overall efficiency to detect light emerging from tissue. For the related test, dedicated solid slab phantoms were devel- oped and quantitatively spectrally characterized to provide sources of known radiance with nearly Lambertian angular characteristics. The responsivity of four time-domain optical brain imagers was found to be of the order of 0.1 m 2 sr. The relevance of the responsivity measure is demonstrated by simulations of diffuse reflectance as a function of source-detector separation and optical properties. Second, the temporal instrument response func- tion (IRF) is a critically important factor in determining the performance of time-domain systems. Measurements of the IRF for various instruments were combined with simulations to illustrate the impact of the width and shape of the IRF on contrast for a deep absorption change mimicking brain activation. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original

We report on the design and first in vivo tests of a novel non-contact scanning imaging system for time-domain near-infrared spectroscopy. Our system is based on a null source-detector separation approach and utilizes polarization-selective detection and a fast-gated single-photon avalanche diode to record late photons only. The in-vivo tests included the recording of hemodynamics during arm occlusion and two brain activation tasks. Localized and non-localized changes in oxy- and deoxyhemoglobin concentration were detected for motor and cognitive tasks, respectively. The tests demonstrate the feasibility of non-contact imaging of absorption changes in deeper tissues.

We report results of the proof-of-principle tests of a novel non-contact tissue imaging system. The system utilizes a quasi-null source-detector separation approach for time-domain near-infrared spectroscopy, taking advantage of an innovative state-of-the-art fast-gated single photon counting detector. Measurements on phantoms demonstrate the feasibility of the non-contact approach for the detection of optically absorbing perturbations buried up to a few centimeters beneath the surface of a tissue-like turbid medium. The measured depth sensitivity and spatial resolution of the new system are close to the values predicted by Monte Carlo simulations for the inhomogeneous medium and an ideal fast-gated detector, thus proving the feasibility of the non-contact approach for high density diffuse reflectance measurements on tissue. Potential applications of the system are also discussed. © 2011 Optical Society of America.

Continuous wave (cw) diode lasers are increasingly being used as light sources in the visible and near-IR regions of the spectrum for cavity ring-down spectroscopy (CRDS) and cavity enhanced absorption spectroscopy (CEAS); the latter technique is also widely known as integrated cavity output spectroscopy (ICOS). The very high sensitivities to weak absorptions that are possible with cw CRDS and CEAS, coupled with the quantitative nature of the absorption measurements, are enabling a rapidly expanding range of applications. We review the benefits and practical implementation of these techniques; methods of data analysis for extraction of quantitative absorption data; the sensitivities of cw CRDS and CEAS, and how they might be optimised; and applications of cw CRDS and CEAS in molecular spectroscopy, atmospheric chemistry, plasma and flame chemistry, analytical science, and medical diagnosis via breath analysis. The development of CRDS and CEAS techniques exploiting cw diode lasers and, very recently, high luminosity light-emitting diodes, has stimulated a wealth of high-sensitivity measurements. Highlights include quantitative measurement of various ultra-trace gases such as: NO3, NO2 and ethene in ambient air samples; CO2 isotopologues, ethane and other organic compounds in human breath samples; and excited electronic states of N2 and O2 in plasmas and discharges. Exciting developments include wavelength extension into the mid-IR and UV regions, and use of novel locked-cavity techniques to increase data acquisition rates and sensitivities.

Melanoma skin cancer is one of the most lethal types of cancer due to comparably early development of metastasis. As preventative medical check-up, optical inspection using polarized light (dermoscopy) is the gold standard in medical practise. If a lesion is diagnosed to be suspicious, it is subsequently excised by a surgeon and analysed by means of histopathology. However, optical inspection so far is hardly capable to reliably distinguish between healthy and cancerous tissue leading to large amounts of lesions which are unnecessarily excised. In addition, if cancerous tissue is confirmed by histopathology, additional skin is removed within defined safety margins to prevent spreading of metastasis [1]. These safety margins are chosen according to the penetration depth of the melanoma, which to date cannot be determined prior to the first surgical intervention.

A novel protocol to determine sensitivity, spatial resolution and quantification of absorption changes in optical brain imaging was applied to assess time-domain instruments and methods of data analysis.

We present results of first in-vivo tests of an optical non-contact scanning imaging system, intended to study oxidative metabolism related processes in biological tissue by means of time-resolved near-infrared spectroscopy. Our method is a novel realization of the short source-detector separation approach and based on a fast-gated single-photon avalanche diode to detect late photons only. The scanning system is built in quasi-confocal configuration and utilizes polarizationsensitive detection. It scans an area of 4×4 cm2, recording images with 32×32 pixels, thus creating a high density of source-detector pairs. To test the system we performed a range of in vivo measurements of hemodynamic changes in several types of biological tissues, i.e. skin (Valsalva maneuver), muscle (venous and arterial occlusions) and brain (motor and cognitive tasks). Task-related changes in hemoglobin concentrations were clearly detected in skin and muscle. The brain activation shows weaker, but yet detectable changes. These changes were localized in pixels near the motor cortex area (C3). However, it was found that even very short hair substantially impairs the measurement. Thus the applicability of the scanner is limited to hairless parts of body. The results of our first in-vivo tests prove the feasibility of non-contact scanning imaging as a first step towards development of a prototype for biological tissue imaging for various medical applications.

Intrinsic reduced scattering coefficient of Intralipid and intrinsic absorption coefficient of Indian ink at NIR wavelengths are accurately assessed in a multi-center study involving different techniques, instrumental set-ups, and analysis methods.