I still can't figure out how the 8x being 2xs more than the 6x is comming up with all that power. The 4x power ratio step up to the 6x not is not exactly mind blowing.
The step up in power from the 6x to the 8x time is very impressive.
Cause, probably, we usually refer to these diodes with the speed of the burning (4x, 6x, 8x) and not with the real power that they can emit, that in some cases, none knows.
So, it's possible that (just for make an example), the 4X diodes was underdrived (where, instead, we try to drive them to their limits), so for step to the 6X, they just had to increase a bit the power of the diode, and we notice this as a limited improvement ..... where, instead, at this point, the power needed for the 6X burning was just the needed, so passing to 8X, they made a quality step and produced a much more powerful diode (that we see as a big increase in max power), and for that what we know, is also possible that these diodes are not used at full range in 8X writing operation, too .....
As daguin already stated
So the 10X is reporting faster burn speeds, but we don't know if the faster speed is the result of a new, more powerful diode, or just better optics and/or software.
so, who know ? ..... maybe, the 10X is the same diode as the 8X, with better optic, or better driving, or also just drived to its normal limit ..... if was 12X or more, i also may considerate a new class of diodes, but with 10X, who really know ?