Tuesday was such an interesting day! I went to a lecture on led's, by Philips Mexico. I find it amazing. I remember last year, when I had a lecture on led's by Philips Sweden, and the retrofixtures they talked about. This one was really different, beginning with the place, as we didn't go to the Philip's showroom, but to Selca showroom.
I'll write down what I learnt about LED's. (I'm so excited about them... but I still have to study so much...)So... here is a small and very simple explanation on leds.
It seems that leds are a big deal. Philips wants to have 75% of their products made out of leds by 2020.
A LED is a diode made with different kinds of minerals, depending on its color. This diode vibrates and that's how light is produced, that's why it doesn't burn out.
It is important to know that there is not an average lifetime of the led, because it depends on the lifetime of each product. This means that several aspects are taken into account as the drivers, the led, the materials, the design, and how fast it can be cooled down (heat disipator), the diods, and the optics.
There are two ways of making white light: with three diods (RGB) combined or with blue diods and a bubble of phosphorus. The phosphorus can be put in two ways: as a bubble over it working as lens, and something called remote phosphorus. This is a small layer of yellow phosphorus over several blue leds. This layer helps diffuse the light, avoids shadows, and creates a light similar to incandescent and halogen lamps.
There are lamps made with leds called retro-fits. These lamps are made to substitute a lamp previously used, like a PAR, or an incandescent, or an AR111 or so on, giving the same light distribution, temperature, and luxes, but with less energy consumption.

As I have said before, led's are made in a very simple way: minerals mixed that are made into a plaque, that is melted and then cut into small pieces, then each piece is cut and tested in a process called binning, then they are categorized, and sold.
The quality of the leds is very important, as well as the design of the lamp, the design of the heat disipation dispositive, the driver and the optics. If one of these things is not working well, then the lamp wouldn't be as good as expected. This is how some lamps can be differenced.