Design of an integrating sphere as a uniform illumination source

1997 ◽  
Vol 40 (2) ◽  
pp. 131-134 ◽  
Author(s):  
A. Ducharme ◽  
A. Daniels ◽  
E. Grann ◽  
G. Boreman
Keyword(s):  
Integrating Sphere ◽  
Uniform Illumination ◽  
Illumination Source

scholarly journals Silicon Lens Optimization to Create Diffuse, Uniform Illumination from Incoherent THz Source Arrays

2021 ◽  
Author(s):  
Robin Zatta ◽  
Daniel Headland ◽  
Eamal Ashna ◽  
Ritesh Jain ◽  
Philipp Hillger ◽  
...  
Keyword(s):  
Integrated Circuit ◽  
Radiation Power ◽  
Thz Radiation ◽  
Far Field ◽  
Uniform Illumination ◽  
Silicon Lens ◽  
Thz Sources ◽  
Source Array ◽  
Illumination Source ◽  
Thz Power

AbstractArrays of terahertz (THz) sources provide a pathway to overcoming the radiation power limitations of single sources. Several independent sources of THz radiation may be implemented in a single integrated circuit, thereby realizing a monolithic THz source array of high output power. Integrated THz sources must generally be backside-coupled to extended hemispherical dielectric lenses in order to suppress substrate modes and extract THz power. However, this lens also increases antenna gain and thereby produces several non-overlapping beams. This is because individual source pixels are relatively large. Hence, their spatial separation on-chip translates to angular separation in the far-field. In other words, there are gaps in their field of view into which very little THz power is projected. Therefore, they cannot homogeneously illuminate an imaging target. This article presents a simple, practical, and scalable method to convert arrays of incoherent THz sources into a diffuse, uniform illumination source without the need for reducing pixel size. Briefly, individual beam divergence is optimized by tailoring the dimensions of the extended hemispherical dielectric lens such that the far-field beams of adjacent source pixels overlap and combine to form a uniform far-field beam. We applied this method to an incoherent 8 × 8-pixel THz source array radiating 10.3 dBm at 0.42 THz as a proof of concept and thereby realized a 10.3-dBm 0.42-THz diffuse, uniform illumination source that was then deployed in a demonstration of THz active imaging.

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.

Subsurface imaging for panel paintings inspection: A comparative study of the ultraviolet, the visible, the infrared and the terahertz spectra

2015 ◽  
Vol 23 (1) ◽  
Author(s):  
A. Bendada ◽  
S. Sfarra ◽  
C. Ibarra−Castanedo ◽  
M. Akhloufi ◽  
J.−P. Caumes ◽  
...  
Keyword(s):  
Subsurface Imaging ◽  
Wide Spread ◽  
Ir Thermography ◽  
Complementary Information ◽  
Ir Sensors ◽  
The World ◽  
Panel Paintings ◽  
Temperature Maps ◽  
Illumination Source ◽  
Ir Reflectography

AbstractInfrared (IR) reflectography has been used for many years for the detection of underdrawings on panel paintings. Advances in the fields of IR sensors and optics have impelled the wide spread use of IR reflectography by several recognized Art Museums and specialized laboratories around the World. The transparency or opacity of a painting is the result of a complex combination of the optical properties of the painting pigments and the underdrawing material, as well as the type of illumination source and the sensor characteristics. For this reason, recent researches have been directed towards the study of multispectral approaches that could provide simultaneous and complementary information of an artwork. The present work relies on non−simultaneous multispectral inspection using a set of detectors covering from the ultraviolet to the terahertz spectra. It is observed that underdrawings contrast increases with wavelength up to 1700 nm and, then, gradually decreases. In addition, it is shown that IR thermography, i.e., temperature maps or thermograms, could be used simultaneously as an alternative technique for the detection of underdrawings besides the detection of subsurface defects.

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.

scholarly journals Camera-based localization microscopy optimized with calibrated structured illumination

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Martin Schmidt ◽  
Adam C. Hundahl ◽  
Henrik Flyvbjerg ◽  
Rodolphe Marie ◽  
Kim I. Mortensen
Keyword(s):  
Data Analysis ◽  
Super Resolution ◽  
Wide Field ◽  
Structured Illumination ◽  
Uniform Illumination ◽  
Localization Microscopy ◽  
Localization And Tracking ◽  
Field Imaging ◽  
Wide Field Imaging ◽  
Localization Information

AbstractUntil very recently, super-resolution localization and tracking of fluorescent particles used camera-based wide-field imaging with uniform illumination. Then it was demonstrated that structured illuminations encode additional localization information in images. The first demonstration of this uses scanning and hence suffers from limited throughput. This limitation was mitigated by fusing camera-based localization with wide-field structured illumination. Current implementations, however, use effectively only half the localization information that they encode in images. Here we demonstrate how all of this information may be exploited by careful calibration of the structured illumination. Our approach achieves maximal resolution for given structured illumination, has a simple data analysis, and applies to any structured illumination in principle. We demonstrate this with an only slightly modified wide-field microscope. Our protocol should boost the emerging field of high-precision localization with structured illumination.

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.

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