scholarly journals Prediction of Particulate Contamination on an Aperture Window

1996 ◽  
Vol 39 (2) ◽  
pp. 42-48
Author(s):  
Aleck Lee ◽  
Michael Fong
Keyword(s):  
Light Scattering ◽  
Incident Light ◽  
Image Analyzer ◽  
Particulate Contamination ◽  
Flight Operations ◽  
Surface Particle ◽  
Particle Counts ◽  
Contaminant Distribution ◽  
Number Of Particles ◽  
Particulate Surface

This paper presents an analysis of light scattering by surface particles on the sensor window of a missile during ascent flight. The particulate contaminant distribution on the window is calculated by tallying the number of particles in a set of size ranges. The particulate contamination at the end of the mission is predicted by adding the contributions from the events of ground and flight operations. The surface particle redistribution caused by vibroacoustic-induced surface acceleration was found to contribute the most to particulate surface contamination. The analytical surface obscuration calculation with a set of particle counts was compared with the results of the image analyzer measurement. The analytical results, which were calculated with a given function of particle shape depending on size, were more conservative than the measurement. A scattering calculation using a verified BSDF model showed that the scattering was less than 0.001 at 20 deg off the direction of the incident light in the mid IR wavelength when the surfaces were at Level 300 initially.

Stress Whitening in Polypropylene. I. Light Scattering Theory and Model Experiments

1995 ◽  
Vol 60 (11) ◽  
pp. 1875-1887 ◽  
Author(s):  
Jaroslav Holoubek ◽  
Miroslav Raab
Keyword(s):  
Refractive Index ◽  
Light Scattering ◽  
Incident Light ◽  
Polymeric Materials ◽  
Wavelength Dependence ◽  
Theoretical Background ◽  
Surrounding Matrix ◽  
Embedded Particles ◽  
The One ◽  
Stress Whitening

Theoretical background for an optical method is presented which makes it possible to distinguish unambiguously between voids and particles as light scattering sites in polymeric materials. Typical dependences of turbidity as a function of diameter of scattering elements, their volume fractions and also turbidity curves as a function of the wavelength of the incident light were calculated, based both on the Lorenz-Mie theory and the fluctuation theory. Such dependences calculated for polypropylene-containing voids on the one hand and particles, differing only slightly from the surrounding matrix in their refractive index, on the other hand, are markedly different. The most significant results are: (i) Turbidity is at least by two orders of magnitude larger for voids in comparison to embedded particles of ethylene-propylene (EPDM) rubber of the same size, concentration and at the same wavelength. (ii) The wavelength dependence of turbidity for EPDM particles and the inherent refractive index fluctuations in the polypropylene matrix is much steeper as compared to voids for all considered diameters (0.1-10 μm). Thus, the nature of stress whitening in complex polymeric materials can be determined from turbidity measurements.

scholarly journals Orientation dependence of optical activity in light scattering by nanoparticle clusters

2022 ◽  
Author(s):  
Atefeh Fazel Najafabadi ◽  
Baptiste Auguié
Keyword(s):  
Optical Properties ◽  
Light Scattering ◽  
Optical Activity ◽  
Incident Light ◽  
Spatial Arrangement ◽  
Orientation Dependence ◽  
Nanoparticle Clusters

The optical properties of nanoparticle clusters vary with the spatial arrangement of the constituent particles, but also the overall orientation of the cluster with respect to the incident light. This...

LIGHT SCATTERING TECHNIQUES FOR DISCRIMINATING BETWEEN OIL AND PARTICULATES IN CONTAMINATED WATER

1977 ◽  
Vol 1977 (1) ◽  
pp. 153-156 ◽  
Author(s):  
Bruce Friedman
Keyword(s):  
Particulate Matter ◽  
Light Scattering ◽  
Intensity Distribution ◽  
Scattered Light ◽  
Incident Light ◽  
Real Life ◽  
The State ◽  
Oil Droplets ◽  
State Of Polarization

ABSTRACT Light scattering techniques are used in several oil-in-water monitors, proposed or in existence. Particulate matter which may interfere with these monitors is also frequently found in oily wastes. An analysis is made of the potential of using measurements of the angular intensity distribution of scattered light in conjunction with determination of the state of polarization of the scattered light for discriminating between oil and particulates. The size conditions which apply to the oil droplets and particulates relative to the incident light allow the scattered light angular intensity distribution to be treated as a consequence of a combination of classical diffraction and of geometrical refraction and reflection. The state of polarization of the scattered light for oil droplets is investigated using expressions for the electric field which are approximations to the expressions of the Mie theory. For the particulate matter, the state of polarization is probed on the basis of light reflected from a plane. It is found that it would be difficult to discriminate between oil and particulates using measurements of the angular intensity distribution of scattered light even in conjunction with the determination of the state of polarization of the scattered light in a real life situation.

scholarly journals Laboratory Study of Physical Barrier Efficiency for Worker Protection against SARS-CoV-2 while Standing or Sitting

2021 ◽  
Author(s):  
Jacob Bartels ◽  
Cheryl Fairfield Estill ◽  
I-Chen Chen ◽  
Dylan Neu
Keyword(s):  
Laboratory Study ◽  
Grocery Stores ◽  
Physical Barrier ◽  
Particle Count ◽  
Engineering Control ◽  
Transparent Barrier ◽  
Particle Counts ◽  
Barrier Efficiency ◽  
Number Of Particles ◽  
Nail Salons

Transparent barriers were installed as a response to the SARS-COV-2 pandemic in many customer-facing industries. Transparent barriers are an engineering control that are utilized to intercept air traveling between customers to workers. Information on the effectiveness of these barriers against aerosols is limited. In this study, a cough simulator was used to represent a cough from a customer. Two optical particle counters were used (one on each side of the barrier, labeled reference and worker) to determine the number of particles that migrated around a transparent barrier. Nine barrier sizes and a no barrier configuration were tested with six replicates each. Tests of these 10 configurations were conducted for both sitting and standing scenarios to represent configurations common to nail salons and grocery stores, respectively. Barrier efficiency was calculated using a ratio of the particle count results (reference/worker). Barriers had better efficiency when they were 9 to 39 cm (3.5 to 15.5 inches) above cough height and at least 91 cm (36 inches) wide, 92% and 93% respectively. Barriers that were 91 cm (36 inches) above table height for both scenarios blocked 71% or more of the particles between 0.35–0.725 µm and 68% for particles between 1 to 3 µm. A barrier that blocked an initial cough was effective at reducing particle counts. While the width of barriers was not as significant as height in determining barrier efficiency it was important that a barrier be placed where interactions between customers and workers are most frequent.

Circular polarized incident light scattering properties at optical clearing in tissues

2016 ◽  
Author(s):  
Dongsheng Chen ◽  
Nan Zeng ◽  
Yunfei Wang ◽  
Honghui He ◽  
Valery V. Tuchin ◽  
...  
Keyword(s):  
Light Scattering ◽  
Incident Light ◽  
Optical Clearing
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