Refraction angle

The technique presented above has been extensively evaluated experimentally using ultrasonic data acquired from a test block made of cast stainless steel with cotirse material structure. Here we briefly present selected results obtained using two pressure wave transducers, with refraction angles of 45° and 0°. The -lOdB frequency ranges of the transducers were 1.4-2.8 MHz and 0.7-1.4 MHz, respectively. The ultrasonic response signals were sampled at a rate of 40 MHz, with a resolution of 8 bits, prior to computer processing. 

Special contact transducers having wedges providing incidence angles for specific appHcations are used widely in industry. For example, normal incidence is used in tests for laminations within sheets, and for sheet or plate thickness where the back surface of the test material parallels, to within perhaps 10°, the front surface. Shear wave transducers typically used for weld examination have 45°, 60°, or 70° inspection (refracted) angles. To locate discontinuities, the transducers may be moved back and forth over selected surface areas until the angled search beam approaches normal incidence on the... 

Reflection and refraction of X-rays follow the laws of optics (Fig. 4.2) The glancing angles of incidence (i) and reflection ( ) are equal. The respective refraction angles follow Snell s law for different phase velocities v in mediums 1 and 2 ... 

When light is moving from a medium with a large refractive index to one with a smaller refractive index, the phenomenon of total internal reflection can occur when the refracted angle is 90° or more. In a... 

Measurement of refraction angles, such as the angle of minimum deviation of a prism n is obtained from Snell s law. This requires samples of high transparency (k = 0). 

Prisms and Gratings. For a prism of refractive index n and refracting angle a, there is an angle of incidence 0 for which the deviation angle S is a minimum this can be used, for example, to determine the refractive index n of a liquid placed inside the hollowed prism (Fig. 2.19). 

By far the most important and simple phenomenon that is made use of in optical wave guides is refraction of light. When a ray of light propagates from one medium to another, it undergoes refraction at the interface such that the ratio of the sine of the incident angle and the sine of the refracted angle equals the inverse ratio of the relative refractive index of the two media. Thus,... 

In general, different radiation wavelengths correspond to slightly different indices of refraction. The main consequence of this aberration is that the refraction angle is wavelength dependent [80]. This aspect is very important for minimising the Schlieren effect by dual-wavelength spectrophotometry (see also 4.23.5). 

Although very effective for compensating the influence of the Schlieren effect, Eq. 4.7 holds only when the intensity of the Schlieren effect is not wavelength dependent, otherwise, correction factors should be added. As the transient mirrors established between fluid elements of different refractive indices are not ideal and the incident light is also partially refracted, the refraction angle is strongly wavelength dependent (Eq. 4.15). Hence, the use of Eq. 4.7 for Schlieren compensation may be subject to restrictions. Moreover, it cannot be directly applied for Schlieren compensation in flow systems with turbidimetric or nephelometric detection. 

The most important part of the monochromator is the infrared radiation splitting system. One of the most popular splitting systems is the prism. The function of a prism is based on having various refraction angles for radiation with various wavelengths. The function principle of a prism is shown in Figure 2.42. 

The prism is made from a faultlessly grown single crystal. The most important values for the resolution ability of the prism are the base size and the refractive index. Both must be selected to be as large as possible in order to get a good resolution. The refraction angles depend upon the value of the refraction index... 

Ifwe rotate the substrate around the x-axis, incident radiation makes an angle 6 relative to the z-axis of the substrate. In this case, we can define a real refraction angle a according to Snell s law as... 

Let us consider a beam of incident light as it undergoes refraction on a flat plane, as shown in Table 1.1 (Refraction). A wave plane PP encounters the refractive plane at point P. The point P reaches the plane at points Q and Q after t seconds. If the light velocities in each medium are v, and v2, respectively, the relationship between the refractive angle and the light velocity is given by... 

In most cases we consider the first medium is a vacuum (or air), and therefore no is equal to 1. Since n is less than 1 in general, the refraction angle 0 is smaller than the incident angle 0o. Consequently at incident angles below a certain critical angle 0C the radiation is totally reflected back into the medium 0 (air). The critical angle is thus given by... 

The scattering angle 9 depends on the outer refraction angles Ui, and on the refractive index of the sample [Eq. (28)]. 

Under oblique incidence ( j=incidence angle, 2=refraction angle, with nisin i = n2 sin 2), the reflection and transmission coefficients depend on the polarization of the incident wave with respect to the incidence plane (see Fig. 6.1). If the polarization (direction of the electric field Eq) is perpendicular to the incidence plane (so-caUed s-polarization), the electric field is everywhere parallel to the interface, and using the same rules as above for the boundary conditions, its amplitude at the interface is now E()X2niCosi+n2Cosg>2), stiU much smaller than Eg [15]. However, if the polarization lies in the incidence plane (so-caUed p-polarization), the electric field has a component parallel to the interface and a component perpendicular to the interface. The parallel... 

Redprocal observations with the GYROMAT on sanie traverse lines were done measuring azimudis twice at each point. The size of the refraction angle dh was in the range of up to 2,0 mgon. 

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