• Albbi@lemmy.ca
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    1 month ago

    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.

    • Coelacanth@feddit.nu
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      1 month ago

      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.

      • MeThisGuy@feddit.nl
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        1 month ago

        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)

        • Captain Aggravated@sh.itjust.works
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          1 month ago

          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.