A Total Internal Reflection (TIR) Technique

Now let us look at light from an LED chip ( Figure 6 ) with a size typically about 040” X .040”—less the head of a pin. We can see the light ,even at the start, is emitted in the forward direction, That is ,in an incandescent filament CFL of HPS light source, where half the light is heading n the opposite direction in has t be reflected backwards even before it is focused in any way

Figure 6 LED chip

Because mathematical rules for lenses and reflectors we mentioned earlier, a lens can be dramatically smaller. We can put over each chip a lens less 40” diameter and using what is called a Total Internal Reflection (TIR) technique.