burning of residuals

14:13 Oct 14, 2012 

The embodiment shown in figure 3 comprises a telecentric optical system consisting of the lens systems 7/8 and a non-imaging optical element 13 as explained with reference to figure 1. Further, the pump light source 1 is a single laser device 31 here, where a laser array can be provided likewise. The laser beam 32 is defocused by a lens system 33, such that it is coupled to the optical system 6 with a slightly diverging angular extent. In this way, the cross-section of the beam 32 is smaller than an image 34 of the aperture 5, as the angular extent of the laser beam 32 is smaller than the aperture angle of the optical system 6. Thus, the focus 35 of the lens 8 is shifted from the entry face 12 of the non-imaging optical element 13 (which is identical to the exit face 12 for the converted light) into the non-imaging optical element 13. Shifting the focus 35 from the entry face 12 prevents a hot spot formation on it, such that a burning of residuals on the surface can be avoided. In addition, the pump light is more efficiently mixed within the non-imaging element 13 and illuminates the phosphor element homogeneously .