The Inner Workings of CD/DVD Drives episodes:

• July 24, 2017But disks are not flat . . . so things get complicated.

  -

  ...more

  

  ---

• July 24, 2017So the lens is suspended inside an electromagnet.

  -

  ...more

  

  ---

• July 24, 2017But we need to figure out how the lens should move.

  -

  ...more

  

  ---

• July 24, 2017Simplfy things by straightening out the beam's path.

  -

  ...more

  

  ---

• July 24, 2017Look more closely at the point where the laser focuses.

  -

  ...more

  

  ---

• July 24, 2017Trace light rays as they pass through the lens and its clone.

  -

  ...more

  

  ---

• July 24, 2017If the disk moves, the beam no longer emerges parallel.

  -

  ...more

  

  ---

• July 24, 2017Fold the path back up and see what happens at the photodetector.

  -

  ...more

  

  ---

• July 24, 2017We could use a circle and ring detector.

  -

  ...more

  

  ---

• July 24, 2017But most CD/DVDs use a more complicated scheme.

  -

  ...more

  

  ---