Correction of Directional Reflectance Measured in the Integrating Sphere

1968 ◽  
Vol 15 (2) ◽  
pp. 139-151 ◽  
Author(s):  
B. Hisdal
Keyword(s):  
Integrating Sphere ◽  
Directional Reflectance

Spectral responses of soybean leaflets crops to different water conditions and tillage systems

Agrometeoros ◽  
2018 ◽  
Vol 26 (1) ◽  
Author(s):  
Tatiana Silva de Almeida ◽  
Denise Cybis Fontana ◽  
Homero Bergamaschi
Keyword(s):  
Water Supply ◽  
Rio Grande ◽  
Incident Radiation ◽  
Conventional Tillage ◽  
Soil Tillage ◽  
Integrating Sphere ◽  
Electromagnetic Spectrum ◽  
Rio Grande Do Sul ◽  
Crop Cycle ◽  
Spectral Responses

The state of Rio Grande do Sul is one of the greatest Brazilian soybean producers, which justifies the use of remote sensing techniques for monitoring areas occupied by this crop. The purpose of this work was to characterize throughout the crop cycle the variability of spectral responses of soybean leaflets, subjected to different conditions of soil tillage and water supply. The experiment was carried out in a 0.5 ha area, located in Eldorado do Sul, Rio Grande do Sul State, southern Brazil, in two systems of soil tillage (no-tillage and conventional tillage) and two levels of water supply (irrigated and non-irrigated). The cultivar Fepagro RS-10 was sown in a row spacing of 0.40 m and in a population of 400,000 plants per hectare. An integrating sphere of a spectroradiometer LI-COR, model LI-1800 was used for measuring the absorbance, reflectance, transmittance on soybean leaflets. The results showed that the pattern of the incident radiation partitioning in the reflectance, transmittance and absorbance components is influenced by the crop phenological stage and by the tillage system. Despite this, there is stability on the reflectance of soybean leaflets in the red and infrared portions of the electromagnetic spectrum, throughout the crop cycle. The inversely proportional relation between absorbance and reflectance of soybean leaflets revealed viability on the reflectance data, in monitoring of agricultural crops.

scholarly journals Process characterization and analysis of ceramic powder bed fusion

2021 ◽  
Author(s):  
Kevin Florio ◽  
Dario Puccio ◽  
Giorgio Viganò ◽  
Stefan Pfeiffer ◽  
Fabrizio Verga ◽  
...  
Keyword(s):  
High Speed ◽  
Ceramic Powder ◽  
Integrating Sphere ◽  
Alumina Powder ◽  
Powder Bed Fusion ◽  
Single Track ◽  
Ceramic Powders ◽  
Pure Alumina ◽  
Powder Bed ◽  
Melt Pool

AbstractPowder bed fusion (PBF) of ceramics is often limited because of the low absorptance of ceramic powders and lack of process understanding. These challenges have been addressed through a co-development of customized ceramic powders and laser process capabilities. The starting powder is made of a mix of pure alumina powder and alumina granules, to which a metal oxide dopant is added to increase absorptance. The performance of different granules and process parameters depends on a large number of influencing factors. In this study, two methods for characterizing and analyzing the PBF process are presented and used to assess which dopant is the most suitable for the process. The first method allows one to analyze the absorptance of the laser during the melting of a single track using an integrating sphere. The second one relies on in-situ video imaging using a high-speed camera and an external laser illumination. The absorption behavior of the laser power during the melting of both single tracks and full layers is proven to be a non-linear and extremely dynamic process. While for a single track, the manganese oxide doped powder delivers higher and more stable absorptance. When a full layer is analyzed, iron oxide-doped powder is leading to higher absorptance and a larger melt pool. Both dopants allow the generation of a stable melt-pool, which would be impossible with granules made of pure alumina. In addition, the present study sheds light on several phenomena related to powder and melt-pool dynamics, such as the change of melt-pool shape and dimension over time and powder denudation effects.

Use of a general purpose integrating sphere as a low intensity near-UV extended uniform light source

Optik ◽  
2021 ◽  
pp. 167169
Author(s):  
Martin Vacula ◽  
Pavel Horvath ◽  
Ladislav Chytka ◽  
Kai Daumiller ◽  
Ralph Engel ◽  
...  
Keyword(s):  
Light Source ◽  
General Purpose ◽  
Integrating Sphere ◽  
Low Intensity

scholarly journals Assessing recent measurement techniques for quantifying black carbon concentration in snow

2012 ◽  
Vol 5 (3) ◽  
pp. 3771-3795 ◽  
Author(s):  
J. P. Schwarz ◽  
S. J. Doherty ◽  
F. Li ◽  
S. T. Ruggiero ◽  
C. E. Tanner ◽  
...  
Keyword(s):  
Black Carbon ◽  
Single Particle ◽  
Carbon Concentration ◽  
Mass Concentration ◽  
Measurement Techniques ◽  
Integrating Sphere ◽  
Recent Measurement ◽  
Atmospheric Sampling ◽  
Careful Assessment ◽  
Snow Samples

Abstract. We evaluate the performance of the Single Particle Soot Photometer (SP2) and the Integrating Sphere/Integrating Sandwich Spectrophotometer (ISSW) in quantifying the concentration of refractory black carbon (BC) in snow samples. We find that the SP2 can be used to measure BC mass concentration in snow with substantially larger uncertainty (60%) than for atmospheric sampling (<30%). Achieving this level of accuracy requires careful assessment of nebulizer performance and SP2 calibration with consideration of the fact that BC in snow tends to larger sizes than typically observed in the atmosphere. Once these issues are addressed, the SP2 is able to measure the size distribution and mass concentration of BC in the snow. Laboratory comparison of the SP2 and the Integrating Sphere/Integrating Sandwich Spectrophotometer (ISSW) revealed significant biases in the estimate of BC concentration from the ISSW when test samples contained dust or non-absorbing particulates. These results suggest that current estimates of BC mass concentration in snow and ice using either the SP2 or the ISSW may be associated with significant underestimates of uncertainty.

scholarly journals Near Infrared Spectroscopy as a Green Technology for the Quality Prediction of Intact Olives

Foods ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1042
Author(s):  
Silvia Grassi ◽  
Olusola Samuel Jolayemi ◽  
Valentina Giovenzana ◽  
Alessio Tugnolo ◽  
Giacomo Squeo ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Olive Oil ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Green Technology ◽  
Soluble Solids ◽  
Integrating Sphere ◽  
Total Phenolic ◽  
Handheld Device ◽  
Quality Design

Poorly emphasized aspects for a sustainable olive oil system are chemical analysis replacement and quality design of the final product. In this context, near infrared spectroscopy (NIRS) can play a pivotal role. Thus, this study aims at comparing performances of different NIRS systems for the prediction of moisture, oil content, soluble solids, total phenolic content, and antioxidant activity of intact olive drupes. The results obtained by a Fourier transform (FT)-NIR spectrometer, equipped with both an integrating sphere and a fiber optic probe, and a Vis/NIR handheld device are discussed. Almost all the partial least squares regression models were encouraging in predicting the quality parameters (0.64 < R2pred < 0.84), with small and comparable biases (p > 0.05). The pair-wise comparison between the standard deviations demonstrated that the FT-NIR models were always similar except for moisture (p < 0.05), whereas a slightly lower performance of the Vis/NIR models was assessed. Summarizing, while on-line or in-line applications of the FT-NIR optical probe should be promoted in oil mills in order to quickly classify the drupes for a better quality design of the olive oil, the portable and cheaper Vis/NIR device could be useful for preliminary quality evaluation of olive drupes directly in the field.

scholarly journals A dual compartment cuvette system for correcting scattering in whole-cell absorbance spectroscopy of photosynthetic microorganisms

2021 ◽  
Author(s):  
John R. D. Hervey ◽  
Paolo Bombelli ◽  
David J. Lea-Smith ◽  
Alan K. Hulme ◽  
Nathan R. Hulme ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Light Scattering ◽  
Integrating Sphere ◽  
Whole Cell ◽  
Absorbance Spectroscopy ◽  
Dual Beam ◽  
Custom Made ◽  
Size And Morphology ◽  
Micro Organisms ◽  
Effect Of Light

AbstractAbsorption spectroscopy is widely used to determine absorption and transmission spectra of chromophores in solution, in addition to suspensions of particles, including micro-organisms. Light scattering, caused by photons deflected from part or all of the cells or other particles in suspension, results in distortions to the absorption spectra, lost information and poor resolution. A spectrophotometer with an integrating sphere may be used to alleviate this problem. However, these instruments are not universally available in biology laboratories, for reasons such as cost. Here, we describe a novel, rapid, and inexpensive technique that minimises the effect of light scattering when performing whole-cell spectroscopy. This method involves using a custom made dual compartment cuvette containing titanium dioxide in one chamber as a scattering agent. Measurements were conducted of a range of different photosynthetic micro-organisms of varying cell size and morphology, including cyanobacteria, eukaryotic microalgae and a purple non-sulphur bacterium. A concentration of 1 mg ml−1 titanium dioxide, using a spectrophotometer with a slit width of 5 nm, produced spectra for cyanobacteria and microalgae similar (1–4% difference) to those obtained using an integrating sphere. The spectrum > 520 nm was similar to that with an integrating sphere with the purple non-sulphur bacterium. This system produced superior results to those obtained using a recently reported method, the application of the diffusing agent, Scotch™ Magic tape, to the side of the cuvette. The protocol can be completed in an equivalent period of time to standard whole-cell absorbance spectroscopy techniques, and is, in principle, suitable for any dual-beam spectrophotometer.

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