Can a blue BD laser read/write to DVD/CD?


#1

On Quora, the user called Michael Daniel claimed to own a BluRay player, which used solely a blue laser for all disc types.


#2

I’ve never heard of that, and am doubtful. Every Blu-ray player or drive I’ve heard of has two laser assemblies, one of which is the longer wavelength red laser used for CD’s and DVD’s.


#3

It is theoretically possible to use separate lasers behind a specially constructed holographic single lens. In a BD white paper I once read that LG displayed such a prototype device at the 2002 Consumer Electronic Show. This may be the basis for the quoted writer’s erroneous impression that a single laser was used. Using different lasers with separate optics was proven to be more reliable for backwards compatibility as the different thicknesses of the cover layers

Single%20lens

It is also possible to use a 3-wavelength laser assembly which would give the same impression on external examination.