Optimization Design of Cylinder Grating Used for Non-Contact Speed Measurement

2013 ◽  
Vol 312 ◽  
pp. 95-100
Author(s):  
Guo Sheng Zhang ◽  
Yan Xu
Keyword(s):  
Light Intensity ◽  
Optimization Design ◽  
Optical Path Length ◽  
Grating Period ◽  
Curvature Radius ◽  
Length Variation ◽  
Speed Measurement ◽  
Total Light ◽  
Analytical Expressions ◽  
Fraunhofer Approximation

In order to realize the detection of diffractive light after the image segmentation using cylinder grating, the parameters of a cylinder grating was optimized using the wave optics theory. By analyzing the relation of optical path length variation with the diffraction angle of single cylinder lens diffraction, and by Fraunhofer approximation, the analytical expressions of cylinder lens diffraction was given. By setting parameters to calculate and simulate, it was found that to increase the ratio of curvature radius and grating period could effectively reduce the spatial distribution of the diffraction light intensity. For the gratings that already exist, by reducing the ratio of refractive index of the gratings material and environment, the spatial light distribution of the grating could be reduced. If the cylinder grating period is too small, the overlap part of images segmentation light diffraction intensity will increase. But it occupies smaller proportion of the total light intensity. After the optimization design of cylinder grating, the results showed that it could be used for non-contact speed measurement in the range of some parameter.

scholarly journals THE ORIENTATION OF ANIMALS BY OPPOSED BEAMS OF LIGHT

1927 ◽  
Vol 8 (6) ◽  
pp. 671-684 ◽  
Author(s):  
W. J. Crozier
Keyword(s):  
Experimental Data ◽  
Light Intensity ◽  
Total Light ◽  
Two Sides ◽  
Average Angle

When orientation is attained under the influence of beams of parallel light opposed at 180° the deflection θ from a path at right angles to the beams is given by tan See PDF for Equation, where I1 and I2 are the photic intensities and H is the average angle between the photoreceptive surfaces. This expression is independent of the units in which I is measured, and holds whether the primary photosensory effect is proportional to I or to log I. When photokinetic side-to-side motions of the head occur, H decreases with increasing total acting light intensity, but increases if higher total light intensity restricts the amplitude of random movements; in each case, H is very nearly proportional to log I1I2. For beams of light at 90°, See PDF for Equation. The application of these equations to some particular instances is discussed, and it is shown why certain simpler empirical formulæ previously found by others yield fair concordance with the experimental data. The result is thus in complete accord with the tropism theory, since the equations are based simply on the assumption that when orientation is attained photic excitation is the same on the two sides.

scholarly journals The ICAD (Iterative Cavity Enhanced DOAS) Method

2019 ◽  
Author(s):  
Martin Horbanski ◽  
Denis Pöhler ◽  
Johannes Lampel ◽  
Ulrich Platt
Keyword(s):  
Light Intensity ◽  
Gas Absorption ◽  
Optical Absorption Spectroscopy ◽  
Light Path ◽  
Calibration Source ◽  
Optical Cavities ◽  
Total Light ◽  
Averaging Time ◽  
Chemiluminescence Detector

Abstract. Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS or BB-CEAS DOAS) allows to make in-situ measurements while maintaining the km-long light paths required by DOAS. These technique have been successfully used for several years to measure in-situ atmospheric trace gases. A property of optical cavities is that in presence of strong absorbers or scatterers the light path is reduced, opposite to classical Long Path DOAS measurements. Typical CE-DOAS or BB-CEAS evaluation schemes correct this effect using the measured total light intensity attenuation. This makes them sensitive to any variations of the light intensity not arising from the trace gas absorption. That means an important DOAS advantage, to be independent of total light intensity, is actually lost. In order to cope with this problem, the instrument setup would require a thorough stabilisation of the light source and a very rigid mechanical setup, which would make instrumentation more complex and error prone. We present a new approach to Cavity Enhanced (CE-) DOAS based on an iterative algorithm (ICAD) which actually models the light path reduction from the derived absorbers in the optical resonator. It allows a sensitive and robust data analysis that does not depend on the total light intensity allowing a simpler and more compact instrument setup. The algorithm is discussed and simulated measurements demonstrate its sensitivity and robustness. Furthermore, a new NO2 ICAD instrument is presented. It takes advantage of the advanced data evaluation to build a compact (50 cm cavity) and light weight instrument (<10 kg) with low power consumption (25 W) for sensitive measurements of NO2 with a detection limit of 0.02 ppbv at an averaging time of 7 minutes. The instrument is characterized with a NO2 calibration source and good long term stability is demonstrated in a comparison with a commercial chemiluminescence detector. As a new application of ICAD we show measurements on an auto mobile platform to investigate the two dimensional NO2 distribution in an urban area. The instrument is so robust that even strong vibrations do not lead to any measurement problems.

scholarly journals ESTIMATION OF TOPOGRAPHIC DEFECTS DIMENSIONS OF SEMICONDUCTOR SILICON STRUCTURES

2018 ◽  
Vol 9 (1) ◽  
pp. 74-84
Author(s):  
S. F. Sianko ◽  
V. A. Zelenin
Keyword(s):  
Calculation Method ◽  
Target Surface ◽  
Curvature Radius ◽  
Surface Geometry ◽  
Semiconductor Wafer ◽  
Semiconductor Silicon ◽  
Quantitative Characteristics ◽  
Silicon Structures ◽  
Analytical Expressions ◽  
Acceptability Criteria

The effect of non-flatness of semiconductor wafers on characteristics of manufactured devices is shown through defocusing of an image of a topological layout of a structure being formed and through reduction of resolution at photolithographic processing. For quality control of non-flatness the Makyoh method is widely used. However, it does not allow obtaining quantitative characteristics of observed defects, which essentially restricts its application. The objective of this work has been developing of a calculation method for dimensions of topographic defects of wafers having semiconductor structures formed on them, which has allowed determining acceptability criteria for wafers, depending on defects dimensions and conducting their timely penalization.A calculation method under development is based on deduction of relationships linking distortion of image elements to curvature of local sections of a semiconductor wafer that has formed structures. These structures have been considered to be image finite elements and within this range the curvature radius has been assumed to be constant. Sequential calculation of deviation of element ends from ideal plane based on determining their curvature radius has allowed obtaining geometry of a target surface in a set range of elements. Conditions of image formation and requirements to structures have been determined.Analytical expressions relating a deviation value of elements of a light-to-dark image with surface geometry have been obtained. This allows conducting effective quantitative control of observed topographic defects both under production and research conditions. Examples of calculation of topographic defects of semiconductor silicon wafers have been provided. Comparison of the obtained results with the data obtained by conventional methods has shown their complete conformity.

scholarly journals Scattered Light in a Flood-plain Lake of Central Amazônia()

1972 ◽  
Vol 2 (2) ◽  
pp. 87-90
Author(s):  
W. L. B. Brinkmann
Keyword(s):  
Surface Layer ◽  
Light Intensity ◽  
Plant Communities ◽  
Water Surface ◽  
Scattered Light ◽  
Flood Plain ◽  
Near Surface ◽  
Central Amazonia ◽  
Total Light ◽  
Floating Plant

Abstract The light intensity below the surface of Lago Castanho was recorded at 10 minute intervals and compared to the total light intensity above the water surface. Scattered light of the lake water was rather constant and it was found to be sufficiently high to support the growth of photoautotrophic organisms in the near-surface layer. Below the floating plant communities scattered light was extremely low in intensity.

Accurate and Fast Estimation of Optical Properties Using Optical Path Length and Spatially Resolved Reflectance Measurement

2011 ◽  
Vol 222 ◽  
pp. 318-321 ◽  
Author(s):  
Takayuki Yamashita ◽  
Masatsugu Niwayama ◽  
Toshitaka Yamakawa
Keyword(s):  
Optical Properties ◽  
Light Intensity ◽  
Path Length ◽  
Continuous Wave ◽  
Practical Method ◽  
Optical Path Length ◽  
Optical Path ◽  
Phase Detector ◽  
Reflectance Measurement ◽  
Spatially Resolved

We developed a new practical method for determining the absorption coefficient and reduced scattering coefficient simultaneously by using the spatial light intensity profile and the optical path length based on the results of a Monte Carlo simulation. The proposed system is optically and electrically robust and practical because (1) light intensity detection of a continuous wave for the spatially resolved reflectance is stable, convenient, and fast, and (2) the optical path length calculated from the phase can be measured precisely using the digital phase detector of a laser rangefinder. The optical properties of the tissue-like medium were measured accurately and quickly.

scholarly journals Estimating of Bending Force and Curvature of the Bending Plate in a Three-Roller Bending System Using Finite Element Simulation and Analytical Modeling

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1204
Author(s):  
Ionel Gavrilescu ◽  
Doina Boazu ◽  
Felicia Stan
Keyword(s):  
Finite Element ◽  
Plastic Hinge ◽  
Plate Thickness ◽  
Practical Importance ◽  
Vertical Displacement ◽  
Curvature Radius ◽  
Bending Force ◽  
Wide Range ◽  
Bending Process ◽  
Analytical Expressions

Many industries such as shipbuilding require steel bending plates in a wide range of radii, thus bending machines are often designed and produced on a custom basis in shipyards. From a design perspective, however, the bending force and the radius of the bending plate as a function of vertical displacement of the upper roller must be known. In this paper, a hybrid numerical–analytical approach is proposed to investigate the three-roller bending process for two plates of steel used in the naval industry. Firstly, the bending process is modeled using the finite element (FE) method and regression models for the bending force as a function of plate thickness and vertical displacement of the upper roller were constructed. Then, based on the findings from FE analysis, using the bent bar theory, two analytical expressions for the bending force were derived. Using geometric and deformation compatibilities, analytical expressions for the vertical displacement of the upper roller as a function of the curvature of the bending plate were also developed. The FE results suggest that the cross section of the plate is practically a plastic hinge in the tangent area of the upper roller and that the deformation compatibilities must be considered in order to estimate the curvature radius of the bending plate using analytical formulations. These results are of practical importance in designing rolling machines to estimate the setting parameters.

scholarly journals The ICAD (iterative cavity-enhanced DOAS) method

2019 ◽  
Vol 12 (6) ◽  
pp. 3365-3381 ◽  
Author(s):  
Martin Horbanski ◽  
Denis Pöhler ◽  
Johannes Lampel ◽  
Ulrich Platt
Keyword(s):  
Light Intensity ◽  
Gas Absorption ◽  
Optical Absorption Spectroscopy ◽  
Light Path ◽  
Calibration Source ◽  
Optical Cavities ◽  
Total Light ◽  
Averaging Time ◽  
Chemiluminescence Detector

Abstract. Cavity-enhanced differential optical absorption spectroscopy (CE-DOAS or BB-CEAS DOAS) allows us to make in situ measurements while maintaining the kilometre-long light paths required by DOAS. This technique has been successfully used for several years to measure in situ atmospheric trace gases. A property of optical cavities is that in the presence of strong absorbers or scatterers the light path is reduced, in contrast to classical long-path DOAS measurements where the light path is fixed. Typical CE-DOAS or BB-CEAS evaluation schemes correct this effect using the measured total light intensity attenuation. This makes them sensitive to any variations in the light intensity not arising from the trace gas absorption. That means an important DOAS advantage, to be independent of total light intensity, is actually lost. In order to cope with this problem, the instrument setup would require a thorough stabilisation of the light source and a very rigid mechanical setup, which would make instrumentation more complex and error prone. We present a new approach to cavity-enhanced (CE) DOAS based on an iterative algorithm (ICAD) which actually models the light path reduction from the derived absorbers in the optical resonator. It allows a sensitive and robust data analysis that does not depend on the total light intensity, allowing a simpler and more compact instrument setup. The algorithm is discussed and simulated measurements demonstrate its sensitivity and robustness. Furthermore, a new ICAD NO2 instrument is presented. It takes advantage of the advanced data evaluation to build a compact (50 cm cavity) and lightweight instrument (<10 kg) with low power consumption (25 W) for sensitive measurements of NO2 with a detection limit of 0.02 ppbv at an averaging time of 7 min. The instrument is characterised with a NO2 calibration source and good long-term stability is demonstrated in a comparison with a commercial chemiluminescence detector. As a new application of ICAD we show measurements on an automobile platform to investigate the two-dimensional NO2 distribution in an urban area. The instrument is so robust that even strong vibrations do not lead to any measurement problems.

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