DETERMINATION OF THE DENSITY VALUE SPECIFICALLY AT THE FOCAL POINT OF THE MIRROR CONCENTRATING SYSTEM

2019 ◽  
Vol 6 (4) ◽  
pp. 49-55
Author(s):  
Yuldash Begzhanovich Sobirov ◽  
Rustam Khakimovich Rakhimov ◽  
Shakhriyor Abdujabbarovich Abdurakhmanov
Keyword(s):  
Energy Distribution ◽  
Focal Plane ◽  
Focal Point ◽  
Angular Size ◽  
Analytical Calculation ◽  
Radiant Flux ◽  
The Sun ◽  
Partial Shading ◽  
Focal Zone ◽  
Reflective Surfaces

When designing mirror concentrating systems, it is necessary to determine in advance the optical-geometric and optical-energy characteristics of the installation. One is required to choose the mirrors with a reflection coefficient to satisfy the expected energy distribution in the focal area and to pay attention to the accuracy of the reflective surfaces of the mirrors, to the accuracy of the tracking system of the heliostats to the trajectory of the apparent motion of the Sun, to the partial shading to the reflective surfaces, etc. Based on these data, it is necessary to calculate the irradiance distribution in the focal zone of the installation. During installation and utilization of the equipment it is necessary to measure and monitor these parameters and, if necessary, to recalculate the energy distribution taking into account the new parameters.The methods for calculating the density distribution of the radiant flux in the focal zone of mirror-concentrating systems have been developed in parallel with the requirements of exploitation. They do not always correctly reflect the true picture formed in the focus of the heliostat. In this paper, the analysis presents the existing methods for calculating paraboloid concentrators based on the Gaussian distribution of energy in the focal plane. Developing the method of fallen and reflected elementary cone beam and on the basis of generated scattered optical images of the Sun and of the visible angular size (2γо = 32 angle of minutes) of the Sun, which shows non-Gaussian nature of the resulting distribution in the focal plane due to the influence of aberration of the optical paraboloidal surface depending on the change of the aperture angle 2U, we obtained an analytical calculation formula to determine the value of the concentrated radiant flux specifically at the focal point of a paraboloid mirror concentrating system.

scholarly journals Influence of Microlensing on Spectral Anomalies of the Lensed Objects

2011 ◽  
Vol 20 (3) ◽  
Author(s):  
S. Simić ◽  
L. Č. Popović ◽  
P. Jovanović
Keyword(s):  
Energy Distribution ◽  
Spectral Energy Distribution ◽  
Angular Size ◽  
Black Body ◽  
Spectral Energy

AbstractHere we consider the influence of microlensing on the spectrum of a lensed object with the angular size 5 μas accepting that the composite emission of this object originates from three different regions arranged around its center. We assume that the lensed object has three concentric regions with a black-body emission; the temperatures of these regions are 10 000 K, 7500 K and 5000 K. We investigate how the integral spectral energy distribution (SED) of such stratified source changes due to microlensing by a group of solarmass stars. We find that the SED and flux ratios in the photometric B, V and R passbands show considerable changes during a microlens event. This indicates that the flux anomaly observed in some lensed quasars may be caused by microlensing of a stratified object.

80 MHz Observations of the Coronal Broadening of the Crab Nebula

1970 ◽  
Vol 1 (7) ◽  
pp. 319-320 ◽  
Author(s):  
J. R. Harries ◽  
R. G. Blesing ◽  
P. A. Dennison
Keyword(s):  
Interplanetary Medium ◽  
Crab Nebula ◽  
Angular Size ◽  
Space Vehicles ◽  
Radio Sources ◽  
The Sun ◽  
Amplitude Scintillation ◽  
Interplanetary Plasma ◽  
The Crab Nebula

Regions of the interplanetary medium currently inaccessible to space vehicles may conveniently be studied using the radio scattering properties of the interplanetary plasma. These effects may give rise to angular broadening of radio sources sufficiently close to the Sun, or to amplitude scintillation of sources of small angular size.

scholarly journals A Method to Generate Vector Beams with Adjustable Amplitude in the Focal Plane

2020 ◽  
Vol 10 (7) ◽  
pp. 2313 ◽  
Author(s):  
Alexandru Crăciun ◽  
Traian Dascălu
Keyword(s):  
Optical System ◽  
Focal Plane ◽  
Focal Point ◽  
Polarization State ◽  
Optical Component ◽  
Stimulated Emission ◽  
Matrix Formalism ◽  
Sted Microscopy ◽  
Diffraction Integral ◽  
Vector Beams

We design and investigate an original optical component made of a c-cut uniaxial crystal and an optical system to generate cylindrical vector beams with an adjustable polarization state. The original optical component has a specific, nearly conical shape which allows it to operate like a broadband wave retarder with the fast axis oriented radially with respect to the optical axis. We show via numerical simulations, using the Debye–Wolf diffraction integral, that the focal spot changes depending on the polarization state, thus enabling the control of the focal shape. Non-symmetrical shapes can be created although the optical system and incoming beam are circularly symmetric. We explained, using Jones matrix formalism, that this phenomenon is connected with the Gouy phase difference acquired by certain modes composing the beam due to propagation to the focal plane. We present our conclusions in the context of two potential applications, namely, stimulated emission depletion (STED) microscopy and laser micromachining. The optical system can potentially be used for STED microscopy for better control of the point-spread function of the microscope and to decrease the unwanted light emitted from the surroundings of the focal point. We give an analytical expression for the shape of the original component using the aspherical lens formula for the two versions of the component: one for each potential application.

The LPL Radial Accelerometer

1984 ◽  
Vol 88 ◽  
pp. 63-86 ◽  
Author(s):  
R.S. McMillan ◽  
P.H. Smith ◽  
J.E. Frecker ◽  
W.J. Merline ◽  
M.L. Perry
Keyword(s):  
Optical Fiber ◽  
Radial Velocity ◽  
Doppler Shift ◽  
Focal Plane ◽  
Incident Light ◽  
The Sun ◽  
Stellar Spectrum ◽  
Entrance Aperture ◽  
Fabry Perot ◽  
Interference Order

AbstractWe have begun to observe radial velocities of stars with an optical spectrometer designed for unusually high accuracy. Light from a star image in the focal plane of a telescope is fed to the entrance aperture of the spectrometer by a single optical fiber. Wavelengths are calibrated by transmission of collimated light through a tilt-tunable Fabry-Perot interferometer. The scrambling of incident light rays by the optical fiber and the intrinsic stability of the Fabry-Perot etalon provide immunity to the sources of systematic errors that plague conventional radial velocity meters. The spectrum is dispersed by an echelle grating crossed with another plane reflection grating. Several echelle orders in the vicinity of 4250-4600 Å are imaged in a two-dimensional format on a charge-coupled (CCD) array of detectors. About 350 distinct points on the profile of the stellar spectrum are sampled by successive orders of interferometrie transmission through the etalon. In the vicinity of 4300 Å each interference order is 47 milliangstroms wide and the sample points are 0.64 Å apart, resulting in distinct , widely-spaced monochromatic images of the entrance aperture to be formed in the focal plane of the camera. Changes in Doppler shift cause changes in the relative intensities of these images, according to the slope of the spectral profile at each point sampled. The instrument is being operated as a null-measurement accelerometer, sensitive only to changes in radial velocity, which simplifies operation and enhances sensitivity. With an argon-filled, iron hollow cathode emission line lamp, the interferometer can be calibrated to two parts in 100 million; this corresponds to ± 6 meters/sec in Doppler shift. Calibrations of the interferometer show variations of ± 27 meters/sec on a time scale of months; observations of stars are corrected for such changes. The internal repeatability of observations of the differential Doppler shift of light from the integrated disk of the Sun is ± 6 meters/sec. The corresponding result from about 70 observations of Arcturus (Kl IIIb; B=1.19) is ± 40 meters/sec internal repeatability for each exposure of 20 square-meter seconds. The external repeatability (day-to-day differential accuracy) of nightly averages of stellar observations is ± 20 meters/second. Since the internal precision on the sun and the argon lamp is much better than it is with short exposures on Arcturus, the quality of our observations of stars is limited by the rate of detected photons. This justifies averaging a number of short exposures of a star to approach “laboratory” precision.

scholarly journals The dispersion of a light pulse by a prism

1914 ◽  
Vol 90 (618) ◽  
pp. 298-312
Keyword(s):  
Energy Distribution ◽  
General Expression ◽  
Light Pulse ◽  
Focal Plane ◽  
Definite Function ◽  
Initial Pulse ◽  
Initial Form ◽  
First Time

This investigation is a continuation of a former one in which an expression was derived for a light pulse with an energy distribution given by Wien's law. The first three paragraphs are supplementary to the former paper; the rest of the investigation deals with the passage of the same pulse through a prism and its separation into the different colours in the focal plane of a telescope. The general principles according to which this must take place are, of course, known, but here the actual disturbance at every point in the focal plane is given for the first time as a definite function of the time and as a result it is possible to state how many waves there are in the trains, which the single initial pulse gives rise to in the various parts of the spectrum. §1. My general expression for the initial form of a light pulse was cos ( n + ½) θ /( x 2 + h 2 ) (2 n +1)/4 , where tan θ = x/h . I did no notice until after the former paper was communicated, that this expression is 1/Г ( n + ½) ∫ ∞ 0 e - ha cos αx α n -½ dα .

scholarly journals Shading, Dusting and Incorrect Positioning of Photovoltaic Modules as Important Factors in Performance Reduction

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1992 ◽  
Author(s):  
Ewa Klugmann-Radziemska
Keyword(s):  
Solar Radiation ◽  
Experimental Studies ◽  
Design Stage ◽  
Photovoltaic Module ◽  
The Sun ◽  
Partial Shading ◽  
Uneven Terrain ◽  
Performance Reduction ◽  
Angle Of Deviation ◽  
The Impact

The amount of solar radiation reaching the front cover of a photovoltaic module is crucial for its performance. A number of factors must be taken into account at the design stage of the solar installation, which will ensure maximum utilization of the potential arising from the location. During the operation of a photovoltaic installation, it is necessary to limit the shading of the modules caused by both dust and shadowing by trees or other objects. The article presents an analysis of the impact of the radiation reaching the surface of the radiation module on the efficiency obtained. Each of the analyzed aspects is important for obtaining the greatest amount of energy in specific geographical conditions. Modules contaminated by settling dust will be less efficient than those without deposits. The results of experimental studies of this effect are presented, depending on the amount of impurities, including their origins and morphologies. In practice, it is impossible to completely eliminate shadowing caused by trees, uneven terrain, other buildings, chimneys, or satellite dishes, and so on, which limits the energy of solar radiation reaching the modules. An analysis of partial shading for the generated power was also carried out. An important way for maximizing the incoming radiation is the correct positioning of the modules relative to the sun. It is considered optimal to position the modules relative to the light source, that is, the sun, so that the rays fall perpendicular to the surfaces of the modules. Any deviation in the direction of the rays results in a loss in the form of a decrease in the available power of the module. The most beneficial option would be to use sun-tracking systems, but they represent an additional investment cost, and their installations require additional space and maintenance. Therefore, the principle was adopted that stationary systems should be oriented to the south, using the optimal angle of inclination of the module surface appropriate for the location. This article presents the dependence of the decrease in obtained power on the angle of deviation from the optimal one.

Optical Analysis of a New Point Focus Fresnel Concentrator

2015 ◽  
Author(s):  
Hany Al-Ansary ◽  
Shaker Alaqel ◽  
Eldwin Djajadiwinata ◽  
Abdullah Mohammed
Keyword(s):  
Concentration Ratio ◽  
Focal Point ◽  
Tracking System ◽  
Average Concentration ◽  
The Sun ◽  
Optical Performance ◽  
Optical Analysis ◽  
King Saud University ◽  
Stirling Engines ◽  
Current Design

This study describes preliminary optical analysis performed regarding a new collector called the Point Focus Fresnel Concentrator (PFFC). This collector combines the concepts of the linear Fresnel collector and central receiver systems to form a new concept of a focal point Fresnel concentrator with a dual-axis sun tracking system. It concentrates direct solar radiation using a number of flat mirrors positioned over a rotating frame. The frame tracks the sun in the azimuth direction, while each row of mirrors tracks the sun in the elevation direction, thereby allowing sunlight to be concentrated on the same point above the collector throughout the day. PFFC is considered suitable for a number of applications, such as power generation by concentrating photovoltaics (CPV) and Stirling engines, and process heat applications. In this study, the first attempt to characterize the optical performance of the collector is made. A prototype of the collector has already been built on the campus of King Saud University. It has a total footprint of 9 m2, and includes 900 mirrors, each of which is 7 cm × 7 cm. The receiver has a diameter of 10 cm. Optical performance is studied by ray tracing methods to obtain flux maps and intercept factors of the receiver. Results show that the average concentration ratio is in the order of 220 to 300 suns when mirrors with a 6-mrad optical error are used. For the same mirrors, the highest attainable average intercept factor (0.674) occurs in the winter due to the low particle loading in the atmosphere. When the optical error is reduced to 2 mrad, the average concentration ratio increases to 290 to 400 suns, and the average intercept factor increases to 0.892. In any case, if the current design of PFFC is to be used in conjunction with CPV, a secondary concentrator would be needed to achieve required concentration ratios in the order of 500 suns.

Energy distribution on the focal plane of a parabolic cylindrical concentrator with angular defocusings

2007 ◽  
Vol 43 (1) ◽  
pp. 30-33
Author(s):  
A. V. Vardanyan ◽  
K. A. Pogosyan ◽  
G. S. Aloyan ◽  
Z. S. Ovsepyan
Keyword(s):  
Energy Distribution ◽  
Focal Plane

A Stress Intensity Factor Tracer

1985 ◽  
Vol 52 (2) ◽  
pp. 291-297 ◽  
Author(s):  
K.-S. Kim
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Focal Plane ◽  
High Speed ◽  
Focal Point ◽  
Crack Tip ◽  
Theoretical Development ◽  
Significant Feature ◽  
High Speed Photography

A new optical method, Stress Intensity Factor Tracer (SIFT), has been developed. The device measures continuously the real-time stress intensity factor variation, K1(t), of a moving crack tip using a single, stationary photodetector. The method uses the fact that any variation in K1(t) leads to a change in the intensity of light, I(t), impinging on a fixed finite area, Γ, on the focal plane. The focal plane is defined as the plane on which initially parallel light rays transmitted through a transparent fracture specimen (or reflected from the surface of an opaque specimen) are focused by a converging lens. Provided that the light detecting area, Γ, excludes the focal point, a simple relation, I(t) =B[K1(t)]4/3, has been obtained for a K1-dominant field. The constant, B, is a product of several experimental parameters including a “shape factor” of the sampling area, Γ, where I(t) is measured. A significant feature of this method is that I(t) is independent of the location of the crack tip in the illuminated zone on the specimen plane. The technique may therefore be applied to dynamic fracture studies without using high-speed photography. Only the constant, B, becomes a function of crack velocity for the dynamic K1-field. This paper presents the theoretical development of the SIFT method, including the wave optics of the system. Experimental results supporting the theory are included.

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