CPC Winston Collector

Compound parabolic concentrator (CPC, also called Winston collector or Winston cone) [95-97] is a reflective nonimaging light concentrator intended to collect incident light from a spatial angle larger than that of imaging concentrators and to 

Two parabolas pi, p2 can be seen in the figure, with their respective focal points in Fi, p2, and their axes being tzi, tza- The parabolas are cut at the line of their focal points and then mutually rotated so that the focal point of one of them coincides with the curve of the other parabola and the very edge of the exit opening. A 3D version of this stmcture is obtained as a body of revolution whose sides are parabolic segments satisfying the same condition. Thus a Winston cone is an ofif-axis parabola of revolution. 

Obviously, a CPC can be tmncated and in real situations often is. This will result in a lower concentration ratio, but the overall length might be more acceptable for implementations. 

There is a relation between the radii of the entry and exit openings 

The equation defining the surface of a CPC in a radial system in which the CPC axis is in z-direction while the radial distance is described as the coordinate p is 

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