It wasn’t the colour, you would burn little bubbles into the disk. The bubbles would deflect a laser and flat parts would not. This would give the 0 or 1 bits.
There were CD- and CD+ versions. I don’t know which is which but one would create a divot, and the other would create a bubble. Either way the laser is diverted away from the sensor.
CDs like laserdiscs before them are read with an infrared laser.
DVDs use a red laser, and Blu-ray does indeed use a blue-violet laser. The smaller wavelengths, plus the ability to do multiple layers, are indeed how they cram more data more densely onto a disc of nearly identical size.
It wasn’t the colour, you would burn little bubbles into the disk. The bubbles would deflect a laser and flat parts would not. This would give the 0 or 1 bits.
There were CD- and CD+ versions. I don’t know which is which but one would create a divot, and the other would create a bubble. Either way the laser is diverted away from the sensor.
Ah, that’s what it was! I always thought it was just a different color for 0 and 1, today I learned! That makes more sense when I think about it.
CD - red laser
BlueRay - blue laser… shorter wavelength --> more data on same size disk
and inbetween there was DL - dual layer
light scribe - could etch a picture on the top of the cd
and RW - rewriteable CDs
(CD is short for compact disc)
I remember having one, but I never actually etched a picture onto the CD, it never seemed worth doing.
CDs like laserdiscs before them are read with an infrared laser.
DVDs use a red laser, and Blu-ray does indeed use a blue-violet laser. The smaller wavelengths, plus the ability to do multiple layers, are indeed how they cram more data more densely onto a disc of nearly identical size.
I stand corrected. thx