led system it is necessary to increase the current applied to the led continuing to increase the led power will have diminishing returns however as the increasing temperature of the led will reduce its efficiency and potentially damage the led the heatsink is therefore important as it is essential for heat to be carried away from the led so as not to cause it any damage the light emitted by a led will increase with applied current provided that the heat produced can be removed but for any individual led design there will come a point where increasing power applied to the led will not result in greater light being emitted because heat is no longer being effectively removed identifying the relationship between power applied and light emitted is an important aspect of the present invention let u03c6 v be the total luminous flux of an led system consisting of n led devices where e is efficacy lumen watt and p d is the real power of one led w it is well known that the efficacy e of leds will decrease with increasing junction temperature of the leds fig3 shows a typical relationship provided by an led manufacturer it can be seen that e e o u2514 1 k e t j u2212 t o u2518 for t j u2266 t o and e u2266 0 2 where.