Fluorescence and reflectance measurements in the ultraviolet, visible, and near infrared using delta-doped silicon arrays with custom coating for medical applications (Conference Presentation)

2017 ◽  
Author(s):  
Samuel R. Cheng ◽  
Dana K. Budzyn ◽  
Shouleh Nikzad
Keyword(s):  
Near Infrared ◽  
Medical Applications ◽  
Doped Silicon ◽  
Silicon Arrays ◽  
Reflectance Measurements

Identification of powdery mildew (Erysiphe graminis sp. tritici) and take-all disease (Gaeumannomyces graminis sp. tritici) in wheat (Triticum aestivum L.) by means of leaf reflectance measurements

2006 ◽  
Vol 1 (2) ◽  
pp. 275-288 ◽  
Author(s):  
Simone Graeff ◽  
Johanna Link ◽  
Wilhelm Claupein
Keyword(s):  
Powdery Mildew ◽  
Disease Severity ◽  
Near Infrared ◽  
Plant Stress ◽  
Stress Factors ◽  
Gaeumannomyces Graminis ◽  
Disease Assessment ◽  
Leaf Reflectance ◽  
Reflectance Measurements ◽  
Take All

AbstractThe ability to identify diseases in an early infection stage and to accurately quantify the severity of infection is crucial in plant disease assessment and management. A greenhouse study was conducted to assess changes in leaf spectral reflectance of wheat plants during infection by powdery mildew and take-all disease to evaluate leaf reflectance measurements as a tool to identify and quantify disease severity and to discriminate between different diseases. Wheat plants were inoculated under controlled conditions in different intensities either with powdery mildew or take-all. Leaf reflectance was measured with a digital imager (Leica S1 Pro, Leica, Germany) under controlled light conditions in various wavelength ranges covering the visible and the near-infrared spectra (380–1300 nm). Leaf scans were evaluated by means of L*a*b*-color system. Visual estimates of disease severity were made for each of the epidemics daily from the onset of visible symptoms to maximum disease severity. Reflectance within the ranges of 490780 nm (r2 = 0.69), 510780nm (r2 = 0.74), 5161300nm (r2 = 0.62) and 5401300 nm (r2 = 0.60) exhibited the strongest relationship with infection levels of both powdery mildew and take-all disease. Among the evaluated spectra the range of 490780nm showed most sensitive response to damage caused by powdery mildew and take-all infestation. The results of this study indicated that disease detection and discrimination by means of reflectance measurements may be realized by the use of specific wavelength ranges. Further studies have to be carried out, to discriminate powdery mildew and take-all infection from other plant stress factors in order to develop suitable decision support systems for site-specific fungicide application.

Analysis of Forest Foliage Spectra Using a Multivariate Mixture Model

1997 ◽  
Vol 5 (3) ◽  
pp. 167-173 ◽  
Author(s):  
Christine A. Hlavka ◽  
David L. Peterson ◽  
Lee F. Johnson ◽  
Barry Ganapol
Keyword(s):  
Mixture Model ◽  
Near Infrared ◽  
Photon Absorption ◽  
Chemical Measurements ◽  
Near Infrared Spectra ◽  
Photon Absorption And Scattering ◽  
Linear Mixture Model ◽  
Wet Chemical ◽  
Nitrogen Bonds ◽  
Reflectance Measurements

Wet chemical measurements and near infrared spectra of dry ground leaf samples were analysed to test a multivariate regression technique for estimating component spectra. The technique is based on a linear mixture model for log(1/ R) pseudoabsorbance derived from diffuse reflectance measurements. The resulting unmixed spectra for carbohydrates, lignin and protein resemble the spectra of extracted plant carbohydrates, lignin and protein. The unmixed protein spectrum has prominent absorption peaks at wavelengths that have been associated with nitrogen bonds. It therefore appears feasible to incorporate the linear mixture model in whole leaf models of photon absorption and scattering so that effects of varying nitrogen and carbon concentration on leaf reflectance may be simulated.

scholarly journals Spectroscopy in heterogenous media and applications for bioprocess and environmental monitoring

2002 ◽  
Vol 4 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Frank Schael ◽  
Oliver Reich ◽  
Sonja Engelhard
Keyword(s):  
Diffuse Reflectance ◽  
Near Infrared ◽  
Transport Theory ◽  
Radiation Transport ◽  
Diffusion Theory ◽  
Nile Blue ◽  
Milk Powder ◽  
Photon Migration ◽  
Heterogenous Media ◽  
Reflectance Measurements

Diffuse reflectance measurements and photon migration studies with near infrared (NIR) diode lasers were employed to elucidate experimental methods for determining absorption and scattering coefficients and species concentrations in heterogenous media. Measurements were performed at a number of wavelengths utilizing several laser sources some of which were widely tunable. In order to establish the applicability of simple photon migration models derived from radiation transport theory and to check the experimental boundary conditions of our measurements, simple light scattering solutions (such as suspensions of titanium dioxide, latex particles, and solutions of milk powder) containing dyes (such as nile blue, isosulfan blue) were investigated. The results obtained from diffuse-reflectance studies at different sourcedetector distances were in accordance with predictions from simple photon diffusion theory. Applications of reflectance measurements for monitoring of cell growth during fermentation processes and forin-situinvestigations of soils are presented.

scholarly journals NIR reflective pigments to mitigate the urban heat islands effect (UHIE)

2020 ◽  
Vol 172 ◽  
pp. 03006
Author(s):  
Andrea Rosati ◽  
Michele Fedel ◽  
Stefano Rossi
Keyword(s):  
Near Infrared ◽  
Sol Gel ◽  
Colorimetric Method ◽  
Urban Heat Islands ◽  
Brown Pigment ◽  
Heat Islands ◽  
Outdoor Environments ◽  
Different Temperatures ◽  
Urban Heat ◽  
Reflectance Measurements

For building applications, coatings are needed in order to obtain an attractive appearance and protection against the outdoor environments. Buildings are responsible for consumption of cooling energy. Cool coatings applied over buildings surface provide an effective solution for passive cooling of building indoors and influencing local outdoor microclimate, mitigating urban heat islands effect (UHIE). Cool coatings have to resistant to weathering and ageing. For this reason, we developed near infrared (NIR) reflective pigments with the aim to add in binder and obtaining a cool coating. A series of pigments displaying YIn0.9Mn0.1O3–ZnO stoichiometry was synthesized by sol-gel route. The dried gel precursor was calcined at different temperatures for 2h (650°C, 800°C and 850°C) to observe the formation of a light brown pigment and two different blue shades. Precursors and calcined final pigments were characterized by using physicochemical analyses. The colour of pigments was studied using CIE-2004 L*a*b* colorimetric method. The cooling effect of pigments and their thermal stability were confirmed by NIR reflectance measurements and TGA respectively.

scholarly journals Factors that Affect the Quality and Quantity of Sunlight Reflected from Alfalfa Canopies

Plant Disease ◽  
2001 ◽  
Vol 85 (8) ◽  
pp. 865-874 ◽  
Author(s):  
J. Guan ◽  
F. W. Nutter
Keyword(s):  
Near Infrared ◽  
Unit Area ◽  
Incident Radiation ◽  
Leaf Wetness ◽  
Small Range ◽  
Negative Effects ◽  
Infrared Wavelength ◽  
Visible Wavelength ◽  
Plant Canopies ◽  
Reflectance Measurements

Experiments were conducted from 1997 to 2000 in Ames and Nashua, IA, to quantify the effects of incident radiation, sun angle, leaf wetness, and sensor height on the quality and quantity of sunlight reflected from alfalfa canopies using a hand-held, multispectral radiometer. Incident radiation had negligible effects on the percentage of sunlight reflected from alfalfa canopies in the visible wavelength bands (460 to 710 nm) and significant negative effects on the percentage of sunlight reflected from alfalfa canopies in the near-infrared wavelength bands (760 and 810 nm). Percentage reflectance values (810 nm) decreased between 0.20 and 0.32% for each 100 watts m-2 increase in incident radiation. Percentage reflectance values in all wavelength bands obtained prior to 1100 h and after 1500 h CST were significantly higher than reflectance measurements obtained between 1100 h and 1500 h. The presence of moisture on leaves (leaf wetness) significantly increased percentage reflectance for all wavelength bands. Sensor height had variable effects on percentage reflectance in all wavelength bands. This variability was most likely due to changes in the heterogeneity of alfalfa canopies with increasing sensor height. In experiments conducted with more homogenous canopies (oat and turfgrass), sensor height had no significant effect on the percentage of sunlight reflected from these canopies. To minimize the effects of all of the above nondisease factors on the measurement of percentage of sunlight reflected from crop canopies, we recommend that percentage reflectance measurements be obtained between 1100 and 1500 h when plant canopies are dry, with a constant sensor height (sampling unit area), and within a small range of incident radiation for all measurements.

scholarly journals Retrieval of Dust Properties From Spectral Snow Reflectance Measurements

2021 ◽  
Vol 9 ◽  
Author(s):  
Alexander Kokhanovsky ◽  
Biagio Di Mauro ◽  
Roberto Garzonio ◽  
Roberto Colombo
Keyword(s):  
Grain Size ◽  
Mass Concentration ◽  
Diffuse Reflectance ◽  
Near Infrared ◽  
Spectroscopy Data ◽  
Field Spectroscopy ◽  
Dust Mass ◽  
The Alps ◽  
Simplified Algorithm ◽  
Reflectance Measurements

In this paper, we present a simplified algorithm to retrieve snow grain size, dust mass absorption coefficient and dust mass concentration from spectral diffuse reflectance measurements at three wavelengths located in the visible and near infrared. The theoretical model is then compared with field spectroscopy data collected in different days from an automated spectrometer in the Alps.

Nano-Structured Silicon: Fabrication, Optical Property, Defect States and Device Application

2019 ◽  
Vol 947 ◽  
pp. 66-70
Author(s):  
Hao Zhong ◽  
Dong Yang Li ◽  
Yu Hao Song ◽  
Wei Li ◽  
Xiang Dong Jiang ◽  
...  
Keyword(s):  
Near Infrared ◽  
Back Surface ◽  
Defect States ◽  
Deep Reactive Ion Etching ◽  
Infrared Wavelength ◽  
Nanostructured Silicon ◽  
Silicon Materials ◽  
Physical Effects ◽  
Silicon Arrays ◽  
Minority Carriers

We use two different methods to fabricate nanostructured silicon on the surface of C-Si: femtosecond laser etching (FLE) and deep reactive ion etching (DRIE) combined with plasma immersion ion implantation (PIII). Nanocone silicon arrays of dense and random distribution are obtained by FLE. Meanwhile, cylindroid silicon nanostructures of excellent regularity and uniform coverage are achieved by DRIE. These nanostructured silicon materials show a remarkable enhancement on absorptance at near-infrared wavelength. Moreover, the minority carriers lifetime measurement is also carried out to evaluate defect states caused by two etching processes and their influence on semiconductor physical effects. A Si-PIN photoelectronic detector with nanostructured silicon at the back surface exhibits high near-infrared responsivity. These novel results may have a potential application in near-infrared photoelectronic devices.

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