A detailed analysis of the different contributions to depth resolution shows that this kinematic effect is the predominant term near the surface, severely limiting the permitted detector acceptance angle, whereas energy straggling dominates the resolution at larger depth.
32.
For line-focus systems, such as a trough concentrator or a linear Fresnel lens, the acceptance angle is one dimensional, and the concentration has only weak dependence on off-pointing perpendicular to the focus direction.
33.
In particular, manufacturers often quote " NA " for single-mode fiber based on this formula, even though the acceptance angle for single-mode fiber is quite different and cannot be determined from the indices of refraction alone.
34.
Parabolic trough concentrators have a simple geometry, but their concentration is about 1 / 3 of the theoretical maximum for the same acceptance angle, that is, for the same overall tolerances of the system to all kinds of errors, including those referenced above.
35.
When high concentration is needed ( 500 1000 times ), as occurs in the case of high efficiency multi-junction solar cells, it is likely that it will be crucial for commercial success at the system level to achieve such concentration with a sufficient acceptance angle.
36.
The OM-4 featured a built-in spot meter [ of a narrow acceptance angle, see Canon FTb ] ( 2 % of view; 3.3? with 50 mm lens ) and was the first camera capable of measuring eight individual areas and averaging them.
37.
It is vital to start with a wide acceptance angle since it must be able to accommodate tracking errors, movements of the system due to wind, imperfectly manufactured optics, imperfectly assembled components, finite stiffness of the supporting structure or its deformation due to aging, among other factors.
38.
For step index fiber, light entering the fiber will be guided if it falls within the "'acceptance cone "'of the fiber, that is if it makes an angle with the fiber axis that is less than the ( half ) "'acceptance angle " '.
39.
Decreasing the number of elements and achieving high acceptance angle, can be relaxed optical and mechanical requirements, such as accuracy of the optical surfaces profiles, the module assembling, the installation, the supporting structure, etc . To this end, improvements in sunshape modelling at the system design stage may lead to higher system efficiencies.
40.
Research published in 2010 showed that higher concentrations and / or higher acceptance angles could be obtained by using nonimaging optics to explore different degrees of freedom in the system such as varying the size and curvature of the heliostats, placing them at a varying height ( on a wave-shape curve ) and combining the resulting primary with nonimaging secondaries.
