The first commercial LED LCU became available after 2000: the LuxOMax LED LCU was a large pen-like cordless battery-powered design which used 7 discrete LEDs. The device had a tapered fused glass fiber light guide that concentrated the light output at the tip. The irradiance measured was 116 mW cm−2. The power output of the blue LEDs and their cost were two main factors responsible for the delay in introducing commercial LED LCU into production.
In 1995, the 5 mm blue LED available from Nichia, had an optical power output of 1.2 mW and cost was approximately 50 USD. In 2012, Nichia offered 5 mm blue LEDs that had a power output of 123 mW with an approximate cost of 0.50 USD. This comparison shows that how over a timespan of seventeen years in one type of LED, its power was increased by two orders of magnitude, while its cost decreased by two orders of magnitude.4
The first generation of LED LCUs LuxOMax LED LCU, was relatively low-powered as to compared to their conventional QTH LCU competitors. This difference led to some disappointing early results, when commercial LED LCUs were compared with commercial QTH LCUs. In 2002, these early comparisons of commercial LED LCUs with QTH LCU sources produced some…show more content… This advantage in turn results in a reduction in electrical power and heat generation if all other parameters remain the same. This design also sets out to overcome the two main disadvantages of tapered light guides: first the light beam is more divergent. This is caused by a progressive increase in the angle of total internal reflection as the light propagates through a tapered fiber, resulted in an exaggerated loss of irradiance compared with a more parallel beam as the LCU tip is moved further away from the tooth. The second is the smaller light tip area which requires repeated overlapping exposures to adequately cover the composite