scholarly journals Ultrasensitive multispecies spectroscopic breath analysis for real-time health monitoring and diagnostics

2021 ◽  
Vol 118 (40) ◽  
pp. e2105063118
Author(s):  
Qizhong Liang ◽  
Ya-Chu Chan ◽  
P. Bryan Changala ◽  
David J. Nesbitt ◽  
Jun Ye ◽  
...  
Keyword(s):  
Frequency Comb ◽  
Breath Analysis ◽  
Detection Sensitivity ◽  
High Spectral Resolution ◽  
Noninvasive Diagnostics ◽  
Spectral Signatures ◽  
Experimental Apparatus ◽  
Monitoring And Diagnostics ◽  
The Individual ◽  
High Finesse

Breath analysis enables rapid, noninvasive diagnostics, as well as long-term monitoring of human health, through the identification and quantification of exhaled biomarkers. Here, we demonstrate the remarkable capabilities of mid-infrared (mid-IR) cavity-enhanced direct-frequency comb spectroscopy (CE-DFCS) applied to breath analysis. We simultaneously detect and monitor as a function of time four breath biomarkers—CH3OH, CH4, H2O, and HDO—as well as illustrate the feasibility of detecting at least six more (H2CO, C2H6, OCS, C2H4, CS2, and NH3) without modifications to the experimental apparatus. We achieve ultrahigh detection sensitivity at the parts-per-trillion level. This is made possible by the combination of the broadband spectral coverage of a frequency comb, the high spectral resolution afforded by the individual comb teeth, and the sensitivity enhancement resulting from a high-finesse cavity. Exploiting recent advances in frequency comb, optical coating, and photodetector technologies, we can access a large variety of biomarkers with strong carbon–hydrogen-bond spectral signatures in the mid-IR.

Generation of stable and tunable optical frequency linked to a radio frequency by use of a high finesse cavity and its application in absorption spectroscopy

2022 ◽  
Author(s):  
Yueting Zhou ◽  
Gang Zhao ◽  
Jianxin Liu ◽  
Xiaojuan Yan ◽  
Zhixin Li ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Absorption Spectroscopy ◽  
Frequency Comb ◽  
External Cavity ◽  
Frequency Instability ◽  
Laser Frequency ◽  
Detection Sensitivity ◽  
Optical Frequency ◽  
Direct Absorption Spectroscopy ◽  
High Finesse

Abstract The laser frequency could be linked to an radio frequency through an external cavity by the combination of Pound-Drever-Hall and Devoe-Brewer locking techniques. A stable and tunable optical frequency at wavelength of 1.5 μm obtained by a cavity with high finesse of 96,000 and a fiber laser, calibrated by a commercial optical frequency comb, has been demonstrated. The locking performances have been analyzed by in-loop and out-loop noises, indicating that the absolute frequency instability could be down to 50 kHz over 1 s and keep to less than 110 kHz over 2.5 h. Then, the application of this stabilized laser to the direct absorption spectroscopy has been performed. With the help of balanced detection, the detection sensitivity, in terms of optical density, can reach to 9.4×10-6.

scholarly journals A New Crop Spectral Signatures Database Interactive Tool (CSSIT)

Data ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 77 ◽  
Author(s):  
Mohamad M. Awad ◽  
Bassem Alawar ◽  
Rana Jbeily
Keyword(s):  
Eastern Mediterranean ◽  
Decision Makers ◽  
High Spectral Resolution ◽  
High Temporal Resolution ◽  
Growth Stages ◽  
Area Index ◽  
Spectral Signatures ◽  
Agriculture Sector ◽  
Interactive Tool ◽  
Physical And Chemical

In many countries, commodities provided by the agriculture sector play an important role in the economy. Securing food is one aspect of this role, which can be achieved when the decision makers are supported by tools. The need for cheap, fast, and accurate tools with high temporal resolution and global coverage has encouraged the decision makers to use remote sensing technologies. Field spectroradiometer with high spectral resolution can substantially improve crop mapping by reducing similarities between different crop types that have similar ecological conditions. This is done by recording fine details of the crop interaction with sunlight. These details can increase the same crop recognition even with the variation in the crop chemistry and structure. This paper presents a new spectral signatures database interactive tool (CSSIT) for the major crops in the Eastern Mediterranean Basin such as wheat and potato. The CSSIT’s database combines different data such as spectral signatures for different periods of crop growth stages and many physical and chemical parameters for crops such as leaf area index (LAI) and chlorophyll-a content (CHC). In addition, the CSSIT includes functions for calculating indices from spectral signatures for a specific crop and user interactive dialog boxes for displaying spectral signatures of a specific crop at a specific period of time.

scholarly journals Spatially resolving the thermally inhomogeneous outer atmosphere of the red giant Arcturus in the 2.3 μm CO lines

2018 ◽  
Vol 620 ◽  
pp. A23 ◽  
Author(s):  
K. Ohnaka ◽  
C. A. L. Morales Marín
Keyword(s):  
Spectral Resolution ◽  
Column Density ◽  
High Spectral Resolution ◽  
Molecular Gas ◽  
Very Large Telescope ◽  
Extended Component ◽  
Outer Atmosphere ◽  
Red Giant ◽  
The Individual ◽  
Photospheric Model

Aim. The outer atmosphere of K giants shows thermally inhomogeneous structures consisting of the hot chromospheric gas and the cool molecular gas. We present spectro-interferometric observations of the multicomponent outer atmosphere of the well-studied K1.5 giant Arcturus (α Boo) in the CO first overtone lines near 2.3 μm. Methods. We observed Arcturus with the AMBER instrument at the Very Large Telescope Interferometer (VLTI) at 2.28–2.31 μm with a spectral resolution of 12 000 and at projected baselines of 7.3, 14.6, and 21.8 m. Results. The high spectral resolution of the VLTI/AMBER instrument allowed us to spatially resolve Arcturus in the individual CO lines. Comparison of the observed interferometric data with the MARCS photospheric model shows that the star appears to be significantly larger than predicted by the model. It indicates the presence of an extended component that is not accounted for by the current photospheric models for this well-studied star. We found out that the observed AMBER data can be explained by a model with two additional CO layers above the photosphere. The inner CO layer is located just above the photosphere, at 1.04 ± 0.02 R⋆, with a temperature of 1600 ± 400 K and a CO column density of 1020 ± 0.3 cm−2. On the other hand, the outer CO layer is found to be as extended as to 2.6 ± 0.2 R⋆ with a temperature of 1800 ± 100 K and a CO column density of 1019 ± 0.15 cm−2. Conclusions. The properties of the inner CO layer are in broad agreement with those previously inferred from the spatially unresolved spectroscopic analyses. However, our AMBER observations have revealed that the quasi-static cool molecular component extends out to 2–3 R⋆, within which region the chromospheric wind steeply accelerates.

scholarly journals Cavity-enhanced optical frequency comb spectroscopy: application to human breath analysis

2008 ◽  
Vol 16 (4) ◽  
pp. 2387 ◽  
Author(s):  
Michael J. Thorpe ◽  
David Balslev-Clausen ◽  
Matthew S. Kirchner ◽  
Jun Ye
Keyword(s):  
Frequency Comb ◽  
Breath Analysis ◽  
Optical Frequency Comb ◽  
Optical Frequency ◽  
Human Breath

scholarly journals VAHCOLI, a new concept for lidars: technical setup, science applications, and first measurements

2021 ◽  
Vol 14 (5) ◽  
pp. 3815-3836
Author(s):  
Franz-Josef Lübken ◽  
Josef Höffner
Keyword(s):  
Middle Atmosphere ◽  
Statistical Tests ◽  
Resonance Scattering ◽  
Field Conditions ◽  
High Spectral Resolution ◽  
High Temporal Resolution ◽  
Stratified Turbulence ◽  
Height Range ◽  
Night And Day ◽  
The Individual

Abstract. A new concept for a cluster of compact lidar systems named VAHCOLI (Vertical And Horizontal COverage by LIdars) is presented, which allows for the measurement of temperatures, winds, and aerosols in the middle atmosphere (∼ 10–110 km) with high temporal and vertical resolution of minutes and some tens of meters, respectively, simultaneously covering horizontal scales from a few hundred meters to several hundred kilometers (“four-dimensional coverage”). The individual lidars (“units”) being used in VAHCOLI are based on a diode-pumped alexandrite laser, which is currently designed to detect potassium (λ=770 nm), and on sophisticated laser spectroscopy measuring all relevant frequencies (seeder laser, power laser, backscattered light) with high temporal resolution (2 ms) and high spectral resolution applying Doppler-free spectroscopy. The frequency of the lasers and the narrowband filter in the receiving system are stabilized to typically 10–100 kHz, which is a factor of roughly 10−5 smaller than the Doppler-broadened Rayleigh signal. Narrowband filtering allows for the measurement of Rayleigh and/or resonance scattering separately from the aerosol (Mie) signal during both night and day. Lidars used for VAHCOLI are compact (volume: ∼ 1 m3) and multi-purpose systems which employ contemporary electronic, optical, and mechanical components. The units are designed to autonomously operate under harsh field conditions in remote locations. An error analysis with parameters of the anticipated system demonstrates that temperatures and line-of-sight winds can be measured from the lower stratosphere to the upper mesosphere with an accuracy of ±(0.1–5) K and ±(0.1–10) m s−1, respectively, increasing with altitude. We demonstrate that some crucial dynamical processes in the middle atmosphere, such as gravity waves and stratified turbulence, can be covered by VAHCOLI with sufficient temporal, vertical, and horizontal sampling and resolution. The four-dimensional capabilities of VAHCOLI allow for the performance of time-dependent analysis of the flow field, for example by employing Helmholtz decomposition, and for carrying out statistical tests regarding, for example, intermittency and helicity. The first test measurements under field conditions with a prototype lidar were performed in January 2020. The lidar operated successfully during a 6-week period (night and day) without any adjustment. The observations covered a height range of ∼ 5–100 km and demonstrated the capability and applicability of this unit for the VAHCOLI concept.

scholarly journals Design of an Active Multispectral SWIR Camera System for Skin Detection and Face Verification

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Holger Steiner ◽  
Sebastian Sporrer ◽  
Andreas Kolb ◽  
Norbert Jung
Keyword(s):  
Face Recognition ◽  
Imaging System ◽  
Short Wave ◽  
Classification Performance ◽  
High Spectral Resolution ◽  
Face Verification ◽  
Camera System ◽  
Spectral Signatures ◽  
Face Images ◽  
Small Band

Biometric face recognition is becoming more frequently used in different application scenarios. However, spoofing attacks with facial disguises are still a serious problem for state of the art face recognition algorithms. This work proposes an approach to face verification based on spectral signatures of material surfaces in the short wave infrared (SWIR) range. They allow distinguishing authentic human skin reliably from other materials, independent of the skin type. We present the design of an active SWIR imaging system that acquires four-band multispectral image stacks in real-time. The system uses pulsed small band illumination, which allows for fast image acquisition and high spectral resolution and renders it widely independent of ambient light. After extracting the spectral signatures from the acquired images, detected faces can be verified or rejected by classifying the material as “skin” or “no-skin.” The approach is extensively evaluated with respect to both acquisition and classification performance. In addition, we present a database containing RGB and multispectral SWIR face images, as well as spectrometer measurements of a variety of subjects, which is used to evaluate our approach and will be made available to the research community by the time this work is published.

scholarly journals Ultrafast optical pulse shaping using dielectric metasurfaces

Science ◽  
2019 ◽  
Vol 364 (6443) ◽  
pp. 890-894 ◽  
Author(s):  
Shawn Divitt ◽  
Wenqi Zhu ◽  
Cheng Zhang ◽  
Henri J. Lezec ◽  
Amit Agrawal
Keyword(s):  
Pulse Shaping ◽  
Near Infrared ◽  
Ultrafast Lasers ◽  
Frequency Comb ◽  
High Spectral Resolution ◽  
High Peak Power ◽  
Pulse Modulation ◽  
Ultrafast Optical ◽  
Large Bandwidth ◽  
Optical Pulse Shaping

Advances in ultrafast lasers, chirped pulse amplifiers, and frequency comb technology require fundamentally new pulse-modulation strategies capable of supporting unprecedentedly large bandwidth and high peak power while maintaining high spectral resolution. We demonstrate how dielectric metasurfaces can be leveraged to shape the temporal profile of a near-infrared femtosecond pulse. Finely tailored pulse-shaping operations, including splitting, compression, chirping, and higher-order distortion, are achieved using a Fourier-transform setup embedding metasurfaces able to manipulate, simultaneously and independently, the amplitude and phase of the constituent frequency components of the pulse. Exploiting metasurfaces to manipulate the temporal characteristics of light expands their impact and opens new vistas in the field of ultrafast science and technology.

scholarly journals Spectral signatures of submicron scale light-absorbing impurities in snow and ice using hyperspectral microscopy

2018 ◽  
Vol 64 (245) ◽  
pp. 377-386 ◽  
Author(s):  
ANNA DAL FARRA ◽  
SUSAN KASPARI ◽  
JAMES BEACH ◽  
THOMAS D. BUCHELI ◽  
MICHAEL SCHAEPMAN ◽  
...  
Keyword(s):  
New Method ◽  
Average Deviation ◽  
Spectral Signatures ◽  
Relative Contribution ◽  
Heterogeneous Samples ◽  
Small Influence ◽  
Submicron Scale ◽  
The Individual ◽  
Good Agreement ◽  
Snow And Ice

ABSTRACTLight-absorbing impurities (LAI) can darken snow and ice surfaces, reduce snow/ice albedo and accelerate melt. Efforts to allocate the relative contribution of different LAI to snow/ice albedo reductions have been limited by uncertainties in the optical properties of LAI. We developed a new method to measure LAI spectral reflectance at the submicron scale by modifying a Hyperspectral Imaging Microscope Spectrometer (HIMS). We present the instrument's internal calibration, and the overall small influence of a particle's orientation on its measured reflectance spectrum. We validated this new method through the comparison with a field spectroradiometer by measuring different standard materials. Measurements with HIMS at the submicron scale and the bulk measurements of the same standard materials with the field spectroradiometer are in good agreement with an average deviation between the spectra of 3.2% for the 400–1000 nm wavelength range. The new method was used (1) to identify BC (black carbon), mineral dust including hematite and the humic substances present in an environmental sample from Plaine Morte glacier and (2) to collect the individual reflectance spectra of each of these types of impurity. The results indicate that this method is applicable to heterogeneous samples such as the LAI found in snow and ice.

scholarly journals Note on rotational-Raman scattering in the O<sub>2</sub> A- and B-bands: implications for retrieval of trace-gas concentrations and terrestrial chlorophyll fluorescence

2012 ◽  
Vol 5 (6) ◽  
pp. 8789-8813 ◽  
Author(s):  
A. Vasilkov ◽  
J. Joiner ◽  
R. Spurr
Keyword(s):  
Chlorophyll Fluorescence ◽  
Raman Scattering ◽  
Spectral Resolution ◽  
High Spectral Resolution ◽  
Trace Gas ◽  
Absorption Bands ◽  
Spectral Signatures ◽  
The Impact ◽  
Compare And Contrast ◽  
Aerosol Characterization

Abstract. Quantifying the impact of rotational Raman scattering (RRS) on the O2 A- and B-bands is important as these bands can be used for cloud- and aerosol-characterization for trace-gas retrievals including CO2 and CH4. In this paper, we simulate the spectral effects of RRS for various viewing geometries and instruments with different spectral resolutions. We also examine how aerosols affect the amount of RRS filling-in. We show that the filling-in effects of RRS are relatively small, but not negligible, in these O2 absorption bands, particularly for high spectral resolution instruments. For comparison, we also compare and contrast the spectral signatures of RRS with those of terrestrial chlorophyll fluorescence.

scholarly journals The formation of planetary systems with SPICA

2021 ◽  
Vol 38 ◽  
Author(s):  
I. Kamp ◽  
M. Honda ◽  
H. Nomura ◽  
M. Audard ◽  
D. Fedele ◽  
...  
Keyword(s):  
Solar System ◽  
European Space Agency ◽  
Planetary Systems ◽  
Relevant Information ◽  
Space Mission ◽  
Detection Sensitivity ◽  
High Spectral Resolution ◽  
General Process ◽  
Infrared Telescope ◽  
Ice Content

Abstract In this era of spatially resolved observations of planet-forming disks with Atacama Large Millimeter Array (ALMA) and large ground-based telescopes such as the Very Large Telescope (VLT), Keck, and Subaru, we still lack statistically relevant information on the quantity and composition of the material that is building the planets, such as the total disk gas mass, the ice content of dust, and the state of water in planetesimals. SPace Infrared telescope for Cosmology and Astrophysics (SPICA) is an infrared space mission concept developed jointly by Japan Aerospace Exploration Agency (JAXA) and European Space Agency (ESA) to address these questions. The key unique capabilities of SPICA that enable this research are (1) the wide spectral coverage $10{-}220\,\mu\mathrm{m}$ , (2) the high line detection sensitivity of $(1{-}2) \times 10^{-19}\,\mathrm{W\,m}^{-2}$ with $R \sim 2\,000{-}5\,000$ in the far-IR (SAFARI), and $10^{-20}\,\mathrm{W\,m}^{-2}$ with $R \sim 29\,000$ in the mid-IR (SPICA Mid-infrared Instrument (SMI), spectrally resolving line profiles), (3) the high far-IR continuum sensitivity of 0.45 mJy (SAFARI), and (4) the observing efficiency for point source surveys. This paper details how mid- to far-IR infrared spectra will be unique in measuring the gas masses and water/ice content of disks and how these quantities evolve during the planet-forming period. These observations will clarify the crucial transition when disks exhaust their primordial gas and further planet formation requires secondary gas produced from planetesimals. The high spectral resolution mid-IR is also unique for determining the location of the snowline dividing the rocky and icy mass reservoirs within the disk and how the divide evolves during the build-up of planetary systems. Infrared spectroscopy (mid- to far-IR) of key solid-state bands is crucial for assessing whether extensive radial mixing, which is part of our Solar System history, is a general process occurring in most planetary systems and whether extrasolar planetesimals are similar to our Solar System comets/asteroids. We demonstrate that the SPICA mission concept would allow us to achieve the above ambitious science goals through large surveys of several hundred disks within $\sim\!2.5$ months of observing time.

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