How the electronic circuit control laser diode? [closed]

Question

I find this scheme here

1 - is data stream come from computer. This 'data' is an electric signal moudulated by the n°2
2 - this is the electronic circuit inside printer that

a) activates the corona wire → b) the corona wire charges up the photoreceptor drum
a) at the same time circuit activates the laser to make it draw the image of the page onto the drum. The laser beam doesn't actually move: it bounces off a moving mirror that scans it over the drum

My question are:

• when data stream come from computer to the printer inside the electronic circuit what happens inside this electronic circuits ? How mechanism 'tranform' this electric signal of data into instruction for laser diode and moving mirror ?
  But this step is possible only if you have correct modulation between data stream and instruction laser otherwise printing should be wrong and electronic circuit may break or not work properly.
  What modulation technique is used for laser diode ?

• which components inside electronic printer is needed to drive and control this ?

Answer 1

What you are asking in similar to how the beam in a CRT monitor is modulated to make lighter and darker areas on the screen.

The lasers used in these devices can be electronically controller to vary their light output. This is done in sync with the laser beam being mechanically swept across the drum. As the laser hits each spot on the drum, the electronics modulates it to get the desired amount of light.

A moving mirror sweeps the laser beam across the drum to make one dimension of the picture, and the drum moves orthogonal to that to make the other dimension of the picture. The result is a 2D image "painted" on the drum with laser light. Again, this is much like the electron beam being swept across the face of a CRT and modulated per pixel to make a 2D image on the face of the CRT.