Introduction to Nonimaging Optics, 2nd Edition

5

Vector Flux

5.1 Introduction

We have seen that if we take the flow-lines generated by a Lambertian source, we obtain an ideal trumpet concentrator. Other shapes of Lambertian sources generate other shapes of flow-lines and those can be taken as concentrators with different geometries. We now consider some more simple examples of nonimaging optics obtained by taking flow-lines generated by Lambertian sources.

An example of uniform illumination is that of sunlight. The sun emits light in all directions, and when it reaches the earth, this light is confined to a small angle ±α and, therefore, it appears to arrive within a cone of angle 2α as shown in Figure 5.1.

We take a plate and orient it perpendicularly to the direction of the sun, ...