Re: How do a CD laser and a DVD laser differ if at all?

First off, yes, the CD laser and the DVD laser are different.  The light 
from a DVD laser has a wavelength of 640 nanometers where the light from a 
CD laser is 780 nanometers.  The smaller DVD laser wavelength allows it to 
focus on the smaller pits in the DVD disk.  Thus, accounting for the 
increase in storage capacity.

Okay…we first state the relation:  velocity = frequency * wavelength.  As 
each laser's light is traveling at the same speed, the one with a smaller 
wavelength (DVD) will have a larger frequency.  This way the product is a 
constant (the speed of light).  

Finally, we state the relation: Photon energy = Plank's constant * 
frequency.  Thus, the light with the higher frequency also carries more 
energy.  Power = Energy / Time…thus, taking each laser operating for the 
same amount of time, the one with the larger energy (larger frequency) 
also delivers more "power" per unit of time.