Receiver solid angle

Receiver solid angle (Q) the solid angle subtended by the receiver aperture stop from the sample origin ... 

Sample radiance (L ) a differential quantity that is the reflected radiant flux per unit projected receiver solid angle per unit sample area. Note In practice is an average calculated from scattered power, P, collected by the projected receiver solid angle, 12 cos 0, from the illuminated area, A. The receiver aperture and distance from the sample determines Q and the angular resolution of the instrument ... 

For a diffuse sphere, each surface element that intercepts incident radiation will reflect the energy into the entire 2ir solid angle above that element. Thus, the radiation scattered into a specified direction will arise from the entire region of the sphere that receives radiation and is also visible from this specified direction. Consequently, the phase function for a diffuse sphere can be obtained as [Siegel and Howell, 1981]... 

The Sun delivers a spectral irradiance at the Earth s surface at AM 1.0 (air mass), without concentrator, of 1.16 W m nm at 2 = 700 nm [2]. The solid angle represented by the Sun seen from the Earth is Q = 6.8 x 10 steradian. From Eq. (10), one calculates in this case Tr = 5500 K, and from Eq. (12) with T = 298 K one obtains rj = 0.946. If the solar spectrum were that of a black body, all wavelengths would lead to the same values of Jr and Figure 1 shows that this condition is fulfilled only if the receiver is outside the atmosphere. At the Earth s surface, absorption by atmospheric oxygen, ozone, water, and carbon dioxide makes the structured solar irradiance spectrum deviate significantly from the ideal black-body spectrum and requires rR(A) to be calculated for each wavelength. 

All surfaces emit radiation, but they al.so receive radiation emitted or reflected by other surfaces. The intensity of incident radiation 1 0, tf>) is defined as the rate at which radiation energy dG is incident from the (0, (f>) dhvction per unit area of the receiving surface normal to this direction and per unit solid angle about this direction (Fig. 12-20). Here 0 is the angle between the direction of incident radiation and the normal of ttie surface. 

SOLUTION A surface is subjected to radiation emitted by another surface. The solid angle subtended and the rate at which emitted radiation is received arc to be determined. 

These are unique to scintillation cameras, known as Auger cameras, used in nuclear medicine studies. Approximately 19-91 PMTs are mounted on a Na(Tl) crystal used in the camera. These crystals are typically-thick. The number of PMTs, which are optically coupled to the back of the crystal, is determined by the size and shape of the crystal. A maximum amount of light will be received by the PMT nearest to the point of interaction compared with the other PMTs, which are positioned differently. The amount of light received in these PMTs is proportional to the solid angle subtended by the PMT. Therefore, X-Y-posi-tioning of the camera has to be controlled and known so that X-Y-coordinate of the y-Ray interaction can be assessed accurately. These data are stored in a computer and then processed or recorded on Polaroid or X-Ray films. 

With e x G, the radiation flow d3wavelength interval dA, from the solid angle element dtp highlighted in Fig. 5.72, can be calculated. According to (5.4), the defining equation for the spectral intensity, it holds for this that... 

Fig. 5.77 Gas space with surface element dAi, which receives radiation from the solid angle element duu which is bounded by the surface element dAi...

Figure 2.1. On the definition of a scattering space V R is a receiver of. scattered light dil is a. solid angle element Vium is a luminous space K is a vessel with scattered medium, D are diaphragms...

The receiver measures the intensity 7 of light scattered on all the particles inside a scattering space V, which is cut by the receiver s solid angle from the luminous space Vjum (Garrabos < t al., 1978), see Figure 2.1... 

Since Equation 14 determines the power of light energy per unit area, a solid angle unit receives... 

Here a is the distance between the two disks, is the radius of the radiating disk, and ri is the radius of the receiving disk. This quantity is the unit of the solid angle that reaches the second aperture [53]. Thus, the flux reaching the second aperture can be described as ... 

A surface element dA of a detector at distance r from the source element dA covers a solid angle d 2 = dA cos 0 /r as seen from the source (Fig. 2.7). With dA and dA, the radiant power received by dA is... 

If the emission of a source with volume AV is isotropic, the radiation power received by a detector of area A at a distance r through the solid angle... 

Where Pq(A) is the transmitted power, T(k) is the transmission of the clean air from the Lidar to target and back to the Lidar, li(A) is the reflection-coefficient of the target, D is the solid angle of the Lidar telescope, absorption coefficient of the investigated gas, P(A) is the received power. 

---