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Köhler Optics and Color-Mixing
Published in Julio Chaves, Introduction to Nonimaging Optics, 2017
Combining the effects in Figure 12.25a and b, the irradiance pattern on R, produced by the light of angular spread 2θS, crossing slit s is as shown in Figure 12.26a. In Figure 12.25b, diameter R3R4 is illuminated by radiation with angular aperture 2θ and RS by radiation with angular aperture 2θS. For that reason, the relative size between R3R4 and RS is the same as between 2θ and 2θS, as shown in Figure 12.26a. The region of R illuminated by the radiation of angular aperture 2θS crossing slit s has a length proportional to 2θ, and width proportional to 2θS.
Light Microscopy
Published in Thomas A. Barber, Control of Particulate Matter Contamination in Healthcare Manufacturing, 1999
NA is related to angular aperture by NA=nsinAA2 where n is the refractive index of the space between the coverslip and the objective front lens and AA is the angular aperture of the lens, that is, the angle through which it accepts illuminating radiation. The highest theoretical NA for a dry objective, where the refractive index of air is 1.00, is 1.00. In actual practice, an NA of 0.95 is the highest available in a dry objective. NA is related to resolving power: The higher the NA, the greater the resolving power; therefore, a high NA is desirable. To increase the NA, increase the AA and/or increase the refractive index of the space between the specimen and the objective.Given a practical maximum focal length and A A, the best method of increasing the NA is by increasing the refractive index of the medium in the space between the coverslip and the objective. Objectives intended for this use are called immersion objectives.Oil immersion objectives have a practical maximum NA of 1.4.
Electrostatic Lenses
Published in Orloff Jon, Handbook of Charged Particle Optics, 2017
An immersion objective lens can be regarded as an accelerating lens followed by a focusing lens (unipotential electrostatic lens, magnetic lens, or a compound lens). The values of the axial aberration coefficients are given essentially by the values of the accelerating lens, because the angular aperture of the focusing lens is much smaller. The overlap of the magnetic field with the electrostatic field of the accelerating lens does not change the aberration coefficients significantly, as can easily be seen from the analytically solvable model with quadratic electrostatic potential superimposed on a homogeneous magnetic field (Lenc, 1995). The axial aberration coefficients of the accelerating lens S(a) (spherical aberration) and C(a) (chromatic aberration) are given to a remarkably good approximation by the simple formula S(a)=C(a)=12∫zoza(ΦoΦ(z))1/2[ΦoΦ(z)−ΦoΦa]dz
A Grid in Perspective for Road Lighting Calculations
Published in LEUKOS, 2023
Florian Greffier, Vincent Boucher, Valérie Muzet, Sandy Buschmann, Stephan Völker
The general principle is the following. Instead of the classic grid, a grid based on observer’s perspective and a given angular aperture is used. The positions of the grid points are defined as the centers of ellipses projected from the observer’s position with given angular apertures in the longitudinal direction and in the transverse direction (Fig. 3). Angular apertures can be chosen to simulate the observer’s vision, then ellipses represent the retinal cells projection on the road surface. Whether they are known, apertures can fit the ILMD ones. For ILMD measurements, (CEN 2015) recommends an angular aperture in the range [1’, 2’].Taking observer’s position as a reference, the first line of the grid is constructed by ellipses projection in front of the observer. It corresponds to the center of the driving lane. This first line (star markers in Fig. 4) is used to the longitudinal uniformity calculation as defined in standards.The whole grid is generated adding ellipses next to the first line according to the ellipses width. As the ellipses width increases with distance, the grid owns more ellipses at the beginning of the mesh than at the end, translating the perspective view.
Complex active sonar targets recognition using variable length deep convolutional neural network evolved by biogeography-based optimizer
Published in Waves in Random and Complex Media, 2022
Mohammad Khishe, Mokhtar Mohammadi, Adil Hussein Mohammed
In this research, experimental underwater scattering measurements are conducted on several target and non-target (non-target) objects of the same size in the east of the Persian Gulf and the west of the Oman Sea, where the water depths were on the order of 40 m. The objective of the experiment was to understand the scattering observed for target and non-target in this shallow water environment. The scattering measurements utilized the active sonobuoy and passive towed array hydrophone system. The geometric layout of the experiment gets shown in Figure 1. The two main components are (1) a 20-m-long vertical active sonobuoy hydrophone array to transmit a wideband linear FM Chirp pulse (Figure 2(a)) and (2) a 40-m long horizontal towed array hydrophones used to collect scattering data over a limited angular aperture (Figure 2(b)).
Radiation Interaction Characteristics of Solutions of La(NO3)3.6H2O and Sm(NO3)3.6H2O in Acetone Using Compton Scattering Technique
Published in Nuclear Science and Engineering, 2022
Mohinder Singh, Akash Tondon, Bhajan Singh, B. S. Sandhu
The angular aperture in the case of Compton scattering geometry is taken as the half-angle of the cone of acceptance of the detector at the center of the plastic container. In the present geometry, the angle made by the scintillation detector at the sample is found to be of the order of deg and takes the value deg at the source from the center of the container. The angular contribution is found to be small enough to neglect the value of this acceptance angle made at the detector.26 Uncertainties are due to impurities present in the different solutions (organic or rare-earth compounds), evaluation of the area under the scattered energy peak, multiple scattering effects occurring in the desired solution in the container, counting statistics, density measurements, mass thickness measurements, and dead time of the counting system.