Nature of light scattering in dental enamel and dentin at visible and near-infrared wavelengths

The complex morphological structure of skin with its variations in the indices of refraction of components therein provides a highly scattering medium for visible and near-infrared wavelengths of light. “Tissue optical clearing” increases transmission of near-collimated light in biological tissue, potentially enabling improved optical analysis and treatment techniques. Numerous methods of tissue optical clearing have been hypothesized using hyperosmostic agents [1]. These methods propose reduction in light scattering by means of dehydration of tissue constituents, replacement of interstitial or intracellular water with higher refractive agents, or structural modification or dissociation of collagen fibers [2]. It has been suggested that dehydration of tissue constituents alone can reduce light scattering by expulsing water between collagen fibrils, increasing protein and sugar concentrations, and decreasing refractive index mismatch [3].

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Electromechanically reconfigurable optical nano-kirigami

Nature Communications ◽

10.1038/s41467-021-21565-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Shanshan Chen ◽

Zhiguang Liu ◽

Huifeng Du ◽

Chengchun Tang ◽

Chang-Yin Ji ◽

...

Keyword(s):

Near Infrared ◽

Large Range ◽

Three Dimensional ◽

High Contrast ◽

Si Substrate ◽

High Modulation ◽

Gold Nanostructure ◽

Infrared Wavelengths ◽

On Chip ◽

Nano Electromechanical System

AbstractKirigami, with facile and automated fashion of three-dimensional (3D) transformations, offers an unconventional approach for realizing cutting-edge optical nano-electromechanical systems. Here, we demonstrate an on-chip and electromechanically reconfigurable nano-kirigami with optical functionalities. The nano-electromechanical system is built on an Au/SiO2/Si substrate and operated via attractive electrostatic forces between the top gold nanostructure and bottom silicon substrate. Large-range nano-kirigami like 3D deformations are clearly observed and reversibly engineered, with scalable pitch size down to 0.975 μm. Broadband nonresonant and narrowband resonant optical reconfigurations are achieved at visible and near-infrared wavelengths, respectively, with a high modulation contrast up to 494%. On-chip modulation of optical helicity is further demonstrated in submicron nano-kirigami at near-infrared wavelengths. Such small-size and high-contrast reconfigurable optical nano-kirigami provides advanced methodologies and platforms for versatile on-chip manipulation of light at nanoscale.

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High Diffraction Efficiency Gratings In Dichromated Gelatin For Near Infrared Wavelengths

10.1117/12.961663 ◽

1989 ◽

Author(s):

F. Chataux ◽

N. Chateau ◽

J. P. Hugonin ◽

J. C. Saget ◽

J. Taboury

Keyword(s):

Diffraction Efficiency ◽

Near Infrared ◽

Dichromated Gelatin ◽

Infrared Wavelengths ◽

High Diffraction Efficiency ◽

High Diffraction

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Spectral characteristics of leafy spurge (Euphorbia esula) leaves and flower bracts

Weed Science ◽

10.1614/ws-03-132r ◽

2004 ◽

Vol 52 (4) ◽

pp. 492-497 ◽

Cited By ~ 17

Author(s):

E. Raymond Hunt ◽

James E. McMurtrey ◽

Amy E. Parker Williams ◽

Lawrence A. Corp

Keyword(s):

Remote Sensing ◽

High Performance ◽

Near Infrared ◽

Spectral Characteristics ◽

Leafy Spurge ◽

Hyperspectral Remote Sensing ◽

Total Carotenoids ◽

Physiological Basis ◽

Infrared Wavelengths ◽

Pigment Concentrations

Leafy spurge can be detected during flowering with either aerial photography or hyperspectral remote sensing because of the distinctive yellow-green color of the flower bracts. The spectral characteristics of flower bracts and leaves were compared with pigment concentrations to determine the physiological basis of the remote sensing signature. Compared with leaves of leafy spurge, flower bracts had lower reflectance at blue wavelengths (400 to 500 nm), greater reflectance at green, yellow, and orange wavelengths (525 to 650 nm), and approximately equal reflectances at 680 nm (red) and at near-infrared wavelengths (725 to 850 nm). Pigments from leaves and flower bracts were extracted in dimethyl sulfoxide, and the pigment concentrations were determined spectrophotometrically. Carotenoid pigments were identified using high-performance liquid chromatography. Flower bracts had 84% less chlorophylla, 82% less chlorophyllb, and 44% less total carotenoids than leaves, thus absorptance by the flower bracts should be less and the reflectance should be greater at blue and red wavelengths. The carotenoid to chlorophyll ratio of the flower bracts was approximately 1:1, explaining the hue of the flower bracts but not the value of reflectance. The primary carotenoids were lutein, β-carotene, and β-cryptoxanthin in a 3.7:1.5:1 ratio for flower bracts and in a 4.8:1.3:1 ratio for leaves, respectively. There was 10.2 μg g−1fresh weight of colorless phytofluene present in the flower bracts and none in the leaves. The fluorescence spectrum indicated high blue, red, and far-red emission for leaves compared with flower bracts. Fluorescent emissions from leaves may contribute to the higher apparent leaf reflectance in the blue and red wavelength regions. The spectral characteristics of leafy spurge are important for constructing a well-documented spectral library that could be used with hyperspectral remote sensing.

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Highly Efficient Near-Infrared Detector Based on Optically Resonant Dielectric Nanodisks

Nanomaterials ◽

10.3390/nano11020428 ◽

2021 ◽

Vol 11 (2) ◽

pp. 428

Author(s):

Reza Masoudian Saadabad ◽

Christian Pauly ◽

Norbert Herschbach ◽

Dragomir N. Neshev ◽

Haroldo T. Hattori ◽

...

Keyword(s):

Quantum Efficiency ◽

High Speed ◽

Near Infrared ◽

Infrared Detector ◽

High Quantum Efficiency ◽

Fast Detection ◽

High Quantum ◽

Resonant Modes ◽

Infrared Wavelengths ◽

Dielectric Metasurface

Fast detection of near-infrared (NIR) photons with high responsivity remains a challenge for photodetectors. Germanium (Ge) photodetectors are widely used for near-infrared wavelengths but suffer from a trade-off between the speed of photodetection and quantum efficiency (or responsivity). To realize a high-speed detector with high quantum efficiency, a small-sized photodetector efficiently absorbing light is required. In this paper, we suggest a realization of a dielectric metasurface made of an array of subwavelength germanium PIN photodetectors. Due to the subwavelength size of each pixel, a high-speed photodetector with a bandwidth of 65 GHz has been achieved. At the same time, high quantum efficiency for near-infrared illumination can be obtained by the engineering of optical resonant modes to localize optical energy inside the intrinsic Ge disks. Furthermore, small junction capacitance and the possibility of zero/low bias operation have been shown. Our results show that all-dielectric metasurfaces can improve the performance of photodetectors.

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Measuring The Tensile Strain of Wood By Visible And Near-Infrared Spatially Resolved Spectroscopy

10.21203/rs.3.rs-570550/v1 ◽

2021 ◽

Author(s):

Ma Te ◽

Tetsuya Inagaki ◽

Masato Yoshida ◽

Mayumi Ichino ◽

Satoru Tsuchikawa

Keyword(s):

Light Scattering ◽

Prediction Accuracy ◽

Tensile Strain ◽

Near Infrared ◽

Mean Squared Error ◽

Calibration Model ◽

Spatially Resolved ◽

Squared Error ◽

Stiffness Evaluation ◽

Spatially Resolved Spectroscopy

Abstract Wood has various mechanical properties, so stiffness evaluation is critical for quality management. Using conventional strain gauges constantly is high cost, also challenging to measure precious wood materials due to the use of strong adhesive. This study demonstrates the correlation between light scattering changes inside the wood cell walls and tensile strain. A multifiber-based visible-near-infrared (Vis–NIR) spatially resolved spectroscopy (SRS) system was designed to rapidly and conventiently acquire such light scattering changes. For the preliminary experiment, samples with different thicknesses were measured to evaluate the influence of thickness. The differences in Vis–NIR SRS spectral data diminish with an increase in sample thickness, which suggests that the SRS method can successfully measure the whole strain (i.e., surface and inside) of wood samples. Then, for the primary experiment, 18 wood samples with the same thickness (2 mm) were tested to construct a strain calibration model. The prediction accuracy was characterized by a determination coefficient (R2) of 0.86 with a root mean squared error (RMSE) of 297.89 με for five-fold cross-validation; for test validation, The prediction accuracy was characterized by an R2 of 0.82 and an RMSE of 345.44 με.

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Biocellulose Masks as Delivery Systems: A Novel Methodological Approach to Assure Quality and Safety

Cosmetics ◽

10.3390/cosmetics5040066 ◽

2018 ◽

Vol 5 (4) ◽

pp. 66 ◽

Cited By ~ 5

Author(s):

Paola Perugini ◽

Mariella Bleve ◽

Fabiola Cortinovis ◽

Antonio Colpani

Keyword(s):

Light Scattering ◽

Bacterial Cellulose ◽

Near Infrared ◽

Gas Permeability ◽

Methodological Approach ◽

Safety Evaluation ◽

Nir Spectroscopy ◽

Quality And Safety ◽

Multiple Light Scattering

Bacterial cellulose (BC) has become of great interest in recent years, as a delivery system in several areas of application, including food, drugs, and cosmetics, thanks to its exclusive advantages, such as high biocompatibility, water holding capacity, and good gas permeability. The novel approach of the authors has led to a protocol for checking the quality and safety of bacterial cellulose matrices in the manufacture of cosmetic masks. Two non-destructive techniques, near-infrared spectroscopy (NIR) and multiple light scattering (MLS), were used to verify different parameters affecting the quality of BC sheets, allowing cellulose masks to be checked over time. NIR spectroscopy allowed for discovering changes in the water content, depending on filling/packaging procedures, like flat-folding. Multiple light scattering was used to ascertain the stability of solutions in contact with masks. From a clinical standpoint, the cutaneous tolerability of biocellulose masks, and their effect on skin parameters, were evaluated through some specific “in vivo” tests. Also, a safety evaluation during application was conducted through different studies: a short-term one after single application, and a long-term one upon continued use.

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Revised SED of the triple protostellar system VLA 1623−2417

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833420 ◽

2018 ◽

Vol 615 ◽

pp. L14 ◽

Cited By ~ 1

Author(s):

N. M. Murillo ◽

D. Harsono ◽

M. McClure ◽

S.-P. Lai ◽

M. R. Hogerheijde

Keyword(s):

Energy Distribution ◽

Near Infrared ◽

Spectral Energy Distribution ◽

Spectral Energy ◽

Gas Emission ◽

Circumstellar Gas ◽

Infrared Wavelengths ◽

Previous Assumption

Context. VLA 1623−2417 is a triple protostellar system deeply embedded in Ophiuchus A. Sources A and B have a separation of 1.1″, making their study difficult beyond the submillimeter regime. Lack of circumstellar gas emission suggested that VLA 1623−2417 B has a very cold envelope and is much younger than source A, which is generally considered the prototypical Class 0 source. Aims. We explore the consequences of new ALMA Band 9 data on the spectral energy distribution (SED) of VLA 1623−2417 and their inferred nature. Methods. We constructed and analyzed the SED of each component in VLA 1623−2417 using dust continuum observations spanning from centimeter to near-infrared wavelengths. Results. The ALMA Band 9 data presented in this work show that the SED of VLA 1623−2417 B does not peak at 850 µm as previously expected, but instead presents the same shape as VLA 1623−2417 A at wavelengths shorter than 450 µm. Conclusions. The results presented in this work indicate that the previous assumption that the flux in Herschel and Spitzer observations is solely dominated by VLA 1623−2417 A is not valid, and instead, VLA 1623−2417 B most likely contributes a significant portion of the flux at λ < 450 µm. These results, however, do not explain the lack of circumstellar gas emission and puzzling nature of VLA 1623−2417 B.

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Bacteriorhodopsin induces a light-scattering change in Halobacterium halobium.

The Journal of Cell Biology ◽

10.1083/jcb.79.3.657 ◽

1978 ◽

Vol 79 (3) ◽

pp. 657-662 ◽

Cited By ~ 3

Author(s):

C L Wey ◽

P L Ahl ◽

R A Cone

Keyword(s):

Absorption Spectrum ◽

Light Scattering ◽

Near Infrared ◽

Action Spectrum ◽

Bright Light ◽

Infrared Region ◽

Halobacterium Halobium ◽

Scattering Response ◽

Near Infrared Region ◽

Hypertonic Shock

When suspensions of Halobacterium halobium are exposed to bright light, the light-scattering properties of the bacteria change. This light-scattering response can produce a transmission decrease of about 1% throughout the red and near-infrared region. The action spectrum for the light-scattering response appropriately matches the absorption spectrum of bacteriorhodopsin. The response is eliminated by cyanide p-trifluoro-methoxyphenylhydrazone, a proton ionophore, and by triphenylmethylphosphonium, a membrane permanent cation. A mild hypertonic shock induces a similar light-scattering change, suggesting that bright light causes the bacteria to shrink about 1% in volume, thereby producing the light-scattering response.

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