
BENT SØRENSEN
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flected upward after suffering total reflection on the lower inside of the
cover glass.
(a) (b)
Figure 14.23a,b. Two-dimensional model of concentrator without cover but filled with
a refracting material (refraction index n
gel
= 1.6), with slight pyramid texture at top.
Incident angles are 10° and 25°.
The result of varying some of the parameters is shown in Fig. 14.21. An
inverted pyramid angle of 0° corresponds to a flat-plate glass cover, and the
figure shows that in this situation the concentration is limited to incident
angles below 20°, going from a factor of four to unity. With increasing
pyramid angle, the ma ...