New confocal microscopy hyperspectral imager for NIR-emitting bioprobes: high spectral resolution for a wide spectral range (Conference Presentation)

AbstractThe PYTHEAS instrumental concept is an attempt to solve the problem of getting a complete tridimensional coverage of the observed field with a high spectral resolution across a wide spectral range. It is an integral field spectrometer derived from the TIGER spectrograph (field sampling with a microlens array) in which a scanning Fabry-Perot (FP) is introduced. The spectral resolution is given by the F P and the spectral range is that allowed by the grism of TIGER. The information is recorded on the CCD as a set of channeled spectra, for each microlens and each scanning step of the FP. The spectrum of each sampled field element is reconstructed from flux measurement of the Fabry spots defining the channeled spectra.The application ranges of this instrument are reviewed with emphasis on the potential interest in globular cluster studies.

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Study of a High Spectral Resolution Hyperspectral LiDAR in Vegetation Red Edge Parameters Extraction

Remote Sensing ◽

10.3390/rs11172007 ◽

2019 ◽

Vol 11 (17) ◽

pp. 2007 ◽

Cited By ~ 10

Author(s):

Changhui Jiang ◽

Yuwei Chen ◽

Haohao Wu ◽

Wei Li ◽

Hui Zhou ◽

...

Keyword(s):

Spectral Range ◽

Spectral Resolution ◽

Spatial Information ◽

Research Direction ◽

Parameter Extraction ◽

Tunable Filter ◽

High Spectral Resolution ◽

Red Edge ◽

Parameters Extraction ◽

Vegetation Parameter

Non-contact and active vegetation or plant parameters extraction using hyperspectral information is a prospective research direction among the remote sensing community. Hyperspectral LiDAR (HSL) is an instrument capable of acquiring spectral and spatial information actively, which could mitigate the environmental illumination influence on the spectral information collection. However, HSL usually has limited spectral resolution and coverage, which is vital for vegetation parameter extraction. In this paper, to broaden the HSL spectral range and increase the spectral resolution, an Acousto-optical Tunable Filter based Hyperspectral LiDAR (AOTF-HSL) with 10 nm spectral resolution, consecutively covering from 500–1000 nm, was designed. The AOTF-HSL was employed and evaluated for vegetation parameters extraction. “Red Edge” parameters of four different plants with green and yellow leaves were extracted in the lab experiments for evaluating the HSL vegetation parameter extraction capacity. The experiments were composed of two parts. Firstly, the first-order derivative of the spectral reflectance was employed to extract the “Red Edge” position (REP), “Red Edge” slope (RES) and “Red Edge” area (REA) of these green and yellow leaves. The results were compared with the referenced value from a standard SVC© HR-1024 spectrometer for validation. Green leaf parameter differences between HSL and SVC results were minor, which supported that notion the HSL was practical for extracting the employed parameter as an active method. Secondly, another two different REP extraction methods, Linear Four-point Interpolation technology (LFPIT) and Linear Extrapolation technology (LET), were utilized for further evaluation of using the AOTF-HSL spectral profile to determine the REP value. The differences between the plant green leaves’ REP results extracted using the three methods were all below 10%, and the some of them were below 1%, which further demonstrated that the spectral data collected from HSL with this spectral range and resolution settings was applicable for “Red Edge” parameters extraction.

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Quantitative spectral classification of Galactic O stars

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833050 ◽

2018 ◽

Vol 616 ◽

pp. A135 ◽

Cited By ~ 6

Author(s):

F. Martins

Keyword(s):

Spectral Range ◽

Spectral Resolution ◽

Equivalent Width ◽

Classification Criteria ◽

High Spectral Resolution ◽

Spectral Classification ◽

Class V ◽

Luminosity Class ◽

Spectral Class

Our goal is to provide a quantification of several spectral classification criteria for O stars. We collect high-spectral resolution spectra of 105 Galactic O-type stars from various archives. We measured equivalent widths of classification lines. We defined average values of classification criteria for given spectral types and luminosity classes. We find that the ratio He I 4471 to He II 4542 well matches the published ratios for spectral types. We have quantified equivalent width ratios of helium and silicon lines among O8–O9.7 stars to refine spectral class typing in this spectral range. We present quantitative criteria to separate between luminosity class V, IV–III–II (grouped), and I among O3–O8.5 stars, mainly based on the strength of He II 4686. We find that these criteria also define very well the f, (f), and ((f)) classes for O3–O7.5 stars. Among O9–O9.7 stars we quantify the ratios of He II 4686 to He I 4713 and Si IV 4089 to He I 4026 for all luminosity classes. The tabulated values of the classification criteria should help classify any new O-type stars. The final step of the classification process should rely on a direct comparison to standard stars of the assigned spectral type or luminosity class.

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High spectral resolution interferometric planetary observations in the 7–25 μ region

Symposium - International Astronomical Union ◽

10.1017/s007418090010261x ◽

1971 ◽

Vol 40 ◽

pp. 44-47

Author(s):

R. A. Hanel ◽

V. G. Kunde ◽

T. Meilleur ◽

G. Stambach

Keyword(s):

Spectral Range ◽

Spectral Resolution ◽

Thermal Emission ◽

Emission Spectra ◽

Rotational Structure ◽

High Spectral Resolution ◽

The Moon ◽

Broad Absorption ◽

Ratio Spectrum ◽

Venusian Atmosphere

The thermal emission spectra of Venus, Mars, Jupiter, and the moon were observed at the coude focus of the McDonald Observatory 107-inch telescope in the 400–1400 cm−1 spectral range with spectral resolutions of 0.3–0.7 cm−1. A preliminary interpretation of the Venus/lunar ratio spectrum allows identification of four upper state CO2 bands in the Venusian atmosphere at 791, 828, 865, and 961 cm−1 and confirms previous observations of the broad absorption-like depression around 890 cm−1. The rotational structure of the 791 and 961 cm−1 bands is well developed at this spectral resolution.

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A Monolithic Spatial Heterodyne Raman Spectrometer: Initial Tests

Applied Spectroscopy ◽

10.1177/0003702820936643 ◽

2020 ◽

Vol 75 (1) ◽

pp. 57-69

Author(s):

Abigail Waldron ◽

Ashley Allen ◽

Arelis Colón ◽

J. Chance Carter ◽

S. Michael Angel

Keyword(s):

Spectral Range ◽

Spectral Resolution ◽

Signal To Noise Ratio ◽

Focal Length ◽

High Spectral Resolution ◽

Signal To Noise ◽

Free Standing ◽

Raman Spectrometer ◽

Construction Techniques ◽

The Stability

A monolithic spatial heterodyne Raman spectrometer (mSHRS) is described, where the optical components of the spectrometer are bonded to make a small, stable, one-piece structure. This builds on previous work, where we described bench top spatial heterodyne Raman spectrometers (SHRS), developed for planetary spacecraft and rovers. The SHRS is based on a fixed grating spatial heterodyne spectrometer (SHS) that offers high spectral resolution and high light throughput in a small footprint. The resolution of the SHS is not dependent on a slit, and high resolution can be realized without using long focal length dispersing optics since it is not a dispersive device. Thus, the SHS can be used as a component in a compact Raman spectrometer with high spectral resolution and a large spectral range using a standard 1024 element charge-coupled device. Since the resolution of the SHRS is not dependent on a long optical path, it is amenable to the use of monolithic construction techniques to make a compact and robust device. In this paper, we describe the use of two different monolithic SHSs (mSHSs), with Littrow wavelengths of 531.6 nm and 541.05 nm, each about 3.5 × 3.5 × 2.5 cm in size and weighing about 80 g, in a Raman spectrometer that provides ∼3500 cm−1 spectral range with 4–5 cm−1 and 8–9 cm−1 resolution, for 600 grooves/mm and 150 grooves/mm grating-based mSHS devices, respectively. In this proof of concept paper, the stability, spectral resolution, spectral range, and signal-to-noise ratio of the mSHRS spectrometers are compared to our bench top SHRS that uses free-standing optics, and signal to noise comparisons are also made to a Kaiser Holospec f/1.8 Raman spectrometer.

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High spectral resolution ozone absorption cross-sections – Part 2: Temperature dependence

Atmospheric Measurement Techniques ◽

10.5194/amt-7-625-2014 ◽

2014 ◽

Vol 7 (2) ◽

pp. 625-636 ◽

Cited By ~ 143

Author(s):

A. Serdyuchenko ◽

V. Gorshelev ◽

M. Weber ◽

W. Chehade ◽

J. P. Burrows

Keyword(s):

Temperature Dependence ◽

Spectral Range ◽

Cross Sections ◽

Spectral Resolution ◽

Uncertainty Budget ◽

Companion Paper ◽

High Spectral Resolution ◽

Absorption Cross ◽

Ozone Absorption ◽

Section Data

Abstract. We report on the temperature dependence of ozone absorption cross-sections measured in our laboratory in the broad spectral range 213–1100 nm with a spectral resolution of 0.02–0.24 nm (full width at half maximum, FWHM) in the atmospherically relevant temperature range from 193 K to 293 K. The temperature dependence of ozone absorption cross-sections was established using measurements at eleven temperatures. This investigation is superior in terms of spectral range and number of considered temperatures compared to the previous studies. The methodology of the absolute broadband measurements, experimental procedures and spectra processing were described in our companion paper together with the associated uncertainty budget. In this paper, we report in detail on our data below room temperature and compare them with literature data using direct comparisons as well as the standard approach using a quadratic polynomial in temperature fitted to the cross-section data.

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Optical properties of Gobi dust and its pure compounds: experimental extinction spectra and complex refractive indices determination.

10.5194/egusphere-egu21-2115 ◽

2021 ◽

Author(s):

Lise Deschutter ◽

Hervé Herbin ◽

Denis Petitprez

Keyword(s):

Optical Properties ◽

Size Distribution ◽

Spectral Range ◽

Spectral Resolution ◽

High Spectral Resolution ◽

Refractive Indices ◽

Effective Medium Approximation ◽

Extinction Spectra ◽

Pure Compounds ◽

Particle Sizer

Spectrometers are powerful instruments to detect atmospheric aerosols, especially on satellites since they allow measurements at a global scale and over different spectral ranges with high spectral resolution. However, to fully exploit their capabilities and to link optical properties, chemical composition and mass concentration, it is essential to have reference optical properties of various particles and mainly the complex refractive indices (CRI). The CRI of a natural aerosol source can be determined from a real sample of it or applying the effective medium approximation using the CRI of the pure compounds present in the natural sample. But in that case, it is necessary to know the mass fraction of each individual compound and above all their CRI. Nevertheless, the literature and CRI databases provide only reflectance measurements on bulk materials or pressed pellets and over a limited wavelength range (Querry et al., 1987).In the present work, dust from the Gobi desert is studied as it is the second most active dust source, after the Sahara desert, in terms of mass emissions (Querol et al., 2019). For that extinction spectra have been recorded for natural Gobi dust sample and for its major compounds (Illite, Calcite and Quartz). Particles as a powder in a vessel are generated thanks to a magnetic stirring and a flow of nitrogen (Hubert et al., 2017). The continuous flow of aerosols is directed into a 10-meters multipass cell fitted to a Fourier transform infrared spectrometer and a 1-meter singlepass cell within a UV-Visible spectrometer which cover a continuous spectral range from 650 cm-1 to 40000 cm-1. Moreover, at the exit of the spectrometers the size distribution is recorded by an aerodynamic particle sizer and a scanning mobility particle sizer which allow to measure size particles from 14 nm to 20 &#181;m. An inversion algorithm is carried out using experimental extinction spectra and the size distribution as input data (Herbin et al., 2017). Applying the Mie theory and the single subtractive Kramers-Kr&#246;ning integral, the real and the imaginary part of the CRI are retrieved at each wavelength with an optimal estimation method.For the first time, CRI of Illite has been retrieved with a high spectral resolution (1 cm-1) and over a wide spectral range for suspended particles. For calcite and quartz particles, the crystalline phase has to be considered by introducing the ordinary and extraordinary indices. These pure compound sets of CRI will be used for testing effective medium approximation on Gobi dust for which effective CRI have been also retrieved.

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Multilayer Mirror Based High-Resolution Solar Soft X-Ray Spectrometer

Frontiers in Astronomy and Space Sciences ◽

10.3389/fspas.2021.647828 ◽

2021 ◽

Vol 8 ◽

Author(s):

S. S. Panini ◽

S. Narendranath ◽

P. Sreekumar ◽

K. Sankarasubramanian

Keyword(s):

High Resolution ◽

Spectral Range ◽

Spectral Resolution ◽

High Spectral Resolution ◽

High Resolution Spectroscopy ◽

Time Variability ◽

Type I ◽

The Sun ◽

X Rays ◽

X Ray

Soft X-ray spectroscopy of the Sun is an important tool to understand the coronal dynamics and composition. The solar coronal X-ray spectrum below 1 keV is the least explored with high-resolution spectroscopy. Recent observations with Hinode XRT using coarse spectroscopy along with high-resolution imaging have shown that abundances in the coronae have variability associated with structures on the Sun. Disk averaged abundances with better spectral resolution spectrometers show time variability associated with flares. Both spatial and temporal variabilities seem to be related to changes in the magnetic field topology. Understanding such short term variabilities is necessary to model the underlying dynamics and mixing of material between different layers of the Sun. A Sensitive high-resolution spectrometer that covers the range in plasma temperatures and emission line complexes would uniquely reveal the entire evolution of flares. We are investigating a design of a multi-layer mirror-based X-ray spectrograph in the spectral range from 0.5 to 7 keV. The instrument operates in four asynchronous spectral channels operating one at a time. The multi-layer mirror placed at the focus of a Wolter type I telescope reflects a narrow band X-rays to the CCD which is placed at Nasmyth defocus. Converging X-rays from the front end optics helps to increase the spectral range of each channel while preserving the spectral resolution. This design is estimated to achieve a spectral resolution of 20 eV in the spectral range of 0.5–7 keV. With such high spectral resolution, we can resolve individual spectral features e.g., 6.7 keV Fe complex which can be used to diagnose high-temperature transient plasma during flares. The instrument design estimated performance and the science capabilities of this instrument will be discussed in detail in the paper.

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