Angle of incidence sampling technique for stray light rejection performance estimation of lunar terrestrial imagers

2020 ◽  
Author(s):  
Sehyun Seong ◽  
Jeeyeon Yoon ◽  
Youngchun Youk ◽  
Sug-Whan Kim ◽  
Haeng Pal Heo
Keyword(s):  
Sampling Technique ◽  
Performance Estimation ◽  
Stray Light ◽  
Angle Of Incidence

scholarly journals Freeform Mirror Design for Novel Laser Warning Receivers and Laser Angle of Incidence Sensors

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2569
Author(s):  
Jacek Wojtanowski ◽  
Marcin Jakubaszek ◽  
Marek Zygmunt
Keyword(s):  
Cross Section ◽  
Dynamic Range ◽  
Numerical Aperture ◽  
Merit Function ◽  
Point Of View ◽  
Field Of View ◽  
Stray Light ◽  
Angle Of Incidence ◽  
Detector Position ◽  
Main Challenge

In this paper, we present a novel configuration of an optical angle-of-incidence (AOI) sensor based on the application of a freeform mirror. The main challenge in designing this mirror was to provide a strictly linear transformation between AOI and the spatial position of the spot created on the linear detector array. Another two goals of this paper were to minimize stray light issues (improve the dynamic range) and create an intermediate focus and lateral shift in the detector position with respect to the plane of incidence. From an optical point of view, the designed mirror can thus be understood as the composition of three components: a high-numerical-aperture (NA) fully achromatic f-theta lens in one cross-section and a perfectly focusing lens, combined with a deviating prism in the second (orthogonal) cross-section. In comparison to the standard “shade” methods, the proposed approach allows a constant angular resolution to be maintained over the entire field of view. The mirror was designed on the basis of fundamental geometrical rules by numerically solving differential problems using an innovative scheme based on the minimization of the specific merit function. The proposed method was practically applied to design a freeform mirror for a 90°/120° field-of-view sensor, showing a satisfactory performance.

Electron Channeling Patterns

1977 ◽  
Vol 35 ◽  
pp. 12-13
Author(s):  
David C. Joy
Keyword(s):  
Electron Diffraction ◽  
Incidence Angle ◽  
Photographic Plate ◽  
Diffraction Effect ◽  
Angle Of Incidence ◽  
Bulk Single Crystal ◽  
Time Resolved ◽  
Electron Channeling ◽  
Spatially Resolved ◽  
Large Bulk

Electron channeling patterns (ECP) were first found by Coates (1967) while observing a large bulk, single crystal of silicon in a scanning electron microscope. The geometric pattern visible was shown to be produced as a result of the changes in the angle of incidence, between the beam and the specimen surface normal, which occur when the sample is examined at low magnification (Booker, Shaw, Whelan and Hirsch 1967).A conventional electron diffraction pattern consists of an angularly resolved intensity distribution in space which may be directly viewed on a fluorescent screen or recorded on a photographic plate. An ECP, on the other hand, is produced as the result of changes in the signal collected by a suitable electron detector as the incidence angle is varied. If an integrating detector is used, or if the beam traverses the surface at a fixed angle, then no channeling contrast will be observed. The ECP is thus a time resolved electron diffraction effect. It can therefore be related to spatially resolved diffraction phenomena by an application of the concepts of reciprocity (Cowley 1969).

Electron-Channelling Patterns: Principles and Techniques

1976 ◽  
Vol 34 ◽  
pp. 400-401
Author(s):  
David C. Joy
Keyword(s):  
Crystal Structure ◽  
Electron Flux ◽  
Lattice Structure ◽  
Incident Beam ◽  
Bloch Wave ◽  
Crystalline Solid ◽  
Angle Of Incidence ◽  
Electron Channelling ◽  
Regular Arrangement ◽  
Backscattered Signals

In a crystalline solid the regular arrangement of the lattice structure influences the interaction of the incident beam with the specimen, leading to changes in both the transmitted and backscattered signals when the angle of incidence of the beam to the specimen is changed. For the simplest case the electron flux inside the specimen can be visualized as the sum of two, standing wave distributions of electrons (Fig. 1). Bloch wave 1 is concentrated mainly between the atom rows and so only interacts weakly with them. It is therefore transmitted well and backscattered weakly. Bloch wave 2 is concentrated on the line of atom centers and is therefore transmitted poorly and backscattered strongly. The ratio of the excitation of wave 1 to wave 2 varies with the angle between the incident beam and the crystal structure.

The Microstructure of Steatite (Protoenstatite)

1985 ◽  
Vol 43 ◽  
pp. 236-237
Author(s):  
W. E. Lee ◽  
A. H. Heuer
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Magnesium Silicate ◽  
Beam Current ◽  
Glassy Matrix ◽  
Angle Of Incidence ◽  
X Ray ◽  
Mechanical And Electrical Properties ◽  
Argon Ions ◽  
High Temperature Polymorph

IntroductionTraditional steatite ceramics, made by firing (vitrifying) hydrous magnesium silicate, have long been used as insulators for high frequency applications due to their excellent mechanical and electrical properties. Early x-ray and optical analysis of steatites showed that they were composed largely of protoenstatite (MgSiO3) in a glassy matrix. Recent studies of enstatite-containing glass ceramics have revived interest in the polymorphism of enstatite. Three polymorphs exist, two with orthorhombic and one with monoclinic symmetry (ortho, proto and clino enstatite, respectively). Steatite ceramics are of particular interest a they contain the normally unstable high-temperature polymorph, protoenstatite.Experimental3mm diameter discs cut from steatite rods (∼10” long and 0.5” dia.) were ground, polished, dimpled, and ion-thinned to electron transparency using 6KV Argon ions at a beam current of 1 x 10-3 A and a 12° angle of incidence. The discs were coated with carbon prior to TEM examination to minimize charging effects.

On resolving fine periodic microstructures in the optical microscope

1989 ◽  
Vol 47 ◽  
pp. 364-365
Author(s):  
W.S. Putnam ◽  
C. Viney
Keyword(s):  
Liquid Crystalline ◽  
Numerical Aperture ◽  
Polarized Light ◽  
Normal Incidence ◽  
Optical Microscope ◽  
Angle Of Incidence ◽  
Resolution Limit ◽  
Crystalline Materials ◽  
Periodic Microstructures ◽  
Liquid Crystalline Materials

Many sheared liquid crystalline materials (fibers, films and moldings) exhibit a fine banded microstructure when observed in the polarized light microscope. In some cases, for example Kevlar® fiber, the periodicity is close to the resolution limit of even the highest numerical aperture objectives. The periodic microstructure reflects a non-uniform alignment of the constituent molecules, and consequently is an indication that the mechanical properties will be less than optimal. Thus it is necessary to obtain quality micrographs for characterization, which in turn requires that fine detail should contribute significantly to image formation.It is textbook knowledge that the resolution achievable with a given microscope objective (numerical aperture NA) and a given wavelength of light (λ) increases as the angle of incidence of light at the specimen surface is increased. Stated in terms of the Abbe resolution criterion, resolution improves from λ/NA to λ/2NA with increasing departure from normal incidence.

Evaluation of bag sequential sampling technique for ambient air analysis. Comments

1979 ◽  
Vol 13 (5) ◽  
pp. 609-610
Author(s):  
Allen Hoffman ◽  
Roger Sperling ◽  
John Polasek ◽  
Jerry Bullin
Keyword(s):  
Sequential Sampling ◽  
Sampling Technique ◽  
Ambient Air ◽  
Air Analysis

Role of Teachers in Building the Concept of Sustainable Development: Success or Failure

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Ayaz Muhammad Khan ◽  
Amber Jamshaid ◽  
Tayyibah Roohi ◽  
Amna Ramzan
Keyword(s):  
Sustainable Development ◽  
Primary School ◽  
Sampling Technique ◽  
School Teachers ◽  
Primary School Teachers ◽  
Primary Level ◽  
Significant Difference ◽  
Role Of Teachers ◽  
Major Factors

Sustainable Development (SD) is a rich, challenging and thought-provoking construct in social sciences. The main purpose of this paper was to identify and explore the role played by primary school teachers in building up the idea of sustainable development (SD) among students. This paper was intended to identify that how a teacher can successfully execute the concept of SD by influencing students’ minds at the primary level. Quantitative survey technique were utilized for data collection. All the primary school teachers of Lahore division comprised the population of the study. Through multistage sampling technique, 352 primary school teachers were selected as participants of the study. A self-developed SD questionnaire incorporating four major factors (teachers’ awareness, pedagogy, curricular and co-curricular activities) with Cronbach’s alpha value = .93 was used to measure the role of teachers in building the sustainability concept among students at primary level. The results indicated a significant mean score difference among SD scores of teachers, sector wise (private and public). Furthermore, the results also reconnoitered the significant difference (p=.04) between the mean scores of female and male teachers in building up the SD concept in students’ minds.

PERCEIVED EFFECTS OF STREET HAWKING ON THE WELL-BEING OF CHILDREN IN ANYIGBA, DEKINA LOCAL GOVERNMENT AREA OF KOGI STATE, NIGERIA

2018 ◽  
Vol 8 (1) ◽  
pp. 01-07
Author(s):  
Alfred Eboh
Keyword(s):  
Local Government ◽  
Survey Design ◽  
Sampling Technique ◽  
Well Being ◽  
Local Government Area ◽  
Negative Consequences ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Perceived Effects ◽  
The Government

Background: The hawking of wares by children has been a serious issue confronting the Nigerian society. Children hawk in some of the most horrible conditions conceivable, where they face a serious risk of injury, chronic illness, kidnapping, rape or death. Objective: The focus of this study was to assess the perceived effects of street hawking on the well-being of children in Anyigba, Dekina Local Government Area of Kogi State. Methods: The population of this study consists of parents of the street hawkers in Anyigba while cross-sectional survey design was used through the purposive sampling technique to choose the sample size of one hundred and sixty-two (162) respondents. The validated structured questionnaire and In-Depth Interviews (IDIs) served as the instruments for the data collection respectively. The hypotheses were tested using Chi-Square at a predetermined 0.05 level of significance. The quantitative data were analysed with the aid of the SPSS (version 20). Results: The results indicated among others that street hawking had significant social implications and physical consequences on children's moral behaviour as well as health status in the study area. Conclusion: The study, therefore, concluded that the government of Kogi State should carry out an enlightenment campaign through the media and religious institutions on the negative consequences of street hawking are recommended as panacea. Also, the child right act instrument and its implementation should be strengthened in order to curb street hawking in the study area.

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