Backscattering properties of topographic targets in the visible, shortwave infrared, and mid-infrared spectral ranges for hard-target lidars

Abstract. Far-infrared (FIR: 100cm-1<wavenumber, ν<667 cm−1) radiation emitted by the Earth and its atmosphere plays a key role in the Earth's energy budget. However, because of a lack of spectrally resolved measurements, radiation schemes in climate models suffer from a lack of constraint across this spectral range. Exploiting a method developed to estimate upwelling far-infrared radiation from mid-infrared (MIR: 667cm-1<ν<1400 cm−1) observations, we explore the possibility of inferring zenith FIR downwelling radiances in zenith-looking observation geometry, focusing on clear-sky conditions in Antarctica. The methodology selects a MIR predictor wavenumber for each FIR wavenumber based on the maximum correlation seen between the different spectral ranges. Observations from the REFIR-PAD instrument (Radiation Explorer in the Far Infrared – Prototype for Application and Development) and high-resolution radiance simulations generated from co-located radio soundings are used to develop and assess the method. We highlight the impact of noise on the correlation between MIR and FIR radiances by comparing the observational and theoretical cases. Using the observed values in isolation, between 150 and 360 cm−1, differences between the “true” and “extended” radiances are less than 5 %. However, in spectral bands of low signal, between 360 and 667 cm−1, the impact of instrument noise is strong and increases the differences seen. When the extension of the observed spectra is performed using regression coefficients based on noise-free radiative transfer simulations the results show strong biases, exceeding 100 % where the signal is low. These biases are reduced to just a few percent if the noise in the observations is accounted for in the simulation procedure. Our results imply that while it is feasible to use this type of approach to extend mid-infrared spectral measurements to the far-infrared, the quality of the extension will be strongly dependent on the noise characteristics of the observations. A good knowledge of the atmospheric state associated with the measurements is also required in order to build a representative regression model.

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Semiconductor light sources for near- and mid-infrared spectral ranges

Journal of Physics Conference Series ◽

10.1088/1742-6596/917/2/022003 ◽

2017 ◽

Vol 917 ◽

pp. 022003

Author(s):

L Ya Karachinsky ◽

A V Babichev ◽

A G Gladyshev ◽

D V Denisov ◽

A V Filimonov ◽

...

Keyword(s):

Light Sources ◽

Mid Infrared ◽

Infrared Spectral ◽

Spectral Ranges

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Influence of moon and clouds on night illumination in two different spectral ranges

Scientific Reports ◽

10.1038/s41598-021-98060-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jürgen Krieg

Keyword(s):

Cloud Cover ◽

The Moon ◽

Artificial Lighting ◽

Artificial Illumination ◽

Infrared Spectral ◽

Night Sky ◽

Spectral Ranges ◽

Shortwave Infrared ◽

Night Illumination ◽

Insight Into

AbstractThe variable brightness of the night sky affects plants as well as animals and humans. However, knowledge about this variability is still insufficient. Outstanding questions regarding how significant the influence of the moon, clouds, and artificial lighting remain. To be able to make statements about these effects, measurements over a long period of time are necessary. Fraunhofer IOSB performs such measurements in the 380–780 nm photopic visual and 800–1700 nm shortwave infrared spectral range. As the latter is only marginally affected by artificial lighting, a comparison of the two bands deepens insight into the influence of artificial lighting. First analyses show that the moon is, as expected, the dominant light source in the night sky, especially during a full moon. Illuminance values up to 200 mlx and irradiance values up to 600 µW/m2 were measured in the visible and infrared respectively. The influence of clouds is more complicated. The measured intensities depend, among other things, on cloud cover and cloud altitude. When the night sky is overcast, the measured intensities can drop as low as 0.5 mlx and 0.5 µW/m2, respectively. These small values were measured during rainfall. The influence of artificial illumination is difficult to estimate, as intensities in the shortwave infrared decrease with increasing cloud cover, but increase in the visual.

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Unveiling the composition of historical plastics through non-invasive reflection FT-IR spectroscopy in the extended near- and mid-Infrared spectral range

Analytica Chimica Acta ◽

10.1016/j.aca.2021.338602 ◽

2021 ◽

pp. 338602

Author(s):

Francesca Rosi ◽

Costanza Miliani ◽

Peter Gardner ◽

Annalisa Chieli ◽

Aldo Romani ◽

...

Keyword(s):

Ir Spectroscopy ◽

Spectral Range ◽

Mid Infrared ◽

Non Invasive ◽

Infrared Spectral Range ◽

Infrared Spectral ◽

Ft Ir ◽

Ft Ir Spectroscopy

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Integrated Optical Phased Arrays for Beam Forming and Steering

Applied Sciences ◽

10.3390/app11094017 ◽

2021 ◽

Vol 11 (9) ◽

pp. 4017

Author(s):

Yongjun Guo ◽

Yuhao Guo ◽

Chunshu Li ◽

Hao Zhang ◽

Xiaoyan Zhou ◽

...

Keyword(s):

Near Infrared ◽

Phased Arrays ◽

Mechanical Stability ◽

Building Blocks ◽

High Yield ◽

Beam Forming ◽

Integrated Optical ◽

Optical Phased Arrays ◽

Infrared Spectral ◽

Spectral Ranges

Integrated optical phased arrays can be used for beam shaping and steering with a small footprint, lightweight, high mechanical stability, low price, and high-yield, benefiting from the mature CMOS-compatible fabrication. This paper reviews the development of integrated optical phased arrays in recent years. The principles, building blocks, and configurations of integrated optical phased arrays for beam forming and steering are presented. Various material platforms can be used to build integrated optical phased arrays, e.g., silicon photonics platforms, III/V platforms, and III–V/silicon hybrid platforms. Integrated optical phased arrays can be implemented in the visible, near-infrared, and mid-infrared spectral ranges. The main performance parameters, such as field of view, beamwidth, sidelobe suppression, modulation speed, power consumption, scalability, and so on, are discussed in detail. Some of the typical applications of integrated optical phased arrays, such as free-space communication, light detection and ranging, imaging, and biological sensing, are shown, with future perspectives provided at the end.

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Submicron structures for nonlinear photonics in the mid-infrared spectral range

2013 International Conference on Advanced Optoelectronics and Lasers (CAOL 2013) ◽

10.1109/caol.2013.6657607 ◽

2013 ◽

Author(s):

E.A. Romanova ◽

A.I. Konyukhov ◽

E.V. Borisov ◽

D.S. Zhivotkov

Keyword(s):

Spectral Range ◽

Mid Infrared ◽

Infrared Spectral Range ◽

Infrared Spectral ◽

Submicron Structures ◽

Nonlinear Photonics

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Application Of Systems With Total Internal Reflection At Novosibirsk Free Electron Laser For Spectroscopy In The Terahertz Range

Siberian Journal of Physics ◽

10.54362/1818-7919-2016-11-3-72-82 ◽

2016 ◽

Vol 11 (3) ◽

pp. 72-82

Author(s):

Vasily Gerasimov ◽

Elvira Grigorieva ◽

Boris Knyazev ◽

Yuliya Choporova

Keyword(s):

Free Electron ◽

Free Electron Laser ◽

Quantum Cascade Lasers ◽

Attenuated Total Reflection ◽

Terahertz Range ◽

Optical Systems ◽

Early Diagnosis Of Cancer ◽

Infrared Spectral ◽

Atr Spectroscopy ◽

Spectral Ranges

Attenuated total reflection (ATR) spectroscopy is widely used in the visible and infrared spectral ranges. Progress in the development of laboratory scale monochromatic sources of terahertz radiation, such as quantum cascade lasers, suggests that in the near future this kind of spectrometers will be widely spread in the terahertz range. For this reason, the development of ATR based methods and devices is highly relevant. In this paper, we discuss the features of the use of ATR spectroscopy in the terahertz range, and describe some of the optical systems, designed for experiments at the Novosibirsk free electron laser (NovoFEL). We show that in the terahertz range the ATR spectroscopy has a number of significant advantages over the absorption spectroscopy. As an example, we are discussing the possibility of using terahertz polarimetry to develop a method for early diagnosis of cancer via the detection of left-handed to right-handed polysaccharide enantiomers ratio. Spectra of selected polysaccharides were recorded with a standard Fourier spectrometer using developed by us an ATR unit. The possibility of studying the polarization characteristics of polysaccharides in aqueous solutions using spectrally selective polarimeter with the NovoFEL as a tunable radiation source was demonstrated.

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Aerosol retrieval from multiangle, multispectral photopolarimetric measurements: importance of spectral range and angular resolution

Atmospheric Measurement Techniques ◽

10.5194/amt-8-2625-2015 ◽

2015 ◽

Vol 8 (6) ◽

pp. 2625-2638 ◽

Cited By ~ 36

Author(s):

L. Wu ◽

O. Hasekamp ◽

B. van Diedenhoven ◽

B. Cairns

Keyword(s):

Refractive Index ◽

Spectral Range ◽

Angular Resolution ◽

Single Scattering ◽

Microphysical Properties ◽

Aerosol Retrieval ◽

Spectral Ranges ◽

Shortwave Infrared ◽

Aerosol Properties ◽

Good Agreement

Abstract. We investigated the importance of spectral range and angular resolution for aerosol retrieval from multiangle photopolarimetric measurements over land. For this purpose, we use an extensive set of simulated measurements for different spectral ranges and angular resolutions and subsets of real measurements of the airborne Research Scanning Polarimeter (RSP) carried out during the PODEX and SEAC4RS campaigns over the continental USA. Aerosol retrievals performed from RSP measurements show good agreement with ground-based AERONET measurements for aerosol optical depth (AOD), single scattering albedo (SSA) and refractive index. Furthermore, we found that inclusion of shortwave infrared bands (1590 and/or 2250 nm) significantly improves the retrieval of AOD, SSA and coarse mode microphysical properties. However, accuracies of the retrieved aerosol properties do not improve significantly when more than five viewing angles are used in the retrieval.

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